KATCH AND KATCH - Essentials of Exercise Physiology

•Chapter 16 Body Composition, Obesity, and Weight Control 587 Effectiveness of a 16-Week Walking Program on Questions & Notes Table 16.7 Body Composition and Blood Lipid Changes in Six For weight loss, is exercise volume or Overfat Young Men intensity more important? PRE- POST- Which component of body composition, is VARIABLE TRAININGa TRAININGa DIFFERENCE most affected by regular physical activity? Body mass (kg) 99.1 93.4 Ϫ5.7b Body density, gиmLϪ1 1.044 1.056 0.012b Body fat (%) Fat mass (kg) 23.5 18.6 Ϫ4.9b Fat-free body mass (kg) 23.3 17.4 Ϫ5.9b Sum of skinfolds (mm) 75.8 76.0 HDL cholesterol, mgиdLϪ1 142.9 104.8 0.2 HDL/LDL cholesterol 32.0 37.0 Ϫ38.1b 0.27 0.34 5.0b 0.07b aValues are means. List 2 examples of the cumulative effects of bStatistically significant regular physical activity designed for From Leon A.S. et al.: Effects of a vigorous walking program on body composition, and carbohydrate weight loss. and lipid metabolism of obese young men. Am. J. Clin. Nutr. 33:1776, 1979. Dose–Response Relationship The total energy expended in physical 1. activity relates in a dose–response manner to the effectiveness of exercise for weight 2. loss. A reasonable goal progressively increases moderate exercise to between 60 and 90 minutes daily or a level that burns 2100 to 2800 kCal weekly. Explain why it is desirable to add resistance exercises to aerobic training to An overfat person who starts out with light exercise such as slow walking enhance body composition changes during accrues a considerable caloric expenditure simply by extending exercise dura- weight loss. tion. The focus on exercise duration offsets the inadvisability of having a seden- tary, obese individual begin a program with more strenuous exercise. The energy cost of weight-bearing exercise relates directly to body mass, allowing the overweight person to expend considerably more calories in such exercise than someone of average weight. Exercise Frequency To determine the optimal exercise frequency for weight loss, subjects exercised for 30 to 47 minutes for 20 weeks by either run- ning or walking, with exercise intensity maintained between 80% and 95% of maximum heart rate. Training twice weekly produced no changes in body mass, Change (kg) 3 What effect does regular exercise have on 2 insulin resistance, independent of weight 1 loss? 0 –1 What is the optimal exercise frequency to –2 promote weight loss? –3 –4 Diet Diet and Exercise only Exercise only –5 Controls Body mass Fat mass FFM Figure 16.32 Changes in body composition with combinations of resistance exer- cise, diet, or both in obese women. (From Ballor, D.L., et al.: Resistance weight training during caloric restriction enhances lean body weight.Am. J. Clin. Nutr., 47:19, 1988.)

•588 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits skinfolds, or percentage body fat, but training 3 and 4 days Eight Benefits of Adding Exercise to weekly did. Subjects who trained 4 days a week reduced Table 16.8 Dietary Restriction for Weight Loss their body weight and skinfolds more than subjects who trained 3 days a week. The percentage body fat decreased 1. Increases overall size of the energy defici similarly in both groups. These findings support a recom 2. Facilitates lipid mobilization and oxidation, especially from mendation to exercise a minimum of 3 days per week to favorably alter body composition; the additional caloric visceral adipose tissue deposits expenditure with more frequent exercise produces even 3. Increases relative body fat loss by preserving fat-free body greater results. The threshold exercise energy expenditure for weight loss probably remains highly individualized. mass The calorie-burning effect of each exercise session should 4. Blunts the decrease in resting metabolism that accompanies eventually reach at least 300 kCal whenever possible. This generally occurs with 30 minutes of moderate to vigorous weight loss by conserving and even increasing fat-free body running, swimming, bicycling, or circuit resistance train- mass ing or 60 minutes of brisk walking. 5. Requires less reliance on caloric restriction to create an energy defici 6. Contributes to long-term success of the weight loss effort 7. Provides significant health-related benefi 8. Offsets the deterioration in immune system function that often accompanies weight loss Self-Selected Energy Expenditures: Mode of 155 men), the largest database of individuals who success- Exercise No selective effect exists among diverse modes fully achieved prolonged weight loss. Criteria for NWCR membership included age 18 years or older and mainte- of large-muscle aerobic exercise to favorably reduce body nance of weight loss of at least 30 pounds (13.6 kg) for weight, body fat, skinfold thickness, and girths, yet other 1 year or longer. Participants averaged 66 pounds (30 kg) of differences may emerge. For individuals without physical weight loss, and 14% lost more than 100 pounds (45.4 kg). activity limitations, running usually provides the most suit- Members maintained the required minimum 30- pound able exercise mode for maximizing energy expenditure dur- weight loss for a 5.5-year average, and 16% maintained the ing self-selected intensities of continuous exercise. loss for 10 years or longer.Most participants had been over- weight since childhood; nearly 50% had one overweight THE IDEAL COMBINATION FOR parent, and more than 25% had both parents overweight. SUCCESS: CALORIC RESTRAINT Genetic background may have predisposed these persons to PLUS EXERCISE obesity, but an impressive weight loss and its maintenance proves that heredity alone need not predestine a person to the Combinations of increased physical activity and caloric obese condition. restraint offer considerably more flexibility for achieving a neg ative caloric imbalance than either exercise alone or diet alone. About 55% of the NWCR members used either a for- Dietary restraint plus increased physical activity through mal program or professional assistance to reduce weight; lifestyle changes offers health and weight loss benefits simi the rest succeeded on their own. Regarding weight loss lar to those from combining dietary restraint and a vigorous methods, 89% modified their food intake and maintaine program of structured exercise. Adding exercise to a weight relatively high physical activity levels (2800 kCal weekly control program facilitates longer term maintenance of fat on average) to achieve goal weight loss. Many walked loss than total reliance on either food restriction alone or briskly for at least 1 hour daily. About 92% exercised at increased exercise alone. Table 16.8 summarizes eight ben- home, and one-third exercised regularly with friends. efits of exercise in a weight loss program Whereas women primarily walked and did aerobic danc- ing, men chose competitive sports and resistance train- MAINTENANCE OF GOAL ing. Only 10% relied solely on diet, and 1% used exercise BODY WEIGHT exclusively. The diet strategy of nearly 90% of partici- pants restricted intake of certain types or amounts of The popular and scientific literature, including TV realit foods—44% counted calories, 33% limited lipid intake, shows, is replete with success stories of individuals who and 25% restricted grams of lipid. Forty-four percent ate have lost considerable amounts of weight using different the same foods they normally ate but in reduced amounts interventions that include nutritional, exercise, and behav- (Table 16.9). ioral approaches. A follow-up study in 2008 provides additional details Success of the National Weight about the weekly energy expenditure patterns among the Control Registry men and women enrolled in the NWCR between 1993 and 2004. Interestingly, participants expended an aver- A project in the National Weight Control Registry (NWCR; age of 2621 kCalиwk–1 in physical activity, but the range www.nwcr.ws) recruited 784 individuals (629 women; of expenditure (2252 kCalиwk–1) was almost as large as the average. Approximately 25.3% reported less than 1000 kCalиwk–1 in physical activity, and 34.9% reported

•Chapter 16 Body Composition, Obesity, and Weight Control 589 Table 16.9 Dietary Strategies to Achieve Weight Loss of Questions & Notes Participants of the National Weight Control Registry (top) and Effects of Weight Loss on Various Is it possible to gain muscle and lose fat Dimensions of Life as Reported by Participants during weight loss? Explain. (bottom) List 4 benefits of adding exercise to dietar PERCENTAGE restriction for weight loss. STRATEGY WOMEN MEN TOTAL 1. Restricted intake of certain 87.8 86.7 87.6 2. types or classes of food 47.2 32.0 44.2 Ate all foods but limited the quantity 44.8 39.3 43.7 31.1 36.7 33.1 Counted calories 25.7 21.3 25.2 Limited % lipid intake 25.2 11.3 22.5 Counted lipid grams 19.1 26.0 20.4 Followed exchange diet Used liquid formula 5.1 6.7 5.5 Ate only 1 or 2 food types AREA OF LIFE IMPROVED PERCENTAGE 3. 4. Quality of life 95.3 NO Level of energy 92.4 DIFFERENCE WORSENED Discuss the effectiveness of specifi Mobility 92.3 exercises to achieve a spot-reducing effect. General mood 91.4 4.3 0.4 Self-confidenc 90.9 6.7 0.9 When gaining weight, what type of Physical health 85.8 7.1 0.6 exercises are most beneficial Interactions with: 6.9 1.6 65.2 9.0 0.1 Opposite sex 5.0 12.9 1.3 Same sex Strangers 69.5 32.9 0.9 Job performance 54.5 46.8 0.4 Hobbies 49.1 30.4 0.1 Spouse interactions 56.3 45.0 0.6 36.7 0.4 37.3 5.9 From Klem MI, et al.: A descriptive study of individuals successful at longterm maintenance of substantial weight loss. Am. J. Clin. Nutr. 66:239, 1997. less than 3000 kCalиwk–1. The amount of activity reported by men decreased over time, but no change was observed in women. The large amount of indi- vidual variability in energy expenditure of successful “weight losers” makes it extremely difficult to pinpoint what amount of activity would constitut optimum to maintain weight loss. Can Targeted Exercise Selectively Reduce For Your Information Local Fat Deposits? EXCESS CALORIES ACCUMULATE FAT The notion of spot reduction stems from the belief that an increase in a muscle’s Each 0.45 kg (1 lb) of adipose tissue metabolic activity stimulates relatively greater fat mobilization from the adipose contains about 87% pure lipid or tissue in proximity to the active muscle. As such, exercising a specific body are 3500 kcal (395 g ϫ 9 kcalиg–1). An region to “sculpt” it should selectively reduce more fat from that area than excess intake of 3500 kCal accumulates exercising a different muscle group at the same metabolic intensity. Advocates 0.45 kg of extra fat. Magic potions, of spot reduction recommend performing large numbers of sit-ups or side- trick diets, or special formula foods bends to reduce excessive abdominal and hip fat. The promise of spot reduc- cannot undo this strategic ratio. tion with exercise seems attractive from an aesthetic and health risk standpoint—unfortunately, critical evaluation of the research evidence does not support its use. To examine claims for spot reduction, researchers compared the girths and subcutaneous fat stores of the right and left forearms of high-caliber tennis

•590 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits players. As expected, the girths of the dominant or playing Increase Lean, Not Body Fat Mass arms exceeded the girths of nondominant arms because of a modest muscular hypertrophy from the exercise over- Endurance exercise training usually increases FFM only load of tennis. Measurements of skinfold thickness, how- slightly, but the overall effect reduces body weight because ever, clearly showed that regular and prolonged tennis of fat loss from the calorie-burning and possible appetite- exercise did not reduce subcutaneous fat in the playing depressing effects of this exercise mode. In contrast, mus- arm. Another study evaluated fat biopsy specimens from cular overload through resistance training, supported by abdominal, subscapular, and buttock sites before and after adequate energy and protein intake (with sufficient recov 27 days of sit-up exercise training. The number of sit-ups ery), increases muscle mass and strength. Adequate energy increased from 140 at the end of the first week to 336 o intake ensures that no catabolism of protein available for day 27. Despite the considerable amount of localized exer- muscle growth occurs from an energy deficit.Thus, intense cise, adipocytes in the abdominal region were no smaller aerobic training should not coincide with resistance training than adipocytes in the unexercised buttocks or subscapu- to increase muscle mass. More than likely, the added energy lar control regions. (and perhaps protein) demands of concurrent resistance and aerobic exercise training impose a limit on muscle Undoubtedly, the negative energy balance created growth and responsiveness to resistance training. In addi- through regular exercise contributes to reducing total body tion, on the molecular level, aerobic exercise training may fat. Conventional wisdom maintains that exercise stimu- inhibit signaling to the protein synthesis machinery of lates mobilization of fatty acids via hormones and enzymes skeletal muscle to negatively impact the muscle’s adaptive that act on fat depots throughout the body, not simply from response to resistance training. A prudent recommenda- areas closest to the active muscle mass. In this connection, tion increases daily protein intake to about 1.6 g per kg of recent advances in microinvasive measurements of subcu- body mass during the resistance-training period. The indi- taneous adipose tissue (SCAT) make it possible to study if vidual should consume a variety of plant and animal pro- localized lipolysis is possible with localized exercise. One teins; relying solely on animal protein which is high in study estimated blood flow and lipolysis in femoral SCA saturated fatty acids and cholesterol potentially increases adjacent to contracting and resting skeletal muscle during heart disease risk. one-legged knee extension exercise at 25% of maximum. Blood flow and SCAT lipolysis were higher adjacent to con If all calories consumed in excess of the energy require- tracting muscle versus adjacent to resting muscle inde- ment during resistance training sustained muscle growth, pendent of exercise intensity . Whether this translates to then 2000 to 2500 extra kCal could supply each 0.5-kg sustained fat loss at a particular site remains unknown, and increase in lean tissue. In practical terms, 700 to 1000 kCal additional experiments certainly seem warranted. added to a well-balanced daily meal plan supports a weekly 0.5- to 1.0-kg gain in lean tissue and additional energy GAINING WEIGHT needs for training. For most people, weight loss to reduce body fat and improve HOW MUCH GAIN TO EXPECT overall health and aesthetic appearance becomes the primary focus of any attempt to alter body composition. Many indi- A 1-year program of intense resistance training for young, viduals desire to gain weight to improve the body composi- athletic men increases body mass by about 20%, mostly tion profile or performance in sports or exercises that requir from lean tissue accrual. The rate of lean tissue gain rap- muscular strength and power. This goal poses a unique idly plateaus as training progresses beyond the first year dilemma that is not easily resolved. Gaining weight per se For athletic women, first-year gains in lean tissue mas occurs all too easily by tilting the body’s energy balance to average 50% to 75% of the absolute values for men, proba- favor greater caloric intake. In a sedentary person, an accu- bly from women’s smaller initial LBM. Individual differ- mulated excess intake of 3500 kCal produces a body fat gain ences in the daily quantity of nitrogen incorporated into of 1 pound because adipocytes store the excess calories. body protein and protein incorporated into muscle also Weight gain for athletes should ideally occur in the form of limit and explain differences among persons in muscle lean tissue, specifically muscle mass and accompanying con mass increases with resistance training. nective tissue. Generally, this form of weight gain takes place if an increased caloric intake (adequate carbohydrate for Individuals with relatively high androgen-to-estrogen energy and protein sparing and enough protein for tissue ratios and greater percentages of fast-twitch muscle fiber synthesis) accompanies the proper exercise regimen. Ath- probably increase their lean tissue to the greatest extent. letes attempting to increase muscle mass often fall easy prey Muscle mass increases most at the start of training in indi- to health food and diet supplement manufacturers who mar- viduals with the largest relative FFM corrected for stature ket “high-potency, tissue-building” substances, including and body fat. Regularly monitoring body mass and body fat chromium, boron, vanadyl sulfate, ␤-hydroxy-methyl verifies whether the combination of training and additiona butyrate, and various protein and amino acid mixture, none food intake increases lean tissue and not body fat. This of which reliably increases muscle mass. requires a valid appraisal of body composition at regular intervals throughout the training period.

•Chapter 16 Body Composition, Obesity, and Weight Control 591 SUMMARY necessarily increase food intake proportionately. Most individuals consume adequate calories to 1. Three methods can unbalance the energy balance counterbalance caloric expenditure. equation to create weight loss: (1) reduce energy intake below daily energy expenditure, (2) maintain normal 9. Combining exercise and caloric restriction offers a energy intake and increase energy output, and flexible yet effective means to weight control. Exercis (3) combine both methods and decrease food intake enhances fat mobilization and utilization for energy, and increase energy expenditure. improves insulin sensitivity, and retards lean tissue loss. 2. Long-term maintenance of weight loss through dietary restriction has a success rate of less than 20%. Typically, 10. Rapid weight loss during the first few days of calori one- to two-thirds of the lost weight returns within deficit comes mainly from body water loss and glycoge 1 year, and almost all of it returns within 5 years. depletion. Continued weight reduction occurs at the expense of greater fat loss per unit weight loss. 3. A caloric deficit of 3500 kCal created through eithe diet or exercise equals the calories in 1 pound (0.45 kg) 11. Successful weight losers generally rely on both food of body fat. intake and physical activity to achieve their goal weight. Increased physical activity for weight 4. Disadvantages of extreme semistarvation include loss maintenance represents a significant component fo of lean body tissue, lethargy, possible malnutrition and these individuals. metabolic disorders, and decrease in the basal energy expenditure. 12. A triggering event or incident (medical, emotional, lifestyle, weight incident, inspirational) usually 5. Adipocyte number stabilizes sometime before precedes successful weight loss. For weight loss adulthood; any weight gain or loss thereafter usually success, intervention strategies must couple with relates to a change in fat cell size. In extreme obesity, “readiness criteria.” cell number can increase after adipocytes reach their hypertrophic limit. 13. Selective fat reduction of specific body areas b targeted or “spot exercise” does not occur. 6. Increases in adipocyte number involve three general time periods: the last trimester of pregnancy, the firs 14. The areas of greatest body fat concentration or lipid- year of life, and the adolescent growth spurt before mobilizing enzyme activity supply the greatest amount adulthood. of energy. 7. The calories expended in exercise accumulate; a 15. Athletes should gain weight as lean body tissue. This modest amount of extra exercise performed routinely occurs with a modest increase in caloric intake plus creates a dramatic calorie-burning effect over time. systematic resistance training. 8. For previously sedentary, overfat men and women, moderate increases in physical activity do not THOUGHT QUESTIONS 1. What strategy, advice, and words of encouragement can 3. Outline a prudent yet effective plan for losing weight you offer to a person who has attempted several diets for a middle-age woman whose physician advises her to yet never achieved long-term weight loss? shed 20 pounds of excess weight. Provide the rationale for each of your recommendations. 2. Respond to this comment: “The only way to lose weight is to stop eating. It’s that simple!” SELECTED REFERENCES Allen, T.W.: Body size, body composition, and cardiovascular Ansari, R.M.: Effect of physical activity and obesity on type disease risk factors in NFL players. Phys. Sportsmed., 38:21, 2 diabetes in a middle-aged population. J. Environ. Public 2010. Health, 195:285, 2009.

