Back Pain - A Movement Problem by Josephine Key

The analysis of movement CHAPTER 4 our bodies – an erect lightness which provides for an as in the transitions between lying, sitting standing ease an effortless in breathing. and walking. We may decide to ‘test’ by observing the manner in which the patient spontaneously Dynamic posture chooses to perform a requested task In functional terms posture is always dynamic as it is These aspects of quality control in movement constantly changing and adapting to support move- have probably received less attention because their ment. However, when walking, running, jumping, interpretation is more subjective; they are usually throwing and lifting1 there is the increased challenge the more subtle aspects of motor control and of adapting to further changed alignment of the require an in depth understanding of the subject segments, momentum and larger perturbations. and considerable practical experience. The signs are relatively ‘soft’ and more difficult to objectively Quantitative and qualitative measure. These aspects are explored. aspects of movement Doing it – but ‘how’ the Effective clinical practice relies upon the ability of movement happens: aspects the practitioner to analyze movement in the clinic of quality control in in a relatively easy, practically relevant, and useful posturomovement way. Trew4 states ‘it is relatively straight forward to measure some of the physical aspects of movement The following aspects are functionally interrelated such as joint range or muscle strength in a non func- in varying respects. tional context but difficulty arises when the quality of the movement must also be considered’. Observing the size, shape and symmetry of the superficial muscles The skilled practitioner is one who has the ability to tells a story see the qualitative ‘soft signs’ as well as the ‘hard signs’ of objectively measurable movement. Janda consid- Janda13 maintained that ‘changes in muscle function ered that the quality of the motor performance was play an important role in the pathogenesis of many of greater importance than testing strength.15 painful conditions of the motor system and constitute an integral part of postural defects in general’. The The qualitative aspects of muscles both cause and reflect altered function.14 movement are observable Simply observing the appearance of the standing While the quantitative aspects of movement func- person’s superficial muscles can provide insights tion are more derived from testing, the qualitative about the patient’s neuromuscular function.15 The size aspects are derived more through observation of shape and symmetry of a muscle provides clues to the patterns of motor response in different situations. the level of its activity. Those muscles which are We are interested in the quality of a person’s sen- used a lot become bulkier and more prominent sory–motor integration. Without any interference (Fig. 4.4) and those that aren’t lose their definition we note how he habitually chooses to stand, sit, or shape. The role of the deeper muscles in postural bend over and perform some of the repetitive deviations may need to be confirmed or negated in actions involved in daily living such as getting later tests (Ch.13). undressed or standing on one leg. Feldenkrais appar- ently coined the term ‘acture’ – posture in action, to The ability to align the body describe the observation of the person moving.12 segments in different functional acts This can reveal a wealth of information such as the presence of organic or pathological movement pat- As infants we spent a deal of time down on the terns, discomfort during motion, the emotion ground as we learned how to move along and get behind the motion, the amount of sensory amnesia ourselves up against the force of gravity. As adults, present, the range of motion, the quality of the we tend to spend most of our time upright in one breathing pattern and the quality of specific tasks 41

Back Pain: A Movement Problem them, which the patient will repeatedly enact during the course of his day. Implicit is the way he does ordinary movements significantly contributes to his predicament. The importance of this ‘functional control’ in every- day activities has also been recognized by McGill who has examined motion patterns of lifting16 and O’Sulli- van who has examined postural patterns of sitting in non back pain and back pain groups.17,18 The ability to generate appropriate patterns of axial stabilisation Any muscle action requires adequate or fixation of one or both of its attachment points to have a firm ori- gin from which to pull. Stability in the spine must ensure protection for the spine itself through move- ment as well as provide support counteracting the tor- ques created by muscles attaching to the torso. Balanced co-activation between the flexors and exten- sors is basic to the complex patterns of axial stabilisa- tion which provide three dimensional control. All muscles contributing to the ‘central stabilisation system’ are interdependent in function. If one muscle is weak or overactive, this never remains isolated, but affects the static and dynamic function of the entire spine. Individual spinal segments will no longer be controlled in a balanced way. In particular, the dia- phragm needs to become integrated into the patterns of central control.19 Observing the quality of the breathing pattern and axial alignment at rest and dur- ing trunk and limb movements tells us a lot about the quality of axial control. Poor patterns of axial make balanced alignment difficult (Fig. 4.5). Fig 4.4  Buttocks like these are an unusual clinical Limb load tests e.g. the active presentation – these are the result of weight training. straight leg raise test way or another and our patterns of motor use repre- sent a fairly constrained repertoire by comparison. The supine active straight leg raise test (ASLR) is a Commonly, most of us use four basic spinopelvic functional test which assesses the quality of the pat- posturomotor patterns and derivatives of them in terns of axial stabilization when the extended leg is the course of our daily living – standing, walking, sit- lifted off the surface. First described by Mens ting and bending/lifting/squatting. et al.,20 the extended leg should be able to effort- lessly lift 5 cm. When control is optimal, three Observing the person’s habitual patterns of func- dimensional alignment of the pelvis21 should be tional control in aligning the body segments or other- maintained as well as the alignment of the whole wise in these primary movement patterns is highly torso while breathing patterns are maintained.22,23 informative as it is these actions and derivatives of The test as originally described, is positive if accompanied by a primary sensation of profound heaviness in the leg and /or pain23 which is relieved by the application of bilateral compression through 42

The analysis of movement CHAPTER 4 Subjective complaints should not be the only decider of dysfunction as probably more important is the observed quality of the axial control patterns. Dys- functional responses include loss of alignment, breath holding, central ‘fixing’ strategies and a functional ‘dis- connect’ between the upper and lower torso. There are numerous other tests using either a short or long limb lever which can be applied in a similar manner in order to test and facilitate axial control strategies. Sequence and degree of muscle activation in a movement Fig 4.5  Inadequate pattern of axial stabilization. Movement stems from a starting point – a ‘posture’ developed on a base of support which is actively con- the ilia either just below the anterior superior iliac trolled before the actual movement happens. The spines or at the level of the symphysis pubis20 (above work of Hodges24,25 has shown that normally transver- or below the hip joint). This compression is considered sus abdominis is active before arm movement begins. to enhance ‘force closure’ through the sacroiliac joint21 Transversus is a member of the ‘central stabilization by simulating muscle forces which would otherwise system’ – a coordinated trunk muscle synergy creating control the movement. The prone ASLR test similarly anticipatory postural adjustment to support limb tests axial patterns of control including the breathing movement. mechanism with hip extension in knee extension. Janda15 maintained that examination of move- Because of the long lever arm of the leg, it repre- ment patterns provides a good indication of the sents a fairly high level challenge to the ability and quality of a person’s motor control. In the presence quality of axial stability. While a positive test result of muscle imbalance or poor central nervous system has been shown to strongly correlate in people with regulation some typical abnormal patterns of muscle pelvic ring instability,20 a positive test does not neces- activation can be clinically observed. He described sarily confer sacroiliac joint instability. However, a six basic movement patterns15,26–28 which essen- positive test is indicative of suboptimal neuromuscu- tially test the quality of axial patterns of control. lar control in the torso and pelvic–hip complex. • Head flexion in supine. • Shoulder abduction in sitting. • Push up from prone. This is a high level test and should be used with discretion. • Hip extension prone. • Hip abduction in side lying. • Trunk curl in supine. These are fully described elsewhere.28 When changed, these usually show certain typical patterns of response. Appreciating the common features of dysfunction (Ch. 8) and clinical sub-classification helps predict the response (Chs 9 & 10). Strength versus control Janda was not interested in muscle strength but rather, the coordinated activity between different muscle groups in a synergy. He says this should be evaluated in at least three ways:29 43

Back Pain: A Movement Problem • The sequence of activation of muscles in the • Economy of effort: movement should be easy and synergy producing the movement i.e. an estimation pleasurable and not hard work of timing. Which muscles activate early and • Lightness of movement rather than heavy or which come in later. Expecting appropriate ‘bound’ patterns of anticipatory axial ‘postural setting’ • Efficiency: without superfluous movement or the and control to support limb movement or use of unnecessary muscles which may interfere conversely the axial spine adjusting to movements with or oppose the desired movement initiated from the limbs. The ‘onset’ may be • Modulation of the degree of force appropriate to central or peripheral depending upon the demand: at times strength and power is required movement. The point of initiation of a movement is • Sustained: a posture/movement should have important and the sequencing of the movement endurance without hardening or ‘holding’ from it. • Selective: the ability to control the point of • Degree of activity of the main muscles or groups – initiation of the movement, either from the centre which muscles dominate the movement and which or the periphery; the ability to perform precise are underactive. discreet actions • Estimation of activity of the so called ‘parasitic • Smooth and free flow rather than jerky and muscles’ – those which should not be activated in uneven that particular movement • Speed: the ability to move both slowly and fast • Flexibility and adaptability to changed He is concerned with the quality of the response – environmental demands: the ability to suddenly and how the task is performed and what, if any, substitu- differently respond when needed tions and compensations occur. • Variety and variability: the availability of multiple movement strategies and the ability to select the There are a multitude of other functional move- appropriate strategy for the task and the ment pattern tests that can be looked at based on environment5 these and other principles. Choice will also depend • Relaxation: the ability to let go tension when the upon which aspect of function needs examining, muscle(s) are not required to work. the age of the patient and the state of irritability of his tissues. The art in the practitioner is to be Further aspects of movement able to gauge what is an appropriate test for that function person’s stage of disorder. Liebenson30 rightly says ‘choosing the correct functional tests is an art not Muscle states a science’. Weakness vs inhibition It is interesting that current thinking and research is pointing more in this direction. Van Specific weakness of certain muscles such as the Die¨en et al31 suggest that certain aspects such as lumbosacral multifidus has been objectively shown altered timing of muscle activity and load sharing in people with back pain,33,34 probably resulting between muscles contribute towards the observed from disturbed joint mechanics, pain and altered altered recruitment patterns seen in people with afference creating inhibitory phenomena.35,36 Ken- back pain. ‘The changes involved are task depen- dall3 and Sahrmann37 note ‘over stretch weakness’ dent, related to the individual problem and hence can occur when a muscle is held in a lengthened highly variable between and probably within position particularly during long periods of rest, cer- individuals’. tainly a common clinical finding in the lower scapula stabilizers due to principal arm use in front of the Motor skill involves various qualities body and poor postural habits (Fig. 4.6). of optimal motor control However, Janda27 maintained that often muscles Trew4 states ‘there is no consensus as to what consti- that appeared weak were inhibited through changed tutes quality of movement’. While this may be partly central nervous motor regulation and performance true in an academic sense, clinical practice assisted by the insights of Bartenieff32 and others helps delin- eate certain qualities in skilled movement: 44

The analysis of movement CHAPTER 4 Fig 4.6  Stretch weakness/underactivity of the interscapular Strength vs endurance and upper thoracic intrinsic muscles. McGill41 defines strength as ‘the maximum force a producing a systemic response in the muscular system muscle can produce during a single exertion to cre- with over activity in some muscles and underactivity ate joint torque; endurance is the ability to maintain in others.13,15,27,29,36 Clinically the underactivity is a force for a period of time’. Studies have variously observed as hypotonia, weakness and especially by a shown deficits in both in LBP subjects31 Clinically, delayed sequence of activation in principal movement strength may be a problem for some; endurance patterns. This underactivity in a muscle may also be appears to be a problem for all. due to direct inhibition because of hyper irritability of its antagonist in accordance with Sherrington’s law Both strength and endurance are dependent upon of reciprocal innervation,15 e.g. underactivity of the well coordinated control throughout the spine, and abdominals and related hyperactivity of the erector in particular from the support of the deep system spinae. Janda says ‘stretch or inhibition of a tight mus- (Ch. 5). Janda noted the tendency for dominant cle can lead to spontaneous facilitation of an inhibited activity of certain ‘postural muscles’ in typical pat- muscle leading to its inclusion in the movement chain terns.38 Overactivity makes muscles stronger tend- and therefore improvement in key motor patterns’.38 ing to inhibit their antagonist creating imbalance in Importantly, when an inhibited or weakened muscle patterns of movement. Clinically, muscles in some is resisted, its activity tends to decrease rather than regions of the spine are found to be consistently increase.15 overactive and ‘strong’ while others appear underac- tive and ‘weak’. When too strong they often ‘don’t Kolar19 notes that a muscle may appear weak let go’, evidenced by a commonly found lack of when it is not, if there is inadequate stabilization of the flexion–relaxation response in studies of its attachment points, which itself is dependent upon patients with back pain42–45 (Fig. 4.7). a chain of muscles. Disturbed function of a muscle can therefore be caused by dysfunction of a far dis- Van Die¨en et al31 suggest that this increased acti- tant muscle. A good example is apparent weakness vation of the trunk muscles may be an adaptive of the deep neck flexors because of inadequate stabi- response to pain aimed at limiting movement and lization of the thorax by the abdominals. so avoiding noxious tensile stresses on injured tis- sues. Clinically this response appears to be both If back pain has been significant and longstanding the cause and the effect of pain. This is discussed and there is relative inactivity, general body de-con- more fully in Ch. 8. ditioning ‘weakness’ can be expected and has been shown.39 However, this is not the case in all Endurance however, or lack of it, particularly at patients by any means. Smeets and Wittink40 ques- low loads, is a common and significant clinical finding tion the deconditioning paradigm and point out that in patients with LBP and has been corroborated by no convincing proof exists as studies have provided contradictory results. Clinically, many highly active Fig 4.7  Lack of flexion relaxation phenomenon in the sports people present with back pain. thoracolumbar extensors. 45

Back Pain: A Movement Problem studies.31,41 Clinically, this is evident in most anti- mechanism originating from the agonist known as gravity posturomovements and particularly in those reciprocal inhibition.4 Otherwise, their eccentric which involve moving further away from the line of contraction helps modulate movement. gravity. The provision of posturomovement ‘staying • Stabilizers or fixators contract to control the power’ appears to be one of the roles of the deep sys- position of the bone(s) to provide a stable base from tem (Ch.5). The Biering-Sorenson test 46,47 is a rea- which the agonist can contract, e.g. in the example sonably high level clinical test for trunk muscle of hip flexion, the lumbar spine and pelvic girdle strength and endurance. Modification in the Key must be appropriately controlled by the trunk Alignment and Control test (Ch.13) is a more func- muscles so that iliopsoas can act at the hip. tional alternative. The quality of the response is as • A synergist is a muscle which helps or informative as the measurable parameter of time. cooperates with other muscles in particular the prime mover, to perform a movement. It may help Reduced endurance and fatigue are not necessar- to stabilize a joint while an action is occurring. ily the same; however, each will lead to the other. Janda48 found synergistic activity in the hip This is an interesting situation and will be dealt with adductors when testing hip flexion in sitting – more fully in Ch.7. particularly if resistance was applied. In reality, probably lots of synergists assist in a movement. Muscle imbalance • A synergy is formed when a number of muscles cooperate and combine their activity to form a Kendall3 defined muscle imbalance as inequality in coordinated pattern of response – stability to the strength of opposing muscles acting on a joint. support movement and or a movement sequence. Faulty alignment, inefficient movement and poor stabilization occur. Concentric, isometric and eccentric muscle interplay Janda38 saw that impaired CNS motor regulation results in defective or uneconomical movement pat- The nervous system stimulates a muscle to generate terns. As a consequence, imbalanced activity between or resist force by utilizing various forms of action. certain muscle groups develops. This includes altered The point of stabilization can either be proximal or timing, degree of activation and load sharing, altered distal. concentric and eccentric control etc. As the spine is a • A concentric muscle action is a shortening system of multiple joints balanced activity between muscle contraction. A simple example of concentric all muscles is important in its alignment and control, activity is flexing the hip. The point of stability is and particularly between the flexor and extensor the pelvis. systems. • An isometric contraction occurs when there is no visible change in the length of the muscle, yet it Various forms of muscle activation maintains a constant level of tension1 e.g. sustaining and movement the hip in flexion. • An eccentric muscle action is a lengthening Roles of muscles in movement muscle contraction which ‘plays out’ an action providing a braking or controlling action in a Many different muscles are involved in providing a movement e.g. lowering the flexed hip. movement but the forces generated by each vary considerably throughout a movement and each mus- A general simplification is that while the agonist is cle can fulfil several roles in a pattern of movement: concentrically contracting the antagonists eccentri- • An agonist or prime mover is the muscle that cally contract in the modulation of movement. plays the major role in initiating carrying out and A nice example is the control of respiration and the maintaining a movement, e.g. ideally in hip flexion, IAP mechanism, where both the diaphragm and iliopsoas is the prime mover assisted by the transversus abdominis are tonically coactivated – on secondary superficial hip flexors acting as synergists. inspiration, the diaphragm concentrically acts while • An antagonist is a muscle which works in the transversus eccentrically lengthens and the converse direction opposite to the agonist, e.g. if the agonist pattern occurs during expiration.49 is a flexor, the antagonist is an extensor. The antagonists are often inhibited by a reflex 46

