Musculoskeletal Changes w/ Aging

Why are older adults "weaker"?

cross sectional area of m. is reduced --> less muscle to produce force (LE>UE)

fewer motor units available to recruit

response to resistance training is inc recruitment much more than m. hypertrophy

What is the dec in CSA in older adults related to in terms of muscle?

related to dec in fast twitch fiber area

What motor fibers are preserved in older adults?

slow twitch area is maintained while fast twitch is decreased

What is muscle mass?

how much muscle fiber is present

What is muscle strength?

the ability to generate max m. force

What is muscle power?

product of force and velocity of contraction

What is muscle power better at in comparison to muscle strength?

better at predicting disability --> therefore you can lose strength but still walk fine

What does loss of power lead to?

limits in stairs, STS and other functional activities

Muscle metabolism changes with aging

min changes in capillaries in active elderly, dec in sedentary elderly --> dec ability to shunt blood to active tissue and reduced effectiveness to vasodilate w/ activity

min changes in anaerobic metabolism

min changes in aerobic; 20-40% dec in sedentary old

Are older adults less "flexible?"

reduced ability of aggrecan to bind water --> less tissue flexibility

articular cartilage dec ability to hold water as we age

hydrostatic lubrication impaired --> lost protection against compressive forces --> OA

What happens w/ collagen as we age?

less soluble, cross linkages stabilize --> inc rigidity

What happens w/ elastin as we age?

less produced, more fragmented-->greater chance of rupture, loss of "rebound" property

Age-related changes in bone - are older adults going to break?

reduced bone formation --> deficit in bone

post menopausal women - bone resorption exceeds bone formation --> deficit in bone

3 main factors that stimulate bone formation

1. WB

2. circulation

3. m. contraction

What are the general considerations for exercise prescription for bone formation?

overload - load more than needed for ADLs

site specific

impact activities

consistent

Exercise effects on endocrine system in older adults

exercise enhances insulin sensitivity, glucose metabolism and some mitochondrial function

Positive impact of aerobic exercise for older adults

elevated insulin sensitivity after the exercise but also elevated the next day