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•594 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits Sacks F.M., et al.: Comparison of weight-loss diets with Tran, Z.V., Weltman, A.: Generalized equation for predicting different compositions of fat, protein, and carbohydrates. body density of women from girth measurements. Med. Sci. N. Engl. J. Med., 360:859, 2009. Sports Exerc., 21:101, 1989. Schoeller, D.A.: Balancing energy expenditure and body weight. Utter, A.C., et al.: Evaluation of air displacement for assessing Am. J. Clin. Nutr., 68(Suppl):956S, 1998. body composition of collegiate wrestlers. Med. Sci. Sports Exerc., 35:500, 2003. Schutte, J.E., et al.: Density of lean body mass is greater in blacks than whites. J. Appl. Physiol., 56:1647, 1984. van Marken Lichtenbelt, et al.: Body composition changes in bodybuilders: a method comparison. Med. Sci. Sports Exerc., Sisson, S.B., et al.: Ethnic differences in subcutaneous adiposity 36:490, 2004. and waist girth in children and adolescents. Obesity (Silver Spring), 17:2075, 2009. Wagner, D.R., Heyward, V.H.: Measures of body composition in blacks and whites: a comparative review. Am. J. Clin. Nutr., Sisson, S.B., et al.: Profiles of sedentary behavior in childre 71:1392, 2000. and adolescents: the US National Health and Nutrition Examination Survey, 2001–2006. Int. J. Pediatr. Obes., Weltman, A., et al.: Accurate assessment of body composition 4:353, 2009. in obese females. Am. J. Clin. Nutr., 48:1179, 1988. St.-Onge, M.P., et al.: Changes in childhood food consumption Whitlock, E.P., et al.: Screening and interventions for childhood patterns: a cause for concern in light of increasing body overweight: A summary of evidence for the US Preventive weights. Am. J. Clin. Nutr., 78:1068, 2003. Services Task Force. Pediatrics, 116:e125, 2005. Stern, L., et al.: The effects of low-carbohydrate versus Wijndaele, K., et al.: Increased cardiometabolic risk is conventional weight loss diets in severely obese adults: associated with increased TV viewing time. Med. Sci. Sports one-year follow-up of a randomized trial. Ann. Intern. Med., Exerc., 42:1511, 2010. 140:778, 2004. Witham, M.D., Avenell A.: Interventions to achieve long-term Stommel, M., Schoenborn, C.A.: Variations in BMI and prevalence weight loss in obese older people: a systematic review and of health risks in diverse racial and ethnic populations. Obesity meta-analysis. Age Ageing, 39:172, 2010. (Silver Spring), 2010, Epub ahead of print. Wyshak, G.: Percent body fat, fractures and risk of osteoporosis Sun, G., et al.: Comparison of multifrequency bioelectrical in women. J. Nutr. Health Aging, 14:428, 2010. impedance analysis with dual-energy X-ray absorptiometry for assessment of percentage body fat in a large, healthy Yu, OK.: Comparisons of obesity assessments in over-weight population. Am. J. Clin. Nutr., 81:74, 2005. elementary students using anthropometry, BIA, CT and DEXA. Nutr. Res. Pract., 4:128, 2010. Torstveit, M.K., Sundgot-Borgen, J.: Participation in leanness sports but not training volume is associated with menstrual Zoladz, J.A., et al.: Effect of moderate incremental exercise, dysfunction: a national survey of 1276 elite athletes and performed in fed and fasted state on cardio-respiratory controls. Br. J. Sports Med., 39:14, 2005. variables and leptin and ghrelin concentrations in young healthy men. J. Physiol. Pharmacol., 56:63, 2005.

17C h a p t e r Physical Activity, Exercise, Successful Aging, and Disease Prevention At least half of all babies born in America in 2007 will live to the age of 104! — Lancet 374, October 2009 CHAPTER OBJECTIVES • Describe the meaning of the the term healthspan. • Describe research showing that regular physical activ- • Explain the concept of successful aging compared ity protects against disease and may even extend life. with traditional views of the aging process. • List the three major causes of death in the United • Distinguish between the terms exercise and States. physical activity. • List and describe the four major coronary heart disease • Explain the basis of the Physical Activity Pyramid. (CHD) risk factors. • Answer the question, “How safe is exercise?” • List secondary and novel risk factors for CHD. • Describe the goals of Healthy People 2010. • List specific components of the blood lipid profile and • What is SeDS, and why is it so important? give values considered desirable for each. • List important age-related changes in muscular • Discuss factors that affect cholesterol lipoprotein levels. strength, joint flexibility, nervous system function, car- • Explain how regular physical activity reduces the risk diovascular function, pulmonary function, endocrine function, and body composition. of CHD. • Describe five field tests to assess the flexibility of • Describe the occurrence of CHD risk factors in major body areas. children. • Explain interactions between CHD risk factors. 595

•596 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits THE GRAYING OF AMERICA century, more than 800,000 Americans will exceed age 100 years, with many in relatively good health. Old-age mortal- Elderly persons make up the fastest growing segment of ity appears to be on the decline because the death rate American society. Forty years ago, age 65 years indicated the (number of people per 100 in a specific age group) level onset of “old age” and represented the average retirement off in the 90-year-old age category (approximately 11 per age of most men in the workforce. Gerontologists now con- 100) and decreases to eight per 100 after age 100 years. sider age 85 years the demarcation of “oldest-old” and age 75 years “young-old.” Currently, nearly 12%, or approximately Figure 17.1B indicates the percentage of individuals age 35 million Americans, exceed age 65 years. By the year 2030, 65 years who survive to specified ages. Among current 65 70 million Americans will exceed age 85 years. Some demog- year-old people, 95.5% will live to age 70 years, 63.3% will raphers project that half of the girls and one-third of the boys live to age 85 years, and nearly 10% will live to be 100 years born in developed countries near the end of the 20th century old. A child born in 2007 should survive to age 100 years or will live in three centuries. Based on the latest research, at more. Life expectancy in the United States has been on the least half of all babies born in America in 2007 will live to the rise for the past decade, increasing 1.4 years—from 76.5 age of 104 years. Most babies born since the year 2000 in years in 1997 to 77.9 in 2007, according to the latest statis- countries with long-lived residents will celebrate their 100th tics from the Centers for Disease Control and Prevention birthday if the present yearly growth in life expectancy con- (CDC; www.cdc.gov/nchs). tinues through the 21st century (Table 17.1). Cigarette smoking, elevated body mass index (BMI), In the short term, disease prevention, improved health excess body fatness, and reduced physical activity provide care, and more effective treatment of age-related heart dis- potent predictors of subsequent morbidity and mortality. ease and osteoporosis help people live longer. Far fewer Changing to a more physically active lifestyle reduces mor- people now die from infectious childhood diseases, and tality from common ailments and greatly improves cardio- those with the genetic potential actualize their proclivity vascular and muscular functional capacities, quality of life, for longevity. On a different but parallel front, anticipated and capacity for independent living. At any age, behavioral breakthroughs in genetic therapies may slow the aging of changes such as becoming more physically active, quitting individual cells. Cellular damage results from (1) accumu- cigarette smoking, and controlling body weight and blood lated mutations in mitochondrial DNA, perhaps induced pressure act independently to delay all-cause mortality and by injury and deterioration from oxidative stress and extend life. Persons with more healthful lifestyles survive (2) gene alterations that depress telomerase synthesis longer with a reduced risk of disability as life progresses. enzyme that protects the protective caps (telomers) at the ends of chromosomes that allow cells to divide properly. THE NEW GERONTOLOGY: Gene therapies could boost human life spans to a much greater extent than improved medical treatment or even SUCCESSFUL AGING eradication of deadly diseases. Many gerontologists maintain that research on aging Figure 17.1A shows that proportionately, centenarians should not focus on increasing life span but rather on currently represent the fastest growing age group in the improving healthspan, the total number of years a per- United States. Numbers range from 30,000 to 50,000, up son remains in excellent health. The new gerontology from the estimated 15,000 in 1980 and almost none at the addresses areas beyond age-related diseases and their pre- beginning of the 20th century. No longer viewed as a quirk vention to recognize that successful aging requires mainte- of nature, one in 10,000 Americans now lives to the age of nance of enhanced physiologic function and physical 100 years. Demographers project that by the middle of this fitness. Much of the physiologic deterioration previousl Oldest Age in Years at Which at Least 50% of a Birth Cohort Is Still Alive in Eight of the Table 17.1 World’s Industrialized Countries BIRTH YEAR COUNTRY 2000 2001 2002 2003 2004 2005 2006 2007 Canada 102 102 103 103 103 104 104 104 Denmark 99 99 100 100 101 101 101 101 France Germany 102 102 103 103 103 104 104 104 Italy 99 100 100 100 101 101 101 102 Japan UK 102 102 102 103 103 103 104 104 USA 104 105 105 105 106 106 106 107 100 101 101 101 102 102 103 103 101 102 102 103 103 103 104 104 From Human Mortality Database. Available at http://www.mortality.org/cgi-bin/hmd/hmd_download.php.

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 597 considered “normal aging” included deleterious changes in blood pressure, uestions & Notes Qbone mass, body composition, body fat distribution, insulin sensitivity, and homocysteine levels. These maladies convey increased health risk, dysfunction, What is the prognosis for how long “you” will live? or actual disease, and depend on lifestyle and environmental influences subjec to considerable modification with proper diet and exercise. For those achievin older age, low muscular strength, diminished cardiovascular function, poor range of joint motion, and sleep disturbances relate directly to functional limi- tations regardless of disease status. Gerontologists consider that successful aging includes four components: 1. Physical health Explain the term “new gerontology.” 2. Spirituality 3. Emotional and educational health 4. Social satisfaction Healthy Life Expectancy: A New Concept Life expectancy estimates consider the overall length of life based on mortality data without considering the quality of life during aging. At some point during the life span, some level of disability detracts from life’s quality. For example, the CDC (www.cdc.gov/nchs/fastats/lifexpec.htm) reports that nearly 1 in 10 Americans For Your Information older than age 70 years requires help with daily activities such as bathing, and PHYSICAL ACTIVITY MODIFICATIONS FOR ELDERLY INDIVIDUALS 4 in 10 use assistive devices such as walk- Physical activity recommendations for elderly people are similar to those of the ers or hearing aids. Approximately one- updated American College of Sports Medicine/American Heart Association half of men and two-thirds of women (AHA) recommendations for healthy adults but with several important differ- older than age 70 years have arthritis; ences. For example, the level of exercise intensity takes into account the older more than one-third of all Americans in adult’s relatively lower level of aerobic fitness. Recommended activities also this age group also have high blood pres- focus on joint flexibiltiy and balance to reduce risks of falls. Physical activity sure, and 11% have diabetes. Of all sen- in this population emphasizes moderate-intensity aerobic activity, muscle- iors, women older than age 85 years are strengthening exercises, reduction of sedentary behavior, and lifestyle risk the most likely to need everyday help, management. (From Nelson M.E., et al.: Physical activity and public health in and 23% require assistance with at least older adults: recommendation from the American College of Sports Medicine one basic activity (e.g., dressing or going and the American Heart Association. Med. Sci. Sports Exerc., 39:1435, 2006.) to the toilet). 2000 72 100 90 2005 101 80 70 2010 131 60 Year 50 Age (y) 40 2020 214 30 20 2030 324 10 2040 447 B0 2050 834 A 0 100 200 300 400 500 600 700 800 900 70 75 80 85 90 95 100 Projected population 100 years and over Probability a 65-year old (in thousands) will live until this age (y) Figure 17.1 The graying of America. (A) Growth in number of centenarians in the United States. (B) Probability that a current 65-year-old person will live to a certain age. (Data from U.S. Bureau of the Census, National Center for Health Statistics, Centers for Disease Control and Prevention: Washington, DC, and actuarial tables from insurance companies.)

•598 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits 85 80 75 70 Life expectancy (y) 65 60 55 50 45 1875 1900 1925 1950 1975 2000 1850 Year Best-practice England & Wales France Germany (East) Germany (West) Japan Sweden USA Figure 17.2 Plot of life expectancy (y) since 1850 to 2010. Thestraight line and data points represent the “best-practice life expectancy,” the highest values recorded in a national population. Life expectancy has risen by 3 months per year since 1840. The colored lines represent individual country average life expectancy.

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 599 To estimate healthful longevity, the World Health Organization ( www. uestions & Notes Qwho.int/whr) introduced the concept of healthy life expectancy (HALE) , the expected number of years a person might live in the equivalent of full health. Explain the concept of healthy life HALE considers the years of ill health weighted according to severity and sub- expectancy. tracted from expected overall life expectancy to compute the equivalent years of healthy life. Of the 191 countries evaluated, HALE estimates reached 70 years in 24 countries and 60 years in more than half. Thirty-two countries were at the lower extreme of less than 40 years. Many of these countries bear the burden of the major epidemics of HIV/AIDS and other causes of death and disability. List 3 factors responsible for decreased life Figure 17.2 shows that life expectancy increases almost linearly in most expectancy in non-Western countries. developed countries, with no sign of deceleration. In fact, best-practice life expectancy—the highest value recorded in a national population—has risen by 1. 3 months per year since 1840 and continues unabated. In the record-holding country, Japan, female life expectancy achieved 86.0 years in 2007, surpassing 85 years considered the upper-limit life expectancy for any one population. 2. Although with lower life expectancies than Japan’s, most developed countries show similar yearly life expectancy increases since 1950. The linear increase in the record life expectancy for more than 170 years does not suggest a looming limit to the human life span. If life expectancy were approaching its limit, some 3. deceleration of progress would probably occur. Continued increases in life expectancy in the longest living populations suggests that we are not close to a limit and a further rise seems likely. The six most prominent factors in order of importance responsible for decreased life expectancy in non-Western countries include those related most List 3 factors responsible for decreased life to disease occurrence and environmental insults: expectancy in the Americas and European 1. Low birth weight countries. 2. Vitamin and mineral deficiency (particularly vitamin A and iron 1. 3. Unsafe water and sanitation procedures 4. Unsafe sex, including HIV 5. Introduction of carcinogens 6. Work-related risk 2. In the Americas and Europe, the six major factors contributing to a decrease in healthy life span relate to lifestyle choices: 1. Tobacco use 3. 2. High blood pressure 3. Increased blood cholesterol Explain differences between the terms 4. Obesity physical activity and exercise. 5. Low levels of physical activity 6. Limited fruit and vegetable consumption PHYSICAL ACTIVITY EPIDEMIOLOGY Epidemiology involves quantifying factors that influence the occurrence of ill ness to better understand, modify, or control a disease pattern in the general population. The specific field o physical activity epidemiology applies the gen- eral research strategies of epidemiology to study physical activity as a health- related behavior linked to disease and other outcomes. Terminology Physical activity epidemiology applies specific definitions to characterize beha ioral patterns and outcomes of the groups under investigation. Relevant termi- nology includes the following: • Physical activity: Body movement produced by muscle action that increases energy expenditure • Exercise: Planned, structured, repetitive, and purposeful physical activity

•600 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits Cardiovascular objective measurement. Despite limitations in assessment, (aerobic) fitness a discouraging picture of physical activity participation worldwide consistently emerges. In the United States, adult Flexibility Health-related Abdominal participation in any physical activity remains quite low as of the physical fitness muscular revealed by these statistics: strength and lower back endurance • Only about 15% engage in regular, vigorous physical and ham- activity during leisure time, three times a week for at least 30 minutes. strings • More than 60% do not engage in any regularly phys- Body composition ical activity. (lean-to-fat ratio) • About 25% lead sedentary lives (i.e., do not exercise). Figure 17.3 Health-related physical fitness components • Walking, gardening, and yard work are the most • Physical fitness Attributes related to how well one popular leisure-time performs physical activity activities. • About 22% engage in light-to-moderate physical ac- • Health: Physical, mental, and social well-being, not tivity regularly during leisure time (five times simply absence of disease week for at least 30 min). • Physical inactivity occurs more frequently among • Health-related physical fitness Components of women than men, blacks and Hispanics than whites, physical fitness associated with some aspect of goo older than younger adults, and less- health or disease prevention (Fig. 17.3) affluent than wealthier persons • Participation in fitness activities declines with age • Longevity: Length of life older citizens typically have such poor functional capacity that they cannot rise from a chair or bed, Within this framework, physical activity becomes a walk to the bathroom, or climb a single stair without generic term with exercise its major component. Similarly, assistance. the definition of health focuses on the broad spectrum of well-being that ranges from complete absence of health Equally discouraging data emerge for children and (near death) to the highest levels of physiologic function. teenagers: Such definitions often challenge our ability to measure an quantify health and physical activity objectively. They do, • Nearly half of those between ages 12 and 21 do not however, provide a broad perspective to study the role of exercise vigorously on a regular basis regardless of physical activity in health and disease. gender. The trend in physical fitness assessment during the pas • About 14% report no recent physical activity; this is 40 years deemphasizes tests of motor performance and ath- more prevalent among females, particularly black fe- letic fitness (i.e., speed, power, balance, agility). Curren males. assessment focuses on functional capacities related to over- all good health and disease prevention. The four most com- • About 25% engage in light to moderate physical ac- mon components ofhealth-related physical fitnes include tivity (e.g., walk or bicycle) nearly every day. aerobic or cardiovascular fitness, body composition, abdom inal muscular strength and endurance, and lower back and • Participation in all types of physical activity declines hamstring flexibility (see Close Up Box 17.1: How to Assess strikingly as age and school grade increase. Joint Flexibility in Common Body Areas, on page 602). • More boys than girls participate in vigorous physical Physical Activity Participation activity, strengthening activities, and walking or bi- cycling. More than 30 different methods can assess physical activ- ity. They include direct and indirect calorimetry, self- Getting America More Physically Active reports and questionnaires, job classifications, physiologi markers, behavioral observations, mechanical or electronic On July 11, 1996, in a landmark announcement, the Sur- monitors, and activity surveys. Each approach offers both geon General of the United States acknowledged the impor- unique advantages and disadvantages depending on the sit- tance of physical activity to the nation with the release of uation and population studied. Obtaining valid estimates the First Surgeon General’s Report on Physical Activity of physical activity of large groups remains difficult becaus and Health (www.cdc.gov/NCCDPHP/sgr/ataglan.htm). such studies by necessity apply self-reports of daily activity This encompassing report summarized the benefits of regu and exercise participation rather than direct monitoring or lar physical activity in disease prevention. The Surgeon General proposed a national agenda that urged the nation to adopt and maintain a physically active lifestyle to combat ailments associated with the country’s generally low level of energy expenditure. The report stated that men and women of all ages benefit from regular physical activity. It became stated goal of the government to encourage all citizens to

