1. 1 Exercise and Aging Skeletal Muscle Brooks - Ch 32 Brooks - Ch 19 (p p414-418) Outline Aging introduction Aging process Physiological capacity and aging –CV, pulmonary, skeletal, joints, sk muscle, disease risk, body composition Exercise Prescription

2. 2 Aging Decline of physiological capacity is inevitable consequence of aging –physical inactivity may contribute to these declines –complicating the quantification of the effects of aging Body composition with aging inc % body fat / dec lean body mass –studies illustrate selective decline in sk ms protein vs non muscle protein –body K+ and Nitrogen levels muscle peaks at 25-30 yrs –decline in X sec area, ms density –inc intra-muscular fat Resting Metabolic Rate (RMR) –decline associated with dec ms mass

3. 3 Life expectancy, Span, and Morbidity Lifestyle (diet, exercise) will influence performance and health with aging, but will not halt the aging process. Life expectancy has changed dramatically in this century –1900: 47 years ; 2000: 76 years –Maximum lifespan (100 years) has not Quality of life, wellness, is important –North Americans only have healthy quality life during 85% of their lifespan, on average –Good lifestyle choices can compress morbidity - state in which they can no care for themselves –Reducing morbidity from 5-10 years to 1 or 2 can add quality years to your life –Table 32-1

4. 4 Aging and Exercise Lifestyle choices (deconditioning) –Some people physically deteriorate with age due to a lack of exercise, obesity, poor diet, smoking, and stress. –Other individuals are active and are still fit in their 50s, 60s and 70s. Disease and physiological function –Disease further complicates our understanding of the aging process.  osteoarthritis, atherosclerosis –Sedentary death syndrome (SeDS) Clear that adaptation to exercise has a genetic basis (plasticity) Effort to find molecular proof that physical inactivity is an actual cause of chronic disease Some researches want to move away from using sedentary individuals as controls in experiments - eg GLUT 4 and diabetes –Physiological systems vary in the extent to which they deteriorate with age.

5. 5 The Aging Process Aging involves diminished capacity to regulate internal environment Body structures are less capable and less resilient Reduced capacity is evident in; –Reaction time, resistance to disease, work capacity, and recovery time Table 32-2 (good summary) –Reduced capacity of many systems Genetics has an important influence on length of life; genetics in concert with environmental factors affects the quality of that life Aging may be related to; –accumulated injury, autoimmune reaction, problems with cell division, –abnormalities of genetic function (free radicals, radiation, toxins), –wear and tear

6. 6 Dietary Restriction and Aging Dietary restriction extended mean lifespan in rats by 30-50 % –Similar results in monkeys Several possible explanations : Retardation of basic metabolism and biological processes of aging Suppression of age-related pathologies - –found to impact immune system, protein turnover, bone loss, neural degeneration Reduction of oxidative stress by ROS through increased antioxidant activity

7. 7 Physiological Capacity Physiological functioning peaks ~ age 30 Table 32-3 ~.75 to 1 % decline per year after 30 –Declines in VO2 max, Q max, strength,power, and neural function; also increases in body fat All positively impacted by training Maximal O2 consumption and age –VO2 max declines ~30% (age 20-65) –Fig 32-1 - (training and age vs VO 2 max) –Significant individual variability –Similar declines with age in trained and untrained - trained has higher capacity –Due to decrease in max HR, SV, Power, fat free mass and A-V O2 difference Heart Rate and age –Sub max - HR lower at relative intensity but higher at same absolute intensity –Cardiovascular drift is higher with age –Longer recovery time –Dec  - adrenergic responsiveness (dec HR max)

8. 8 Stroke Volume and Cardiac Output (Q) Aging  the hearts capacity to pump blood Q and SV are less during exercise –Both relative and absolute intensity Gradual loss of contractile strength due to – dec Ca ATPase and myosin ATPase activities and myocardial ischemia Often, heart wall stiffens, delaying ventricular filling - dec SV… dec Q The elasticity of blood vessels and the heart  due to connective tissue changes. Heart mass usually  and there are fibrotic changes in the heart valves Vascular stiffness  the peripheral resistance,  the afterload of the heart. –  peripheral resistance also raises SBP during rest and exercise (no change in DBP).

