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Chapter 18

Chapter 18. Aging in Sport and Exercise. Chapter 18 Overview. Height, weight, and body composition Physiological responses to acute exercise Physiological adaptations to exercise training Sport performance Special issues. Introduction to Aging and Sport.

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Chapter 18

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  1. Chapter 18 • Aging in Sport and Exercise

  2. Chapter 18 Overview • Height, weight, and body composition • Physiological responses to acute exercise • Physiological adaptations to exercise training • Sport performance • Special issues

  3. Introduction to Aging and Sport • Number of individuals over age 50 engaged in sport and exercise increased compared to 30 years ago • Recreation • Competition • More fit compared to older sedentary counterparts • Performance declines with age

  4. Introduction to Aging and Sport • Exercising into old age an unusual pattern • Natural tendency to be sedentary • Motivating factors? • Primary aging versus comorbidities of age • Cross-sectional versus longitudinal studies • Medical care, diet, lifestyle factors • Selective mortality • Applicability of findings to larger aged population?

  5. Figure 18.1

  6. Height, Weight, and Body Composition • Height  with age • Starts at 35 to 40 years • Compression of intervertebral discs • Poor posture • Later, osteopenia, osteoporosis • Weight , then  –  25 to 45 years:  physical activity,  caloric intake –  65+ years: loss of body mass,  appetite

  7. Figure 18.2

  8. Height, Weight, and Body Composition • Body fat content tends to increase • Active versus sedentary older adults vary • Older athletes  body fat content • Older athletes  central adiposity • Fat-free mass  starting around age 40 –  Muscle, bone mass • Sarcopenia (protein synthesis ) • Due (in part) to lack of activity –  Growth hormone, insulin-like growth factor 1

  9. Figure 18.3

  10. Height, Weight, and Body Composition • Bone mineral content  • Bone resorption > bone synthesis • Due to lack of weight-bearing exercise • Body composition variables • Body weight • Percent body fat • Fat mass • Fat-free mass (FFM)

  11. Figure 18.4a

  12. Figure 18.4b

  13. Figure 18.4c

  14. Figure 18.4d

  15. Height, Weight, and Body Composition • Training alters age-related body composition changes –  Weight, percent body fat, fat mass –  FFM (more likely with resistance training than with aerobic training) • Men > women • Biggest results with diet + exercise

  16. Physiological Responses to Acute Exercise • Strength and neuromuscular function  with age • Interferes with activities of daily living • Manifests ~age 50 to 60 years • Results from  muscle mass • Strength  offset by resistance exercise

  17. Figure 18.5

  18. Figure 18.6

  19. Physiological Responses to Acute Exercise • Type II fiber loss with aging • Decrease in type II motor neurons • Type I neurons innervate old type II fibers? • Higher percent type I fibers • Training slows or stops fiber-type change

  20. Figure 18.7

  21. Physiological Responses to Acute Exercise • Size and number of muscle fibers  with age • Size of both type I and type II  • Lose 10% per decade after age 50 • Endurance training  no impact on decline in muscle mass with age • Resistance training  reduces muscle atrophy,  muscle cross-sectional area

  22. Physiological Responses to Acute Exercise • Reflexes slow with age • Exercise preserves reflex response time • Active older people ≈ young active people • Motor unit activation  with age • Exercise retains maximal recruitment of muscle – Some studies show  strength due to local muscle (not neural) factors • Exercise maintains muscle physiology • Number of capillaries unchanged • Oxidative enzyme activity only mildly reduced

  23. Physiological Responses to Acute Exercise • Central and peripheral cardiovascular decrements with age • Reduced maximal HR • Reduction varies considerably • Electrical and receptor changes with age • Same for active and sedentary people • HRmax = [208 – (0.7 x age)]

  24. Physiological Responses to Acute Exercise • Maximal stroke volume (SV)  with age – Contractility, response to catecholamines • Partial loss of Frank-Starling mechanism • LV, arterial stiffening • Exercise attenuates decline in SVmax • VO2max with age due to Qmax • Due more to HRmax, less to SVmax • Exercise attenuates decline in VO2max

  25. Physiological Responses to Acute Exercise • Sedentary habits  risk for vascular aging –  Cardiac and arterial compliance • Endothelial dysfunction • Reduced vasodilation • Exercise   risk • Less arterial stiffening, endothelial dysfunction • Preserved vasodilator signaling • Research ongoing on proper exercise dose for cardiovascular benefit

  26. Physiological Responses to Acute Exercise • Peripheral blood flow  with age • ~10 to 15% reduction even with exercise • Due to  vasoconstriction,  vasodilation –  (a-v)O2 difference compensates for  flow • Effects of primary aging versus cardiovascular deconditioning • Which changes result from aging alone? • Which changes result from reduced activity?