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 601 REDUCE Questions & Notes • TV viewing List the 4 components of health-related • Internet surfing physical fitness • Excessive reading 1. and computer use 2. AT LEAST TWICE WEEKLY 3. Leisure-lifestyle Flexibility 4. List 4 methods to assess physical activity. activities (low- and strength 1. aerobic exercise) • easy calisthenics • golf • yoga • light gardening • light-moderate • housework resistance training AT LEAST THREE TIMES WEEKLY 2. 3. Aerobic exercise Recreational exercise • walking • tennis • jogging • hiking • swimming • racquetball • bicycling • basketball • aerobics DAILY (AS OFTEN AS POSSIBLE) 4. • carrying groceries • stair climbing List 2 major goals of the Healthy People • walking to work 2010 initiative. • pushing lawn mower 1. Physical Activity Pyramid Figure 17.4 The Physical Activity Pyramid: prudent goals for increasing daily phys- 2. ical activity. include moderate physical activity such For Your Information as 30 minutes of brisk walking or raking leaves, 15 minutes of running, or 45 LET'S MOVE – THE NEW INITIATIVE TO COMBAT CHILDHOOD OBESITY minutes of playing volleyball on most, if not all, days of the week. In February 2010 First Lady Michelle Obama with support from the U.S. government rolled out a national initiative against childhood obesity, dubbed The Physical Activity Pyramid (Fig. “Let’s Move.” Along with the First Lady’s influential leadership, the project 17.4) summarizes major goals for received a commitment of $1 billion a year in federal funds for 10 years, and increasing the level of regular physical the first national task force on solving the childhood obesity epidemic with activity in the general population; the members from the departments of the Interior, Health and Human Services, pyramid emphasizes diverse forms of Agriculture and Education. behavioral and lifestyle options. The initiative has four core pillars: better nutrition information, increased Healthy People 2010 physical activity, easier access to healthy foods and personal responsibility. Specific actions revolve around food labeling, school food quality, and encour- The Healthy People 2010 initiative aging kids to exercise each day and doctors to monitor body mass index. (www.healthypeople.gov) launched on January 25, 2000, builds on the initiatives This campaign is comprehensive in nature that builds on effective strategies, of the previous two decades as an instru- and mobilizes public and private sector resources. Let’s Move will engage every ment to improve national health for the sector that impact the health of children and will provide schools, families and first decade of the 21st century. Health communities simple tools to help kids be more active, eat better, and get People 2010 outlines a comprehensive, healthy. To support Let’s Move the nation’s leading children’s health founda- nationwide health promotion and disease tions have come together to create a new independent foundation - the prevention agenda as a roadmap to pro- Partnership for a Healthier America - to accelerate existing efforts towards the mote health and prevent illness, disability, national goal of solving childhood obesity within a generation. and premature death among all people in the United States.

•602 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits BOX 17.1 CLOSE UP How to Assess Joint Flexibility in Common Body Areas Two types of flexibility include (1) static, which is full sedentary lifestyle remains unclear. On average, women range of motion (ROM) of a specific joint, and (2 remain more flexible than men at any age dynamic, which is torque or resistance encountered as the joint moves through its ROM. Improper alignment of FIVE COMMON FIELD TESTS OF the vertebral column accounts for more than 80% of all STATIC FLEXIBILITY lower back and pelvic girdle ailments; this often results from poor flexibility in regions of the lower back, trunk Field tests assess static flexibility indirectly through linea hip, and posterior thigh (common in runners) and weak measurement of ROM. A minimum of three trials should abdominal and erector spinae muscles. be administered after a warm-up. SPECIFICITY AND FLEXIBILITY Test 1: Hip and Trunk Flexibility (Modified Sit-and-Reach Test) Considerable specificity exists for joint ROM dependin Starting position: Sit on the floor with the back and hea on joint structure. Triaxial joints (ball and socket) of the hip and shoulder afford a greater degree of movement against a wall with the legs fully extended with the than either uniaxial or biaxial joints (wrist, knee, elbow, bottom of the feet against the sit-and-reach box. Place and ankle). “Tightness” of the soft tissue structures of the the hands on top of each other, stretching the arms joint capsule and muscle and its fascia, tendons, ligaments, forward while keeping the head and back against the and skin constitute major factors that influence static wall (A). Measure the distance from the fingertips t and dynamic flexibility. Other influences include a wel the box edge with a yardstick. This becomes the zero developed musculature and excess fatty tissue of adjacent or starting point. body segments. Flexibility progressively decreases with Movement: Slowly bend and reach forward as far as pos- advancing age, mainly because of decreased soft-tissue sible (the head and back move away from the wall), extensibility. How decrements in flexibility reflect tr sliding the fingers along the yardstick; hold the fin aging or result from a “disuse” effect of an increasingly position for 2 seconds (B). Score: The total distance reached to the nearest one-tenth inch A B Modified Sit and Reach, Age Range PERFORMANCE MEN WOMEN RATING AGE Ͻ35 YEARS AGE 36–49 YEARS AGE Ͻ35 YEARS AGE 36–49 YEARS Excellent Ͼ17.9 Ͼ16.1 Ͼ17.9 Ͼ17.4 Good 17.0–17.9 14.6–16.1 16.7–17.9 16.2–17.4 Average 15.8–17.0 13.9–14.6 16.2–16.7 15.2–16.2 Fair 15.0–15.8 13.4–13.9 15.8-16.2 14.5–15.2 Poor Ͻ15.0 Ͻ13.4 Ͻ15.4 Ͻ14.5 Adapted from Johnson, B.L., Nelson, J.K.: Practical Measurements for Evaluation in Physical Education, 4th ed. New York: Macmillan Publishing, 1986.

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 603 Test 2: Shoulder–Wrist Flexibility Movement: Extend both arms in front of the chest and (Shoulder and Wrist Elevation Test) rotate the arms overhead and behind the back; as Starting position: Lie prone on the floor with the arm resistance occurs, slide the right hand farther from the left hand along the rope until the rope touches against fully extended overhead; grasp a yardstick with the the back. hands shoulder width apart. Movement: Raise the stick at high as possible. 1. Measure the distance on the rope between the thumb of each hand after successfully rotating overhead 1. Measure the vertical distance (nearest 1/2 in) the with the rope against the back. yardstick rises from the floor 2. Measure shoulder width from deltoid to deltoid. 2. Measure arm length from the acromial process to the Subtract the rope distance from the shoulder width tip of longest finger distance. 3. Subtract the best vertical score from arm length. Score: Shoulder-width distance Ϫ Rope distance (near- est 1/4 in) Score: Arm length Ϫ Best vertical score (nearest 1/4 in) Shoulder and Wrist Elevation PERFORMANCE MEN WOMEN Shoulder Rotation RATING Ն12.00 PERFORMANCE Excellent Ն12.75 11.75–11.0 RATING MEN WOMEN Good 12.50–11.75 10.75–7.75 Average 11.50–8.50 7.50–5.75 Excellent Ն20.00 Ն18.00 Fair Good 19.75–14.75 17.75–13.25 Poor 8.25–6.25 Յ5.50 Average 14.50–11.75 13.00–10.00 Յ6.00 Fair 11.50–7.25 Poor 9.75–5.25 Adapted from Johnson, B.L., Nelson, J.K.: Practical Measurements Յ7.00 Յ5.00 for Evaluation in Physical Education, 4th ed. New York: Macmillan Publishing, 1986. Adapted from Johnson, B.L., Nelson, J.K.: Practical Measurements for Evaluation in Physical Education, 4th ed. New York: Macmillan Test 3: Trunk and Neck Flexibility Publishing, 1986. (Trunk and Neck Extension Test) Test 5: Ankle Flexibility (Ankle Flexion Test) Starting position: Lie prone on the floor with the hand Starting position: Stand facing a wall. With the feet fla clasped together behind the head. on the floor, lean into the wall Movement: Raise the trunk as high as possible while Movement: Slowly slide back from the wall as far as pos- keeping the hips in contact with the floor. An assistan sible while keeping the feet flat on the floor, body a can hold down the legs. knees fully extended, and chest in contact with the wall. Score: Vertical distance (nearest 1/4 in) from the tip of the nose to the floo Score: Distance between the toe line and the wall (nearest 1/4 in) Trunk and Neck Extension PERFORMANCE MEN WOMEN Ankle Flexion RATING Ն10.00 PERFORMANCE Excellent Ն10.25 9.75–8.00 RATING MEN WOMEN Good 10.00–8.25 7.75–6.00 Average 8.00–6.25 5.75–2.25 Excellent Ն35.50 Ն32.00 Fair 6.00–3.25 Good 35.25–32.75 31.75–30.50 Poor Յ2.00 Average 32.50–29.75 30.25–26.75 Յ3.00 Fair 29.50–26.75 26.50–24.50 Poor Adapted from Johnson, B.L., Nelson, J.K.: Practical Measurements Յ26.50 Յ24.25 for Evaluation in Physical Education, 4th ed. New York: Macmillan Publishing, 1986. Test 4: Shoulder Flexibility Adapted from Johnson, B.L., Nelson, J.K.: Practical Measurements for Evaluation in Physical Education, 4th ed. New York: Macmillan (Shoulder Rotation Test) Publishing, 1986. Starting position: Grasp one end of a rope with the left hand; 4 inches away, grasp the rope with the right hand.

•604 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits Healthy People 2010 attempts to achieve two primary (www.cpsc.gov/LIBRARY/neiss.html) that characterizes goals: sports- and recreation-related injuries in the U.S. popula- tion revealed an overall rate of 11.2 injuries per 100,000 1. Increase the quality and years of healthy life population participants. For persons 15 to 24 years of age 2. Eliminate health disparities among the nation’s citi- the injury rate equalled 30 injuries per 100,000 popula- tion, the highest recorded for any age group. Basketball zens reported 159 injuries per 100,000 participants, and bicycle- related injuries were 171 per 100,00 participants. With 150 Progress will be monitored through achievements within injuries per 100,000 participants, football ranked close 467 objectives in 28 focus areas. Many goals and objectives, behind. The most frequent injury diagnosis included several of which either directly or indirectly involve upgrad- strains or sprains, fractures, contusions or abrasions, and ing the national level of regular physical activity, converge lacerations. The body parts injured most commonly were on interventions designed to reduce or eliminate illness, dis- the ankles, fingers, face, head, and knees ability, and premature death among individuals and com- munities. Other objectives focus on broader issues such as SEDENTARY DEATH SYNDROME improving access to quality health care, strengthening pub- lic health services, and improving availability and dissemi- A review of the world literature over the past 60 years has nation of health-related information. Each objective has a led to the conclusion that physical inactivity produces a target for specific improvements and explicit guidelines o constellation of problems and conditions that eventually how to achieve the stated goal by the year 2010. lead to premature death. Sedentary death syndrome (SeDS; hac.missouri.edu) describes this condition that Safety of Exercising denotes a collection of disorders directly caused by or worsened by physical inactivity that ends in death. SeDS Several well-publicized reports of sudden death during will contribute to 1 in 10 premature deaths, or 2.5 million exercise raise the question of exercise safety. It may sur- deaths in the United States alone, at a projected cost of prise some that the death rate during exercise has declined $1.5 trillion over the next 10 years. In summary: over the past 25 years despite an overall increase in exer- cise participation. In one report of cardiovascular episodes • SeDS will cause 2.5 million Americans to die prema- over a 65-month period, 2935 exercisers recorded 374,798 turely over the next decade. hours of exercise that included 2,726,272 km of running and walking. N o deaths occurred during this time, and • SeDS will cost $1.5 trillion in health care expenses only two nonfatal cardiovascular complications occurred. in the United States in the next decade. This amounts to two complications per 100,000 hours of exercise for women and three complications for men. • Chronic diseases have increased because of physical inactivity. In the United States, type 2 diabetes has The relative risk of sudden death among athletes versus increased ninefold since 1958, obesity has doubled nonathletes was 1.95 for men and 2.00 for women. The higher since 1980, and heart disease remains a leading risk of sudden death in athletes strongly related to underlying cause of death. cardiovascular diseases such as congenital coronary artery anomaly, arrhythmogenic right ventricular cardiomyopathy, • Children are now experiencing SeDS-related dis- premature coronary artery disease. Interestingly, athletic par- eases. American children have become increasingly ticipation did not cause the enhanced mortality, but instead overweight, showing fatty streaks in their arteries triggered sudden death in athletes affected by cardiovascular and developing type 2 diabetes at an alarming rate. conditions predisposing them to life-threatening ventricular arrhythmias during physical exercise. • SeDS relates to 26 medically related conditions that include angina, heart attack, coronary artery disease, Intense physical exertion poses a small risk of sudden arthritis pain, arrhythmias, breast cancer, colon can- death (e.g., one sudden death per 1.51 million episodes of cer, congestive heart failure, depression, digestive exertion) during the activity compared with resting an equiv- problems, gallstone disease, gastroesophageal alent time, particularly for sedentary people with a genetic disease, high blood triglyceride level, high blood predisposition to sudden death. Prospective epidemiologic cholesterol level, hypertension, less cognitive research evaluated clinically significant medical incidents an function, low blood high-density lipoprotein emergencies for 7725 low-risk, apparently healthy corporate cholesterol (HDL-C) level, lower quality of life, fitness enrollees in a supervised facility at a major medica menopausal symptoms, osteoporosis, pancreatic center. Over 2.5 years, 15 medically significant events (0.04 cancer, peripheral vascular disease, physical frailty, per 1000 participant-hours) and two medical emergencies premature mortality, prostate cancer, respiratory (both recovered; 0.0063 per 1000 participant-hours). This problems, sleep apnea, stroke, and type-2 diabetes. extremely low rate of medical incidents in a supervised health-fitness facility shows that the health-related fitne More medical-based evidence must convince the world benefits far outweigh the small risk of participation population that physical inactivity promotes unhealthy gene expression. We wholeheartedly endorse that regular, vig- The most recent report in 2007 from the National Elec- orous physical activity should play an increasingly more tronic Injury Surveillance System All Injury Program important role in the lives of all individuals.

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 605 AGING AND BODILY FUNCTION Questions & Notes Figure 17.5 shows that bodily functions improve rapidly during childhood and Identify the most prevalent medical reach a maximum at about age 30 years; thereafter, a decline in functional complication from exercising. capacity occurs. A similar age trend exists for physically active persons; physio- logic function averages about 25% higher compared with sedentary counter- What do the initials SeDS stand for? parts at each age category (e.g., an active 50-year-old man or woman often maintains the functional level of a 30-year-old man or woman). All physiologic List 10 medical conditions related to SeDS. measures eventually decline with age, but not all decrease at the same rate. 1. 2. Nerve conduction velocity, for example, declines only 10% to 15% from age 3. 30 to 80 years, but resting cardiac index (ratio of cardiac output to body surface area) and joint flexibility decline 20% to 30%; maximum breathing capacity a age 80 years averages 40% of values for a 30-year-old person. Brain cells die at a fairly constant rate until age 60 years, but the liver and kidneys lose 40% to05% of their function between ages 30 and 70 years. By the seventh decade of life, the average woman has lost 30% of her bone mass, while men lose only 15%. Aging and Muscular Strength 4. 5. Men and women achieve maximum strength between ages 20 to 30 years, when 6. muscle cross-sectional area often achieves maximum size. Thereafter, strength 7. progressively declines for most muscle groups; by age 70 years, overall “gen- 8. eral” strength has decreased by 30%. 9. Decrease in Muscle Mass Strength decreases with age because of reduced fat-free body mass (FFM), a condition termed sarcopenia. The smaller muscle mass in older adults reflects a loss of total muscle protein induced b physical inactivity, aging, or the combined effects. Some loss in muscle fibe number also takes place with aging. For example, whereas the biceps of a new- born contains about 500,000 individual fibers, the same muscle for an 80-year old man contains 300,000 fibers, or 40% less Muscle Trainability Among Middle Aged and Elderly Persons 10. Regular exercise retains body protein and blunts the loss of muscle mass and strength with aging. Healthy men between age 60 and 72 years participated in a 12-week 120General level of physiologic function (%) 100 100% value 80 sedientary 60 40 20 0 10 20 30 40 50 60 70 80 90 Age (y) Active Sedentary Figure 17.5 Generalized curve for age-related changes in physiologic function. All comparisons were made against the 100% value achieved by the 20- to 30-year-old sedentary person.

