Chapter 18

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