  27. Figure 18.8

  28. Physiological Responses to Acute Exercise • Respiratory function with sedentary aging –  Vital capacity and FEV1.0,  residual volume, total lung capacity unchanged • Less air exchanged –  Lung and chest wall elasticity with age • But does not limit exercise capacity • Exercise maintains ventilatory capacity • Pulmonary ventilation does not limit aerobic capacity • Oxygen saturation remains high

  29. Physiological Responses to Acute Exercise • VO2max changes with aging • Measured in L/min or ml/kg/min? • Absolute versus relative decrement • VO2max in normally active older people • Declines steadily from 25 years to 75 years • ~1% per year (~10% per decade)

  30. Table 18.1

  31. Physiological Responses to Acute Exercise • VO2max in older male athletes • 5 to 6% decline per decade in active adults • 3.6% decline over 25 years in elite athletes • 15% decline per decade in previously active adults • VO2max in older female athletes • Fewer studies but similar to men • ~1% decline per decade • Longitudinal changes > cross-sectional changes

  32. Figure 18.9

  33. Table 18.2

  34. Physiological Responses to Acute Exercise • Percent decline in VO2max related to intensity of training before and during aging • Factors that affect rate of decline • Genetics • General activity level • Intensity and volume of training • Age-related body composition changes • Age range

  35. Figure 18.10

  36. Figure 18.11

  37. Physiological Responses to Acute Exercise • Lactate threshold (as % VO2max)  • Not predictive of running performance with aging • Percent VO2max may not be best measure • Remember: absolute VO2 with age • Lactate threshold (as absolute VO2) 

  38. Physiological Adaptations to Exercise Training • Effects of resistance training on strength –  Strength (men, women: 30%; some studies of men: 50-200+%) • Fiber hypertrophy –  Cross-sectional area of types I, II • Neural adaptations •  Muscle mass, muscle size, bone mineral density • Improved activities of daily living,  risk of falls

  39. Physiological Adaptations to Exercise Training • VO2max improvement with training • Independent of sex, age, initial fitness • Young:  maximal cardiac output (central) • Older:  oxidative enzymes (peripheral) • Anaerobic capacity with training • Less known than aerobic training results • Lactate threshold bad predictor of performance

  40. Sport Performance • Running performance  with age • Rate of decline independent of distance • Both 100 m, 10 km records slow with age • Decline accelerates past age 60

  41. Figure 18.12

  42. Sport Performance • Swimming performance  with age • Decline accelerates past age 70 • Decline in women > decline in men

  43. Sport Performance • Cycling performance • Peaks between 25 and 35 years • Speed then decreases by 0.7% per decade • Weight-lifting performance • Peaks between 25 and 35 years • Sum of power lifts then declines 1.8% per year

  44. Figure 18.13

  45. Special Issues • Higher risk of death from hyperthermia • Higher core temperature than young subjects • Metabolic heat gain related to absolute VO2 • Heat loss related to relative percent VO2max • Physical training affects thermoregulation • Improves skin vasodilation (convection) • Improves sweat rate (evaporation) • Improves redistribution of cardiac output

  46. Figure 18.14

  47. Special Issues • Exercise in cold   risk of hypothermia • Risk not as great as hyperthermia • Reduced ability to generate metabolic heat • Excessive convective heat loss • Core temperature can drop even with mild cold stress • Must add behavioral thermoregulation

  48. Special Issues • Exercise and longevity • Mild caloric restriction increases longevity • Exercise may contribute to caloric balance • Exercise  compression of mortality • Exercise can lead to injury • Tendon injury (rotator cuff, Achilles) • Cartilage injury (meniscus, focal injuries) • Stress fractures • Exercise can reduce risk of falls

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