•606 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits 70 Extension 60 Flexion 50 1 - RM, kg 40 30 20 Figure 17.6 Weekly measurement of dynamic muscle strength (1-RM) 10 in left knee extension (yellow) and flexion red) during a 12-week period 0 2 4 68 10 of resistance training in men age 60 to 0 72 years. (Data from Frontera, W.R., Weeks of training et al.: Strength conditioning in older 12 men: Skeletal muscle hypertrophy and improved function. J. Appl. Physiol., 64:1038, 1988.) standard resistance-training program.Figure 17.6 shows that Thyroid dysfunction from lowered pituitary gland the men’s muscle strength increased progressively through- release of the thyroid-stimulating hormone thyrotropin out the program, averaging about 5% each exercise session (a (and reduced output of thyroxine from the thyroid gland) training response similar to young adults). Exercise special- commonly occurs among elderly people. This affects meta- ists who work with elderly people argue that improving bolic function that includes decreased glucose metabolism strength effectively maintains muscle mass, increases mobil- and protein synthesis. ity, and reduces injury incidence for this age group. Figure 17.7 depicts changes in three additional hor- Aging and Joint Flexibility monal systems associated with aging: the hypothalamic– pituitary–gonadal axis, adrenal cortex, and growth hor- With advancing age, connective tissue (cartilage, ligaments, mone (GH) and insulin-like growth factor-1 (IGF-1) axis. and tendons) becomes stiffer and more rigid, which reduces joint flexibility. It is unclear whether these changes resul Hypothalamic–Pituitary–Gonadal Axis Alter- from biologic aging or reflect the impact of chronic disus through sedentary living or degenerative tissue diseases of ations in the interaction among stimulating hormones from specific joints. Regardless of the cause, appropriate exercise the hypothalamus and anterior pituitary gland and gonads that regularly move the joints through their full ROM decrease ovarian output of estradiol. This effect probably ini- increase flexibility 20% to 50% in men and women at all ages tiates permanent cessation of menses (menopause) in aging women. Changes in hypothalamic–pituitary–gonadal axis Endocrine Changes with Aging activity in men occur more slowly and subtly. For example, serum total and free testosterone decline with aging in men. Endocrine function changes with age, particularly the pitu- Age-related decreases in gonadotropic secretions from the itary, pancreas, adrenal, and thyroid glands. About 40% of anterior pituitary gland characterize male andropause. individuals between ages 65 and 75 years and 50% of indi- viduals older than age 80 years have impaired glucose toler- Adrenal Cortex Adrenopause refers to the decrease in ance that leads to type 2 diabetes, the most common diabetes form. Impaired glucose metabolism leading to high blood adrenal cortext output of dehydroepiandrosterone (DHEA) glucose levels in type 2 diabetes results from three factors: and its sulfated ester (DHEAS). In contrast to the glucocor- ticoid and mineralocorticoid adrenal steroids whose plasma 1. Decreased effect of insulin on peripheral tissue levels remain relatively high with aging, a long, progressive, (insulin resistance) but slow decline in DHEA occurs after about age 30 years. This has led to speculation concerning DHEA’s role in aging, 2. Inadequate pancreatic insulin production to control prompting a dramatic increase in unregulated supplementa- blood sugar (relative insulin deficienc ) tion of this hormone. 3. Combined effect of insulin resistance and relative Growth Hormone and Insulin-Like Growth insulin deficienc Factor-1 Axis Mean pulse amplitude, duration, and With the exception of a genetic predisposition, increased fraction of secreted GH gradually decrease with aging, a prevalence of type 2 diabetes largely relates to “controllable” condition termed somatopause. A parallel decrease in cir- factors such as poor diet, inadequate physical activity, and culating levels of IGF-1 also occurs. IGF-1, produced by increased body fat (particularly in the visceral–abdominal fat). the liver and other cells, stimulates tissue growth and pro- tein synthesis. The trigger for the age-related GH decrease

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 607 Questions & Notes Pacemaker of Aging Give 2 reasons older individuals develop impaired glucose tolerance leading to type 2 diabetes. 1. 2. GH decreases Anterior Posterior Corticotropic Hormone pituitary pituitary and ACTH, no change Define the term menopause. Gonadotropic Hormones Adrenal (LH/FSH) decrease cortex Liver + Kidney Define the term andropause. other tissues IGF-1 decreases Testes Cortisol (Somatopause) no change DHEA decreases Ovaries (Adrenopause) Define the term adrenopause. Estradiol Testosterone Define the ter somatopause. decreases decreases (Menopause) (Andropause) Figure 17.7 Age-related decline in three hormone systems that affect the rate of bio- logical aging. Left. Decreased growth hormone (GH; released by the anterior pituitary) depresses production of insulin-like growth factor-1 (IGF-1) to inhibit cellular growth (a condition of aging termed somatopause). Middle. Decreased output of luteinizing hormone (LH) and follicle-stimulating hormone (FSH) by the anterior pituitary, coupled with reduced estradiol secretion from ovaries and testosterone from testes, causes menopause (in women) and andropause (in men).Right. Adrenocortical cells responsible for dehydroepiandrosterone (DHEA) production decrease their activity (termed adrenopause) without clinically evident changes in this gland’s corticotropin (adrenocorticotropic hormone [ACTH]) and cortisol secretion. A central “pacemaker” in the hypothalamus or higher brain areas probably mediates these processes to produce aging-related changes in the ovaries, testicles, and adrenal cortex. probably lies in the interaction between the hypothalamus and anterior pitu- itary gland. To what extent changes in gonadal function (menopause and andropause) contribute to adrenopause and somatopause in both genders remains unknown. A growing body of evidence indicates that functional correlates, such as muscle size and strength, body composition, bone mass alterations, and progression of ather- osclerosis, directly relate to hormonal changes with aging. Hormone replacement therapy, nutritional supplementation, and regular exercise may suppress aspects of hormone-related aging dysfunction. Aging and Nervous System Function A 37% decline in the number of spinal cord axons and 10% decline in nerve conduction velocity reflect cumulative effects of aging on central nervous sys

•608 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits tem (CNS) function. Such changes partially explain age- 35-year-old men and 15% below values for women (see related decrements in neuromuscular performance. Parti- tioning reaction time into central processing time and Fig. 7.14). A slower rate of decline occurs for individuals muscle contraction time indicates that aging exerts the greatest effect on stimulus detection and information pro- who maintain an active lifestyle that includes regular aero- cessing to produce a response. For example, the knee-jerk reflex does not require CN S processing; it becomes les bic trainin. g. Physical activity does not entirely offset aging’s affected by aging than voluntary responses and movement effect on V O2max even when adjusting for a person’s quantity patterns. of muscle mass. . Despite the real effects of aging on reaction and move- ment time, physically active young or old groups move Figure 17.8 shows the relationship between VO2max and faster than a corresponding less active age group. These observations fuel speculation that regular participation in active appendicular muscle mass for younger (average age, physical activity thwarts biologic aging of certain neuro- muscular functions. 25 y) and older (average age, 63 y) aerobically trained men Aging and Pulmonary Function and women. Younger subjects had trained for 9 consecu- Cross-sectional studies indicate that dynamic pulmonary tive years, and older subjects had trained for 20 consecu- capacity of older endurance-trained athletes exceeds that of sedentary peers. Although longitudinal studies will provide t.ive years. Older men and women exhibited a 14% lower a definitive answer, available data suggest that regular phys VO2max than younger counterparts throughout the broad ical activity retards pulmonary function deterioration asso- ciated with aging. Regular, more vigorous exercise promotes range of variation in muscle mass among subjects. In other the maintenance of ventilatory musculature power and endurance. words, despite an equivalence in appendicular muscle Aging and Cardiovascular Function mass between a young .and older person, the younger per- son exhibited a higher VO2max. Regular physical activity exerts a profound influence o age-related decrements in cardiovascular function and . Three factors partially account for the deterioration in exercise endurance. VO2max with aging: . 1. Age-associated loss of muscle mass 2. Increase in body fat Maximal Oxygen Uptake Beyond age 35, V O2max 3. Altered cardiovascular and pulmonary functions declines at a nonlinear rate that accelerates after age 45 years The reductions in aerobic power per kilogram of active mus- so that by age 60 years, it averages 11% below values for cle mass with aging displayed inFigure 17.8 can reflect onl age-associated reduced oxygen delivery, reduced oxygen extraction at the active muscle, or both. Skeletal muscle oxidative capacity and capillarization, both important com- ponents of oxygen extraction, remain similar in older and younger individuals with comparable physiologic character- istics and training histories. Consequently, the well-docu- mented reduction in cardiac output (decreases in maximum heart rate and stroke volume) r.epresents the most likely explanation for the decrease in VO2max per kilogram of active muscle that accompanies aging. 5.0 •VO2max , L • min-1 4.0 Young subjects 3.0 Older subjects 2.0 Males . 16 Females Figure 17.8 Maximal oxygen uptake (VO2max) related to appendicular muscle mass in young 20 24 28 32 36 a.nd older endurance-trained men and women. Appendicular muscle mass, kg VO2max per kg of active muscle mass decreases with age, independent of training status. (Modi- fied from Proctor, D.N., Joyne.r, J.: Skeletal mus cle mass and the reduction of VO2max in trained older subjects. J. Appl. Physiol., 82:1411, 1997.)

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 609 Aging Response to Exercise Training For the healthy elderly, exer- Questions & Notes . cise training enhances the heart’s capacity to pump blood and increases aerobic Give the percentage rate decline in VO2max capacity to the same relative degree as in younger adults.. Nine to 12 months of between ages 20 and 60. endurance training in healthy older adults increased V O2max 19% in men and 22% in women. These values represent the high end of the typical training D. escribe the general relationship between response for young adults. Middle-aged men who regularly engaged in aerobic VO2max , Lиmin–1 and appendicular muscle training for more than 20 years delayed the expected 10% to 15% decline in mass, kg. exercise capacity and aerobic fitness. At age 55 years, these active m. en main tained nearly the same values for blood.pressure, body mass, and VO2max as at age 35 years; by age 70 years, their V O2max equaled values for individuals 25 years younger. These remarkable findings attest to the adaptability of the aer obic system to successful training at any age. Cardiovascular and Body Composition Can the healthy elderly enhance cardiovascular capacity with exercise Age-Related Changes training to the same relative extent as younger counterparts. Figure 17.9 shows longitudinal changes for maximum heart rate, minute pul- monary ventilation, and different body composition variables of 21 men tested at ages 50 (T1), 60 (T2), and 70 years (T3). The men trained continuously throughout the 20-year period; each had placed either first, second, or third i regional, national, or international competition in running events during a 10- year measurement interval. With the exception of pulmonary ventilation (small increase at T2), each shows definitive “aging effects.” Maximum heart rate decreased by 5 to 7 beats per min at each measurement over the 20 years (a smaller decrease than b • min-1 180 % mm 85 L • min-1 175 80 170 75 165 70 160 65 155 60 A D 160 18 155 17 150 16 145 15 140 14 135 13 130 12 125 11 120 10 115 110 E B 62 1.0 61 Waist ÷ Hip Ratio 0.9 kg 60 0.8 T2 (60-y) T3 (70-y) 59 T2 (60-y) T3 (70-y) T1 (50-y) Age (y) 58 Age (y) C 57 56 T1 (50-y) F Figure 17.9 Changes in maximum heart rate (A), minute ventilation (B), waist-to-hip girth ratio (C), sum of skinfolds (D), percent- age body fat (E), and fat-free body mass (F) for 21 endurance athletes who continued to train over a 20-year period, starting at age 50 years. (Modified from Pollock, M.L., et al.: Twenty-year follow-up of aerobic power and body composition of older track athltes. J. Appl. Physiol., 82:1508, 1997.)

•610 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits generally reported for nonathletes). Age-related decre- Other studies of physically active older individuals suggest ments in maximum heart rate have been attributed to three that the typical individual grows fatter with age, but those factors: who remain physically active counter the “normal” age- related loss in FFM while depressing the typical increase in 1. Alterations in sinoatrial (SA) node activity body fat percentage. 2. Reduced sympathetic activity output from the In addition to weight-bearing exercise’s positive role in medulla preserving FFM, the lack of weight-bearing (mechanical 3. Reluctance of researchers to encourage older, loading) exercise deserves concern because such exercise helps to counter the deleterious effects of osteoporosis with nonathletic individuals to train “all out” to achieve aging. Longitudinal research of bone mineral content a maximal effort during testing assessed every 6 months in children from age 6 to 12 years showed that 26% of adult total body bone mineral accrued Other age-related cardiovascular changes include reduced during just 2 years of peak bone mineral deposition. Such blood flow capacity to peripheral tissues, narrowing of direct evidence seems self-evident for its long-range impli- the coronary arteries (30% obstruction by middle age), cations in helping to preserve lean tissue mass. Perhaps the and decreased elasticity or compliance of major blood eventual “cure” for osteoporosis and its attendant medical vessels. and societal costs really should be viewed as a problem of young age (pediatric medicine) and not older age (geriatric Despite the almost 30 years of continuous training with- medicine). We strongly endorse the position that vigorous out changes in body mass (T1, 70.1 kg; T2, 69.4 kg; T3, physical activity should play an increasingly more important 70.8 kg), gains occurred in body fat while FFM declined. role in the home and schools as children grow into adoles- The roughly 3% body fat unit increase per decade paral- cence and adulthood. leled similar increases in waist girth. These data support an argument that some alterations in body composition and body fat distribution represent a normal aging response. Number of Individuals 700,000 600,000 500,000 Heart 400,000 disease 300,000 Cancer 200,000 100,000 Stroke Chronic lower 0 respiratory disease A Accidents Diabetes Alzheimer’s Influenza pneumonia Nephritis Septicemia Number of Individuals 500,000 450,000 400,000 Tobacco Figure 17.10 (A) Leading causes of deaths in the 350,000 United States in 2006. (B) Actual causes of preventa- 300,000 Poor diet ble deaths in the United States in 2006. (From the 250,000 National Heart Lung and Blood Institute. Available 200,000 Alcohol at http://www.nhlbi.nih.gov.) 150,000 use 100,000 Microbial 50,000 agents 0 Toxic B agents Motor vehicle Firearms Sexual activity Drug use

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 611 REGULAR EXERCISE: A FOUNTAIN OF YOUTH? Questions & Notes Exercise may not necessarily represent a “fountain of youth,” yet the prepon- Give 2 reasons for age-related decrements derance of evidence shows that regular physical activity retards the decline in in maximum heart rate. functional capacity associated with aging and disuse. Exercise participation can reverse the loss of function regardless of when a person becomes more physi- 1. cally active. 2. Causes of Death in the United States During the past 2 decades, changes in lifestyle have resulted in variations in Describe what happens to waist girth, per- causes of death in the United States. Whereas mortality rates from heart disease, centage body fat, and FFM with aging, stroke, and cancer have declined, prevalence of obesity and type 2 diabetes independent of physical activity level. increased Figure 17.10A summarizes the latest research detaili ng causes of death in the United States for theyear 2006 (reported in late 2009). Clearly, dis- List the 3 leading causes of death in the eases of the heart, malignant neoplasms and cancers, and cerebrovascular dis- United States in the year 2006. ease account for the majority of deaths. 1. Figure 17.10B shows causes of preventable deaths during the same time period. The most striking finding is the substantial increase in the number o 2. deaths attributable to poor diet and physical inactivity. The gap between deaths caused by poor diet and physical inactivity and those caused by cigarette smok- 3. ing has narrowed substantially.Clearly, most preventable deaths can be attributed to a small number of largely preventable behaviors and exposures that relate directly to physical inactivity, dietary exccess, and overfatness . Unless curtailed, the increasing trend of overfatness, poor diet, and physical inactivity will overtake cigarette smoking as the leading preventable cause of mortality. Does Exercise Improve Health and Extend Life? Medical experts have debated whether a lifetime of regular exercise con- tributes to good health and perhaps longevity compared with a sedentary Give 2 major findings of the Harvard Alumn “good life.” Because older, fit individuals exhibit many functional character Study of physical activity and health. istics of younger people, one could argue that improved physical fitness an 1. a vigorous lifestyle in older age retard biologic aging and confer health ben- efits later in life Research concerning lifestyles and exercise habits of 17,000 Harvard alumni who entered college between 1916 and 1950 showed that only moderate aero- 2. bic exercise, equivalent to jogging 3 miles a day, promotes good health and adds time to life. Men who expended 2000 kCal in weekly exercise had up to one- third lower death rates than classmates who did little or no exercise. To achieve a 2000-kCal energy output weekly requires moderate additional physical activ- ity such as a daily 30- to 45-minute brisk walk or a moderate run, cycle, swim, cross-country ski, or aerobic For Your Information dance participation. The following summarizes the results of the long-term study of alumni: LARGE ARTERY COMPLIANCE 1. Regular exercise counters the life-shortening Compliance of large arteries declines with age from changes in effects of cigarette smoking and excess body the arterial wall’s structural and nonstructural properties. The weight. inability of the internal diameter of an artery to expand and recoil in response to fluctuations in intravascular pressure dur- 2. Even for people with high blood pressure (a pri- ing the cardiac cycle associates with impaired cardiovascular mary heart disease risk), those who exercised function and elevated heart disease risk factors, including regularly reduced their death rate by half. hypertension, stroke, atherosclerosis, thrombosis, myocardial infarction, and congestive heart failure. Regular endurance 3. Regular exercise countered genetic tendencies exercise slows or prevents the “stiffening” of the large arteries toward early death. Individuals with one or both with advancing age and slows the decline in limb vasodilator parents who died before age 65 years (another capacity with healthy aging. significant but nonmodifiable risk) reduced the death risk by 25% with a lifestyle of regular exercise.