The analysis of movement CHAPTER 4 Eccentric muscle control deserves From a functional perspective, the interplay more attention between the various modes of contraction is ever changing according to prevailing demands of postur- Clinically, patients with spinal pain disorders appear omovement control. In order that the range and quality to have more difficulty with eccentric control par- of movement is full there must be balanced activity ticularly with lowering to gravity movements and between concentric/eccentric control.51 Not all eccen- those requiring more complex control hence further tric control is the same.52,57 It can occur in response to: examination is warranted. • Lowering to gravity as when lowering a raised From a neurophysiological perspective, Enoka57 limb or moving down into a squat says that there is accumulating evidence that control of eccentric contractions is different from that for • Controlling the momentum and lengthening of an concentric and isometric contractions. Eccentric outward swing such as kicking a ball contractions appear to be unique in several respects: • To balance the concentric activity in antagonistic • Eccentric control strategies are highly reliant muscles as part of the coactivation patterns upon afferent feedback to provide information on controlling a joint, and in resisting imposed loads the progress of the movement and achieve a desired during the give and take of posturomovement trajectory. Eccentric contractions involve more control. sustained and often greater discharge by Group 1a afferents in the muscle spindles compared to Hartley51 suggests that attempting to release concentric actions. Disruption to sensory feedback muscle by forcefully stretching and pulling does has been shown to disturb eccentric control and not fundamentally change the muscle length and coordination. The predominant effect of feedback requires daily practice and tearing to keep the from Group 1a afferents is excitatory on motor apparent length. Changing the ‘mind’ of the muscle neurons yet there is less EMG during an eccentric in the way that it is used changes the unconscious action. This is because: neuromuscular patterns. By focusing upon the eccen- trically lengthening muscles in a movement, and • Fewer motor units are involved in an eccentric ‘actively create (ing) the sensation of extending contraction compared with a shortening through the whole length of that muscle, we can contraction. The reduced EMG is a consequence of in fact increase the contractility and natural resting the greater force that muscles can exert during these length of the muscle and free it from a state of contractions. Compared with concentric, eccentric habitual contraction or tension’.51 We have termed exercises may provide more effective stimulation this ‘active elongation’ (see Ch.13). Bainbridge for muscle hypertrophy.57 The variability of motor Cohen52 notes dancers are more likely to injure unit discharge during eccentric actions can mean themselves with ‘pulls’ and ‘tears’ during eccentric reduced steadiness in performance, particularly at activity and the incidence of hamstring tears in 5% of MVC.57 football is legion. • During eccentric contraction, the muscle stores The coordination and ‘phrasing’ of eccentric activ- elastic energy and some of this can be released ity assists in balancing the forces in movement and in during a concentric action. When an eccentric the sequencing and support of movement especially contraction precedes a concentric one there is more in the spine and other weight bearing structures.52 power in the concentric action.57 This is also Eccentric control thus plays an important role in pos- dependent upon the architectural properties of the turomovement control. It is particularly involved muscle and the kinematic details of performance. A in postural adjustment, weight shift and in ‘yield good example is the counter movement in a jump and push’ to provide ‘grounding’ through the base where the lowering to gravity precedes the spring of support (Ch. 13) for antigravity control. giving it power. Another example is psoas in walking where it eccentrically lengthens during hip Co-activation or co-contraction extension (increasing the stored elastic energy) of muscles before it contracts to flex the hip.50 More subtle though important is its shuffling concentric/ In practice when an agonist is called to perform a eccentric control of the column during lateral desired motion the agonist and antagonist contract weight shift. simultaneously, and co-activation occurs.1 While the 47

Back Pain: A Movement Problem agonist is concentrically contracting, the antagonist the limb movement. Here the femoral or humeral eccentrically contracts to balance its activity and head move against the ‘fixed’ joint cavities of the help control the movement e.g. to bend your elbow, proximal girdles (Fig. 4.8A). Free movements of the extensors need to play out and lengthen. This the head and neck can also be seen as open chain co-activation provides stability for the joint; how- movements; the point of stability provided by ever it needs to be well modulated to allow for appropriate positioning and control of the thoracic flexible adjustment of the joint, particularly impor- spine and shoulder girdle etc. Open chain move- tant in weight bearing situations. If co-activation is ments can be more ballistic in which case they excessive the joint becomes rigid or ‘held’; if inade- may involve more activity of superficial muscles. quate the joint(s) is not well controlled or ‘unstable’. All skilled movement involves co-activation. Closed chain movements are those where the more distal supporting part or limb provides the A certain level of muscular co-activation in the point of fixation or stability and the more proximal axial skeleton is always necessary in providing suit- parts are free to move. The proximal axiogirdle able stabilizing synergies for adaptable antigravity support and control in three dimensions. The appli- Moving Stable cation of external load such as carrying a bucket of water increases the response53 and further so when preparing for short term unexpected and sudden loading or heavier loads. However, while protecting the spine, these greater responses are energetically and mechanically costly54 if maintained beyond the time of their short term need. Problems arise when there is too much co-activation55,56 or too lit- tle.53 There is evidence that isometric strength training appears to involve a reduction in the coacti- vation of the antagonist.57 Clinical practice reveals common consistent pat- terns of reduced co-activation in some regions of the spine and excessive co-activation in others. The alignment, shape and function of the body change. A Open and closed kinetic chain movements The performance of any task is achieved by a Moving sequential activation of muscle synergies and move- Stable ment of body segments referred to as a kinetic chain. Movement sequences from one limb girdle B to the other through the spine. Movement control Fig 4.8  Proximal stability with distal movement in (A) distal of the spine is further understood by considering stability and proximal mobility in (B). the different roles the spine plays in the control of open and closed (kinetic) chain movements. Func- tional movement control includes mixed elements of both. Open chain movements are those where the proximal parts are stabilized and the distal parts move, e.g. any free movement of a limb where appropriate positioning and control of the axial spine and proximal girdles provide the stability to support 48

The analysis of movement CHAPTER 4 muscles now pull against a fixed more distal point Fig 4.9  Acute hamstring spasm changes the line of pull of and the joint cavities move around or against the psoas. Note the associated abdominal hyperactivity. femoral and/or humeral heads19(Fig. 4.8B), e.g. sit- ting with the feet on the ground, the legs provide movement control it contributes to vertical stability the point of stabilization allowing the pelvis to tilt and support of the spine, and controlling lateral on the femur enabling the torso to freely adjust flexion torques;2,61 shows an oscillating concentric/ and move (see Fig. 6.25). In all fours the limbs are eccentric action during walking;61,62 helps control the stable point and the proximal girdles and spine load transfer between the legs to the body; and it can move and adjust between them. assists the functional pattern of flexing the pelvis on the femur2 while helping to control the spine, Studies on the pattern of quadriceps activation in as in the pattern of forward bending. In certain open and closed chain movements of the knee have instances it could act as a hip extensor as Schleip63 shown more balanced initial activation in closed suggests, i.e. if in crook lying and performing a ‘pel- chain movements.58 The joint compression afforded vic roll’, psoas could contribute to synergies produc- in closed chain exercise facilitates more balanced ing hip extension and lumbar flexion. Clinically, this co-contraction of the muscles around the joint ren- is sometimes apparent in an acute trunk ‘list’ where dering them a more superior form of exercise in hamstrings spasm posteriorly rotates the pelvis and providing optimal joint loading and stability.59 The psoas appears to flex the lumbar spine (Fig. 4.9). added proprioception afforded in closed chain movements more optimally recruits the deep Sys- McGill64 found that loss of the lumbar lordosis temic Local Muscle System synergies (Ch. 5). They changed the line of action of the largest extensor are a nice way to facilitate activation of this system muscles, compromising their role to support ante- in less gravitationally loaded postures so that repro- rior shear forces. gramming of the postural reflex responses can be experienced and learnt. Mobilizing and stabilizing elements interact (see Ch.13) The head also initiates closed chain movements of the spine serving as the point of support, e.g. Laban apparently taught: ‘stability and mobility doing a head stand. alternate ceaselessly’.8,32 The role of muscles change during movement according to whether they Anatomical vs functional actions of muscles The brain knows about movement, not single mus- cles. No muscle works in isolation but as part of a synergy in varying manner of contraction required in that particular movement. Anatomists tend to describe the actions of single muscles according to a presumed shortening contraction occurring between the fixed proximal origin and the more dis- tal insertion, i.e. principally in terms of open chain actions. Practically, muscles also work with a ‘reversed origin and insertion’ – where the distal attachment is stable and the proximal part moves as occurs in closed chain movements. A good exam- ple is serratus anterior providing stability for the ribs to move when weight bearing through the arm, and stabilizing the scapula when freely reach- ing the arm. Understanding this principal is important in understanding functional movement control of the spine. Psoas demonstrates the principle well. Usu- ally considered a hip flexor60 yet in functional 49

Back Pain: A Movement Problem are required to provide support or movement; work • Muscles 1 and 3 are one joint hip and knee in closed or open chain movements; work eccentri- extensors cally, concentrically etc. In addition, factors such as posture, the line of gravity, internal and external • Muscles 2 and 4 are one joint hip and knee forces, weight shift etc., will all affect the timing flexors and degree of muscle action and their shifting role between providing stability or mobility. • Muscles 5 and 6 are two joint muscles. These muscles can be activated in various combinations The two-joint muscles to exert extensor torques about the hip and knee joints. A significant number of muscles span two joints. The role of the two joint muscles as described by They are usually ‘superficial’ and generally known Enoka is useful in understanding the ‘extensor mech- as ‘global’ muscles (see Ch. 5). anism’ and the myomechanics of the hips and knees in positioning and controlling the pelvis during the Enoka describes the two joint muscles as pattern of forward bending and lifting (see Ch. 6). providing at least three advantages in control of the musculoskeletal system.57 Balanced proximal girdle muscle • They allow coupled motion at the two joints they force couples cross, e.g. the semimembranosus concurrently contributes to hip extension and knee flexion. This Both proximal limb girdles house sockets to accom- coupling can be achieved by a reduction in EMG in the modate the big spheroidal heads of the long bones, one joint muscle (gluteus maximus) and an increased allowing multiplanar movements at the shoulder EMG in the two joint muscle (semimembranosus) and hip all of which are actually all rotations. This • The shortening velocity of a two joint muscle rotary action is controlled by means of coplanar mus- (e.g. rectus femoris) is less than half of its one joint cle force couples formed when two or more muscles synergist (vastus medialis oblique)and hence it is simultaneously produce forces in different linear capable of exerting a force that is a greater directions, although the torques act in the same proportion of the isometric maximum rotary direction2 as in turning a steering wheel. This • The two joint muscles can redistribute muscle serves to either rotate the limb on the girdle or the torque, joint power and mechanical energy girdle on the limb. In order that the joint remains cen- throughout a limb (Fig. 4.10). trated and the axis of rotation is ‘pure’ at the joint, the muscle force couples obviously need to be balanced. Problems arise when they are not. Hip 2. Hip flexor Compensatory motion 5. Hip flexor and 1. Hip extensor knee extensor Sahrmann37 notes that the stabilizing action of mus- 6. Hip extensor and 3. Knee extensor cles can either be excessive or insufficient. This will knee flexor tend to create regions in the spine with reduced Knee intersegmental movement and regions which are 4. Knee flexor relatively flexible or even show excessive move- ment. When analyzing movement function in the spine, due regard should be paid for the occurrence of compensatory motion. Commonly this occurs in the cervical and lumbar spines as a result of insuffi- cient movement in the thoracic spine, shoulders and hips and inadequate axiopelvic control (Fig. 4.11). Motivation and motor performance Fig 4.10  Model of the hip and knee and the one and two Parameters of functional evaluation have been joint flexor/extensor muscles. strongly correlated with cognitive state.65 Strength tests demand motivation and cooperation from the 50

The analysis of movement CHAPTER 4 The impairment is clinically recognizable even if symptoms are minimal. Depending upon the primary localization of the impairment, for example reflex changes in the corresponding segment may be deficient, or changes in movement patterns, early onset of fatigue and faster switch into more primitive movement patterns in fatigue of the motor system etc. The functional impairment will present itself, however by discomfort and pain if additional provoking factors come into play. Fig 4.11  Compensatory motion occurs in some regions of Pain results when one has run out of compensa- the spine when the thorax and shoulders are stiff. tions. It may be considered as the major and most frequent sign of impaired function of the motor patient which can confound objective assessment. system. Cox et al65 suggest that complex spinal coordination is a better indicator of spinal dysfunction. Observing Until recently the thinking has been that the how the patient performs ordinary actions and task- motor control changes occur as a result of pain. In an ing certain motor acts without the need for effort, excellent paper, Van Die¨en et al31 analyzed the liter- reveals a lot about that person’s ability to organize ature to determine how LBP effects muscle recruit- posture and movement control. Trying less hard does ment in the trunk extensors. They found equivocal little to change the organization and so his ability to results – there is evidence for both increased and significantly influence the outcome. In fact, trying decreased muscle activity if you have back pain. They too hard invariably diminishes movement quality. interpreted the altered activity as an adaptive func- tional response in order to mechanically stabilize the Continuum concept spine and limit noxious tensile stresses on painful tis- of dysfunction sues. Importantly they allowed that while disturbed motor control was not likely to be adaptive, the loss In general terms pain doesn’t ‘just occur’ but results of control leads to the adaptive changes differs from what Janda66 termed a ‘functional pathology between patients and the developmental stage of of the motor system’. Neuromuscular dysfunction the disorder. is evident before the onset of pain. He says: There is some evidence emerging pointing towards pre-existing motor control changes.67–69 When it is recognized that the dysfunction is pre- existing, and patients are sub-classified many of the outcomes reported in the literature can be better understood. Janda’s momentously important contribution towards the understanding of back pain is that altered control precedes the development of pain. When pain evolves, further changes in neuromuscular function occur. Patients presenting to the clinician display varying degrees of neuromusculoskeletal dys- function at varying stages of disorder. Van Die¨en et al.31 importantly recognize that with respect to research studies, ‘between-subject variation may occur to differences between patients in the develop- mental stage of their low back disorder’. The clinician needs to gain some insight as to where in the continuum of dysfunction, the pre- senting patient lies (Fig. 4.12). An understanding of the expected patterns of normal and dysfunctional 51

Back Pain: A Movement Problem Abnormal/Abnormal Marked neuro-myoarticular dysfunction Ideal 'normal' Becomes 'a patient' Increasing incidence/ severity of symtoms; Occasional short Acute on chronic interlocking dysfunction lived symptoms, episodes and symptom development, usually spontaneously chronic regional pain syndromes. Requires treatment Require judicious manual and resolved to resolve motor retraining interventions Efficient movement patterns Declining quality Poor quality Symptoms unusual Posturo-movement control Multiple symptoms Fig 4.12  Continuum concept of dysfunction. control of movement allows the practitioner to The more common patterns of clinical presenta- choose to examine appropriate component parts of tion are presented in subsequent chapters to help movement relevant to the stage of the patient’s dis- the understanding of this and provide a framework order and to be able to interpret the results. for assisting assessment and intervention strategies. References [1] Norkin C, Levangie PK. Joint Stability & Lumbopelvic Pain. [12] Mes S. Neurophysiology in Structure and Function: a Edinburgh: Churchill Livingstone; Action. 5th Interdisciplinary comprehensive analysis. 2nd ed. 2007. World Congress on Low Back and Philadelphia: F.A. Davis Pelvic Pain. Melbourne; 2004 Company; 1992. [7] Singer KP, Malmivarra A. Post Congress Course Pathoanatomical characteristics of proceedings. [2] Neumann DA. Kinesiology of the the thoracolumbar junctional Musculoskeletal System: region. In: Giles LGF, Singer KP, [13] Janda V. Muscles, Central Foundations for Physical editors. Clinical anatomy and Nervous Regulation and Back Rehabilitation. Missouri: Mosby; management of thoracic spine Problems. In: Korr EM editor. 2002. pain. Oxford: Butterworth Neurobiologic Mechanisms in Heinemann; 2000. Manipulative Therapy. New [3] Kendall FP, McCreary EK, York: Plenum Press; 1978. Provance PG. Muscles: Testing [8] Hackney P. Making Connections: p. 27–41. and Function – with Posture and total body integration through Pain. 4th ed. Williams and Bartenieff Fundamentals. New [14] Tunnel PW. Protocol for Visual Wilkins; 1993. York: Routledge; 2002. Assessment Postural Evaluation of the Muscular System through [4] Trew M, Everett T. Human [9] Steindler A. Kinesiology of the Visual Assessment. J Bodywork Movement: an introductory text. Human Body under Normal and Movt Ther 1996;1(1):21–7. 5th ed. Elsevier Churchill Pathological Conditions. Livingstone; 2005. Springfield, Illinois: Charles C [15] Janda V. Muscles and Motor Thomas; 1955. Control in Back Pain: Assessment [5] Shumway-Cook A, and Management. In: Twomey L, Woollacott MH. Motor Control: [10] Hodges PW, et al. Coexistence of editor. Physical Therapy of Theory and Practical stability and mobility in postural the Low Back. New York: Applications. 2nd ed. Maryland: control: evidence from postural Churchill Livingstone; 1987. Lippincott Williams and Wilkins; compensation for respiration. Exp p. 253–78. 2001. Brain Res 2002;144(3):293–302. [16] McGill SM. Low Back Disorders: [6] Gracovetsky S. Stability or [11] Farhi D. The breathing book: Evidence Based Prevention and controlled instability. In: Good health and vitality through Rehabilitation. USA: Human Vleeming A, Mooney V, essential breath work. New York: Kinetics; 2002. Stoeckart R, editors. Movement, Henry Holt and Company; 1996. 52

