Skeletal MM

Question 1

Major structural and functional ____ occur in response to _______ ________

Answer 1

adaptations

physical inactivity

Question 2

Structural changes:

Answer 2

• MM mass reduced
• MM fiber # and size are reduced,
• Total # of motor unitis decreases by 25 %
• Diameter of motor axons is reduced, as is NCV (nerve conduction velocity

Question 3

MM fiber # and size:

Answer 3

are reduced at young age 50/50 fast vs slow twitch fibers (in elderly more marked reduction in type II, fast twitch fibers) Type II are anaerobic: for short bursts of speed

Question 4

Total # of motor units decreases by 25%

Answer 4

there is a resultant increase in the size of motor units or innervation ration, 1st in the mm’s of the LE= less precise grading or control of mm force

Question 5

Strength _____ with aging

Answer 5

declines

Question 6

_____%-____% reduction in maximal ______ strength by the ___th and ___th decades have been demonstrated

Answer 6

20-40%
isometric
7th and 8th

Question 7

Loss of leg mm _____ is _______ than loss of _____ mm strength; LE strength loss is _____ proximally

Answer 7

strength
greater
arm
greater

Question 8

Power (governed by the ____ of shortening and force-generating capacity of mm) is ___ by about ___% functinal abilities as maximal walking speed, stair climbing ability, and ability to respond ___ enough to a loss of balance will be affected

Answer 8

Shortening
reduced
20%
quickly

Question 9

_______ endurance also declines (possibly due to contractile, _____, and blood supply changes); functional losses and ____ can result.

Answer 9

Muscular
metabolic
disability