•612 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits Reduction in death rate (%) 50 40 30 20 Walking one mile 10 burns about 100 kCal 0 5-10 10-15 15-20 20-25 25-30 30-35 >35 Figure 17.11 Reduced risk of death <5 with regular exercise. (Data from Miles walked per week Paffenbarger, R.S. Jr., et al.: Physical activity, all-cause mortality, and longevity of college alumni. N. Engl. J. Med., 314:605, 1986.) 4. A 50% reduction in mortality rate occurred for colleagues, an example of why more does not necessarily active men whose parents lived beyond 65 years. produce greater exercise benefits Figure 17.11 shows that among physically active peo- Improved Fitness: A Little Goes ple, the more a person exercises, the more risk of death a Long Way declines. For example, men who walked 9 or more miles a week had a 21% lower mortality rate than men who walked A study of more than 13,000 men and women over an 3 miles or less. Exercising in light sports activities 8-year interval indicates that even modest amounts of increased life expectancy 24% over men who remained exercise substantially reduce the risk of death from heart sedentary. From a perspective of energy expenditure, the life disease, cancer, and other causes. The study evaluated expectancy of Harvard alumni increased steadily from a fitness performance directly rather than relying on verbal weekly exercise energy output of 500 to 3500 kCal, the or written reports of physical activity habits. To isolate equivalent of 6 to 8 hours of strenuous weekly exercise. In the effect of physical fitness per se, the researchers addition, active men lived an average of 1 to 2 years longer accounted for factors of smoking, cholesterol and blood than sedentary classmates. Additional research confirms tha sugar levels, blood pressure, and family history of coro- regular exercise confers an expected increase in life nary heart disease. Based on age-adjusted death rates per expectancy of about 10 months. 10,000 person-years, Figure 17.12 illustrates that the least fit group died at a three times greater rate than th N o additional health or longevity benefits accrue most fit subjects beyond weekly exercise of 3500 kCal. Men who performed extreme exercise had higher death rates than less active 90 Number of deaths per 10,000 80 All-cause death risk70 High Low 60 64.0 Sedentary Moderately active Very active 50 Low High Aerobic fitness 40 39.5 30 Figure 17.12 Physical fitnes and risk of death. The greatest 20 25.5 27.1 20.5 reduction in death rate risk occurs 21.7 when going from the most seden- tary category to a moderate fitnes 18.6 level. (Data from Blair, S.N., et al.: Physical fitness and all-cause mor 10 12.2 tality: a prospective study of 6.5 healthy men and women. JAMA., 8.5 262:2395, 1989.) 01 2 3 4 5 1234 5 Low High Low High Aerobic fitness

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 613 Importantly, the group rated just above the most sedentary category derived the uestions & Notes Qgreatest change in health benefits Whereas the decrease in death rate for men from the least fit to the next category equaled 38 (64.0 vs. 25.5 deaths pe Describe the relationship between reduced 10,000 person-years), the decline from the second group to the most fit cate risk of death with increases in regular gory equaled only seven deaths per 10,000 person-years. Women obtained sim- exercise. ilar benefits as men. The amount of exercise required moving from the mos sedentary category to the next more fit category (the jump showing the greates increase in health benefits) was moderate-intensity exercise such as walkin briskly for 30 minutes several times weekly. If life-extending benefits of exercis exist, they associated more with preventing early mortality than improving overall life span. Only moderate exercise enables individuals to live more productive and healthy lives. Changes in Physical Activity and For Your Information Mortality Among Older Women STRUCTURED PHYSICAL ACTIVITY NOT NECESSARY Studies of changes in physical activity and mortality Researchers monitored two groups of sedentary middle-aged men have mostly examined middle-aged male populations. and women ages 35 to 60 years during a 2-year clinical trial. One It remains unclear whether adoption of a physically group exercised vigorously for 20 to 60 minutes by swimming, stair active lifestyle by previously sedentary older women, stepping, walking, or biking at a fitness center up to 5 days a week. particularly those with chronic cardiovascular dis- The other group incorporated 30 minutes a day of “lifestyle” exer- ease, diabetes, and physical frailty, produces similar cises such as extra walking, raking leaves, stair climbing, walking benefits typically observed for men. Figure 17.13 around the airport while waiting for a plane, and participating in a summarizes a unique study of 9704 mostly white, 65- walking club most days of the week. The lifestyle participants also year-old women followed for 12.5 years. They were learned cognitive and behavioral strategies to increase daily physi- classified at baseline and 4.0 to 7.7 years later into on cal activity. For each of the programs, the intervention consisted of of four groups (quintiles, from highest to lowest) 6 months of intensive exercise followed by 18 months of based on physical activity level (amount of walking maintenance. At the end of 24 months, both groups showed similar per day and frequency and duration of other leisure improvements in physical activity, cardiorespiratory fitness, time activities such as dancing, gardening, aerobics, systolic and diastolic blood pressure, and body fat percentage. or swimming). The four groups were (1) active at These findings reinforce the conclusion that the health-derived baseline and stayed active during follow-up, (2) active benefits from regular exercise do not require highly structured or at baseline but became sedentary during the follow- vigorous exercise. up, (3) sedentary at baseline and remained sedentary at follow-up, and (4) sedentary at baseline but became active at follow-up. All-cause mortality data All-Cause Mortality 0.25 Cumulative Mortality Stayed Sedentary For Your Information 0.20 Became Sedentary Stayed Active 0.15 Became Active MOST POPULAR EXERCISES FOR AMERICANS 0.10 0.05 Activity Men Women (%) (%) 0 0.8 1.6 2.4 3.2 4.0 4.8 5.6 Walking 30 48 0 Follow-up, y Resistance 20 9 16 Figure 17.13 All-cause mortality by change in total physical activity by years of training 12 15 follow-up in older women. (From Gregg, E.W., et al.: Relationship of changes in physi- Cycling 10 6 cal activity and mortality among older women.JAMA., 289:2379, 2003.) Running Stair climbing 3 12 Aerobics 10

•614 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits were compared between groups up to 12.5 years after base- indicates that disease symptoms, progression, and out- line (6.7 y after the follow-up visit). come differ in women and men. Four gender-related heart disease differences include: Compared with continually sedentary women, those who were active or who became active had lower all-cause mor- 1. Women usually die sooner after a heart attack. tality. N otably, sedentary women who increased daily 2. Women who survive a heart attack frequently expe- physical activity to the equivalent of 1 mile of walking between baseline and follow-up had 40% to 50% lower all- rience a second episode. cause mortality rates than chronically sedentary women. 3. Women become more incapacitated by heart These findings take on added importance because th population of older women in the United States will dou- disease-related pain and disability. ble in the next 30 years, and more than one-third are now 4. Women are less likely to survive coronary artery sedentary. bypass surgery. CORONARY HEART DISEASE Changes on the Cellular Level The main graph of Figure 17.14 shows the prevalence of cardiovascular diseases in U.S. adults age 20 and older by Apparent Breakthrough Predisposing factors to age and gender for 2005 to 2006. The inset pie chart illus- trates the percentage breakdown of deaths from the diverse CHD involve degenerative changes in the intima or inner diseases of the heart and blood vessels. lining of the larger arteries that supply the myocardium. Damage to the arterial walls begins as a low-grade chronic Deaths from CHD have declined more than 35% since inflammatory response to injury. Eight contributing factor 1970, yet heart disease remains the leading cause of death include hypertension, cigarette smoking, infection, homocys- in the Western world. For every American who dies of can- teine, elevated cholesterol, free radicals, reaction to obesity- cer, almost two die of heart-related diseases. Death rates for related substances, and immunologically mediated factors. women lag about 10 years behind men, but the gap has Discovering the cause(s) of CHD had escaped researchers rapidly closed for women who smoke; for them, heart dis- until a recent breakthrough by a team of English ease is now the leading cause of death. Available evidence researchers identified the trigger for inflammation and ti sue breakdown in arterial plaque. The specialized molecule, toll-like receptor 2 (TLR-2), resides on the surface of an immune cell. When TLR-2 recognizes harmful molecules and cells its role switches the immune cell into attack mode Percentage breakdown of Coronary Heart 100 deaths from cardiovascular Disease Stroke diseases (male and female) Heart Failure High Blood 90 7 4 14 Pressure 85.9 7 Diseases of the 79.3 Arteries 73.3 72.6 80 Other 80+ Percentage of Population 70 52 38.5 17 60 50 40 37.9 30 20 15.9 10 7.8 0 40-59 60-79 20-39 Age range (y) Men Women Figure 17.14 Prevalence of cardiovascular diseases in adults age 20 and older by age and gender in the United States for 2005 to 2006. The inset pie chart illustrates the percentage breakdown of deaths from the diverse diseases of the heart and blood vessels. (From Heart Disease and Stroke Statistics: 2009 Update at a Glance. American Heart Association.Available at www.americanheart.org/ downloadable/heart/1240250946756LS-1982%20Heart%20and%20Stroke%20Update.042009.pdf.)

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 615 to protect the body. TLR-2 also can switch on immune cells when the body Questions & Notes encounters stress. In addition, bacteria may switch on the TLR-2 molecules, increasing the risk of plaques bursting and causing strokes and heart attacks. The Health benefits from regular exercise ar scientists demonstrated for the first time that antibodies could block the TLR- about the same for men and women. trigger mechanism. In their experiment, sections of the atherosclerotic carotid arteries were taken from 58 patients after they had a stroke. The arterial tissues were decomposed with enzymes until they formed a suspension of single cells in liquid. They analyzed the liquid after 4 days and found that the cells had pro- duced an unusually large amount of inflammatory molecules and enzyme Name the leading cause of death in the known to damage the arteries. The cells were then grown with several different Western world. antibodies designed to block different receptors and other molecules involved in the inflammation process. Blocking TLR-2 using an antibody dramaticall reduced the production of inflammation molecules and enzymes. The next ste in future research would be to pinpoint specific parts of molecules that switch o TLR-2 and trigger inflammation Give 2 gender-specific differences relate Other Considerations One response in the degenerative changes in the to heart disease. coronary arterial wall triggers the chemical modification of various compounds 1. including oxidation of low-density lipoprotein cholesterol (LDL-C). LDL-C oxi- dation represents a crucial step in a complex series of changes that produce lesions that sometimes bulge into the vessel lumen or protrude into the arterial 2. wall. The first signs of atherosclerosis involve lesions that take the form of fatt streaks, With further inflammatory damage from continued lipid deposition an proliferation of smooth muscle and connective tissue, the vessels congest with lipid-filled plaques, fibrous scar tissue, or both. Progressive occlusion gradual reduces blood flow capacity, causing the myocardium to become ischemic o poorly supplied with oxygen. Describe the function of the TLR-2 molecule. Vulnerable Plaque: Difficult to Detect Yet Lethal Vulnerable plaque, a soft type of metabolically active, unstable plaque, does not necessarily produce significant coronary artery narrowing but tends to fissure and burst. T rupture of unstable plaque—the sudden breakdown of fatty plaques in the lining of the coronary arteries—exposes the blood to thrombogenic compounds. This triggers a cascade of chemical events that culminates in clot formation (throm- bus) and leads to a myocardial infarction (MI) and possible death. The sudden, complete obstruction of a coronary artery frequently occurs in blood vessels with only mild to moderate obstructions ( ϳ70% blockage). Arterial blockage often occurs before the coronary vessel has narrowed enough to produce angina symp- toms or ECG abnormalities or to indicate the need for revascularization proce- dures (e.g., coronary bypass surgery or balloon angioplasty). Acute disruption and rupture of arterial plaque provides a plausible explanation for sudden death from acute physical exertion or emotional stress in middle-aged men with coro- nary artery disease compared with sudden death under resting conditions. The beneficial effects of cholesterol-lowering strategies on heart disease risk do no always improve coronary blood flow. A reduction in overall blood cholesterol For Your Information however, may improve the stability of vulnerable plaque, which would reduce the likelihood of future rupture of existing arterial plaque. DIABETES RISK LOWERED WITH REGULAR EXERCISE A Lifelong Process Men who exercise five or more times a week show a 42% lower risk of Landmark studies of atherosclerosis in 22-year-old American soldiers killed in type 2 diabetes than men who exercise Korea in 1950–1953 showed advanced lesions. These findings surprised th less than once a week. The exercise medical community and focused attention on the possible childhood origins of benefits become most pronounced atherosclerosis. Researchers now know that fatty streaks and clinically signifi among obese participants. The risk of cant fibrous plaques develop rapidly during adolescence through the thir diabetes decreases approximately 6% decade of life. for every 500 kCal of additional weekly exercise. BMI, systolic and diastolic blood pressure, and total serum cholesterol, triacyl- glycerols, and LDL-C strongly and positively related (HDL-C related negatively)

•616 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits A Platelets Displaced smooth muscle cells Artery wall Fatty deposit Smooth muscle Cholesterol- Cholesterol- containing LDL gorged macrophages (foam cells) B Figure 17.15 A. Deterioration of a coronary artery in atherosclerosis; deposits of fatty substances roughen the vessel’s center. B. Cast of coro- nary artery vasculature. to the extent of vascular lesions in the deceased young peo- thrombus (clot) forms and plugs the artery, depriving the ple. History of cigarette smoking magnified the vascula myocardium of normal blood flow with its oxygen supply damage. As the number of risk factors increased, so did the When the thrombus blocks one of the smaller coronary severity of atherosclerosis. Analyses of microscopic qualities vessels, a portion of the heart muscle dies (callednecrosis), of coronary atherosclerosis in teenagers and young adults and the person has a heart attack or MI. who died as a result of accidents, suicide, and murder indi- cated that many had arteries so clogged that they could If coronary artery narrowing leads to brief periods of experience an MI. Two percent of those ages 15 to 19 years inadequate myocardial perfusion, the person may experi- and 20% of those ages 30 to 34 years had advanced plaque ence temporary chest pains termed angina pectoris (see formation, the blockages considered most likely to separate Chapter 18). These pains usually emerge during exertion from the arterial walls and trigger a heart attack or stroke. because increased physical activity creates a greater Collectively, these and other data support the wisdom of demand for myocardial blood flow. Anginal attacks pro primary prevention through risk factor identification an vide painful, dramatic evidence of the importance of ade- intervention of artherosclerosis early in childhood or quate myocardial oxygen supply. adolescence. Seven Heart Attack Warning Signs The AHA Figure 17.15 shows the progressive occlusion of an artery from a buildup of calcified fatty substances in ather (www.aha.org) and other medical experts claim that one or osclerosis. The first overt sign of atherosclerotic chang more of these seven warning signs help identify an occurs when lipid-laden macrophage cells cluster under impending heart attack: the endothelial lining to form a bulge (fatty streak) in the artery. Over time, proliferating smooth muscle cells accu- 1. Uncomfortable pressure, fullness, squeezing, or mulate to narrow the artery’s lumen (center). Typically, a pain in the center of the chest lasting more than a few minutes

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 617 2. Pain spreading to the shoulders, neck, or arms. The pain ranges from Questions & Notes mild to intense. It may feel like pressure, tightness, burning, or heavy weight. It may be located in the chest, upper abdomen, neck, jaw, or List 4 variables that positively relate to inside the arms or shoulders vascular lesions. 3. Chest discomfort with lightheadedness, fainting, sweating, nausea, or 1. shortness of breath 2. 3. 4. Anxiety; nervousness; or cold, sweaty skin 4. 5. Paleness or pallor 6. Increased or irregular heart rate 7. Feeling of impending doom Cardiovascular Disease Epidemic List 3 heart attack warning signs. 1. Each year, cardiovascular diseases top the list of the country’s most serious health problems. CHD remains the leading health problem and the primary 2. cause of death. It represents the most expensive condition to treat as it exem- plifies a resource-intensive chronic condition. Consider recent (2005–2006 3. statistics for the United States released by the AHA shown in the accompaning box: • At least 80 million people (one person in three) has some form of cardiovascular disease. For Your Information • Cardiovascular disease is the primary killer of women and men. Diseases of the cardio- HEART ATTACK VERSUS CARDIAC vascular system claim the lives of more than half a million women every year, about one ARREST death per minute. • Cardiovascular disease accounts for almost 1 of every 2.4 deaths. • Heart attack: Caused by (1) block- • Since 1900, cardiovascular disease was the leading cause of death every year but age in one or more arteries supplying 1918, and it caused more deaths than the next seven causes combined. the heart, thus cutting off myocardial • Every 37 seconds, a person has a coronary event, and each minute, someone dies from blood supply, or (2) sudden spasms one. (constrictions) of a coronary vessel, • Among whites, only 11.4% have heart disease, 6.1% have CHD, and 2.2% have had a causing part of the heart muscle to stroke. die (necrosis) from lack of oxygen • Among African Americans, 10.2% have heart disease, 6.0% have CHD, 31.7% have (anoxia). hypertension, and 3.7% have had a stroke. • Among Asian Americans, 6.9% have heart disease, 4.3% have CHD, 19.5% have • Cardiac arrest: Caused by irregular hypertension, and 2.6% have had a stroke. neural–electrical transmission within the myocardium. This produces Cigarette Smoking chaotic, unregulated beating in the heart’s lower chambers Cigarette smoking, either active or passive through environmental exposure, (ventricular fibrillation). directly increases the risk of CHD. Smokers experience twice the risk of death from heart disease as nonsmokers. The risk increases further for smokers with For Your Information diabetes and hypertension. The CDC estimates that every cigarette smoked steals 7 minutes from a smoker’s life. This adds up to 5 million years of poten- EXERCISE IS GOOD MEDICINE FOR tial life Americans lose to cigarettes yearly. CHD risk increases the more one THE COLON smokes or receives passive exposure, the deeper one inhales, and the stronger the cigarette (for tars and noxious by-products). The increasing death rate from Research based on the health and exer- heart disease among women in the United States almost parallels their increased cise habits of Harvard alumni indicates cigarette use. British researchers estimate that smokers between ages 30 and that physically active men had about 40 years have five times as many heart attacks as nonsmokers in the same ag half the risk of colon cancer as inactive range. When these relatively young smokers have a heart attack, an 80% chance classmates. The protection disappeared exists that smoking caused it; this percentage averages nearly 70% for smokers if the men stopped exercising. One in their 50s and 50% for smokers in their 60s and 70s. Also, smokers run a fiv mechanism proposes that exercise times greater risk for stroke than nonsmokers, and those who smoke one pack protects against this major killer by or more each day are 11 times more likely to have a specific type of a sudden speeding the passage of food residues deadly stroke most common in younger men and women. Surprisingly, the through the digestive tract that reduces CHD risk from smoking correlates with a greater number of deaths than excess the colon’s exposure to potential food mortality of cigarette smokers from lung cancer. carcinogens. Smoking risk usually remains independent of other risk factors. If additional risk factors exist, then smoking accentuates their influence. Cigarette smokin