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Chapter Five 5 Classification of muscles General overview gradations of force. These are also known as slow twitch fibres. Hannon1 describes muscles as having a wide variety of functions serving as springs, engines, braces and Type 11 fibres in contrast, are fast to contract and brakes. Attempting to understand these versatile relax. They are recruited only during high force activ- roles, scientists and clinicians have variously classi- ity and fatigue rapidly. These are also known as fast fied muscles according to certain characteristics twitch fibres. These also provide the rapid responses such as morphology, actions or functional role. to perturbations of sudden and high loading. These are explored. According to Trew and Everett,3 during low Individual muscle morphology force contractions of a muscle, only Type 1 fibres may be recruited and so these are used mainly for Morphology refers to the basic form or structure of normal everyday activities which do not require a muscle. This involves two aspects: maximal or high force contractions. Their resistance • The shape of the muscle partly reflects its role. The to fatigue suits them well for this role. As the force direction of the muscle fibres are variously arranged generated by the muscle increases, the Type 11 into differing forms to generate differing ranges of fibres are progressively recruited and during maxi- force. In general, pennate muscles produce greater mal activity all motor units are involved. However maximal force than fusiform muscles of similar size.2 maximal force rapidly declines due to the high • Fibre type. All skeletal muscles are composed of fatigue rate of the force generating fibres. There is a spectrum of Type 1 and Type 11 fibres, the a wide variation in the proportion of the different relative proportions of each within a single muscle fibre types between muscles and between people. will depend upon the principle role of that muscle Each person has a unique proportion of Type 1 to as either a constant worker or as a producer of 11 fibres and the fibre type is largely determined intermittent large range and or strong movements. genetically.3 Each motor unit within a muscle con- As can be seen in Table 5.1, there are differences in tains fibres of only one type.5 histochemistry, contractile properties and metabolism of the different fibre types. Limb immobilization studies have demonstrated a conversion of fibre types with a decrease in slow twitch We see that the Type 1 fibres are more resistant fibres and increase in the proportion of fast twitch.6 to fatigue, are recruited early in low force muscle activity due to their small axon size. The number Classification of muscles according of muscle fibres in slow motor units is small and to functional role so motor unit recruitment can result in fine In attempting to simplify and aid the conceptual understanding of the complex roles that muscles perform, various different functional classification

Back Pain: A Movement Problem Table 5.1 Characteristic differences between skeletal muscle fibre types Property Type 1 fibre Type 11a fibre Type 11b fibre (slow twitch) (fast twitch red) (fast twitch white) Muscle fibre type Slow oxidative (SO) Fast oxidative glycolytic (FOG) Fast glycolytic (FG) Fibre diameter Small Intermediate Large Muscle colour Red Red white Motor unit type Slow (S) Fast fatigue resistant (FR) Fast fatigable (FF) Motor unit size Small Medium Large Twitch tension Low Moderate High Mechanical speed Slow Fast Fast Rate of fatigue Slow Intermediate Fast Capillary density High Medium Low Myoglobin content High Medium Low Adapted from 3,4 (Trew & Everett 2005 and Norkin & Levangie 1992) systems have been adopted. However, the different Tonic muscles are those with a predominance of nomenclature used has to some extent confused the Type 1 fibres. These muscles work at a low grade of issue and there is a lack of general consensus on the contraction in a sustained manner thus have a lot of subject. Each aspect is examined and a more holistic endurance. They are often also termed stability or and inclusive classification system is subsequently postural muscles as they help to maintain stability proffered. of the body,4 e.g. the soleus is almost continually active in standing and owing to the high proportion Movement actions of Type 1 fibres can make small adjustments in muscle tension required to maintain body balance The simplest form of classification – muscles with and counteract gravity. equivalent or similar actions are grouped together, e.g. those muscles which externally rotate the hip Phasic muscles are those muscles with a predom- are known as the external rotators of the hip. How- inance of Type 11 fibres. These play a major role in ever, it is never so straight forward as the hip exter- large movements and those requiring more power nal rotators also play an important role in stabilizing and speed. They are either called mobility or phasic and controlling the pelvis. In the torso we talk of muscles. However, they fatigue more quickly and fol- the flexor and extensor systems of muscles which lowing intermittent bouts of high intensity exercise contribute to antigravity control as well as flexion recover more slowly than the tonic muscles,4 e.g. extension and so on. Similarly we may talk of the the gastrocnemius. Table 5.2 presents the more upper limb flexors or the lower limb extensors. commonly used distinguishing features4 of the tonic and phasic muscles. Tonic and phasic muscles Besides the differences in function and structure Although a considerable amount of variability exists outlined above, Kolar7 importantly draws attention among muscles in regard to the number, size, to the differences in the neural control of the differ- arrangement and type of muscle fibres it has how- ent muscle fibres – it is the type of the motor neuron ever, been common practice by some to classify which determines the type of muscle fibre, creating the muscles themselves into two main groups as either tonic or phasic motor units. This difference either predominantly tonic or phasic muscles. becomes particularly striking in the light of our indi- vidual motor and phylogenetic or evolutionary 56

Classification of muscles CHAPTER 5 Table 5.2 Different characteristics of tonic and phasic that in motor control, both types of muscles have muscles (after Norkin and Levangie4) dual functions participating in both posture and movement. The decisive difference between them Tonic Phasic consists of the timing of their development. Postural activity of the tonic system (his phasic) comes into Fibre type High proportion Type High proportion Type play as central nervous control becomes more highly 1 fibres 11 fibres developed. The functioning between the two systems Parallel needs to become integrated and balanced. Fibre Penniform arrangement Superficial and Muscle classification according cross more than one to Vladimir Janda Location Deep and cross one joint joint Mobility Professor Janda saw that the muscular system lies at a functional crossroad because it is influenced by Primary Stability Flexion adduction stimuli from both the central nervous system and function and internal rotation musculoskeletal system.8 From the clinical point of Extension, abduction view, Janda’s significant contribution has been to Action and external rotation show that dysfunction in the muscular system is usually a reflection of dysfunction in the peripheral development. At birth, the infant’s posture is pre- or central neural system. Impaired central motor dominantly influenced by the phylogenetically older regulation results in defective or uneconomical phasic (as described in Table 5.2) muscle system. movement patterns. As a consequence, imbalanced (Kolar calls this the tonic system!) The tonic system action between two structurally and functionally (Table 5.2) is less evident, but as the central nervous different muscle groups occurs in a systematic, system (CNS) matures these muscles play an increas- regular and predictable manner.9 He proposed a ingly important part in the development of upright pos- more general classification of muscles throughout ture and its stabilization with movement (Kolar calls the body into two groups based on characteristics this system the phasic system). This system is phylo- of their structure and function and observed actions genetically younger, more vulnerable and tends to in the clinical situation. They are the ‘postural mus- become weak. Maturity of this system is not achieved cles’ which are prone to over-activity which in turn until the child is 4 years old. tends to create relative underactivity in the antago- nistic ‘phasic muscles’. These functional differences It is important to point out at this point that the are further elaborated: nomenclature used by the Czech School of Manual Medicine can be confusing and appear contradictory The ‘postural muscles’ have a tendency to tight- as is evidenced by the paragraph above. This may ness, hypertonia, over-activity and shortening. They account for a less wide understanding and accep- tend to be activated early and dominate in a given tance of their valuable work. In addition it may con- movement and in states of pain, fatigue, injury, tribute some of the current confusion on the stress and emotional states this tendency is increa- subject. Their use of the terms tonic and phasic is sed. These muscles tend to be relatively ‘strong’. different to that shown in Table 5.2, and further compounded when talking of postural and phasic The ‘phasic muscles’ are prone to inhibition, muscles. This is further elaborated upon when hypotonia, atrophy and weakening and are less read- examining Janda’s classification, and the muscle ily activated in most movement patterns, particu- classification debate (see p. 60). larly under conditions of injury fatigue and stress. He classified certain muscles into either functional Kolar7 does clarify that tonic motor units have a group as shown in Table 5.3. more postural role and phasic motor units have a more kinetic role and that both motor units are You will note that he was undecided about the present in differing proportions in every muscle. role of the scalenes and the abdominals, classifying However, he also adopts the nomenclature used by them differently at different times. Janda making his work more difficult to interpret. Janda defined the muscles which tend to become Importantly, Kolar7 questions which position is short and tight as those having an antigravity pos- decisive in opposing gravity and I agree. He sees tural function, particularly those activated when standing on one leg. Janda5 considered the postural 57

Back Pain: A Movement Problem Table 5.3 Functional division of muscles according to local and global muscles as they acted to control Janda8,10 local stability in the lumbar spine including transfer of load between the thorax and pelvis Postural: tightness Phasic: weakness (Fig. 5.1) prone muscles prone muscles The local system includes ‘all those muscles Gastrosoleus Peroneii10 which have their origin or insertion (or both) at Tibialis posterior Tibialis anterior the lumbar vertebrae with the exception of psoas’. Short hip adductors Vasti particularly medialis The muscles included are shown in Table 5.4. This Hamstrings Gluteus maximus, medius, system is involved in the posture of the lumbar Rectus femoris spine and used to ‘control the (lumbar) curvature Iliopsoas and minimus and to give sagittal and lateral stiffness to maintain Tensor fascia lata Rectus abdominus10 mechanical stability of the lumbar spine’. Piriformis Whole abdominal wall8 Erector spinae – especially Serratus anterior Rhomboids lumbar, thoracolumbar Lower and middle trapezius and cervical potions Short cervical flexors Quadratus lumborum Scalenes8 Pectorals Extensors of the upper limb Upper Trapezius /levator Scapulae Scalenes10 Sternocleidomastoid Short deep cervical extensors Flexors of the upper limb muscles were approximately one-third stronger than A Internal those prone to inhibition. In subjects with altered Erector spinae muscles oblique or poor movement patterns their degree of activation External increases. In addition, he notes that in certain struc- B oblique tural lesions of the CNS, as seen in cases of cerebral vascular accident or cerebral palsy, the muscles Rectus which show evident spasticity are the same as those abdominal included in the postural group. muscles Janda himself said there were a lot of misconcep- Fig 5.1  The local (A) and global (B) muscles. tions and discrepancies about the use of the term ‘postural muscles’.11 However, examining his mus- Table 5.4 Local and global muscles of the lumbar spine cle system groupings it is apparent that they more 12 closely resemble the phasic muscles as described in Table 5.2. described by Bergmark His nomenclature is confusing for our purposes Local muscles Global muscles as you will see (p. 60). However, conceptually and functionally his approach has been very helpful. Multifidus Thoracic erector spinae which is Interspinales and about 2=3 of the muscle area Local and global muscles acting on the lumbar spine intertransversarii Internal and external obliques Lumbar erector spinae – Rectus abdominus Bergmark12 in examining the conditions for Lateral fibres of quadratus mechanical stability in the lumbar spine presented medial and lateral a concept of functional muscle classification into fibres lumborum Medial fibres quadratus lumborum 58

Classification of muscles CHAPTER 5 The global system ‘consists of the active com- The influence of Bergmark:stabilizers ponents i.e. the muscles and IAP which transfer the load directly between the thoracic cage and and mobilizers pelvis’. The muscles have ‘origin on the pelvis and insertions on the thoracic cage’. These include Richardson et al14., collectively known as The the global muscles shown in Table 5.4. The main Queensland Group, have produced some fine role of this system ‘appears to be to balance the research and have been at the forefront of the motor outer load so that the resulting force transferred control approach to effective lumbopelvic stabiliza- to the lumbar spine can be handled by the local tion in the treatment of low back pain. They have system. Thus large variations of the distribution been strongly influenced by Bergmark as seen in of the outer load should give rise to only small Table 5.5, choosing to include transversus abdomi- variations of the resulting load on the lumbar nus and some of internal oblique into the local spine. The local system therefore is essentially group.14,42 dependent upon the magnitude (not the distribu- tion) of the outer load and of the posture (curva- In addition, Richardson13 also makes distinction ture) of the lumbar spine’. between monoarticular, bi-articular and multijoint muscles. Their capacity to provide joint stabilization He says ‘the global system can be said to differs in each category. The monoarticular muscles respond to changes of the line of action of the could also be called local muscles. The multijoint outer load whereas the local system responds to muscles are phylogenetically the oldest and can be changes in the posture of the lumbar spine. Both called the global muscles.13 systems respond to changes in the magnitude of the outer load’. ‘Generally speaking, smaller forces Comerford and Mottram15 have interlinked the in the global system imply larger forces in the local concepts of local/global and stabilizer/mobilizer into system as could be expected’. He says intra what they see as a more clinically useful classifica- abdominal pressure (IAP) theoretically has a local tion. This encompasses three different functional and global mechanical role. ‘The global role is to muscle roles: local stability muscles; global stability act directly on the thoracic cage or on the curved muscles; global mobility muscles. Some muscles global muscles. The local action consists of the trans- stabilize and some mobilize. verse force in the posterior direction acting direc- tly on the lumbar spine thus inducing a flexion However, there are inherent problems for under- moment’. standing functional control in seeing some muscles as stabilizers and others as mobilizers. As we have This paper has been very influential and is freq- seen in Chapter 3 in the process of motor develop- uently quoted in the literature. This is interesting, ment, movement and stability develop together and as his is a study in mechanical engineering looking at forces and load transfer in the lumbar spine Table 5.5 Categorization of the lumbar and abdominal rather than functional control of movement. He muscles based on their role in stabilisation according to admits that how the CNS controls loads is not sufficiently understood to allow detailed model- 14 ing; does not include iliopsoas in the local system or accord it any role in lumbar control; and treats Richardson et al. the thoracic cage as a rigid body. While he thought psoas should be referred to the global system he Local stabilizing Global stabilizing excluded both it and latissimus dorsi from his system system analysis as he felt they do not have a substantial role in maintaining mechanical stability of the back Intertransversarii Longissimus thoracis pars system. Interspinales thoracis Multifidus While his muscle classification principle is very Longissimus thoracis pars Iliocostalis lumborum pars useful, it needs to be applied to more than the lum- thoracis bar spine and we need to appreciate that control of lumborum the lumbar spine will be dependent upon control Iliocostalis lumborum pars Quadratus lumborum lateral through the entire axial skeleton including the fibres pelvis. lumborum Quadratus lumborum - medial Rectus abdominus Obliquus externus fibres Transversus abdominus abdominus Obliquus internus abdominus Obliquus internus abdominis (fibre insertion into thoracolumbar fascia) 59

Back Pain: A Movement Problem are always in constant interaction in mature motor ‘postural muscles’ equate more to the muscles with behavior. Kolar7 points out that any muscle may a high Type 11 fibre content which are actually pha- be required to work in a stabilizing role one moment sic muscles as defined in Table 5.2. Janda later and then as a movement producer the next. While tended to describe the postural muscles more in some muscles may appear to have a predominantly terms of ‘tightness prone’ while still maintaining stabilizing role e.g. the local muscles in the lumbar that they were the ones predominantly activated spine as described by Bergmark, importantly, they when standing on one leg – the primary posture, also sub serve a postural role and are also producers according to him. The confusion becomes further of fine subtle movements as well as being control- compounded when both he8 and Kolar7 at times lers and discrete adjusters. Danneels et al.16 found use the term ‘tonic muscle system’ referring to increased multifidus action in concentric lifting those muscles as described in his ‘postural group’ which could indicate that it participates in torque when in fact they are describing phasic muscle production. It is an oversimplification of function activity. Kolar7 however, does also allow that tonic and erroneous to consider that they do not produce motor units have a postural role. any appreciable movement and ‘just stabilize’. Most of the respondents in the above mentioned Cholewicki and VanVliet17 refute the classifica- paper appeared to be in agreement that phasic mus- tion of muscles into local and global as a means for cles (as defined in Table 5.2) equate to global mus- discriminating between muscles responsible for cles, mobilizer muscles, kinetic muscles, and, by intersegmental stability and spine motion. All trunk inference, Janda’s postural muscles. Muscles with a muscles contribute to spine stability and their con- more postural function have a greater proportion tribution depends upon many variables including of Type 1 fibres and tonic motor units and have posture and loading conditions. McGill18 and Kavcic tended to be called local or stabilizer muscles. They et al.19 express similar sentiments. The patterns of behave with some similarity to Janda’s phasic mus- muscle activation change as the form and magnitude cles as he described them. of spine loading patterns change (See ‘spinal stabi- lity’ p. 86). Most respondents agreed that the principal issue was altered motor control rather than strength and Muscle classification debate endurance. All incorporate various aspects of mus- cle classification into clinical practice. Is muscle classification relevant and if so, which of The case for a new and the above muscle classifications is most clinically inclusive muscle classification useful? As can be seen, muscle classification has system based upon depended in part upon which aspects of function posturomovement control have been appreciated. ‘Muscle impairment classifications should describe In 2000, the Journal of Bodywork and Movement categories and provide a basis for treatment’.21 Therapies published a paper entitled ‘The muscle Although any classification of muscles is likely to be designation debate: the experts respond’.20 The an oversimplification, appreciating the nature of pos- paper was a response to readers who had communi- turomovement function as it develops helps inform a cated their confusion over the apparent contradic- clinically useful muscle classification system which tions in the way that different researchers and encompasses the structural and functional properties clinicians refer to muscle categorizations. The editor of muscles in a functional movement context. says ‘When words postural/phasic or stabilizer/ mobilizer are applied to particular muscles practical Normal postural reflex mechanism as well as linguistic difficulties become apparent’.20 (NPRM) The preceding classification summary highlights the problem. Good movement control requires good postural control which is dependent upon normal function- The principal confusion probably stems from ing of this system. As we have seen, this is not Janda’s use of the terms postural and phasic muscles (see page 57). Comparing Table 5.2 – tonic and phasic muscles with Table 5.4 – postural and phasic muscles of Janda – we see that frequently his 60