9. 9 A-V O2 difference Dec with age - contributing to dec aerobic capacity Decreases from 16 vol % (20 yrs) to 12 vol % (65 yrs) ( mlO 2 /dl) Reductions due to –  fiber/capillary ratio –  total hemoglobin –  respiratory capacity of muscle –  in muscle mito mass –  oxidative enzymes However, A-VO 2 is higher at any absolute exercise intensity with age Capacity of autonomic reflexes that control blood flow is reduced

10. 10 Pulmonary Function The lungs have a large reserve capacity to meet ventilation requirements of exercise Reserve begins to deteriorate between 30, more rapidly after 60 Changes include; –Inc size of alveoli (dec vasculature) –Dec elasticity of support structure increases work of breathing –Weakening of respiratory muscle Deterioration is similar to that in CV system, and does not limit endurance performance in young or old (disease free) Training will improve max vent capacity in parallel with changes in Q

11. 11 Skeletal System Bone loss is a serious problem in older people, particularly women. –Women begin to lose bone mineral at 30 and men at 50 years of age. Estrogen deficiency in women, post- menopause, is thought to accelerate bone loss –HRT - (hormone replacement therapy) is no longer recommended over long time- due to CVD and Breast cancer risks Although the exact mechanism of bone loss is not completely understood, contributing factors are; –inactivity, diet, skeletal blood flow and endocrine function. Exercise is important in prevention and treatment of osteoporosis –Bones become stronger when stresses are placed on them

12. 12 Joints Joints become less stable and less mobile with age. Aging is associated with: –degradation of collagen fibers; –cross-link formation; –fibrous synovial membranes; –joint surface deterioration; –  viscosity of synovial fluid. It is difficult to separate aging from accumulated wear and tear –Trauma to the joint cartilage results in formation of scar tissue –impairs ROM ROM exercises can  flexibility.

13. 13 Skeletal Muscle Loss of muscle mass and strength can severely impact quality of life Muscle strength decreases aprox 8% per decade after the age of 45. Aging results in a  in isometric and dynamic strength and speed of movement. Strength losses are due to: –  size and # of muscle fibers –atrophy or loss of type II fibers –  in the respiratory capacity of muscle –  in connective tissue and fat Eg sarcopenia

14. 14 Muscle Fiber Types With age there is a selective loss of type II fibers, –  is more rapid in the lower body. –  available strength and power. The mechanisms involved in muscle contraction are also impaired: –less excitable, greater refractory period –[ ] of ATP and CP are  –maximum contractile velocity  There is loss of biochemical capacity with age. –  in glycolytic enzymes (LDH). –There are no changes or slight  in oxidative enzymes *Controversy over whether there is a decrease in oxidative capacity or not with ageing Relative strength  with training are similar in young and old individuals. –Only short term studies available

15. 15 CVD risk factors Exercise (even low intensity) has health benefits in the elderly. Exercise  blood insulin levels and improves glucose tolerance (if impaired) and insulin sensitivity –Less dramatic impact than in young Exercise  resting and exercise SBP. Exercise improves plasma lipid profiles:  plasma triglyceride and cholesterol;  HDL Metabolic syndrome

16. 16 Body composition and Stature Body composition and stature change markedly with age. Body weight  from age 20 to 60 and then . –due to an  in % body fat. A greater proportion of body fat is stored internally rather than subcutaneously. Stature  with age (avg 6 cm ) due to: – rounding of the back(kyphosis); disc compression; vertebrae deterioration. Exercise is very important in managing body composition in the elderly. –Maintain lean body mass to maintain metabolic rate and minimize fat gain

17. 17 Training Response Older people readily respond to endurance and strength training Endurance Training helps –Maintain CV function –Enhances exercise capacity –Reduces risks for heart disease, diabetes, insulin resistance and some cancers Strength training –Helps prevent loss of muscle mass and strength –Prevents bone mineral loss –Improves postural stability reduces risks of falls and fractures –Mobility exercises improve flexibility and joint health Training also provides psychological benefits –Improved cognitive function, reduced depression and enhanced self efficacy Training does not retard the aging process, it just allows the person to perform at a higher level - Fig 32.1

18. 18 Endurance Training Similar improvements in Aerobic capacity for young and old –6 months ~20% increase in VO 2 max Observe –Dec submax HR at absolute load –Dec resting and submax SBP –Faster recovery of HR –Improvements in ECG abnormalities –Inc SV and Q Elderly require a VO 2 max of ~20 ml/Kg for an independent lifestyle –A conservative well structured program can bring most elderly to this level of fitness within ~3 months

19. 19 Exercise Prescription The principles of exercise prescription are the same for everyone, –however caution must be taken with the elderly to  the risk of injury. Elderly have more abnormal ECG’s during exercise. –Start slowly with walking and swimming - low impact exercises –Running, racket-ball… only when fit Problems with using estimates of Max HR for prescribing intensity –considerably variation in the elderly (Max HR range : 105 - 200 for 60yr olds) Principles –Progress carefully with intensity and duration –Warm up slowly and carefully –Cool down slowly - to less than 100bpm –Stretching - reduce DOMS