•618 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits Risk of Death from CHD AccordingDeaths per 1000 men150 mgиdLϪ1. A cholesterol level of 230 mgиdLϪ1 increases to Blood Cholesterol Levelduring 6-year follow-upheart attack risk to about twice that of 180 mg иdLϪ1, and 300 mg иdLϪ1 increases the risk fourfold. For triacylglyc- 18 erols, the National Cholesterol Education Program (www. nhlbi.nih.gov/about/ncep/index.htm) considers 200 mgиdLϪ1 14 an upper limit of normal triacylglycerol level, with 200 to 400 mgиdLϪ1 as borderline, requiring changes in exercise, 10 diet, and possibly drug treatment if accompanied by other CHD risk factors. More than likely, triacylglycerol levels 6 above 100 mg иdLϪ1 pose a cardiac risk. Individuals with triacylglycerol levels above 100 mgиdLϪ1 (after a 12-h fast) 2 show a 50% greater CHD risk than those with triacyl- 160 200 240 280 glycerols below 100 mgиdLϪ1, even after controlling for HDL-C. Blood cholesterol level (mg • dL–1) Major clinical drug trials show conclusively that reduc- Figure 17.16 Generalized risk for death from coronary heart ing cholesterol lowers death rates and attenuates heart disease (CHD) in relation to total serum cholesterol level. attacks. Medications that affect blood lipids include (1)bile (Adapted from Martin, M.J., et al.: Serum cholesterol, blood acid sequestrants (e.g., cholestyramine resin and colestipol pressure and mortality: implications from a cohort of 361,662 hydrochloride), which bind (sequester) cholesterol-rich bile men. Lancet, 2:933, 1986.) in the gastrointestinal tract and prevent its reabsorption from the gut; (2) fibric acid derivatives (e.g., gemfibrozi facilitates heart disease through its potentiating effect on probucol, clofibrate), which lower triacylglycerols an serum lipoproteins; individuals who smoke have lower lev- LDL-C (5% to 20%) and elevate HDL-C (average 6% per els of HDL-C than nonsmokers. When smokers quit, the year); and (3) the remarkably effective statins (e.g., lovas- HDL-C and heart disease risk return to levels of nonsmok- tatin, pravastatin, simvastatin, atorvastatin), which inhibit ers. A frightening statistic predicts that by the year 2030, an enzyme that controls cholesterol synthesis by the cells, smoking will become the world’s single leading cause of increase LDL-C receptors in the liver, and facilitate LDL-C death and disability (unless obesity continues its meteoric removal from serum (18% to 55% reduction). Raising increases with unprecedented effects on disease processes). HDL-C by 34 mg иdLϪ1 via a 5-year gemfibrozil therap trial reduced heart attacks, strokes, and death by 24% in Blood Lipid Abnormalities patients with initially low HDL-C levels. An abnormal blood lipid level, or hyperlipidemia, provides Lipids do not circulate freely in blood plasma; rather, a crucial component in the genesis of atherosclerosis. they combine with a carrier protein to form lipoproteins Figure 17.16 shows the increasing rate of death from CHD composed of a hydrophobic cholesterol core and coat of related to total serum cholesterol. Current guidelines focus free cholesterol, phospholipid, and a regulatory protein less on total cholesterol and more on its lipoprotein com- (apolipoprotein [Apo]). Table 17.2 lists the four differ- ponents (see Close Up Box 17.2: How to Classify Choles- ent lipoproteins, their approximate gravitational densi- terol, Lipoproteins, and Triacylglycerol Values,on page 619). ties, and their percentage composition in the blood. Early treatment becomes crucial because of a strong asso- Serum cholesterol reflects a composite of the total cholestero ciation between high serum cholesterol as a young adult contained in each of the different lipoproteins.Although dis- and cardiovascular disease in middle age. A cholesterol cussions commonly refer to hyperlipidemia, the more level of 200 mg иdLϪ1 or lower is usually desirable, meaningful focus addresses the different types of hyper- although risk for a fatal heart attack begins to increase at lipoproteinemias. Cholesterol distribution among the various lipopro- teins provides a more powerful predictor of heart disease Table 17.2 Approximate Composition of Lipoproteins in the Blood VERY LOW-DENSITY LOW-DENSITY HIGH-DENSITY LIPOPNROTEI S LIPOPNROTEI S LIPOPNROTEI S CHYLOMICRONS (VLDL: PREBETA) (LDL:BETA) (HDL: ALPHA) Density, gиcmϪ3 0.95 0.95–1.006 1.006–1.019 1.063–1.210 Protein, % 0.5–1.0 5–15 25 45–55 Lipid, % 99 75 50 Cholesterol, % 2–5 95 40–45 18 Triacylglycerol, % 85 10–20 5–10 2 Phospholipid, % 3–6 50–70 20–25 30 10–20

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 619 BOX 17.2 CLOSE UP How to Classify Cholesterol, Lipoproteins, and Triacylglycerol Values Important risk factors for the development of atheroscle- debris, minerals, and cholesterol) include the aorta and rosis include high levels of serum cholesterol, triacylglyc- carotid, coronary, femoral, and iliac arteries. Specific cut erol, and LDL-C and a low level of HDL-C. The primary off values for the diverse blood lipid forms relate to sites for artery-narrowing plaque formation (i.e., incor- increased CHD risk. The following tables present current poration of connective tissue, smooth muscle, cellular guidelines for the various blood lipids and lipoproteins. Table 1 Classification of Serum Total Cholesterol, Low-Density Lipoprotein Cholesterol, and High-Density Lipoprotein Cholesterol Levels CHOLESTEROL CLASSIFICATION (mg и dLϪ1) Total cholesterol Ͻ200 Desirable Borderline high cholesterol 200–239 High cholesterol Ͼ240 Optimal (recommended for people with CHD or diabetes) LDL Desirable Ͻ70 Borderline high cholesterol Ͻ130 High cholesterol 130–159 Very high cholesterol 160–189 Ͼ190 Low cholesterol High cholesterol HDL Ͻ35 Ͼ60 From Diabetes Education Research Center and American Heart Association, 2004. Table 2 Classification of Triacylglycerol Levels SERUM TRIACYLGLYEROLS (mg и dLϪ1) CLASSIFICATION COMMENTS Ͻ150 Normal Check for accompanying primary or secondary dyslipidemias 150–199 Borderline high Check for accompanying primary or secondary dyslipidemias 200–499 High Increased risk for acute pancreatitis Ͼ500 Very high From Diabetes Education Research Center and American Heart Association, 2004. risk than total blood cholesterol. Specifically For Your Information elevated HDL-C levels relate causally with a lower heart disease risk, even among individ- SHOULD CHOLESTEROL BE MEASURED IN CHILDREN? uals with total cholesterol below 200 mgиdLϪ1. Overwhelming evidence links high Guidelines issued by the National Cholesterol Education Program LDL-C and Apo B levels with increased CHD (www.americanheart.org) conclude “yes” if a family history of high risk. A more effective evaluation of heart dis- cholesterol or heart disease exists particularly if a parent had a heart ease risk than either total cholesterol or LDL- attack before age 50 years. Shockingly, this parental “cardiac proneness” C levels divides total cholesterol by HDL-C. includes up to 25% of the United States adult population! Research with A ratio greater than 4.5 indicates a high heart children ages 10 to 15 years indicates that lifestyle habits of regular exer- disease risk; a ratio of 3.5 or lower represents cise, improved cardiovascular fitness, and a prudent nutritional profile a more desirable risk level. contribute to favorable lipid profiles similar to effects with adults.

•620 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits LDL-C (synthesized in the liver) and very low–density ure, heart attack, stroke, and kidney failure. From 1995 to lipoprotein cholesterol (VLDL-C) provide the transport 2005, the death rate from hypertension increased 25.2%, medium for fats to cells, including the smooth muscle and the number of deaths rose 56.4%. walls of arteries. Upon oxidation, LDL-C participates in artery-clogging, plaque-forming atherosclerosis by stimu- Modification of lifestyle behaviors can lower hig lating monocyte–macrophage infiltration and lipoprotei blood pressure, often called the “silent killer”; important deposition. LDL-C’s surface coat contains the specifi modifications include weight loss, regular physical activ apolipoprotein (Apo B) that facilitates cholesterol removal ity, cessation of smoking (nicotine constricts peripheral from the LDL-C molecule by binding to LDL-C receptors blood vessels that elevates blood pressure), and reducing of specific cells. Prevention of LDL-C oxidation slows th salt intake (excess sodium retains fluid that elevate progression of CHD. The potential benefit of the dietar blood pressure in susceptible individuals). Unfortunately, antioxidants vitamins C and E and␤-carotene on heart dis- the cause(s) of hypertension remains unknown in more ease risk reflect how well they blunt LDL-C oxidation than 90% of individuals. Men and women ages 30 to 54 years with mild hypertension modestly lowered their LDL-C targets peripheral tissue and contributes to arte- systolic by 2.9 mm Hg and diastolic blood pressure by rial damage, and HDL-C (also produced in the liver and 2.3 mm Hg when they reduced their body weight and salt whose levels relate to genetic factors) facilitates reverse intake over an 18-month period. N o blood pressure cholesterol transport. HDL-C promotes surplus cholesterol changes occurred for subjects who undertook only stress removal from peripheral tissues including arterial walls for reduction and relaxation techniques or consumed cal- transport to the liver for bile synthesis and subsequent cium, magnesium, phosphorus, and fish oil dietary sup excretion via the digestive tract. The apolipoprotein A-1 plements. Prescription drugs that either reduce flui (Apo A-1) in HDL-C activates the enzyme lecithin acetyl volume or decrease peripheral resistance to blood flo transferase (LCAT) that converts free cholesterol into cho- effectively treat high blood pressure. Lowering systolic lesterol esters. This facilitates removal of cholesterol from blood pressure just 2 mm Hg reduces deaths from stroke lipoproteins and other tissues. by 6% and heart disease by 4%. Factors that Affect Blood Lipids Six behaviors Diabetes favorably impact the blood lipid profile Diabetics are up to four times more likely to develop car- diovascular disease from multiple risk factors usually coin- 1. Weight loss cident with the diabetic condition. These four factors 2. Regular aerobic exercise (independent of weight include: loss) 1. Obesity represents a major risk factor for cardiovas- 3. Increased intake of water-soluble fibers (fibers cular disease that strongly associates with insulin resistance. Insulin resistance may provide the beans, legumes, and oat bran) mechanism by which obesity leads to cardiovascu- 4. Increased intake of polyunsaturated to saturated lar disease. Weight loss improves cardiovascular risk, decreases blood insulin concentrations, and fatty acid ratio and monounsaturated fatty acids and increases insulin sensitivity. elimination of trans fatty acids 5. Increased intake of the polyunsaturated fatty acids 2. Physical inactivity is a modifiable risk factor fo in fish oils (omega-3 fatty acids insulin resistance and cardiovascular disease. Exer- 6. Moderate alcohol consumption cising more while reducing excess body weight (and fat) prevents or delays the onset of type 2 dia- Four variables adversely affect cholesterol and lipoprotein betes, reduces blood pressure, and reduces heart levels: attack and stroke risk. 1. Cigarette smoking 3. Hypertension positively correlates with insulin 2. Diet high in saturated fatty acids, trans fatty acids, resistance in diabetes. For a person with both hypertension and diabetes, a common combination, and preformed cholesterol the risk for cardiovascular disease doubles. 3. Emotionally stressful situations 4. Oral contraceptives 4. Atherogenic dyslipidemia, often called diabetic dyslipidemia in people with diabetes, relates to Hypertension: A Prevalent Disorder insulin resistance characterized by high levels of tri- acylglycerols (hypertriglyceridemia) and high levels About 73.6 million people in the United States age 20 years of small LDL particles and low levels of HDL. The and older have high blood pressure that exceeds 140 mm Hg components of this lipid triad contribute to athero- (systolic hypertension) or diastolic pressure that exceeds 90 sclerotic risk. mm Hg (diastolic hypertension; www.americanheart.org/ presenter.jhtml?identifie ϭ4621). These values form the According to the latest statistics from the 2007 National lower limit for the classification of borderline high blood Diabetes Fact Sheet (the most recent year for which data pressure. One of every four or five people experience chronic, abnormally high blood pressure sometime during life. Uncorrected hypertension can precipitate heart fail-

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 621 are available; www.diabetes.org/diabetes-basics/diabetes-statistics), 3.6 million uestions & Notes Qchildren and adults in the United States—7.8% of the population—have diabetes. Roughly 17.9 million people have been diagnosed, 5.7 million people remain List the 4 major risk factors for diabetes. undiagnosed, and 57 million people are prediabetic. Unfortunately, 1.6 million 1. new cases of diabetes will be diagnosed in people age 20 years and older each year, and the numbers continue to increase yearly at an alarming rate. Other Coronary Heart Disease Risk Factor Candidates 2. 3. The following factors represent potentially potent CHD risk predictors. 4. Age, Gender, and Heredity Age represents a CHD risk factor as it asso- ciates with other risk factors—hypertensi on, elevated blood lipid levels, and glucose intolerance. After age 35 years in men and age 45 years in women, the chances of dying from CHD increase progressively and dramatically. Heredity also represents a risk factor in that heart attacks that strike at an early age tend to run in families. Such familial predisposition probably relates to a genetic role in determining the risk of heart disease. Immunologic Factors An immune response may trigger plaque develop- ment within arterial walls. During this process, mononuclear immune cells pro- duce proteins called cytokines, some of which stimulate plaque buildup; others inhibit plaque formation. Within this framework, regular exercise may stimulate For Your Information the immune system to inhibit agents that facilitate arte- rial disease. For example, 2.5 hours of weekly exercise FIBER INTAKE AND CORONARY HEART DISEASE IN for 6 months decreased cytokine production that facili- THE ELDERLY tates plaque development by 58%; cytokines that An inverse association exists between fiber consumption from inhibit plaque formation increased by 36%. cereal sources (including whole grains and bran) and coronary heart disease risk in elderly men and women (average age, 72 y). Homocysteine Homocysteine, a highly reactive, Compared with medical or surgical interventions, increasing fiber intake by the equivalent of two slices of whole grain bread sulfur-containing amino acid, forms as a by-product of per day is easy to incorporate into the daily routine, is low cost, methionine metabolism. Researchers in the 1960s and and is widely available. 1970s described three different inborn errors of homo- cysteine metabolism involving B-vitamin enzymes. High levels of homocysteine in the blood and urine For Your Information were common to all three disorders of the affected individuals, and half of these individuals developed PHYSICAL ACTIVITY AND WOMEN: HOW MUCH IS GOOD arterial or venous thrombosis by age 30 years. It was ENOUGH? postulated that moderate elevation of homocysteine in the general population predisposes individuals to ath- Modest levels of physical activity (30 minutes per day on most erosclerosis similarly to elevated cholesterol concen- days) decrease the risk of chronic diseases, including breast cancer. tration. Appropriate dietary restraint, coupled with increased physical N umerous studies have shown a nearly lockstep activity, can help overweight women reduce their weight. When association between plasma homocysteine levels and prescribing physical activity, set a goal of 30 minutes per day of heart attack and mortality in men and women similar moderate-intensity activity. This can be accumulated in bouts of at to that of smoking and hyperlipidemia. This metabolic least 10 minutes daily. For those willing to do more and for whom abnormality is present in nearly 30% of CHD patients no contraindications exist, greater duration and increased intensity and 40% of patients with cerebrovascular disease. Exces- of activity confers additional benefits. (Jakicic, J.M.: Effect of exer- sive homocysteine causes blood platelets to clump, fos- cise duration and intensity on weight loss in overweight, sedentary tering blood clots and deterioration of smooth muscle women: a randomized trial. JAMA., 290:1323, 2003; Lee, I.-M. cells that line the arterial wall. Chronic homocysteine Physical Activity and Women: How Much Is Good Enough? exposure eventually scars and thickens arteries and pro- JAMA., 290:1377, 2003; and Manson, J.E.: Walking compared vides a fertile medium for circulating LDL-C to initiate with vigorous exercise for the prevention of cardiovascular events damage. In the presence of other conventional CHD in women. N. Engl. J. Med., 347:716, 2002.) risks (e.g., smoking and hypertension), synergistic

•622 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits effects magnify the negative impact of homocysteine on C-Reactive Protein Mounting evidence indicates cardiovascular health. In general, people in the highest quartile for homocysteine levels have nearly twice the that painless chronic low-grade arterial inflammation risk of heart attack or stroke compared with those in the including that of the coronary arteries remains central to lowest quartile. Why some people accumulate homocys- every stage of atherosclerotic disease and a major trigger teine is uncertain, but the evidence points to a deficienc for heart attack—more substantial even than high choles- of B vitamins (B6, B12, and particularly folic acid); ciga- terol. The inflammation produces heart attacks by weaken rette smoking, frequent coffee intake, and high meat ing blood vessels walls, making plaque burst, and consumption are also associated with elevated homocys- interfering with substances that increase myocardial circu- teine concentrations. lation. C-reactive protein (CRP) is a protein found in the blood that increases during the inflammatory response t Excessive Body Fat Excess body fat has received tissue injury or infection. The liver primarily synthesizes CRP with its release stimulated by interleukin 6 (IL-6) and attention as a CHD risk factor, but its relationship fre- other proinflammatory cytokines. Small increases in CR quently coexists with hypertension, elevated cholesterol, within the normal range predict future vascular events in type 2 diabetes, and cigarette smoking. The number of apparently healthy, asymptomatic individuals. Such pre- annual deaths attributable to overfatness in the United dictive accuracy of CRP extends to patients with preexist- States adult population easily exceeds 350,000. Weight ing vascular disease. Higher CRP levels are associated with loss and accompanying body fat reduction, whether abdominal obesity, and increased levels predict the risk of through diet or exercise, usually normalize cholesterol and developing type 2 diabetes.Strategies to lower CRP include triacylglycerol levels and exert beneficial effects on bloo weight loss, abstinence from cigarette smoking, consum- pressure and type 2 diabetes. ing a healthful diet, and regular exercise (e.g., combined aerobic/resistance training). Physical Inactivity Regular physical activity offers Lipoprotein(a) Liporotein(a) [Lp(a)] is an LDL-like protection against heart disease. Sedentary men and particle largely under genetic control that varies substan- women are twice as likely to suffer a fatal heart attack as tially between individuals depending on the size of the more physically active counterparts. Maintenance of aer- apo(a) isoform present. Lp(a) levels vary little with diet or obic fitness throughout life also provides protectio exercise, unlike the other lipoproteins LDL and HDL. The against CHD risk factors and disease occurrence. One biological function of Lp(a) remains unclear, but strong could argue that genetic factors contribute more to fitnes evidence suggests its role in responding to tissue injury level than to daily exercise patterns. However, fitnes and vascular lesions, to prevent infectious pathogens from level relates closely to individual differences in physical invading cells, and to promote wound healing. High Lp(a) activity level among most individuals, making regular in blood is a risk factor for coronary artery disease, cere- exercise assume greater importance than simply genetics brovascular disease, atherosclerosis, thrombosis, and in determining physical fitness and related health bene stroke. Lp(a)’s most important role may be to inhibit the fits. Table 17.3 summarizes possible biologic mecha- breakdown of clots (fibrinolysis) at the site of tissue injury nisms for how regular aerobic exercise confers protection These properties make Lp(a) a highly atherothrombotic against CHD progression. lipoprotein. Possible Mechanisms for Eight Beneficial Effects of Regular Aerobic Exercise on Table 17.3 Risk of Coronary Heart Disease and Mortality 1. Improves myocardial circulation and metabolism to protect the heart from hypoxic stress. Improvements include enhanced vascularization and increased coronary blood flow capacity via altered control of coronary vascular smooth muscle and increase reactivity of coronary resistance vessels. Modest increases in cardiac glycogen stores and glycolytic capacity also prove benef cial if the heart’s oxygen supply suddenly becomes compromised. 2. Enhances the mechanical properties of the myocardium to enable the exercise-trained heart to maintain or increase contractility during a specific challenge 3. Establishes more favorable blood-clotting characteristics and other hemostatic mechanisms, including increased fibrinolysis a d production of endothelial prostacyclin. 4. Normalizes the blood lipid profile to slow or reverse atherosclerosis 5. Favorably alters heart rate and blood pressure so myocardial work decreases during rest and exercise. 6. Suppresses age-related body weight gain and promotes a more desirable body composition and body fat distribution (particularly a reduced level of intraabdominal adipose tissue). 7. Establishes a more favorable neural–hormonal balance to conserve oxygen for the myocardium; improves the mixture of carbohydrate and fat metabolized by the body. 8. Provides a favorable outlet for psychological stress and tension.