Classification of muscles CHAPTER 5 present at birth but with the motor development of • Equilibrium in the low load state is accomplished the infant, this will become highly complex and by small segmental rotary shifts and adjustments of varied and allow the development of motor skill in the axial skeleton and proximal limb girdles to a gravity based environment. perturbations in the centre of gravity caused by, e.g. breathing, head turning, limb use, unstable base of Functions ascribed to the postural support, torque produced by large superficial reflex mechanism muscle action etc. • Equilibrium control in high load states is In the ‘ideal’ state, the functions mediated by the accomplished by more forceful coactivation of the normal postural reflex mechanism can be essentially whole muscle system to control the relationship of distilled as providing: individual spinal segments as well as that between • ‘Uprightness’ against gravity with the axial the various body parts while accommodating the skeleton and the proximal limb girdles optimally forces imposed by gravity or otherwise. aligned and controlled with respect to the line of • Appropriate postural sets to support limb gravity and the current requisite activity, with movement – involve prepositioning and adaptive minimal muscular effort. This includes axial spinal movements of the axial skeleton and proximal limb segmental control in the normal spinal curves, girdles in appropriate spatial relationships for particularly the lumbar lordosis and the generation effective limb activity. This includes control of of intra abdominal pressure (IAP) for spinal weight shift. support. The proprioceptive system probably provides the predominant graviceptive The NPRM essentially controls forces – gravity and information.22 Feldenkrais23 considered that people the intrinsic/extrinsic forces related to it, to provide with a fine kinesthetic sense maintain tonic a stable platform of control on which to superim- muscular activity with less effort. Effort disables pose movements. Without this, the person has to the ability to detect small differences. ‘hold himself up’ and is not free to adjust and selec- • Breathing in an energy efficient manner i.e. tively move his spine and proximal limb girdles. principally via the diaphragm with related function Many with spinal pain and related disorders can of the axial skeleton providing optimal alignment move, but cannot adequately posture themselves and control to allow effective movement of the ribs prior to and during movement. The postural system and adjustments within the thoracic cage to shifts in is dependent upon gravity, suitable demand and the centre of gravity; to allow diaphragmatic adequate proprioceptive and other afferent infor- breathing to continue despite strong actions of mation for its wellbeing. many of the large muscles attaching to the thoracic cage e.g. abdominals, serratus anterior/posterior, Ideally, we demonstrate a ‘central intelligence’ in pectorals. Breathing is the most fundamental the torso – balancing upright control, movement motor act. and breathing in an energy efficient manner. • Maintenance of equilibrium in both ‘low’ and ‘high’ load antigravity situations by the provision of: Proposed functional classification of muscles • Anticipatory ‘feed-forward’ postural presetting and ‘stability’ of the axial skeleton When the aspects of function provided by the to support limb movement. Studies NPRM are appreciated in movement control, holis- conducted by Cresswell24 and Hodges25 tic muscle designation becomes more apparent and demonstrate the role of transversus abdominus clinically useful. as part of a feed-forward postural synergy. The proposed model applies to the body as a • Compensatory ‘feed-back’ adjustments and whole, particularly the torso. Its genesis results postural reactions activated by sensory events from the integration of clinically observed changed following loss of desirable alignment and muscle behavior, contemporary thought and avail- control resulting from intrinsic and extrinsic able research to date. It includes a similar polarity perturbations to the body while stationary or of spatially defined muscle function as proposed moving. by Bergmark, as well as structural and functional differences according to convention and also that proposed by Janda. 61

Back Pain: A Movement Problem The concept of a local and global muscle system • The torso muscles in this system are generally acting on the lumbar spine has gained acceptance as deep, often small and may be uni- or poly a result of Bergmark’s influence. However, clinically, segmental. Being close to the joint they control and lumbar spine problems are also functionally linked to many containing a large number of muscle spindles, problems elsewhere in the spine. Hence it makes it is likely that they have a large role in kinesthetic sense to try to understand spinal control in a more sense and postural control. The small deep universal way. Anatomical and empirical knowledge intersegmental muscles of the spine contain a very suggests that different functions are sub served by high density of muscle spindles and more than likely the deep and superficial muscles. Accordingly, the act as large proprioceptive transducers30 or muscular system in particular that pertaining to func- vertebral position sensors at every segmental level.31 tion of the torso, is essentially seen in terms of a sys- Optimal spinal movement control depends on temic deep system and a systemic superficial system. adequate sensory input into and from this system. In health, optimal motor control involves systemic Normal studies involving reduced mechanical local function with balanced systemic global activity. loading or microgravity and related reduced The whole dynamically functions to permit grace, proprioceptive input have demonstrated atrophy32 economy of effort in fruitful and refined action and conversion of these deep muscles from slow appropriate to the situation or task. tonic firing to more phasic function.33 This classification is functionally related and of • Their form and function produces more course conceptual, as no muscle or system works continuous but varying tonic motor activity at in isolation but as part of a coordinated synergy low levels of contraction34 which provides within and between the systems related to need. endurance and staying power, particularly useful in counteracting gravity and maintaining the breathing The work of Richardson et al.14 and in particular cycle. Tonic low level activation of transversus in Hodges,14,26 has largely been about examining standing has been reported.35,36 Saunders et al.37 aspects of deep system function. The manner of found tonic activation of transversus during walking response noted in those muscles which have been which continued into running up to speeds of studied in this system implicates separate CNS 3msÀ1. Clinically they are best recruited during control. slow, sustained and non effortful movements. Moseley et al.27 also showed different activation • Rather than generators of force, their principal behaviors between muscles in the deep and superfi- role is more one of antigravity postural control cial muscle systems of the lumbar spine and Lee including stability. This entails movement which has shown that this also occurs in the thoracic is subtle and finely modulated! Activity oscillates spine.28,29 between concentric and eccentric control as required. The adoption of upright postures with the Systemic local muscle system (SLMS) spine aligned close to the normal spinal curves and the line of gravity have been shown to readily It is proposed that the role of the SLMS is more activate various muscles in this system.38–40 The closely linked to the underlying functions provided deep abdominal muscles have also been shown to by the NPRM: antigravity support; the more ‘intrin- automatically respond to postural changes evoked sic’ movements – spinal segmental control, small through decreasing the base of support while postural shifts and adjustments and discrete move- sitting.41 ments; and the fundamental motor act – respiration. This is in line with Richardson et al.26 who proposed • Their early activation prior to a movement that ‘the local muscles form part of a larger antigrav- occurring25,27,42,43 renders the torso as an ity muscle system which links the joints of the adjustable, yet stable base of support to allow for entire functional kinetic chain including both the more effective and even forceful actions of the large upper and lower limbs’. more superficial global muscles as required. Their early action is also necessary to create appropriate They function to provide inner support and con- axial ‘postural sets’ for effective control of the head trol of the axial skeleton as a whole and particularly and weight shift for limb movements. around the body’s centre of gravity. They provide the foundation for movement (Fig. 5.2). • The muscles work synergistically in patterns of co-activation as part of a coordinated system The more general features of this system are explored and summarized in Table 5.6. 62

Muscles of mastication and speech Rectus capitus Suboccipitals Longus capitus Longus Suboccipitals colli Rhomboids Internal intercostals External intercostals Middle and Supraspinatus lower trapezius (cut) Rotatores Interspinalis Infraspinatus Intertransversarii Deep extensors Subscapularis Serratus anterior of the forearm Teres major Teres minor Glutei minimus, Diaphragm medius Triceps brachii Transversus abdominis Deep hip Internal oblique Multifidius rotators Extensors of Pelvic floor muscles Quadratus the forearm Vastus medialis lumborum Iliacus Psoas major Gluteus maximus Vastus medialis Soleus Intrinsic muscles of the hand Intrinsic muscles of the foot Fig 5.2  Graphic depiction of the conceptual systemic local muscle system (SLMS) as a continuous innermost sleeve of myofascial support. 63

Back Pain: A Movement Problem Table 5.6 Different structural and behavioral characteristics between the SLMS and the SGMS Systemic local muscle system (SLMS) Systemic global muscle system (SGMS) deep system superficial system Architecture 1 small, deep, more pennate 1 large, superficial, more fusiform Uni and polysegmental Polysegmental Fibre type/ Type I fibre/tonic motor unit dominant Type II fibre/phasic motor unit dominant activity 1 postural/stabilizing/control and small movements 1 larger movements; ballistic; higher force and faster Role and shifts at low force generation. speed 2 postural/stabilizing at higher magnitude loads Loading Work more so and optimally in closed chain Work more so and optimally in open chain movements movements particularly fast/ballistic Timing Pre activate before SGMS in movement Activate after SLMS in movement Action Work in synergies in patterns of coactivation Work singly or as part of a synergy; co-activate in high load or perturbation situations Directionality Non direction dependent Direction dependent 1 unilateral activation; asymmetrical Activation 1 bilateral activation - may/not be symmetrical Inherent Tend to: inhibition, hypotonia, atrophy weakness, Tendency to: over activity, strength tightness shortness behavioral delayed activity particularly in states of pain injury tendency fatigue, stress emotion and to dominate in movements particularly in states of pain injury fatigue stress and emotion or when working out new or complex movements9 response. Balanced co activation or co-contraction • The patterns of muscle activation may be around a joint provides for stability of the joint26 independent of movement direction. and centered joint control and load transmission. Perturbation studies of the spinal reaction forces This is particularly important in the spine where engendered from limb movement have shown that the control of the segments against gravity transversus and multifidus continue to be active including compressive and shear forces is with repetitive movement of the arm in both particularly important. Coordinated coactivation directions25,27 and similarly so with movements of the leg.24,47 McCook et al.48 have shown not only ensures control around individual joints consistent transversus activity during both trunk but also control of the orientation and alignment of flexion and extension. However, Allison et al.49 the spine as a whole. Another example of measured transversus bilaterally and found its synergistic coactivation is the generation of the activity was specific to the direction of arm movement. Herrington50 reported symmetrical intra abdominal pressure mechanism (IAP) which action occurred in different positions, particularly depends upon coactivation and modulation in standing. between the diaphragm, transversus abdominis and • Clinically it appears that this muscle system pelvic floor. Studies of some of the muscles which response is more bilateral however this may not are active in deep system synergies have necessarily be symmetrical49 as it controls demonstrated early coactivation e.g. of the reaction forces or allows for movement diaphragm with transversus abdominis;44,45 pelvic floor muscles with abdominal muscle activity;46 adjustments during say weight shift. Danneels transversus with deep multifidus;27 internal et al.16 found bilateral coactivation of internal oblique with multifidus.43 64

Classification of muscles CHAPTER 5 oblique and multifidus in asymmetric lifting tasks These more superficial muscles are generally with differences in the symmetry of multifidus activity between lifting and lowering. polysegmental and provide for the more ‘extrinsic’ • The inherent behavior of the muscles in this movements and are activated in situations of larger system is more akin to Janda’s ‘phasic muscles’. He maintains they have a tendency to hypotonia, perturbations of the torso and limb movements, atrophy weakness and inhibition and to be less readily activated in movement patterns particularly if fast or large ‘actions’ using effort. They particularly under conditions of pain,51 injury, fatigue and stress and emotional states.10,52,53 are short acting force producers. They show a direc- Weight bearing appears to be a significant afferent tion dependent stabilizing role.19 Smith et al.61 factor in generating antigravity extensor muscle activity, particularly the one joint extensors. demonstrated selective recruitment of the phasic Selective atrophy of multifidus muscle has been shown to occur after 8 weeks of bed rest in otherwise ankle extensors in ballistic fast paw shake move- healthy individuals.32,54 Richardson55 notes the ments in cats. Wohlfahrt et al.62 found that rapid ‘weight bearing muscles’ tend to more readily fatigue. abdominal exercises appear to recruit the prime However, there appear to be some important differ- ences between Janda’s ‘phasic muscle’ group and moving (superficial) muscles with a simultaneous the SLMS: decrease in static (deep) abdominal function. • The SLMS appears to have a greater role in basic Richardson63 also notes that these muscles are more postural control. Janda saw his ‘postural muscle’ (tonic) group as more important in postural control.11,56 favorably activated in open chain ballistic or speed • Janda was more concerned about the effects of loading situations. Conversely, the deep one joint the postural muscles and clearer about classifying them. Those classified as phasic were less muscles are optimally recruited in closed chain longi- numerous.10 He stated that those muscles he had not classified ‘can be described as neutral or not yet tudinal loading which provides joint compression and determined’9 or ‘doubtful’.57 We have included more muscles in this system than Janda did in his constant sensory input from the periphery guiding phasic group. motor performance. Janda64 suggested that there • He did not necessarily see the ‘phasic muscle’ may be a correlation between these muscles with a activity as a deep or systemic response. tendency to tighten and those participating mainly • Clinical evidence points to iliacus and psoas as important inclusions in this deep system. Janda in flexor reflexes and a correlation between muscles classified them in his ‘postural muscle’ group. with a tendency to weakness and those participating Effective activity of the SLMS promotes a ‘supple uprightness’ – ‘buoyancy’, elongation, opening, and in extensor reflexes. flexibility of the torso. When the system is working well, the person has equipoise, grace and lightness in The muscles in this system require a stable and movement. And he breathes well. adaptable base of support provided by good preced- Systemic global muscle system (SGMS) ing systemic local muscle activation. There appears to be much less ambiguity and confu- sion about this system. The muscles in this system They have an inherent tendency to be easily acti- equate to those in Janda’s Postural Muscle group; 9,10 vated,65 strengthened and dominate in posture and Bergmark’s Global muscles;12 with subsequent movement patterns in low and high load situations and adoption by Richardson et al.,13,58 O’Sullivan,59,60 are prone to tightness26 and shortness.10 Janda main- Comerford and Mottram.15 Many are two-joint tained that their action is increased in states of pain, muscles (see Ch. 4). fatigue,66 injury,67 stress and effort or when working out new or complex movement patterns.9 Tight muscles also act in an inhibitory way on their antagonists64 It is important that the therapist fully appreciates this inherent behavior. This is certainly the case clinically and is observed in the fitness industry where overactivation of these muscles has largely given rise to the ‘stretch industry’. A generally overactive global system will manifest in diminishing our dimensions, making our bodies shorter, narrower flatter and effectively closing them.68 The person moves in a loping, heavy and somewhat grounded and awkward manner. This sys- tem is dominant in states of action, stress, tension and effort – the ‘flight and fight’ response with related sympathetic dominance. The aggressive, fighting warrior postures are SGMS dominant. The more general features of their behavior are summarized in Table 5.6. 65

Back Pain: A Movement Problem Assignation of muscle/groups into each • Abdominal imbalance. Some of the superficial functional system muscles or part of a muscle exhibit SGMS behavior creating imbalance within the group: The assigning of muscles into either group as shown in Table 5.7 has been much influenced by Janda and • Hyperactivity of the ‘upper abdominals’ and serves as a guiding principle. It is based upon muscle hypoactivity of the ‘lower abdominals’. This architecture, their role in more ideal postural and clinical observation is also corroborated by movement control and their behavioral tendencies Kendall 69 who saw it as the most common determined through research and observed in clini- altered pattern. cal practice. Obviously there is not a clear demarca- tion between systems as they both cooperate in a • O’Sullivan et al.70 found altered motor control coordinated manner in posturomovement function. strategies during the active straight leg raise These tendencies appear to be inherent in us all – test in subjects with sacroiliac joint pain. This with or without back pain. The presence of back included underactivity of the deep transversus pain tends to compound the picture. and lower internal oblique with related hyperactivity of the more superficial oblique System switching behavior abdominals, in particular external oblique. Motor behavior is complex and variable. Depending • Psoas may become overactive and tight and act as upon the pattern of neuromuscular strategies a per- a global muscle son adopts, some muscles belonging in one func- • Serratus anterior acts in a global manner. tional muscle system may begin to act as though in • Piriformis & the obturator group act in a global the other. This may only involve a part of the mus- manner cle. When the behavior of a muscle changes, so does its role in posturomotor control. The most notable Abdominal muscle group clinical observations are: Functionally these are a very interesting group of muscles. Hodges’ work25,36,42,47 has convincingly Table 5.7 Suggested classification into SLMS and SGMS of those muscles deemed significant in torso and related function Systemic local muscle system (SLMS) Systemic global muscle system (SGMS) Short intersegmental muscles of the entire axial spine: rotatores; Erector spinae: 1 thoracolumbar and cervicothoracic interspinales; intertransversarii; suboccipitals (recti & obliques) Quadratus lumborum: 1 lateral fibres Sternocleidomastoid Multifidus of entire axial spine: 1 deep Scalenes Deep neck flexor group: longus capitis & colli Upper trapezius; levator scapula Abdominal group in particular the deep muscles: transversus Serratus posterior: sup & 1 inferior Pectorals abdominus, internal oblique & ‘lower abdominals’ Latissimus dorsi: 1 lateral fibres Pelvic floor muscles Hamstrings Diaphragm Rectus femoris Intercostals: internal and external; levators costarum Tensor fascia lata Psoas Short hip adductors Iliacus Gastrocnemius Quadratus lumborum: 1 medial fibres Flexors of the upper limb Glutei: minimus, medius, maximus Lower and medial scapular stabilizers: middle and lower trapezius; rhomboids Serratus anterior Intrinsic foot and hand muscles Soleus Deep rotators of the hip and shoulder Jaw, masticatory and speech muscles Vasti: 1 medialis Extensors of the upper limb 66

