week 6

20%

• 60% • sedentary life may be to blame for as many as 200,000 death in US per year • yet older adults are the most likely to benefit from regular exercise

• with aging, nerves undergo structural, functional, and biochemical changes • loss of myelinated nerve fibers • decreased ability of nerve to regenerate and reinnervate muscle

• deficits in muscle activation

• changes in ST flexibility/compliance • ligaments and tendons: • collagen becomes more cross-linked (more stiffness) • elastin udnergoes structural changes • decreased water content of connective tissue (less flexibility)

• osteopenia: between 1 and 2.5 SD below average bone density • osteoporosis: less than 2.5 SD below average • progressive loss of bone mineral density leads to a disruption in microarchitecture, more susceptible to fracture (women > men)

• changse in muscle strength • largely drive by sarcopenia: age-related loss of muscle mass • morphological, physiological, central activation • greater change in LE than UE • proximal before distal muscles affected

• decreased total number of fibers (type I and II) • preferential atrophy of type II fibers • loss of motor units with increase in size of remaining motor units - lose sensitivity to grade finer motor units • increase in intramuscular fat • size of vastus lateralis of older individuals was 18% smaller and total number of fibers was 25% lower

• slower contractile properties: slower time to peak tension, slower rate of relaxation • decreased maximum shortening velocity • minimal changes in metabolism with active lifestyle if muscle mass is fully maintained

• muscle activation deficits may magnify weakness from morphological and physiological causes - ability to activate decreases • age-related central activation deficits vary from muscle to muscle: bicep and quadricep 5-6% deficits in healthy older adults

• evidence for greater protein turnover with increasing age • inadequate dietary protein intake may be an important cause of sarcopenia • need 0.5g of protein/pound of body weight

• changes in joint stiffness • increase co-contraction of antagonist muscles • changes in vestibular ocular reflex • slower postural responses - 20-30 ms delay

• offset age-related loss of muscle mass and strength • decrease risk for osteoporosis • increase basal metabolic rate

• purpose is to improve CV health • older adults do not need endurance training to increase endurance of muscle but rather to improve CV response to aerobic exercise • (older muscle doesn’t fatigue as fast and is more endurant, so target of endurance training is truly CV)

• progressive degeneration of cardiac structures: • loss of elasticity • fibrotic changes in vales of heart • infiltration with amyloid • decreased contractility of the heart’s left ventricular wall so pumping capacity decreases with age

• decrease elasticity of arteries • decreased elasticity of veins • decreased elasticity of aorta

• decrease number of pacemaker cells in SA node • increase in elastic and collagenous tissue in all parts of conduction system • fat infiltration

• for an 85 YO to live independently, need a minimum aerobic capcity of: • 18 ml/O2/kg/min for men • 15 ml/O2/kg/min for women

• 4-5.5 decrease each decade for men • 2-3.5 decrease each decade for women • older adults still have capacity to increase VO2 max considerabily with proper training intensity • 10-15% gains when training mode matches testing mode