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 623 Fibrinogen Fibrinogen, a circulating glycoprotein synthesized by the liver, uestions & Notes Qacts at the final step in the coagulation response to vascular tissue injury. Fib rinogen, similar to CRP, is an acute-phase reactant, with other characteristics List 6 factors not causally linked that are that make it biologically plausible as a possible participant in vascular disease: nevertheless potent CHD risk factors. (1) regulation of cell adhesion, chemotaxis (movements of cells in response to 1. substances exhibiting chemical properties), and cell proliferation; (2) vasocon- striction at sites of vessel wall injury; (3) stimulation of platelet aggregation; and (4) determinants of blood viscosity. 2. Epidemiologic data support an independent association between elevated fibrinogen levels and cardiovascular morbidity and mortality. Elevated bloo 3. fibrinogen, independent of classic CHD risk factors, correlates with ischemi stroke and peripheral vascular disease. Several factors other than inflamma tion modulate fibrinogen levels. A dose–response relationship exists betwee 4. number of cigarettes smoked and fibrinogen level. Fibrinogen tends to be higher in patients with diabetes, hypertension, obesity, and a sedentary 5. lifestyle. 6. CORONARY HEART DISEASE RISK FACTOR INTERACTIONS Smoking generally acts independently of other risk factors to increase CHD List 3 possible exercise-induced risk. The other risk factors interact with each other and CHD itself to accen- mechanisms for reducing CHD risk. tuate disease risk. Figure 17.17 quantifies the interaction of three primary CHD risk factors in the same person. With one risk factor, a 45-year-old 1. man’s chance for CHD symptoms during the year averages about twice that of a man without risks. The chance for chest pain, heart attack, or sudden 2. death with three risk factors increases five times compared with no risk factors. 3. CORONARY HEART DISEASE RISK FACTORS IN CHILDREN Briefly explain the role of C-reactive protein as a CHD risk factor. The frequent occurrence of multiple CHD risk factors in young children empha- sizes the need for early CHD initiatives to reduce atherosclerosis risk later in life. Obesity and a family history of heart disease represent the two most common risk factors in physically active and apparently healthy boys and girls. A rela- tively large percentage of these children also show abnormally high blood lipid concentrations. As with adults, the association between body fat and serum lipid levels becomes apparent in overfat children. The fattest children usually have the highest levels of serum cholesterol and triacylglycerols. For them, general adiposity and visceral adipose tissue relate to unfavorable hemostatic factors that increase CHD morbidity For Your Information and mortality in adulthood. Of 62 overfat children ages 10 to 15 years, only 1 child had just one CHD risk factor. Of the APOPROTEIN remaining children, 14% had two risk factors, 30% had three Apoproteins represent a class of specific proteins embed- risk factors, 29% had four risk factors, 18% had five risk fac ded in the outer shell of a lipoprotein particle that tors, and the remaining five children (8%) had six risk factors (1) increase the solubility of the lipoprotein’s cholesterol A subsample of these children was then enrolled in a 20-week and triacylglycerol components, (2) act as ligands for program to evaluate the effects on the risk profile of either (1 specific lipoprotein receptors in cell membranes, and diet plus behavior therapy (DB) or (2) regular exercise plus (3) serve as important cofactors to activate enzymes in diet and behavior therapy (EDB). No changes resulted in mul- lipoprotein metabolism. Specific apoproteins may more tiple-risk reduction in the control group (CON) or in those reliably predict heart disease proneness than total receiving diet with behavior treatment. In contrast, children cholesterol level. who exercised, dieted, and underwent behavior therapy

•624 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits BOX 17.3 CLOSE UP Calculate Your Coronary Heart Disease Risk CHD risk inventories provide a qualitative means to To determine risk profile, review each risk factor an assess an individual’s susceptibility to CHD. The table accompanying numerical “point” value. Insert the respec- below presents the Framingham 10-year CHD risk esti- tive points into the applicable box at the top of the table. mate. This is the most widely used “traditional” risk The total number of points represents the 10-year risk for analysis system. developing CHD expressed as a percentage. Framingham 10-Year CHD Risk Estimate Worksheet nn nn n n ϭn AGE HDL-C SBP TC SNMOKI G TOTANL POI TS 10-y RISK (%) Age (y) Systolic Blood Pressure (SBP), mm Hg Women Points Men Points Women Points Men Points 20–34 Ϫ7 20–34 Ϫ9 mm Hg Treated Untreated mm Hg Treated Untreated 35–39 Ͻ120 0 0 Ͻ120 0 0 40–44 Ϫ3 35–39 Ϫ4 45–49 120–129 1 3 120–129 0 1 50–54 0 40–44 0 55–59 130–139 2 4 130–139 1 2 60–64 3 45–49 3 65–69 140–159 3 5 140–159 1 2 70–74 6 50–54 6 75–79 Ͼ160 4 6 Ͼ160 2 3 8 55–59 8 10 60–64 10 12 65–69 11 14 70–74 12 16 75–79 13 Points for Total Cholesterol (TC) at Each Age Category (y) Points for Total Cholesterol (TC) at Each Age Category (y) Women Men TC TC (mgиdLϪ1) 20–39 40–49 50–59 60–69 70–79 (mgиdLϪ1) 20–39 40–49 50–59 60–69 70–79 Ͻ160 00 000 Ͻ160 0 000 0 0 160–199 43 211 160–199 4 3 2 1 0 1 200–239 86 421 200–239 7 5 3 1 1 240–279 11 8 53 2 240–279 9 6 4 2 Ͼ280 13 10 7 4 2 Ͼ280 11 8 5 3 Points for Smoking at Each Age Category (y) Points for Smoking at Each Age Category (y) Women Men 20–39 40–49 50–59 60–69 70–79 20–39 40–49 50–59 60–69 70–79 Nonsmoker 0 00 0 0 Nonsmoker 0 000 0 Smoker 9 74 531 1 2 1 Smoker 8 Men Predicated 10-Year CHD Risk From Point Total 10-Year Risk (%) Women Ͻ1 Point Total 10-Year Risk (%) Point Total 1 2 Ͻ9 Ͻ1 0 3 9–12 1 1–4 4 13–14 2 5–6 5 37 6 15 48 8 16 59 10 17 6 10 12 18 8 11 16 19 11 12 20 20 14 13 25 21 17 14 Ն30 22 22 15 23 27 16 24 Ն30 Ն17 Ն25

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 625 CHD incidence per 100,000 persons 700 600 500 400 300 200 100 0 One Two Three None Number of CHD risk factors Figure 17.17 Relationship between a combination of abnormal CHD risk factors (cholesterol Ͼ250 mgиdLϪ1; systolic blood pressure Ͼ160 mm Hg; smoking Ͼ1 pack a day) and inci- dence of CHD. dramatically reduced multiple risks ( Fig. 17.18). These encouraging finding demonstrate that supervised programs of moderate food restriction and exercise with behavior modification reduces CHD risk factors in obese adolescents Adding regular exercise augmented the effectiveness of risk factor intervention. If regular physical activity upgrades or at least stabilizes a poor risk factor profile, then school curricula at all grade levels particularly at the kindergarte and elementary grades, should strongly encourage more physically active lifestyles. In this regard, not implementing daily, required physical education seems counterproductive from a public health policy standpoint. EDB multiple risk factors DB multiple risk factors Control multiple risk factors 6 6 6 5 5 5 Number of subjects 444 333 222 111 000 123456 7 8 123456 7 8 123456 7 8 Number of risk factors Number of risk factors Number of risk factors Pre-treatment Post-treatment Figure 17.18 Multiple coronary heart disease risk factors for obese adolescents before and after treatment. DBϭ diet behavior change group; EDB ϭ exercise diet behavior change group. (From Becque, M.D., et al.: Coronary risk incidence of obese adoles- cents: reduction by exercise plus diet intervention.Pediatrics, 81:605, 1988.)

•626 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits SUMMARY 14. Life-extending benefits of exercise correlate more wit preventing early mortality than improving overall 1. Elderly persons make up the fastest growing segment life span. Although the maximum life span may not of American society. Thirty years ago, age 65 years extend greatly, only moderate exercise enables many represented the onset of old age. Gerontologists now men and women to live more productive and healthy consider 85 years the demarcation of “oldest-old” and lives. age 75 years “young-old.” 15. Sedentary white women who increase their physical 2. Nearly 12% or approximately 35 million Americans activity to the equivalent of about 1 mile/day of exceed age 65 years; by the year 2030, 70 million walking exhibit approximately 40% to 50% lower Americans will exceed age 85 years. all-cause mortality rates than chronically sedentary counterparts. 3. “Healthspan” refers to the total number of years a person remains in excellent health. 16. CHD represents the single largest cause of death in the Western world. The pathogenesis of CHD involves 4. The “new gerontology” addresses areas beyond age- degenerative changes in the inner lining of the arterial related diseases and their prevention to recognize that wall that leads to progressive occlusion. successful aging maintains enhanced physiologic function and physical fitness 17. Four major modifiable cardiovascular risk factor (smoking, diabetes mellitus, hypertension, and 5. “Healthy life expectancy” refers to the expected hypercholesterolemia) account for 80% to 90% of number of years a person might live in the equivalent CHD cases. Physical inactivity and excessive body of full health. weight also contribute to disease risk. 6. The specific field of physical activity epidemiolo 18. Cigarette smoking, either active or passive through applies the general research strategies of epidemiology environmental exposure, directly relates to CHD risk. to study physical activity as a health-related behavior Smokers experience twice the risk of death from heart linked to disease and other outcomes. disease as nonsmokers. 7. The Physical Activity Pyramid summarizes major goals 19. The receptor molecule TLR-2 represents the trigger for to increase the level of regular physical activity in the inflammation and tissue breakdown in arterial plaqu general population; it emphasizes many forms of that leads to CHD. behavioral and lifestyle options. 20. A cholesterol level of 200 mgиdLϪ1 or lower is usually 8. Healthy People 2010 describes a comprehensive, desirable, although risk for a fatal heart attack begins nationwide health promotion and disease prevention to increase at 150 mgиdLϪ1. A cholesterol level of agenda as a roadmap for promoting health and 230 mgиdLϪ1 increases heart attack risk to about twice preventing illness, disability, and premature death that of 180 mgиdLϪ1, and 300 mgиdLϪ1 increases the among all people in the United States. risk fourfold. 9. Inactivity alone produces a constellation of conditions 21. For triacylglycerol level, less than 150 mgиdLϪ1 is eventually leading to premature death. The term SeDS considered a nominal level, with 200 to 499 mgиdLϪ1 identifies this condition considered high. 10. Physiologic and performance capabilities generally 22. Behaviors that favorably affect cholesterol and decline after age 30 years. The decline rates of various lipoprotein levels include weight loss; regular aerobic functions differ within and among individuals. Regular exercise; increased intake of water-soluble fibers exercise enables older persons to retain higher levels of moderate alcohol consumption; increased intake of fatty functional capacity, particularly cardiovascular and acids in fish oils (omega-3 fats); elimination of tran muscular functions. fatty acids; and adjusting the intake of polyunsaturated, monounsaturated, and saturated fatty acids. 11. Aging alters endocrine function, particularly for the pituitary, pancreas, adrenal, and thyroid 23. Variables that adversely affect cholesterol and glands. lipoprotein levels include cigarette smoking, a diet high in saturated fatty acids and preformed cholesterol, 12. A physically active lifestyle throughout life confers emotionally stressful situations, and oral considerable health-related benefits contraceptives. 13. Approximately one-half of all deaths in the United 24. A systolic blood pressure that exceeds 140 mm Hg or States reflect a limited number of largely preventabl diastolic pressure that exceeds 90 mm Hg form the behaviors and exposures, most of which relate directly to physical inactivity and overweight and obesity.

•Chapter 17 Physical Activity, Exercise, Successful Aging, and Disease Prevention 627 lower limit for the classification of borderline hig 27. CHD risk factors interact with each other and CHD blood pressure (hypertension). itself to accentuate disease risk. 25. People with diabetes are two to four times more likely 28. The frequent occurrence of multiple CHD risk to develop cardiovascular disease from obesity, physical factors in young children emphasizes the need inactivity, hypertension, and atherogenic dyslipidemia, for early initiatives to reduce atherosclerotic risk maladies usually coincident with the diabetic condition. later in life 26. The following ten variables represent positive CHD 29. Implementing daily, required physical education to predictors: age, gender, heredity, immunologic factors, reduce childhood CHD risk should become a homocysteine, excessive body fat, physical inactivity, prioritized public health policy imperative. C-reactive protein, lipoprotein(a), and fibrinogen THOUGHT QUESTIONS 1. Does risk factor modification always change disease risk 3. Respond to the question: “Overwhelming epidemiologic evidence links physical activity on the job or in leisure 2. If regular physical activity contributes little to overall time to reduced CHD risk, but does this prove that life span, what other reasons exist for maintaining a exercise benefits cardiovascular health? physically active lifestyle throughout middle and old age? SELECTED REFERENCES Aagaard P, et al.: Mechanical muscle function, morphology, and Blair, S.N., et al.: Changes in physical fitness and all caus fibert type in lifelong trained elderly. Med. Sci. Sports Exerc., mortality: a prospective study of healthy and unhealthy 39:1989, 2007. men. JAMA., 273:1093, 1995. ADA/ACSM: ADA/ACSM diabetes mellitus and exercise joint Blair, S.N., et al.: Influences of cardiorespiratory fitness a position paper. Med. Sci. Sports Exerc., 29:I, 1997. other precursors on cardiovascular disease and all-cause mortality in men and women. JAMA., 276:205, 1996. Albert, C.M., et al.: Triggering of sudden death from cardiac causes by vigorous exertion. N. Engl. J. Med., Blair, S.N., et al.: Physical activity, nutrition, and chronic 9:343, 2000. disease. Med. Sci. Sports Exerc., 28:335, 1997. Always, S.E., Siu, P.M.: Nuclear apoptosis contributes to Bodegard, J., et al.: Reasons for terminating an exercise test sarcopenia. Exerc. Sport Sci. Rev., 36:51, 2008. provide independent prognostic information: 2014 apparently healthy men followed for 26 years. Eur. Heart J., American College of Sports Medicine: ACSM position stand 26:1394, 2005. on exercise and type 2 diabetes. Med. Sci. Sports Exerc., 32:1345, 2000. Booth, F.W., et al.: Waging war on modern chronic diseases: primary prevention through exercise biology. J. Appl. American College of Sports Medicine: ACSM position stand on Physiol., 88:774, 2000. physical activity and bone health. Med. Sci. Sports Exerc., 36:1985, 2004. Booth, F.W., Laye M.J.: The future: genes, physical activity and health. Acta. Physiol. (Oxf)., 199:549, 2010. American College of Sports Medicine and American Heart Association: Joint position statement. Exercise and acute Carnethon, M.R., et al.: A longitudinal study of physical activity cardiovascular events: placing the risks into perspective. and heart rate recovery: CARDIA, 1987–1993. Med. Sci. Med. Sci. Sports Exerc., 9:886, 2007. Sports Exerc., 37:606, 2005. Andrews, N.P., et al.: Telomeres and immunological diseases of Caspersen, C.J., Fulton, J.E.: Epidemiology of walking and type aging. Gerontology, 56:390, 2010. 2 diabetes. Med. Sci. Sports Exerc., 40(Suppl):S519, 2008. Baker, J., et al.: Physical activity and successful aging in Canadian Chen, F.Y., et al.: Effects of a lifestyle program on risks for older adults. J. Aging Phys. Act., 17:223, 2009. cardiovascular disease in women. Taiwan J. Obstet. Gynecol., 48:49, 2009. Banda, J.A., et al.: Protective health factors and incident hypertension in men. Am. J. Hypertens., 23:599, 2010. Church, T.S., et al.: Metabolic syndrome and diabetes, alone and in combination, as predictors of cardiovascular disease Barnes, D.E., et al.: Physical activity and dementia: the need for mortality among men. Diabetes Care, 32:1289, 2009. prevention trials. Exerc. Sport Sci. Rev., 35:24, 2007. Corrado, D., et al.: Does sport activity enhance the risk of Blair, S.N.: Physical activity, physical fitness, and health. Res. Q. sudden death in adolescent and young adults? J. Am. Coll. Exerc. Sport, 64:365, 1993. Cardiol., 42:1959, 2003. Blair, S.N., Connelly, J.C.: How much physical activity should Davi, G., et al.: Nutraceuticals in diabetes and metabolic we do? The case for moderate amounts and intensities of syndrome. Cardiovasc. Ther., 28:216, 2010. physical activity. Res. Q. Exerc. Sport, 67:193, 1996.