Classification of muscles CHAPTER 5 confirmed transversus abdominus as an important to have task dependent independent activation as deep system synergist with probable separate well as synergistic coactivation between them.38 CNS control to some or all of the others. Internal oblique has also been found to behave in a similar Janda classified the iliopsoas as a ‘postural mus- manner.31,43 This early activity has led to its inclu- cle’ (global system in our context). Bergmark nomi- sion in the local system by some13,16 such that in nated psoas as a global muscle,12 but chose to the literature the deep abdominals consist of the exclude it from his model. He ignored iliacus. How- transversus and internal oblique. These can be ever, their anatomical architecture and empirical viewed as the major stabilizers.71 However, some evidence in functional control point to their inclu- count internal and certainly external oblique as a sion as important members of the deep SLMS. global muscle13 and rectus abdominus always earns that title. Although clinically, parts of these mus- Apart from the work of Andersson et al.,38 ilia- cles may be tight or overactive, other regions are cus’ important contribution to functional control underactive. The entire abdominal wall may be of the spine has been largely overlooked. Review underactive. The obliques and rectus are also of the literature on psoas reveals conflicting views important for postural alignment and orientation as to its primary role – spinal control or hip flexion. and control of the thorax on the lumbar spine as Functional control of movement involves both. As well as the generation of IAP at higher magnitude Andersson et al.38 point out; activation of a muscle loads, hence their inclusion into the SLMS. is not always predictable from its anatomical arrangement and mechanical advantage but involves Urquhart et al.72–74 found regional variations in a high degree of task specificity.75 This will also the structure and recruitment of transversus abdomi- involve its action in relationship to the line of grav- nis and internal oblique in a healthy population. More ity as well as synergistically counteracting both tonic activity was greatest in the lower and middle internal and external forces. The contribution of regions compared to the upper region which showed iliacus and psoas in lumbopelvic movement control more phasic activity in line with its greater role here will be dealt with more fully in Chapter 6. with respiration. They also showed the postural responses differed between body positions with Importantly an antigravity postural role has been recruitment delayed in sitting compared to stand- ascribed to psoas by numerous authors. While ing.74 This variation of structure and function within McGill sees quadratus lumborum as the most a muscle lends credence to the examination of pat- important stabilizer of the lumbar spine76 he does terns of movement in controlling certain actions accord some stabilizing role to psoas in the presence rather than individual muscle function. While indi- of some hip flexor torque.31 In a simulated model, vidual muscles have been grouped to aid conceptual he proposed that it has the potential to posturally understanding, it is the degree of their synergistic stabilize the spine with compressive loading and activity in a movement which is significant. with bilateral activation.77 However, symmetrical activation (the analogy of guy wires stabilizing the While clinically, underactivity of the deep mast), imposes large compressive forces to the abdominals is usual, both over activity and under spine.78 EMG studies have further confirmed pos- activity in the superficial abdominals can occur. As tural activity of psoas in standing,79 sitting38and also significant, is the different activity level between in bending and lifting.80,81 An antigravity postural ‘upper’ and ‘lower’ sections of the group. stabilizing role for psoas has also been supported by Gracovetsky,82 Gibbons,83 Penning84 and Travell Changed patterns of activity within and between and Simons.85 the abdominal and the iliopsoas groups in concert with altered deep system control, largely gives rise Overview to the two primary clinical classification systems for back pain (see Ch. 9). The architecture and functional behavior of the SLMS as described forms a reasonably continuous The case for the inclusion of iliacus and inner neuromyofascial sleeve of support which pro- psoas in the SLMS vides a primary platform of control for body postures and movements (Fig. 5.2). The muscular system can It has been common practice to lump these two be conceptually viewed as comprising an ‘inner tube’ muscles together as one, despite the fact that they supporting the ‘outer slings’. The deep muscles are have separate nerve supplies and have been shown 67

Back Pain: A Movement Problem the supporters; the superficial muscles are the ten- evolutionary and embryonic perspective. As the mesoderm splits it forms a trilaminar myofascial sioners. The deep muscles provide the foundation external body wall. The two superficial layers contain ‘fields of contractility’ which are whole organism in for control while the superficial are more akin to scaf- scope and produce core mammalian movement pat- terns such as flexing/extending, lateral flexing and folding. There is a lively interplay between ‘inner con- twisting. If carried too far these archetypal move- nectivity’ and ‘outer expressivity’.86,87 ment patterns will shorten and buckle the body. The deepest layer provides a field of contractility Drawing attention to the myofascial continuity of whose prime function is squeezing and sucking the the muscular system, Myers88 notes that the deep body wall to thus preserve longitudinal integrity. Included is the anterior scalenes, transversus, the dia- ‘locals’ determine the postural ‘set’ more than the phragm, the intercostals, quadratus lumborum and levator ani. superficial ‘expresses’ and are ‘too often ignored The recognition of the concept of intrinsic and because they are out of sight out of mind’. The extrinsic musculature and their differing roles has it seems always been in some respects culturally SLMS has some similarities with his ‘Deep Front acknowledged. Analyzing Egyptian art, Brecklin- ghaus94 notes that the people portrayed ‘give the Line’ and ‘Lateral Line’. The SGMS has features in impression of having been well balanced with respect to the integrated use of their intrinsic and common with his ‘Superficial Front and Backlines’, extrinsic musculature and rarely display the over developed armored extrinsic musculature typical in the ‘Functional Lines’ and the ‘Spiral Line’. He fighting and aggressive cultures’. notes the influence of the early German anatomist Hoepke in him seeing the spiral and oblique muscu- lar chains in the superficial muscle system (Fig. 5.3). Similarly, others have described anterior and poste- rior oblique muscle slings89 and also local longitudi- nal and lateral slings90 in the global muscle system, which are proposed to assist regional stabilization of the pelvis. Interestingly, Beach91–93 recently presented a ‘new model of human movement’ with an Serratus- rhomboideus- schlinge Pectoralis- obliquus int.- schlinge Obliquus int.- gluteus medius- schlinge Obliquus ext.- adduktoren- schlinge Fig 5.3  Functional myofascial meridians according to Hoepke. 68

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Classification of muscles CHAPTER 5 [65] O’Sullivan PB, et al. Effect of between regions of these muscles [84] Penning L. Psoas muscle and different upright sitting postures and between body positions. Gait lumbar spine stability: a concept on spinal-pelvic curvature and Posture 2005;22(4):295–301. uniting existing controversies. trunk muscle activation in a pain Critical review and hypothesis. free population. Spine 2006; [75] Andersson EA, et al. EMG Eur Spine J 2000;9:577–85. 31(19):E707–12. activities of the quadratus lumborum and erector spinae [85] Travell JG, Simons DG. [66] Potvin JR, O’Brien PR. Trunk muscles during flexion-relaxation Myofascial pain and dysfunction: muscle co-contraction increases and other motor tasks. the trigger point manual the during fatiguing isometric lateral Clin Biomech 1996;11(7): lower extremities, vol. 2. bend exertions: possible 392–400. Baltimore: Williams and implications for spine stability. Baltimore; 1992. Spine 1998;23(7):774–80. [76] McGill SM. Low back exercise: evidence for improving exercise [86] Bartenieff I. Body movement: [67] Sole G, et al. Altered muscle regimens. Phys Ther 1998; coping with the environment activation of hamstring muscles 78(7):754–65. gordon and breach australia. following posterior thigh injury. 2002. In: Proc. 6th Interdisciplinary [77] Santaguida PL, McGill SM. World Congress on Low Back and The psoas major muscle: a three [87] Hackney P. Making connections; Pelvic Pain. Barcelona; 2007. dimensional geometric study. total body integration through J of Biomechanics 1995;28(3): bartenieff fundamentals. New [68] Bond M. The new rules of 339–45. York: Routledge; 2002. posture: how to sit, stand, and move in the modern world. [78] Santaguida PL, McGill SM. A 3D [88] Myers TW. Anatomy trains: Rochester: Healing Arts Press; mechanical study of the psoas myofascial meridians for manual 2007. major muscle with respect to the and movement therapists. spine. J Biomech 1993;26(3):351. Edinburgh: Churchill Livingstone; [69] Kendall FP, McCreary EK, 2001. Provance PG. Muscles: testing [79] Basmajian JV. Electromyography and function. 4th ed. Baltimore: of iliopsoas. Anat Rec [89] Vleeming A, et al. The posterior Williams and Wilkins; 1993. 1958;132:127–32. layer of the thoracolumbar fascia: its function in load transfer from [70] O’Sullivan PB, et al. Altered [80] Nachemson A. Electromyo- spine to legs. Spine 1995;20:753. motor control strategies in graphic studies on the vertebral subjects with sacroiliac joint pain portion of the psoas muscle; with [90] Lee D. The pelvic girdle: an during the active straight leg raise special reference to its stabilising approach to the examination and test. Spine 2002;27(1):E1–8. function of the lumbar spine. treatment of the lumbopelvic-hip Acta Orthop Scand region. 3rd ed. Edinburgh: [71] Norris CM. Spinal stabilisation: 1966;2:177–90. Churchill Livingstone; 2004. stabilisation mechanisms in the spine. Physiotherapy 1995;81 [81] Nachemson A. The possible [91] Beach P. The contractile field: a (2):72–9. importance of the psoas muscle new model of human movement. for stabilisation of the lumbar J Bodyw Mov Ther 2007; [72] Urquhart DM, et al. Regional spine. Acta Orthop. Scand 11(4):308–17. morphology of transversus 1968;1:47–57. abdominis and internal oblique. [92] Beach P. The contractile field: a In: Proc. Musculoskeletal [82] Gracovetsky S. An hypothesis for new model of human movement. Physiotherapy Australia Twelfth the role of the spine in human Part 2. J Bodyw Mov Ther Biennial conference. Adelaide; locomotion: a challenge to current 2008;12(1):76–85. 2001. thinking. J Biomed Eng 1985;3:205–16. [93] Beach P. The contractile field: a [73] Urquhart DM, et al. Abdominal new model of human movement. muscle recruitment during a [83] Gibbons SGT. The model of Part 3. J Bodyw Mov Ther range of voluntary exercises. Man psoas major stability function. 2008;12(2):158–65. Ther 2005;10(2):144–53. In: Proc. 1st International Conference on Movement [94] Brecklinghaus HG. The rowing [74] Urquhart DM, Hodges PW, Dysfunction. Edinburgh; 2001. style in ancient Egypt. Found: Story IH. Postural activity of the http//www.Somatics.de/ abdominal muscles varies BrecklinghausRowing. 71

Chapter Six 6 Salient aspects of normal function of the torso The spine or ‘backbone’ is the segmented connecting to the lumbar spine, without understanding the func- rod of the body common to all vertebrates. However, tional interrelationships between all four regions of man is unique, in being the only one to have evolved the spine. Control of the spine as a whole is also to a consistent upright posture on two legs upon mutually dependent upon control of the rest of the which the spine is further required to function both axial skeleton – the occiput, thorax and proximal vertically and horizontally in relation to the earth’s limb girdles – all function as part of an interrelated surface while balancing its super incumbent load. support and movement system. More specialized function of the limbs has evolved more complex function in the proximal limb girdles The spine performs many roles and as we have seen their control is intimately related to control of the spine. Rolf1 describes the In the process of phylogenesis and ontogenesis the spine as the ‘vital core that integrates the human spine’s structural architecture has evolved providing with his gravity environment poorly, well or ade- for its many roles. The process of our motor develop- quately as the case may be’. Its function is complex ment ensures the necessary spectrum of patterns of and various aspects considered important in facilitat- neuromuscular control needed to serve its various ing improvement in its control are explored. This is functions. Much of the current spine research is examined within four main functional components: involved with trying to dissemble and better under- • The axial spine stand these responses and how they are altered in • The pelvic girdle people with spinal pain. • The upper pole of the ‘body cylinder’ • Functional interrelationship between the upper The spine is a remarkable piece of structural bio- and lower body cylinder. engineering acting as the central support yet also capable of assuming different shapes in multiple Part A: The axial spine planes. It has been described as an unstable struc- ture stabilized by the nervous system.2 Its roles Structural mechanical aspects can be essentially distilled as providing: • A flexible yet stable central weight bearing The axial spine functions as a system column supporting and connecting the head and limbs and assisting load transfer between them. No one part of the spine functions independently. • Acting as a scaffold or lattice supporting The treatment of low back pain continues to pro- myofascial structures, it also helps distribute vide poor outcomes. Perhaps the focus of much of weight.1 the research and interventions has been too specific • Movements which enlarge the scope of head and limb movements.

Back Pain: A Movement Problem • Contribution to the support and function of the training effect and so on. Clinically, those with spinal breathing mechanism. pain have altered perception of a neutral spine and • Contribution to locomotion. Gracovetsky states difficulty achieving this throughout the spine. ‘the spine does not stop at L5. It goes all the way to the acetabulum’2 and acts as an ‘engine’ whereby The term ‘neutral zone’ was conceived by White the lordotic lumbar spine converts a lateral bending and Panjabi5 who defined control of the neutral moment into an axial torque which drives pelvic zone as ‘a low load response near or beyond the neu- rotation in walking.3 tral position. . . . up to the beginning of significant resistance . . . due to the application of a small • Its geometry and structure of alternating force’.5 Movement further into range is into the viscoelastic and firm elements allow it to act as a ‘elastic zone’ up to the physiological limit, after spring loaded shock absorber, while its elastic recoil which, ‘failure’ occurs. This is more likely with helps minimize the energy expenditure of the adoption of end range postures with or without locomotion and movement. superimposed movements. White and Panjabi5 state • It houses and protects the central nervous system ‘a significant amount of spinal motion takes place and supports the autonomic nervous system. When around the neutral position (which) is not accounted spinal function is healthy so is the person. When for’. In most usual everyday activities, a lot of the spinal joints are ‘out of kilter’, altered afference can required spinal movement ideally oscillates in and influence the function of the entire nervous system. around the neutral zone or ‘mid position’ of every spinal segment in the axial column under fairly The requirement for both effective stability and low loads and is directionally balanced. This is mobility is achieved through the interdependent important to recognize when facilitating functional function between the nervous, myofascial and osseo- neuromuscular control of the spine. The active ligamentous systems as has been suggested by Janda4 control of these small low load movements is largely and White and Panjabi.5 performed by the systemic local muscle system (SLMS). Larger loads and movements into the ‘elas- The spine is more centrally located within the tic zone’ involve more activity from the SGMS (see body than is generally appreciated. Its pyramidal Ch. 5). shape and frontal plane symmetry means it can sup- port, carry and control all its superimposed The spine comprises multiple weights.6 Maintaining control of the regions where functional spinal units (FSU) the curves change, particularly the thoracolumbar and lumbosacral is important in balancing the struc- Otherwise known as the motion segment, the FSU ture of the lower spine. The natural state of the is the smallest segment of the spine that exhibits lumbar spine is arched. Gracovetsky3 and Farfan7 the biomechanical characteristics similar to those have long stressed the biomechanical advantage of of the whole spine.5 It consists of two adjacent ver- the lumbar lordosis and hip extension for effective tebrae, the articulating surfaces between them – the upright activity. two facet joints, separated by an intervertebral disc, and the connecting ligamentous tissues. The behav- A neutral spine and the ior of the FSU is dependent upon the physical prop- ‘neutral zone’ erties of each of these components. Generally speaking, motion at any FSU is extremely limited While the spine can readily change its form, it is and consists of a small amount of gliding (transla- important that it is able to return to ‘home base’ or tion) and rotation.9 This occurs from a combination its neutral alignment. Here, the curves assume their of rocking through the disc30 and sliding of the physiologic position and act to balance one another; facets which act to steer the movement. The total the head is balanced over the pelvis such that there behavior of the spine results from the composite is minimal displacement from the line of gravity, behaviors of the multiple FSUs connected in series and minimal muscle work is needed to maintain the which constitute its structure. position. There is balance of all segments in all planes. The curves are characterized by a range Significantly, between each intervertebral level, defined by natural variability.8 This can also be influ- the spinal nerve exits through the intervertebral enced by differing postural habits, body types and foramen (Fig. 6.1). Here it has important relations. 74

Salient aspects of normal function of the torso CHAPTER 6 Ligamentum flavum the disc loses height the facet mechanics change. Effective clinical interventions generally result from Facet or restoring the movement in the facet and through zygapophysial joint the segment which reduces the inflammation and so the pain. Disc Movements of the axial spine A Nerve root The health of the spinal joints is largely dependent Spinal cord Posterior longitudinal ligament upon a variety of repeated small amplitude move- ments. Normal antigravity control is provided by a well Nerve root integrated normal postural reflex system including bal- anced activity between the deep and superficial muscle Ligamentum flavum Facet joint systems. The fine modulation of flexor/extensor co- activity provides the appropriate sagittal alignment of B the spine so that the occiput is balanced over the sacrum. This provides good foundations for movement. Fig 6.1  Functional spinal unit showing relations of the disc and particularly the facet joint to the spinal nerve from Spinal movements result from the contribution of the side (A) and above (B). small movements in some or all of the FSUs. Spinal motion is generally described as flexion/ extension, In the front is the intervertebral disc and adjacent lateral bending and rotation occurring in the sagittal, regions of the vertebral body. Behind are the facet frontal and horizontal planes respectively. Lateral or zygapophysial joints.10 Like any synovial joints, bending produces translation and rotation of the ver- these can become inflamed and swollen when the tebrae in the frontal plane as well as axial rotation vertebral mechanics change. This spinal joint because of the inherent properties of the FSU.5 inflammation not only disturbs local joint function but can also compromise the lumen of the foramen Functional movements are actually rarely pure and directly impact upon the spinal nerve creating plane, but variable combinations of these movements local and referred pain syndromes (Ch.12). The albeit within a primary movement direction, providing marked implications of facet inflammation are three-dimensional control. Axial movement is more understood when injecting saline into the joints of one of adjustment and sequencing through the spinal pigs produced an immediate reduction in paraspinal segments. Big movements are provided by the large muscle activity.11 Clinically, most spinal pain and multi-axial ball and socket joints. Problems ensue if related disorders stem from dysfunction of one (or their movement is reduced so that some regions of multiple) FSUs where, through altered loading, the spine become the axis of movement. both the disc and the facet are implicated. When In crude terms, all vertebrae consist of a body and a bony ring with processes containing the articu- lating surfaces. In each region there are differences in the size of the vertebral body and the orientation of the facet joints consistent with its load bearing role and which favors some movements over others. Kinematic differences thus occur within each region of the spine and in depth analyses are provided by numerous authors.5,9,12 Figure 6.2 shows the seg- mental and regional movement characteristics. Briefly: • Cervical. The most mobile region of the spine with freedom of movement in all three planes. • Thoracic. The facet shape affords more mobility in rotation and lateral flexion and least mobility in extension. Rotation freedom decreases in a cranio- to caudal direction.12 75

Back Pain: A Movement Problem Combined One side One side flexion/extension lateral bending axial rotation ( x-axis rotation) (z-axis rotation) (y-axis rotation) C0–C1 C2–C3 Cervical C4–C5 C6–C7 T1–T2 T3–T4 T5–T6 Thoracic T7–T8 T9–T10 T11–T12 L1–L2 Lumbar L3–L4 L5–S1 5º 10º 15º 20º 25º 5º 10º 15º 5º 10º 15º 35º 40º Fig 6.2  Composite summary of segmental kinematics and regional variations. Reproduced from White AA and Panjabi MM. 1990 with permission JB. Lippincott & Co. • Lumbar. Facet orientation favors movements in torsion and side bending. Ipso facto, these the sagittal plane – flexion and extension, with a movements involve corresponding movements in cephalocaudal increase.5 A recent study13 has both the spine and the pelvis. shown most segmental sagittal movement at L3/4 A decrease in the range of all spinal movements with increasing age is apparent.19 followed by L4/5. Side bending and particularly Pelvic (sacral) spatial position rotation are limited. Rotation has been shown to affects spinal alignment increase in flexed postures leaving all segmental The sacrum/coccyx forms the base of the spine. structures more vulnerable.14 However reduced The pelvis is partly formed by and in turn also sup- ports them and so control of its spatial position will rotation at the end of flexion and extension ranges affect the alignment and control of the whole spine, the lumbar spine in particular. This is the case for compared with that in the neutral position has all static and dynamic postures and movements in been shown.15 all planes both in relationship to the body and grav- ity. This is important to appreciate. While the static • Sacrococcygeal. The vertebral segments within picture does not necessarily equate to functional the sacrum and coccyx are fused, but there is a reality, the principles provide for conceptual ease fibrocartilaginous joint between them10 which and can be extrapolated to all spinal movements. allows flexion and extension deemed by some to be In the frontal plane when the pelvis is in the neu- largely passive16 while others see it as the most tral balanced position the spine is vertical, symmetrical mobile part of the pelvis17 Lee18 reported a MRI and balanced. If the pelvis is oblique or laterally tilted, study which showed flexion of the coccyx with pelvic floor muscle contraction and extension during a Valsalva maneuver or straining. The saccrum is stabilized in the pelvic ring which limits its mobility and provides stability. Movements of the saccrum/ coccyx principally involve those in the sagittal plane – nutation and counternutation with some 76

Salient aspects of normal function of the torso CHAPTER 6 the pelvis will shift to the high side, the lumbar spine • However, Rock20 suggests that in optimal functional alignment, the anterior superior iliac will side bend to that side. This in turn will then create spines move slightly in front of the symphysis which facilitates dynamic activity in the postural reflex compensatory adjustments throughout the spine – a mechanism. Here the shear forces imposed upon pronounced case of which is seen in scoliosis.23 the sacro-iliac joint (SIJ) are offset as the sacrum is suspended between the two innominates in slight In the sagittal plane the lumbar spinal curvature is nutation.18 clearly dependent upon pelvic tilt.23 A neutral lordo- • When the pelvis tilts anteriorly the lordosis increases.21 sis is achieved with a corresponding neutral tilt of the • When the pelvis tilts posteriorly the lordosis reduces and the lumbar spine flexes. pelvis. A neutral pelvis has been variously defined: Mutual behavior between the curves • When either the anterior iliac spines lie on a horizontal with the posterior iliac spines or the anterior superior iliac spine lies on a vertical with the symphysis pubis.9 • Rolf defines pelvic balance as a horizontal line between the coccyx and pubes and a vertical between the pubes and anterior iliac spine1 (Fig. 6.3). C - inclination of pelvis A change in one curve will generally be reflected in B the others. Try lying down on the floor with your knees bent. If you flatten your low back to the floor, 60º invariably your chin will poke forward and your neck hyper extend. If you increase the lumbar lor- 90º A dosis the neck will lengthen and the chin retract. A Gravity plane - horizontal This has implications for clinical practice. Black et al.22 showed this opposite relationship between C Right half lumbar and cervical posture in sitting – as the lum- B bar spine moved toward extension, the cervical spine flexed and vice versa. Marked stiffness in Left half the thoracic spine will modify this response. Fig 6.3  A balanced ‘neutral’ pelvis – reproduced from ‘Rolfing’ The junctional regions with permission Harper and Rowe New York 1977. According to Lewit,23 not all vertebral segments have the same importance for the functioning of the spine. There are ‘key segments or regions’, mostly the transition areas where the anatomy and the function in the column changes between very mobile and relatively immobile regions. These ‘junctional regions’ marry the transitions between the three principal units of body weight – the head thorax and pelvis. They accommodate forces while transmitting movement through the spine. They occur at the top and bottom of the segmented spine and the top and bottom of the thorax. Ideally, the line of gravity passes through them.24,25 Lewit maintains it is in these regions that the spinal column suffers first jeopardizing function of the spine as a whole, and causing sec- ondary lesions.23 They all share a common ten- dency to hypomobility or stiffness creating compensatory relative increased mobility in seg- ments adjacent and/or far removed. 77

Back Pain: A Movement Problem • The craniocervical junction (C0/1/2). These balanced upright spine they are aligned. The head are the most anatomically and kinematically is balanced on the occipital condyles and the coc- complex joints in the axial skeleton.5 They allow cyx through the pelvis is balanced on the femoral triplanar mobility, rotation at C1/2 and sagittal condyles. Ideally this relationship is also main- nodding of the occiput on the condyles being most tained in numerous other postures whatever the significant. In physiological terms the receptive field base of support. for the tonic neck reflexes which influence muscle tone throughout the postural trunk musculature lie The head and the tail bone can be viewed as mostly within the C0/1 and C1/2 joints.26 functional ‘limbs’. Thus there are six ‘limbs’ from Importantly, if function here is disturbed, there is which spinal movement may be initiated. Addition- frequently hypertonus of the ‘postural muscles’, ally the spine transmits sequences and adjusts disturbances of equilibrium and locomotor/ movements between the upper and lower body movement deficit23 which has to be compensated and between the various ‘limbs’. Hackney28 notes for elsewhere in the cervical spine. that in all movements both simple and complex, where the spine is a dynamic link between the • The cervicothoracic junction (C7/T1/2) where limbs and the upper and lower body, the ‘head the most mobile region of the spine, the neck, and tail are in a constant and always changing inter- joins the relatively immobile thoracic spine and active relationship’. where the powerful muscles of the upper limb and shoulder attach to the torso. Dysfunction over this Unhealthy spinal control is characterized by a junction contributes towards compensatory poor head/tail relationship, difficulty initiating movements in the neck and is implicated in movement from the six ‘limbs’ as well as controlling shoulder pain syndromes. the ‘centre’. • The thoracolumbar junction (T10/11/12/L1) Spinal loading and the control where the less mobile thorax joins the more mobile of forces in movement lumbar spine. Nature has attempted to soften the transition with the 11th and 12th ribs floating and White and Panjabi5 define load as ‘a general term bearing similarity to transverse processes. The describing the application of a force and/or upper facet joints of T12 retain the thoracic moment (torque) to a structure’. All structures pattern while the lower joints have the lumbar including the body are subject to forces and in pattern. According to White and Panjabi5 and the physical universe action and reaction are Bergmark,27 the highest torsional stiffness is always equal and opposite. Movement is loading. typically exhibited at this junction and the T12/L1 It can occur in response forces acting on the body FSU is a site of high stress concentration. which in turn creates other forces which further Clinically, it is a region which suffers badly from need to be controlled. While ‘forces’ and ‘loads’ both postural collapse and regional muscular may imply the idea of ‘maximal’, in the spine they holding patterns. Disturbed function here causes can be minimal occasioning merely a tonus shift to intense spasm not only of the back muscles but also counter them. the psoas23 in particular, as well as compromised diaphragm function. This is common and clinically Interested in structural balance and the mechan- important. ical forces which affected this, Todd6 says ‘the direction in which any force acts upon an object in • The lumbosacral junction (L5/sacrum) where relation to its internal axis determines the nature the relatively rigid sacrum joins the more mobile of the stress endured by the object’. She lists ‘axial segmented lumbar spine. Disturbance of the hip– and other stresses’. pelvis complex affects saccral kinematics which in • Compression and tensile stresses are called turn affects the kinematics of L5/S1 segment as axial as both operate along the axis without well as the alignment of the rest of the spine. changing it. In the skeleton the compression members are the uprights, the bones, and the The head–tail bone relationship direction of the forces is downward with gravity. ‘The tensile members are the suspensory parts The head and tail bone or coccyx represent which direct weight to points on the upright the top and bottom of the spine and in a well 78

Salient aspects of normal function of the torso CHAPTER 6 Tensile The role of the ‘passive tissues’ Compression These provide structural support and help counter the applied forces to the spine. Importantly, most exhibit viscoelastic behavior, in particular the disc. This means that when a constant load is applied to the tissues, over time they will deform or ‘creep’. The tissues are variably sensitive to the rate that the load is applied. The load can be tensile or compressive. When the load is removed the tissue may not recover and return to its origin dimensions, known as ‘hysteresis’. Both creep and hysteresis have been shown to increase with age.29 These phenomena play a significant role in spinal pain syndromes. The adoption of habitual altered posturomovement strategies creates chronic aber- rant loading of the tissues. Fig 6.4  Vertebral column as a spring. Balance of tensile and The vertebrae compression forces in the axial spine. Reproduced from “The Thinking Body” Mabel E Todd 1937 with permission from The architecture of vertebrae makes them well Princeton book company. designed to bear compressive loads, most of which is taken through the vertebral body although some which may be received and transferred to occurs through the facet joints.5,30 The vertebral the ground through the bones’. The direction bodies become progressively larger at the bottom of of tensile forces is opposed to gravity (Fig. 6.4). the spine and studies have shown these to be stronger in compressive loading as may be expected. Bone If these two forces are combined or directed in mineral content has been shown to increase in such a way as to interfere with the axis, three other response to mechanical demand.31 In general though, stresses may occur as follows: vertebral strength decreases with age.5 • Torsion where the tension or compression is so exerted as to cause the structure to twist about its The facet joints or posterior intervertebral axis which weakens the structure for support in the joints30 contribute to load sharing. The amount of area affected compressive load borne will depend upon the spinal • Shearing occurs when the force is directed at an posture and has been shown to vary between nil angle to its axis causing one part to slide over the (becomes tension loading in marked flexion) and other disrupting its axis nearly half the load in extension.5 Their geometry • Bending is a combination of tension and affords them a significant role in checking the ten- compression applied in such a way that the axis is sile, torsional, shear and bending stresses that the curved so that the structure is weakened for support. spine is subject to. It may be caused by an unevenly distributed load or a too top heavy load. It is the most serious of the The intervertebral disc stresses and the hardest to counter. Its design provides for the combined roles of weight The effect that loading has on the spine will also bearing and load transference while allowing depend on the duration and the magnitude of the multidirectional rocking movements between the force. These can be divided into two main categories:5 vertebrae. Besides compression, the dense annular • Short duration–high amplitude as in a jerk lift fibres act like strong ligaments and help resist ten- • Long duration–low magnitude as in postural sile, torsional, bending and shear stresses. However, collapse. combined loads make it more vulnerable. Flexion bending and torsional loads are probably more Loading can be static or dynamic. Dynamic loading harmful than compression,5 although both cyclic with a repetitive pattern is called cyclic loading. and high compressive forces in hyperextension 79

Back Pain: A Movement Problem have demonstrated disc damage.32 The disc also The dynamic role of the has the capacity to absorb and store energy, has neuromyofascial system elastic recoil and provides shock absorption30 and damping through the spine. In its healthy state, Fascial system acting as a tense pillow between the vertebrae, it assists the correct apposition of the facet joints The thoracolumbar fascia has been ascribed a bio- and so helps ensure their function and stability. mechanical role in the stability of the lumbar spine. Intradiscal pressure within normal physiological In fact, Gracovetsky37 considers it the most impor- ranges appears to provide an essential mechanical tant structure insuring the integrity of the spinal stimulus for maintenance of the proteoglycan machinery. Traditionally though, fascia has not been matrix and the consequent load bearing capacity considered as a system and accorded little impor- of the disc.33 As we age, the disc degenerates. This tance in musculoskeletal mechanics. However, can be apparent from the age of 20 and by the age there is growing interest in the potential major role of 50, 97% of all lumbar discs have been shown to that fascia may play in providing structural support, be degenerated, in particular the lowest three stability and contributing to movement coordina- levels.5 When the disc degenerates, the facet joints tion. It has been described as: tend to stiffen or can override, become sloppy and ‘unstable’. Segmental dysfunction involves the The soft tissue component of the connective tissue whole FSU – problems with the disc involve the system that permeates the human body forms a facets and vice versa. It is quite extraordinary whole body, continuous three-dimensional how this one structure has been assumed to be matrix of structural support. It interpenetrates the mainstay of most low back pain. Treatment and surrounds all organs, muscles, bones and directed at the movement impairment of the nerve fibres, creating a unique environment for whole segment invariably ameliorates the pain body systems functioning. It includes all fibrous while the radiological changes remain the same, connective tissues, including aponeuroses, being usual and age related. ligaments, tendons, retinacula, joint capsules, organ and vessel tunics, the epineurium, the Ligaments meninges, the periostia and all the endomysial and intermuscular fibres of the myofascia.38 Binding the vertebrae together, ligaments readily resist tensile forces in the direction in which the According to Rolf,1 there are different kinds of fibres run. As such they are also good at resisting fascial sheaths. The superficial is a fibroareolar tis- torsion, shear and bending. With the muscles, sue that houses much of the body fats, can stretch they share the role of providing stability to the in any direction and adjust quickly to strains of all spine within its physiologic curves and ranges kinds. The deep fascia is a denser layer, provides of motion including maintaining the relation- good resistance to tensile strain and its smooth coat- ship between each vertebra, protecting the spinal ing permits neighbouring structures to slide over cord and nerve roots. They demonstrate adaptive one another. She was particularly interested in the changes in response to increasing demand or fascial envelope surrounding muscle. Rolf1 and her immobilization.34 They are considered sensory disciples and those interested in biotensegrity39 organs and have significant input to sensation view the fascia as the prime organ of support and and reflexive/synergistic activation of muscles.35 the bones, rather than providing support in the Solomonow et al.36 demonstrated that mechanical Newtonian sense, act as spacers serving to position overload of spinal ligaments recruits local muscles and relate different areas of connective tissue. This in a protective response which increases with the may help explain how the ‘human spine can accept ligament stress. ‘The functional complexity of loads from any direction with arms and legs canti- ligaments is amplified when considering their levered out in any direction’.39 Muscles provide inherent viscoelastic properties such as creep, the source and direction of movement and as they tension–relaxation, hysteresis and time or fre- are encased within it and attach to it, they can act quency-dependent length-tension behavior’.35 as tensioners to the system. Variously described as Dysfunctional ligaments thus result in various the ‘internet’,40 ‘the endless web’,41 ‘a spider’s sensorimotor disorders. web reaching out to every nook and cranny’,42 being 80