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NOTES

18C h a p t e r Clinical Aspects of Exercise Physiology CHAPTER OBJECTIVES • List six clinical areas and corresponding diseases • Outline the approach for individualizing an “exercise and disorders in which physical activity (exercise) prescription.” as therapy exerts positive influence. • Give advantages and disadvantages of submaximal • List three different diseases of the heart muscle. versus maximal exercise stress testing. • Categorize two diseases that affect heart valves and • Give the pros and cons of the different stress test the cardiac nervous system. protocols. • Describe the major steps in cardiac disease assessment. • Discuss of the role of physical activity and exercise • List different laboratory-based coronary heart disease prescription in pulmonary rehabilitation. (CHD) screening tools. • Describe the role of exercise in the diagnosis and • List three reasons for including stress testing to treatment for diseases and disorders of the evaluate CHD. cardiovascular system. • List several indicators of CHD during an exercise • Describe the role of exercise in the diagnosis and stress test. treatment for diseases and disorders of the neuromuscular system. • Give two advantages and limitations of different • Describe the role of exercise in the diagnosis and modes of exercise for graded exercise stress testing. treatment for cancer. • Define the following terms for stress test results: true- • Describe the role of exercise in the diagnosis and positive, false-negative, true-negative, and false-positive. treatment for depression. • List four reasons for stopping an exercise stress test. 631

•632 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits The promotion of regular exercise is widespread and Clinical Areas and Corresponding increasing in the global prevention of disease, in the reha- Table 18.1 Diseases and Disorders Where bilitation from injury, and as adjunctive therapy for diverse medically related disorders. This chapter focuses Exercise Therapy Applies on understanding the mechanisms by which exercise improves health, physical fitness, and the rehabilitatio Cardiovascular diseases Ischemia, chronic heart failure, potential of patients challenged by chronic disease and and disorders dyslipidemias, cardio- disability. This chapter highlights several clinical applica- myopathies, cardiac valvular tions of exercise interventions for some of the medical and Pulmonary diseases disease, heart transplantation, health conditions that exercise positively influences liste and disorders congenital abnormalities in Table 18.1. Neuromuscular Chronic obstructive pulmonary CARDIOVASCULAR DISEASES diseases and disorders disease, cystic fibrosis, asthm and exercise-induced asthma AND DISORDERS Metabolic diseases and disorders Stroke, multiple sclerosis, As detailed in Chapter 17, diseases of the cardiovascular Parkinson’s disease, system account for the greatest number of deaths in indus- Immunologic and Alzheimer’s disease, polio, trialized nations. Because increased physical activity re- hematologic diseases cerebral palsy presents the prudent first line of defense to comba and disorders cardiovascular diseases, exercise physiologists need to Obesity (adult and pediatric), become familiar with all aspects of this category of disease. Orthopedic diseases diabetes, renal disease, Table 18.2 lists three categories of heart disease that lead and disorders menstrual dysfunction to functional disability: Aging Cancer, breast cancer, immune 1. Diseases affecting the heart muscle Cognitive and deficiency, allergies, sickle cell 2. Diseases affecting heart valves disease, HIV and AIDS 3. Diseases affecting the cardiac nervous system emotional disorders Osteoporosis, osteoarthritis and Diseases of the Myocardium rheumatoid arthritis, back pain, sports injuries Diseases of the myocardium become prevalent with advancing age. The following terms frequently describe Sarcopenia these diseases: degenerative heart disease (DHD), athero- Anxiety and stress disorders, sclerotic cardiovascular disease, arteriosclerotic cardiovas- cular disease, coronary artery disease (CAD), and coronary mental retardation, depression heart disease (CHD). and low HDL (high-density lipoprotein) and high LDL Advances in molecular biology have isolated possible cholesterol levels. genetic links to CHD. One of these genes (on chromo- some 19 near the gene related to low-density lipoprotein CHD pathogenesis progresses as follows: [LDL] cholesterol receptor functioning), called the ath- erosclerosis susceptibility gene ( ATHS), accounts for 1. Injury to the coronary artery’s endothelial cell wall about 50% of all CHD cases. TheATHS gene causes a set 2. Fibroblastic proliferation of the artery’s inner lining of characteristics that triples a person’s risk of myocar- dial infarction (MI). These include abdominal obesity or intima 3. Accumulation of lipids at the junction of the arterial intima and middle lining, further obstructing blood flo 4. Deterioration and formation of hyaline (a clear, homogeneous substance formed in degeneration) in the vessel’s intima 5. Calcium deposition at the edges of the hyalinated area The major disorders from reduced myocardial blood supply include angina pectoris, MI, and congestive heart failure (CHF). Table 18.2 Three Categories of Heart Disease That Lead to Functional Disability DISEASES AFFECTING DISEASES AFFECTING DISEASES AFFECTING THE HEART MUSCLE THE HEART VALVES THE CARDIAC NERVOUS SYSTEM Congestive heart disease Rheumatic fever Arrhythmias Angina Endocarditis Tachycardia Myocardial infarction Mitral valve prolapse Bradycardia Pericarditis Congenital malformations Congestive heart failure Aneurysms

•Chapter 18 Clinical Aspects of Exercise Physiology 633 Table 18.3 Similarity of Symptoms of Angina and Heartburn Questions & Notes ANGINA HEARTBURN Diseases of which organ become most prevalent with advancing age? Gripping, viselike feelings of pain Frequent feeling of heartburn or pressure Name 3 terms to describe diseases of the Frequent use of antacids to relieve pain myocardium. Pain that radiates to the neck, jaw, back, shoulders, or arms (usually left) Waking up at night 1. Acidic or bitter taste in mouth Toothache Burning sensation in chest Burning indigestion Discomfort after eating spicy food Shortness of breath Difficulty swallowin Nausea Frequent belching Angina Pectoris Angina pectoris, characterized by acute chest pain, occurs 2. 3. from an imbalance between the oxygen demands of the heart and its oxygen supply. The pain results from metabolite accumulation within an ischemic seg- List 3 characteristics of the ATHS gene. ment of heart muscle. The sensation of angina pectoris, often confused with 1. simple heartburn, includes squeezing, burning, and pressing or “choking” in 2. the chest region (Table 18.3). The pain usually lasts up to 3 minutes but can 3. continue for longer intervals. One-third of all individuals who have angina will die suddenly from MI. Several types of angina exist, including chronic stable Name the 3 disorders resulting from angina, often referred to as “walk-through” angina; it occurs at a predictable reduced myocardial blood supply. level of physical exertion (e.g., metabolic equivalent [MET] level or exercise heart rate). Vasodilators (e.g., fast-acting nitroglycerin, commonly used since 1. the 19th century, and longer acting isosorbide dinitrate and mononitrate) 2. reduce cardiac workload and thus oxygen requirements to effectively control 3. this uncomfortable and potentially debilitating condition. Figure 18.1 shows the usual pain pattern associated with acute angina pec- toris. Pain frequently occurs in the left shoulder or along the arm to the elbow. Occasionally, angina pain emanates in the back area of the left scapula along the spinal cord. Myocardial Infarction MI (heart attack or coronary occlusion) results from a severely inadequate perfusion of blood in the coronary arteries or a Name 2 diseases that affect the myocardium. 1. 2. List 3 common symptoms of angina pectoris. 1. 2. 3. Figure 18.1 Location of pain generally associated with angina pectoris.

•634 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits Localized just Common Mid-chest and Upper under breastbone; combination: inside arms; left abdomen—where or in larger area of mid-chest, neck, arm and shoulder more frequent most often mid-chest; or and jaw mistaken for entire upper chest than right indigestion Larger area of Lower center Inside Between chest, neck, jaw, neck; to both right arm from shoulder blades and inside arms sides of upper armpit to below neck; and jaw elbow; inside left from ear to ear arm to waist; left arm and shoulder more frequent than right Figure 18.2 Location of early warning signs of myocardial infarction. Note diverse locations of pain. dramatic imbalance in myocardial oxygen demand and counteracted by lifestyle changes that include diet, exer- supply from occlusion of a portion of the coronary vascu- cise, and medications. The heart can fail from intrinsic lature. Sudden occlusion results from prior clot formation myocardial disease, chronic hypertension, or structural initiated by plaque accumulation in one or more coronary defects that impair pump performance. In HF, the amount arteries. Severe fatigue for several days without specifi of blood pumped from the left ventricle relative to the total pain often precedes the onset of an MI. amount of blood received, called the ejection fraction, decreases. With diminished left ventricular output (ejec- Figure 18.2 displays the locations of early warning tion fraction usually well below 50%), blood accumulates signs of an MI. Severe, unrelenting chest pain can last up to in the pulmonary vasculature. This causes dyspnea and 1 hour during an MI. eventual flooding of the pulmonary alveoli with plasma fi trate, a condition termedpulmonary congestion. Common Pericarditis Pericarditis, an inflammation of th HF symptoms include dyspnea, coughing with large amounts of frothy blood-tinged sputum, pulmonary heart’s outer pericardial lining, classifies as either acute o edema, general fatigue, and overall muscle weakness. HF chronic (recurring or constrictive). Acute pericarditis can occur from the right or left side of the heart, each with symptoms vary but usually include chest pain, shortness of different symptoms and prognosis depending on initiation breath (dyspnea), and elevated resting heart rate and body of treatment. temperature. In chronic pericarditis, inflammation create extreme chest pain caused by fluid accumulation in th Aneurysm Aneurysm represents an abnormal dilata- pericardial sac, which prevents the heart from fully expand- ing during diastole. The prognosis for acute viral pericardi- tion in the walls of arteries or veins or within the tis remains excellent, but chronic pericarditis from bacterial myocardium itself. Vascular aneurysms occur when a origin presents a persistent serious pathology. vessel’s wall weakens from trauma, congenital vascular disease, infection, or atherosclerosis. Aneurysms are iden- Heart Failure Heart failure (HF; CHF or chronic tified as either “arterial” or “venous” and classified accor ing to the specific vasculature area affected (e.g., thoraci decompensation) occurs when cardiac output cannot keep aneurysm). Routine chest radiography uncovers most pace with venous return. This common incurable condi- tion varies widely in severity and often can be effectively

•Chapter 18 Clinical Aspects of Exercise Physiology 635 aneurysms. Common symptoms include chest pain with a specific, palpable uestions & Notes Qpulsating mass in the chest, abdomen, or lower back. Heart Valve Diseases Name 3 locations generally associated with early warning signs of myocardial Diseases and abnormalities that affect heart valve structure and function infarction. include: 1. • Stenosis: Valve narrowing or constriction that prevents the valve from 2. opening fully; caused by growths, scars, or abnormal mineral deposits. 3. • Insufficienc (also called regurgitation): Valves do not close properly, causing blood to flow back into the heart’s chambers during diastole • Prolapse (only affects mitral valve): Enlarged valve leaflets bulg backward into the left atrium during the cardiac cycle. Valvular abnormalities increase myocardial workload, requiring the heart to Name a symptom of acute pericarditis. generate greater force to pump blood through a constricted valve or to maintain Name a symptom of chronic pericarditis. cardiac output if blood seeps back into a chamber. Rheumatic fever, a poten- tially fatal infection by streptococcal bacteria that can lead to rheumatic heart disease causing valvular scarring and heart valve deformity, usually causes heart valve stenosis. The two most common symptoms of this heart valve pathology include fever and joint pain. Endocarditis Endocarditis, an inflammation of the innermost layer of th Give 2 reasons for heart failure. 1. heart (endocardium) usually of bacterial origin, damages the tricuspid, aortic, or mitral valves from direct invasion of bacteria into the tissue. Patients initially 2. have musculoskeletal symptoms, including arthritis, low-back pain, and gen- eral weakness in one or more joints. Many antibiotic drugs effectively treat this List 2 diseases that affect heart valves. disease before it becomes fatal. 1. Congenital Malformations Congenital heart defects appear in one of every 100 births; they include defects of the heart valves, such as ventricular or atrial septal defects (a hole between the ventricles and atria) and patent duc- tus arteriosus (a shunt caused by an opening between the aorta and pulmonary artery). These defects require surgical repair. Mitral Valve Prolapse Mitral valve prolapse (MVP) occurs in about 2. 10% of Americans and involves variations in either the mitral valve’s shape or List 2 diseases that affect the cardiac nerv- structure. This defect has been called “floppy valve syndrome,” “Barlow’s syn ous system. drome,” and the “click-murmur syndrome.” MVP usually remains benign, but the frequency of diagnosis has increased over the past decade because of MVP’s 1. association with endocarditis, atherosclerosis, and muscular dystrophy. MVP probably results from connective tissue abnormalities in mitral valve leaflets 2. Sixty percent of patients with MVP have no symptoms; the remainder experi- ence profound fatigue during exercise. List 2 types of dysrhythmias. 1. Cardiac Nervous System Diseases 2. Diseases that affect the heart’s electrical conduction system include dysrhyth- mias (arrhythmias) that cause the heart to beat too quickly (tachycardia), beat too slowly (bradycardia), generate extra beats (ectopic, extrasystole, orprema- ture ventricular contractions [PVCs]), or fibrillate (fine, rapid contractions twitching of myocardial fibers) Dysrhythmias usually change circulatory dynamics and result in low blood pressure, HF, and shock. They often occur after a stroke induced by physical exertion or other stressor. In adults, sinus tachycardia represents a resting heart rate greater than 100 bиminϪ1, and sinus bradycardia represents a resting heart rate below 60 b иminϪ1. Asymptomatic sinus bradycardia often occurs in endurance

•636 SECTION VI Optimizing Body Composition, Successful Aging, and Health-Related Exercise Benefits athletes. This benign dysrhythmia may reflect a benefi- potential coronary ischemia. In contrast, failure of systolic cial training adaptation because it provides a longer dias- blood pressure to increase during moderate physical activity tole for ventricular filling during the cardiac cycle and (hypotensive exercise response) indicates left ventricular hence the possibility for a greater stroke volume. dysfunction; a hypotensive response in intense exercise sig- nals a serious mortality risk. Individuals unable to elevate CARDIAC DISEASE ASSESSMENT systolic blood pressure above 140 mm Hg during maximal exercise often have serious but dormant cardiac disease. A thorough cardiac disease assessment typically includes Heart Auscultation Listening to heart sounds, termed the following: auscultation, provides important information about cardiac 1. Patient medical history function. Exercise physiologists should become familiar with 2. Physical examination abnormal heart sounds, including how to identify those 3. Laboratory tests related to heart murmurs. Auscultation can readily diagnose 4. Physiologic tests valvular diseases (e.g., MVP diagnosed by the classic click- murmur sounds) and congenital abnormalities (e.g., regur- Patient Medical History gitation sounds in ventricular septal defects). A proper patient history documents the most common Laboratory-Based Screening complaints and establishes a basis for CHD risk profiling Because CHD symptoms frequently include chest pain, and Assessment making this pain’s differential diagnosis is a primary focus. Table 18.4 lists a limited differential diagnosis of chest The following laboratory-based screenings provide consid- pain, including possible causes and pathogenesis. erable information for confirming and documenting th extent of CHD: Physical Examination A physician, nurse, or physi- • Chest radiography: Chest radiographs reveal the size cian’s assistant usually conducts the physical examination and shape of the heart and lungs. that includes the patient’s vital signs (body temperature, heart rate, breathing rate, and blood pressure; see accom- • Electrocardiogram (ECG): Resting and exercise ECG panying Close Up Box 18.1: How to Recognize Vital Signs, provide essential information to assess myocardial on page 637). electrical conductivity and oxygenation. Correctly reading and interpreting an ECG requires specialized For purposes of prescribing exercise and identifying early training and considerable practice. Table 18.5 lists warning signs of CHD, the clinical exercise physiologist the six different categories of ECG interpretations. must know the patient’s heart rate and blood pressure Later in this chapter, various ECG abnormalities and response to incremental exercise. For example, an increase abnormal physiologic responses to exercise are de- in systolic blood pressure of 20 mm Hg or more in low-level scribed; we also detail how to count heart rate from physical activity of 2 to 4 METs ( hypertensive exercise ECG tracings. Careful monitoring of ECG changes response) indicates overall cardiovascular impairment and during exercise targets individuals with potential CHD warns of increased myocardial oxygen demand suggestive of for further evaluation. Table 18.6 lists common ECG changes associated with CHD. Table 18.4 Chest Pain Diagnosis PAIN/COMPLAINT/FINDINGS POSSIBLE CAUSES STIMULI POSSIBLE PATHOLOGY Exertion; cold; smoking; CHD Pressure, ache, tightness, or burning in MI midsternum, left shoulder, arm; heavy meal; fluid Pericarditis diaphoresis; nausea; vomiting; Inflammatio overload Myocarditis; endocarditis S-T segment changes Infection Pulmonary embolism Pulmonary Acute MI Esophageal reflu Sharp pain worsens with inspiration, Referred pain Aortic stenosis; mitral valve improves with sitting Ventricular outflow IV drug use; microbes prolapse Chest tightness with breathlessness; tract obstruction Recent surgery low-grade fever Heavy meal; spicy food Sharp, stabbing pain; breathlessness; cough; loss of consciousness Exertion; CHD Burning pain in stomach; indigestion relieved by antacids Angina pain; breathlessness; wide pulse pressure; ventricular hypertrophy on ECG