Salient aspects of normal function of the torso CHAPTER 6 a continuous system – a force applied to one part or position and movement of joints; to sense the force a local restriction – can have quite far reaching as effort and heaviness associated with muscle contrac- well as local effects. The anatomical continuity of tions; and the ability to perceive the timing of mus- the myofascial and viscerofascial systems as well as cle actions.49 Exteroception comes through the the neuroanatomical relationship of somatic and vis- senses with which we orient ourselves to the envi- ceral structures mean that recruitment patterns of ronment and the sense of space around us – vision spinal muscles may change due to dysfunction of labyrinths and touch. structures outside the musculoskeletal system.42 Effective motor control is dependent upon ade- Artificially increasing the tension in the lumbar quate peripheral afference from receptors in the fascia has been shown to alter lumbar segmental joints, ligaments, fascia muscles tendons etc so that translation and rotation.43 Fascia is also capable of the magnitude and timing of the muscle response is remodeling in response to changing mechanical appropriate to the loading conditions. The various loads and muscle activity.44 Recent research has kinesthetic receptors are in tissues which are visco- demonstrated the presence of smooth muscle like elastic and the adoption of slouched postures has contractile cells in fascia with higher densities found been shown to subsequently affect subjects’ abil- in the lumbar fascia indicating its ability to influence ity to reposition their spines.50 Normally we can musculoskeletal mechanics.45 Smith46 provides a accurately spatially position our spine and this is seductive view of its role: ‘fascia is now seen as an independent of the magnitude of the range of antagonist to muscular action, and movement is movement.51 Brumagne52 has shown that precise seen less as the coordinated action of antagonistic muscle spindle input from multifidus is essential muscles and more in terms of the elastic and oscilla- for accurate positioning of the pelvis and lumbosa- tory properties of the myofascial network as a cral spine in sitting. whole’. As well as its static attributes, fascia ‘has the potential for certain rhythmic or oscillatory The neuromuscular system essentially deals with movement patterns that arise from its elastic, balancing the intrinsic and extrinsic forces imposed hydraulic and tensegrity properties’. ‘These inher- upon the body as a result of gravity, movement ent rhythmic movement patterns are independent and loads. This system is fragile and its dysfunction, of muscle activity. However, they may be either according to Janda,53 is one of the first signs to be reinforced or inhibited by muscle action’. ‘Muscular clinically recognizable and is responsible for the gen- action works primarily to maintain the oscillatory esis of many spinal pain disorders. There are certain patterns with an occasional and timely input of normal neuromuscular responses relating to spinal energy each movement cycle’. The whole body control which merit looking at. response seen in Craniosacral Therapy47 is based upon the concept of a fascial continuity throughout Aspects of normal the body. Gracovetsky48 remarks ‘it is the viscoelas- neuromuscular behavior tic behavior of collagen that drives the stability of around the spine the spine. . . the integrity of the collagen structure is as important as that of the muscles’. The fascial Muscle coactivation or system appears to serve as the structural and func- cocontraction (see Ch. 4) tional link between the frank passive and active tissues in movement. Neuromuscular system This is a normal muscle response from the trunk muscles in order that the spine may be controlled This interdependent system converts a structural in a stable neutral posture54 and ready to respond body into a functional body. to the complex and unexpected loading patterns during our everyday activities. The column is sup- In our relationship with gravity, the body is con- ported and controlled from all sides. Activity at low stantly adjusting to changing circumstances. We do load states is primarily in the deep SLMS and as this through information coming from our senses, the load increases so does the magnitude of the co- from within (proprioception) and without (extero- activation, as the superficial muscles become more ception). Proprioception essentially provides posi- involved. Antagonistic trunk muscle coactivation tion and movement sense. It allows us to sense the 81

Back Pain: A Movement Problem occurs during sudden loading of the torso, accelera- the passive tissues. In functional movement, is the tions of the torso as in slipping, isometric trunk flexion relaxation response different? Is it partly a moments, axial torques and heavy exertions in order consequence of decreased SLMS coactivation syner- to provide the necessary stability.54 Co-contraction gies affording poor adaptable support and control is a normal response to fatigue as the spine attempts where limiting pelvic shift and locking the legs to protect itself.55 However, Radebold et al.56 allows one to utilize the passive system more than showed that sudden perturbations to the trunk in is healthy? normal people produced more flexible muscle recruitment responses in the superficial muscles O’Sullivan et al66 have examined the response and did not necessarily involve co-contraction. Their when moving from sitting upright to slumped sit- study did not access the deeper muscles. ting. They found that superficial multifidus and internal oblique – both important in segmental con- At high loads, trunk muscle coactivation resem- trol, exhibited a consistent and significant decrease bles muscle guarding or splinting and spinal motion in activity at mid range spinal flexion. The thoracic is limited. Quint et al.57 showed this can be reduced erector spinae response was highly variable with by as much as 20%. High levels of co-contraction several different patterns of activity demonstrating have been shown to degrade postural control.58 the variable and complex nature of motor control. While stabilizing the spine to manage heavy loads, They found that adopting a neutral lordosis in sit- it imparts a high compressive loading on the spine. ting, best facilitated activity in the deep system In the normal state this is not a problem, as they muscles. are generally short lived to say lift a box, or prevent a fall. The reflex muscular responses to arousal/stress Flexion relaxation phenomenon Arousal, a state of internal alertness, is a component Studies have shown that when standing still and of several emotional responses including fear and bending forward, the low back extensors eccentri- anxiety and is mediated by the neuroendocrine sys- cally contract and then fall electrically silent, the tem and includes the limbic system.67 The level of load then being borne by the passive tissues – liga- arousal can vary from deep sleep to the fight-or- ments, disc, gut and some elastic recoil in the mus- flight response. The body and mind are inextricably cles,59 and the fascial system.60 The point in the linked, our emotions being reflected in our neuro- flexion range where this occurs is variably reported muscular being. Stress is a natural phenomenon as between two-thirds of maximum trunk flexion and necessary for our survival. There is a normal (and corresponding half-range hip flexion),61 to near cyclic variation between periods of stress when we the end of trunk flexion.59 The relaxation effect has are aroused and periods of relaxation where also been reported to include the hamstrings and depleted energy is restored. In times of stress or much of the thoracic erector spinae.60 However, hyper arousal, the sympathetic system is activated relaxation of the lumbar extensors associated with initiating a ‘fight or flight response’. This occasions reciprocal thoracic erector spinae activation has also an increase in the cardiac and respiratory rate and been found.62 Bogduk et al.63 estimate that the tho- other bodily changes to get ready for action. Hyper- racic erector spinae contribute to 50% of the total ventilation is part of this normal reaction to sudden extensor moment exerted on L4/5. Andersson danger or excitement. There is over activity of the et al.64 found that quadratus lumborum did not general body musculature, particularly of the facial relax with the lumbar extensors suggesting a pos- and jaw muscles, neck and shoulders. Activity in tural stabilizing role for this muscle.59 the SGMS predominates. The upper limbs are held in flexion, the trunk is generally held stiff and because Limiting the posterior shift of the pelvis and hip of tension in the abdominal musculature, diaphrag- flexion has been shown to produce the response ear- matic breathing can be inhibited and replaced by lier in range.65 While a lack of this response is a upper chest breathing.68 Classically adduction and common finding in subjects with LBP suggesting flexion patterns are symptomatic of stress.68,74 The an increased ‘protective’ role from the superficial higher levels of muscle activation found in states extensors, it is not universal. The question needs of increased arousal have been shown to decrease to be asked as to the desirability of depending on 82

Salient aspects of normal function of the torso CHAPTER 6 performance in highly anxious subjects yet improve it vertical axis of the body, their closure blocks the in those less anxious.67 adaptive responses to gravity through the body. Again, these reactions are characterized by associated over Repeated exposure to stress creates a risk that activity in the superficial systemic global muscle stress changes from a natural transient reaction to system (SGMS). When repeatedly triggered, which a chronic pathological state. The person finds it dif- is indeed common in today’s stress inducing society, ficult to relax. Symptoms such as hyperventilation these basic responses easily become habitual behavior. syndrome become common and will have effects As Hanna says: on the whole body including the neuromuscular sys- tem.69,70,71 The line between normal and abnormal Habituation is the simplest form of learning. It behavior becomes blurred. occurs through the constant repetition of a response. When the same bodily response occurs The protective and defensive over and over again, its pattern is gradually reactions ‘learned’ at an unconscious level. Habituation is a slow relentless adaptive act which ingrains It is a basic instinct of all animals and humans to itself into the functional patterns of the central protect or defend themselves when threatened. nervous system.72 Hanna72 was influenced by Selye’s statement And this occurs in ‘normal’ ‘healthy’ as yet ‘pain that stress is a response to good things as well as free’ people! bad. He describes stress as being both positive and negative and creating a specific reflex response of In states of acute pain, we are all familiar with the neuromuscular system in two basic ways: the need to protect, guard, splint and ‘hold • Positive or ‘eustress’ is the action and perhaps against’, particularly if we sense the pain ‘is causing effort response which primarily activates the damage’. This is generally associated with reflex extensor muscle system. It is assertive behavior and breath holding. If pain persists the risk is that the Hanna termed it the Green Light Reflex. Its splinting and holding persist. These responses are specific effect is the habitual contraction of the important when working with patients both with back muscles – the extensor system. It contributes manual treatment and therapeutic directed exer- to a ‘posture of defense’. cise. Accessing painful joints and stiff regions can • Negative or ‘distress’ creates a basic provoke discomfort. The art of the therapist is to neuromuscular withdrawal response which gauge the right degree of intervention so that these primarily occurs on the front of the body. It is a responses are not triggered. The patient’s belief primitive reflex of survival – a ‘rapid motor act’ that systems regarding pain being ‘good’ or ‘bad’ can helps our survival by withdrawing from danger. further sensitize the response or otherwise. It is Hanna termed it the Red Light Reflex – a protective also common to see these reactions being triggered response to negative events which threaten us such during many fitness endeavors such as gyms and as fear and anxiety. It is associated with a reflex some yoga studios where being pushed beyond contraction of the abdominal muscles which pulls one’s capability engenders features of unconscious the trunk into more flexion, depresses the chest, ‘defending’ and ‘holding against’ in the motor response inhibits activity of the diaphragm and so causes patterns. shallow breathing. It contributes to a ‘posture of protection’. Trauma will invoke a protective Effort response response guarding against pain, e.g. trunk list. These are unconscious, involuntary rapid reflex motor acts Movement should on the whole be easy and effort- which primarily affect the muscles around the body’s less, achieved from well integrated activity between centre of gravity. the SLMS and the SGMS. When performing a task that requires a high level of effort, there is a spread Bond40 suggests that the horizontal, crosswise of activation to other muscles besides those princi- muscles (the vocal, thoracic and pelvic diaphragms) pally responsible for the task. This enhances pos- are the sites of our most internal motions of protec- tural stability and enables the transfer of power tion as they constrict whenever we hunker down across joints by the two-joint muscles.67 under pressure. Acting like valves through the 83

Back Pain: A Movement Problem Laban73 was interested in the economy of effort configuration changes. The smaller and the more afforded by the use of appropriate motor skills. Effi- unstable the base of support (see Ch.4) the greater ciency is gauging the right proportionality of weight, is the demand from the control system. The central space, timing and control of the flow of movement. nervous system (CNS) automatically attempts to The inherent rhythm in movement is important and control the orientation of the head and trunk with is disturbed by the use of excess and unnecessary respect to the gravity axis. The magnitude of the effort. ‘Any inappropriate use of movement is just perturbation both intrinsic and extrinsic and its a waste of effort.’73 The harder we work the more duration will determine the relative contribution the SGMS is called into action, a feature of their from the deep and superficial systems. If SLMS innate behavior (see Ch.5). In times of higher load- activity is reduced, it is common to observe central ing they serve to provide the added stiffness the ‘holding patterns’ in the torso which will com- spine needs. However, the amount of effort promise the equilibrium responses in the torso. expended needs to match the demand of the situa- Too much trunk muscle coactivation degrades tion. People with a poorly integrated systemic local postural control.58 Habitual postures influence how muscle system rely more on their SGMS and so muscles are recruited and coordinated for recovery tend to use more effort than necessary in low load of stability. activities and with unhealthy kinematic patterns. Importantly, those actions requiring increased Todd6 notes that upright equilibrium occurs effort, should involve the adoption of biomechani- when the pelvis can act as a mechanical de-coupler cally sound movement patterns. and freely swing between the spinal axis and the leg axis which are not in continuous but parallel Often, when a person ‘tries to please’ and ‘tries planes. These axes result from the effects of gravity, too hard’ he invariably activates a neuromuscular bones muscles, ligaments and fascia. All are involved response which is more effortful and SGMS domi- in maintaining a balance between the compression nant than is required by the situation. Excess effort forces coming down through the spine at the back in movement leads to grosser movement. This is a and the tensile forces being transmitted up the common response in people being directed in exer- front. The two planes should be parallel to the line cise, whether it is therapeutic or recreational. of gravity which bisects the body vertically through the three main centres of weight. Keeping them Postural equilibrium parallel and close together will bring all joints of the connecting parts into the best mechanical rela- Feldenkrais noted: ‘human upright posture is a tionship and equilibrium (Fig. 6.5). dynamic equilibrium . . .our nervous system as well as our body works to restore equilibrium rather than Ideal alignment of the body segments minimizes to keep it.’74 How we physically organize ourselves the effect of gravitational forces and reduces the in relation to gravity is reflected in both our posture amount of muscle activity needed to remain upright and our breathing. The primary breathing muscles and for equilibrium. are also postural muscles. The body constantly adjusts to the disturbance created by breathing and Most of the postural stability control research has so even in the ‘static’ state there is always a degree been conducted in standing. Functional equilibrium of movement in the form of small oscillations of pos- is necessary in all manner of ‘postures’. Vertical tural sway. In adulthood, for most functional tasks we equilibrium has been examined in the following maintain a vertical orientation of the body. In the pro- ways: cess of establishing and maintaining this verticality we use multiple sensory references including gravity • Changes in the amplitude of postural sway (the vestibular system), the support surface (the during quiet stance. Traditionally, small amplitude somatosensory system) and the relationship of our movements of the body reflected as the centre of body to objects in the environment (visual system).75 pressure over the base of support (BOS) have been seen to reflect ‘good’ control of balance and larger Postural stability or balance is the ability to main- amplitude movements to reflect ‘poor’ control.75 tain the body in equilibrium in both ‘static’ and When sensory inputs are decreased the centre of dynamic states and this will change as the body pressure motion tends to increase. • Motor strategies as a response to perturbed stance. Characteristic patterns of synergistic muscle activity occur in response to perturbation. 84

Salient aspects of normal function of the torso CHAPTER 6 Compression forces are transmitted down the spinal axis Spinal axis Too long Compression Compression Too short Pelvis Balanced muscle Pelvis in forces (only those very slight Pelvis anterior tilt acting anteriorly Too long are shown) Hip joint axis of rotation Too short Tensile Tensile L.O.G L.O.G B C Leg axis Tensile forces are transmitted up the leg axis Line of gravity A Fig 6.5  The pelvic cantilever should swing freely between the spinal axis and the leg axis. (A) Imbalance in the tension elements disturbs equilibrium (B) and (C). Adapted from Todd ‘The Thinking Body’ with permission from Princeton Book Company. Anteroposterior stability gastrosoleus, hamstrings, and finally the The common patterns of response are: paraspinal muscles to return the body mass • The ankle strategy. Here anteroposterior stability is regained by a sequential firing of the over the BOS. It is apparently most commonly used when perturbations to equilibrium are small and the support surface is firm.75 Adequate 85

Back Pain: A Movement Problem ankle mobility and strength is required for early in vitro studies which found buckling occurred effective control. at fairly low forces. Related studies and Panjabi’s • The hip strategy. This strategy controls motion of influence,78,79 has lead to the current concept of the centre of mass of the body by producing large and ‘instability’ and that the spine is ‘not stiff enough’. rapid motion at the hip joints with anti phase In fact clinical practice and some of the recent rotations at the ankles.75 The hip strategy is used in research shows that parts of it at least, are ‘too stiff’. response to larger faster perturbations, or when the support surface is compliant or smaller than the feet Gracovetsky2 points out that ‘it is not clear to what as when standing on a beam. Artificially increasing extent the hypotheses underlying these engineering hip and trunk stiffness has shown reduced balance ‘stability’ theories are appropriate for viscoelastic control and increased arm movements to regain structures. Current concepts of musculoskeletal sta- stability.76 Poorly integrated lumbopelvic–hip bility are developed without considering the advan- control including hip stiffness as well as tages of being an unstable structure stabilized by hyperstability of the trunk through muscular a complex control system’. The process of our motor ‘holding’ patterns will obviously jeopardize balance.77 development ensures the necessary spectrum of pat- • The stepping strategy. When the closed chain terns of neuromuscular control needed to serve its strategies are insufficient a step or a hop are used to function. return the BOS back under the centre of mass of the body. This may be a more common response in Similarly, Todd6 suggests that the living being people with back pain – changing the BOS seems maintains its stability because it is excitable and easier than resolving the perturbation through the capable of modifying itself according to external sti- body? (See Ch. 3.) muli and adjusting the response to the stimulation. Slight instability is the necessary condition for the Researchers believe that in normal people, combina- true stability of the organism. Bond40 suggests that tions of all three strategies are used in controlling if our perceptual orientation to our surroundings is sagittal displacements.75 These anteroposterior insufficient, we compensate by stabilizing too much, responses are organized in a distal to proximal the muscle contractions serving to diminish our manner. dimensions making our bodies shorter, narrower flatter and effectively closing them. Movement has Mediolateral stability limited expression. Here control occurs primarily through the hip, pel- Various dynamic mechanisms are proposed to vis and trunk as there is little mediolateral move- contribute to the spine’s stability and function and ment in the knee and ankle. Apparently these are explored. show a descending response organization, with head movements occurring first, followed by those in the The intra-abdominal pressure hip and the ankle. Head movements occur in the mechanism (IAP) opposite direction to those at the hip and ankle.75 Of significance is the clinical observation that many This was first proposed by Bartelink80 as a mecha- with back pain have altered head control and ability nism to protect the spine when lifting heavy loads. to control lateral weight shift. Stability is therefore It is a ‘high load’ strategy. Utilizing a natural reflex likely to be predictably compromised. response the Valsalva maneuver, intra-abdominal pressure can be voluntarily increased by vigorous Spinal stability: examining contraction of the abdominal muscles against a proposed mechanisms which closed glottis, creating a rigid vertical column of contribute control high pressure within the abdomen that pushes up against the diaphragm and down against the pelvic It has been said that structures build their needs. floor.12 Acting as an inflated ‘intra-abdominal bal- However, the human spine is often seen to be a loon’ this mechanism was proposed to support the complex mechanical structure which is inherently spine from the front and partially reduce the unstable. This notion probably stems in part from demands on the lumbar extensor muscles and so lower the compression forces on the lumbar spine. However because strong abdominal activity creates a flexion torque on the spine, increased co-activity 86

Salient aspects of normal function of the torso CHAPTER 6 in the extensors is also necessary to counter this, in both expected and unexpected loading. They creating overall increased myogenic compression and direct splinting on the lumbar spine. While a concluded that the increased IAP was part of a useful short term strategy to achieve postural stabil- ity and protect the spine against high loads, the vital feed-forward postural response designed to improve function of respiration is sacrificed to it,23 hence it becomes a problem if used long-term. Thompson81 trunk stability. The further work of Richardson noted that global abdominal bracing may overcome Hodges et al86,87 has helped provide increasing evi- pelvic floor activity causing the floor to descend. The realization that the generation of this mechanism dence about activity of certain muscles in the deep as originally described, depended upon a strong/vig- orous abdominal activation probably spawned some system (SLMS) and our understanding of possible of the confused beliefs about the ‘necessity for strong abdominals if you have back pain’. mechanisms of spinal support and control in so A study by Marras and Mirka82 found that IAP called ‘low load’ states. Hodges has examined the levels only significantly increased in response to sig- postural support role of the diaphragm88–91 and nificant trunk asymmetry, torque and velocity. The transversus abdominus in generating IAP.92 Allison idea that stiffness equates to stability was further et al.93 also found postural activity in the dia- explored by Cholewicki et al.83 who reported lum- bar stability under sudden loading is augmented by phragm. Similarly postural responses have been voluntary increase in IAP plus increased coactiva- observed in the pelvic floor muscles.94 In response tion of muscles belonging primarily to the more superficial system (SGMS). The pressure increase to axial perturbation, co-activation between the dia- can only be optimal if there is sufficient coactivation of the diaphragm and pelvic floor. It is an example phragm, transversus abdominus and the pelvic floor of a strong postural splinting role for the diaphragm and the pelvic floor. During the Valsalva, the glottis occur and raise IAP in the low load state as part may be closed with the diaphragm in either the inspiratory (descended) position or expiratory (ele- of a feed-forward anticipatory postural control vated). Hagins et al.84 reported that during lifting, response.92,95,96 Notably, these responses occurred higher levels of IAP were reached by inhalation both in inspiration and expiration. Hodges et al.90 and holding the breath over natural breathing or holding in expiration. also artificially increased IAP by electrical stimula- It is important to recognize that in creating a tion of the diaphragm, without concurrent activity ‘rigid muscular cylinder’, the spine is indeed ‘stable’ but the body constricted, compromising the free of the abdominal and back muscles, and demon- descent of the diaphragm and the important func- tions of breathing, continence and equilibrium. strated a trunk extensor moment the size of which The low load postural response was proportional to the increase in IAP, confirming model of IAP: a function of the SLMS the diaphragm’s contribution to IAP and spinal sta- IAP is also elevated during many fairly ordinary bility. Hodges has been particularly interested in everyday activities. Cresswell et al85 found that in the role of transversus abdominus.92 He describes response to sudden unexpected and expected ven- tral and dorsal trunk perturbations, there was an its activity as ‘reducing the circumference of the automatic increase in IAP well in advance of the anticipated extensor torque production. Transversus abdominal wall; flattening the abdominal wall in abdominus was always the first muscle to be active the lower region to increase IAP and tensioning the thoraco lumbar fascia; control of the abdominal contents and respiration’.97 Its influence on segmen- tal stability can only be in a general, non direction specific manner.92 Rather than a torque producer, transversus ‘is considered to have its major effects on lumbopelvic stability via increases in IAP and fas- cial tension and via compression of the sacroiliac joints and potentially the symphysis pubis’.87 This author considers its role in pelvic control very signif- icant. Hodges draws attention to the importance of coactivation of the diaphragm and pelvic floor accompanying transversus activation; otherwise there will be minimal effect upon the creation of IAP and fascial tension. This, he graphically repre- sented by the ‘abdominal canister’ in Figure 6.6. Also important is that the postural activity of transversus, diaphragm and pelvic floor muscles is also coordinated with their role in respiration. During quiet inspiration, the diaphragm and PFM concentrically contract in order to maintain the integrity of the continence mechanism against the 87

Back Pain: A Movement Problem anticipatory postural control of the spine. IAP, local muscle activity and fascial tension control vertebral movement without restricting overall movement.98 Rather than maximal stability, dynamic control provides more optimal stability. The breathing mechanism: the central role of the diaphragm in breathing and related postural support Fig 6.6  The abdominal canister: The diaphragm, transversus Stability and control of the torso are inextricably linked abdominus muscle and pelvic floor muscles. with vertical posture and breathing.1,6, 23,46,74 Breath is the most basic movement of life. Gravity is the most rise in IAP.98 However, the inspiratory PFM activity basic force.100 Breath and posture influence one may not be identified in all individuals, the tonic another. Both should be natural and effortless. This activity and passive tension in the floor being depends upon freedom and coordination of the mus- sufficient to meet the demands of IAP.98 This cles involved and no unnecessary antagonist activity. PFM activity creates a slight sacro-coccygeal counter- The breathing mechanism is highly sensitive to changes nutation partly explaining the respiratory wave in the other body systems, readily reflecting the status (p. 92, 108). While expiration is generally passive of the psyche and the soma which includes the muscu- recoil during quiet breathing, the transversus is the loskeletal and the internal organ/endocrine systems. first muscle recruited when expiratory flow or volume is increased.99 When respiration is increased, IAP Breathing underlies the expression of us – it is increases biphasically – on inspiration (as described the link between motion and emotion.101 ‘Breath- above) and also on expiration associated with the con- ing’ is in general, poorly understood. traction of the abdominal muscles, particularly trans- versus with coactivation again from the PFM to help Normal quiet breathing at rest principally involves increase IAP and elevate and lengthen the dia- inspiratory activity of the diaphragm.10 Expiration is phragm.98 Hence complex patterns of coordination considered to occur from the passive elastic recoil between the diaphragm, PFM and transversus cre- of the lungs and chest wall97 the effects of gravity16 ates a modulated, oscillating concentric/eccentric and eccentric activity of the inspiratory mus- interplay between them and varies according to cles.10,102 When the respiratory demand increases, demand. If one part of the synergy is inappropriately so does the rate and depth of inspiration and expira- overactive or underactive, stability, respiration and tion becomes an increasingly active component. continence will be compromised. When not exerted, the average normal breathing rate is between 10 and 14 breaths a minute.110 Breathing Hodges work demonstrates that rather than the rate and volume fluctuate in response to physical or magnitude of the response being important, it is this emotional demands but normally return to relaxed balanced co-activation and the early timing of IAP patterns when the stimuli cease.70 Breathing should that is an important component in feed forward or occur through the nose which also has a facilitatory effect on the diaphragm.102,110,111 The overall body posture and flexibility of the thoracic cage greatly affect the quality of breathing. According to Cumpelik,103 establishing postural function is a prerequisite to addressing breathing function. If the posture is ‘right’ the breathing will follow. The inspiratory muscles The principal muscle is the diaphragm10 aided by the external intercostals16 and the parasternal inter- costals.104 Classified within the systemic local 88

Salient aspects of normal function of the torso CHAPTER 6 muscle system (SLMS) they are active at all intensi- combined muscle action around the inferior thoracic ties of breathing. As respiratory demand increases outlet strongly depresses the thoracic floor, deflates the upper secondary accessory muscles of inspiration the rib cage, and narrows the diameter of the thoracic become sequentially active – the scalenes; sternomas- outlet. The same is involved in all expulsive acts toid; upper trapezius, pectoralis major and minor; (vomiting, coughing, sneezing etc.) as well as the serratus posterior superior; superior fibres of iliocos- Valsalva manoeuvre.10 The central torso becomes talis; and if the upper limb is fixed or elevated, sub- cyclically constricted and hyperstabilized. Note that clavius and omohyoid, the inferior fibres of serratus most belong to the SGMS. Spatially, they are all anterior; and the latissimus dorsi.10,16,70 Additionally ‘below’ or lower than the diaphragm. the longissimus and iliocostalis may work in synergy to extend the thoracic spine and facilitate a greater In summary, quiet breathing occurs because of range of rib motion.10 Note that practically all these contraction and relaxation of the diaphragm in muscles belong to the SGMS (see Ch.5). Architectur- the centre of the torso supported by appropriate ally, they are ‘above’ the diaphragm and assist in lifting SLMS activity. Of the abdominal muscles, trans- the ribs. versus has the lowest threshold for respiratory activity.98,99 As the respiratory demand increases The diaphragm needs stable points of attachment so does the superficial SGMS activity above and from which to work, and this is provided by the below the diaphragm around the superior and transversus, psoas and quadratus lumborum (as it inferior thoracic outlets in order to increase both anchors the 12th rib) and the levator ani and the coc- inspiration and expiration and pump more air in cygeus and the deep segmental extensors. It is sug- and out (Fig. 6.7). gested that collectively, these should be termed the ‘lower primary accessory muscles of inspiration’6 as There are three primary breathing patterns102 they form important stabilizing synergies of inferior support around the thoraco lumbar junction and • Abdominal – known also as diaphragmatic lumbar spine and all share fascial connections or breathing. It represents the first stage of the interdigitating fibres. Importantly they all belong to diaphragm’s activity (see p. 92). This is the most the SLMS and have an equally important postural role energy efficient taking up less than 5% of the body’s in supporting and adjusting the torso in response to energy to breathe. There is little or no movement of the subtle oscillatory disturbances resulting from the chest at rest. the breath through to the more overt dynamic adjust- ments. Allowing these oscillations to be reflected • Lateral costal breathing comes into play with in the body promotes postural buoyancy and ease in increased air flow when singing or exercising etc. movement. As these oscillations involve subtle This represents the second stage of the diaphragm’s weight shifts, the receptors in the soles of the feet activity. There is noticeable lateral expansion of the are cyclically stimulated; refuelling the antigravity lower thorax through the ‘bucket handle’ action of response which includes activation of the dia- the lower ribs. phragm103 and so dynamic breathing and posture rhythms are set up. • Apical or upper chest breathing – can take up to 30% of the body’s energy as it involves a lot of The expiratory muscles secondary accessory muscle use. Here the chest expansion is more in an anteropostero direction due The primary muscles of active expiration are the to the ‘pump handle’ action in the upper ribs. internal intercostal muscles16,104 and transversus thoracis.12 As demand increases so does activity in These normal physiological responses are mixed the lower secondary or accessory muscles of expira- and matched in all sorts of combinations with move- tion; the abdominals (transversus10 internal and ment patterns appropriate to the functional task. All external obliques, rectus abdominis16); and muscles muscles of the body can assist in breathing when the over the thoracolumbar region – the lower fibres of need is great, but in the primary patterns of move- iliocostalis and longissimus; serratus posterior infe- ment, the upper accessory muscles are the last to rior and quadratus lumborum.1 One can infer that it be called upon. is the ‘upper abdominals’ rather than the ‘lower abdominals’ which are most dominantly active. The Diaphragm The diaphragm is universally acknowledged as the prime muscle of inspiration, is responsible for about 70–80% of the work of inspiration.12 It also pro- vides support in postural control89,105 (Fig. 6.8). 89

Back Pain: A Movement Problem Principal upper secondary muscles of inspiration Sternocleidomastoid Scalenes Upper trapezius Pectoralis minor (and major) Primary inspiratory muscles External intercostals Diaphragm Lower primary accessory muscles of inspiration Spinal intrinsics Quadratus lumborum Transversus abdominis Psoas major Fig 6.7  The primary, lower primary accessory and upper secondary accessory muscles of inspiration. Its anatomy and hence function are often difficult than the front.106 The muscular fibres are on the to grasp as it a three-dimensional musculofibrous periphery and arise from the circumference of the sheet forming an irregular dome which separates inferior thoracic outlet, the lumbar spine and related the internal body space into two cavities. Its struc- fascia and all converge to insert into a central sheet ture has been likened to a lopsided mushroom with like tendon. The diaphragm’s muscular fibres can its stem nearer to the back margin than the front6; be grouped into three parts based on their bony the back of the irregular dome being more developed attachments:10,12 sternal; costal and lumbar and have 90

Salient aspects of normal function of the torso CHAPTER 6 Sternal part of diaphragm Sternocostal triangle Central tendon of diaphragm Caval opening Left phrenic nerve Diaphragm Esophagus Right phrenic nerve Median arcuate ligament Costal part of Abdominal aorta diaphragm L1 Medial arcuate ligament Greater splanchnic L2 Left crus of nerve diaphragm Lesser splanchnic L3 nerve 12th rib Right crus of L4 Lateral arcuate ligament diaphragm Psoas major Quadratus lumborum Fig 6.8  The diaphragm and its attachments. different lengths and directions and so the effects of postural control. Continuous fascial connections their contractions differ. have also been described extending from the pelvic Extending as high as the 7th rib and as low as L3, the diaphragm provides a lot of internal myofascial floor, up through the diaphragm, mediastinum up ‘shoring up’ over the thoracolumbar junction to help to the occiput.70,100 spread the load of the ‘thoracic barrel’ meeting the ‘lumbar stem’. It significantly influences both static Its actions bear closer analysis. When the dia- and dynamic function of the torso. phragm contracts, it can move the tendinous central Its sole motor nerve supply is the phrenic nerve (C345), with sensory fibres coming from the lower dome, the base of the rib cage, the lumbar spine or a six or seven intercostal nerves.10 Any mechanical combination of all three.102 The costal fibres appear interference involving the nerve or its immediate to play the prime role in expanding the rib cage108 relations throughout its course can influence the behavior of the diaphragm. Similarly, any acutely while the crural region probably provides more irritable joints between T7 and L3 can also signifi- cantly affect its function. direct postural support through its attachment to the lumbar spine.109 Clinically its overall action The intimate relationship and fascial continuity that the diaphragm enjoys with the transversus appears to lengthen the spine and ‘open the centre’ abdominus, psoas and quadratus lumborum impli- cate a close functional relationship between all of providing important internal postural counter sup- them in the mechanics of breathing as well as port for the muscles of the torso. Essentially, con- traction of the muscle fibres of the ‘stem’ and the ‘rim’, creates a piston like action where the muscu- lotendinous sheet descends in the body cavity rather like the plunger in a coffee pot increasing the vertical, anteroposterior and particularly trans- verse diameter of the central body16 while drawing 91