Week 4- muscle ageing

Question 1

Where in the body do strength losses appear greater?

Answer 1

Lower body

Question 2

What is the power equation?

Answer 2

power = force x velocity

Question 3

What is the muscle mass loss after 40years old?

Answer 3

8% per decade, until 70 where it increased to 15%

Question 4

What muscle fibre types especially get smaller with age?

Answer 4

Type II

Question 5

What is greater loss in muscle strength or muscle mass loss?

Answer 5

Loss in muscle strength

Question 6

What accumulates in the muscle more as we age?

Answer 6

Fat

Question 7

What is the consequence of a decrease in motor units?

Answer 7

muscle fibres become denervated and can cause muscle fibre atrophy and potential fibre loss
less motor units = less force

Question 8

How does denervation and collateral re-innervation alter muscle characteristics?

Answer 8

-increased co-expression of myosin isoforms
-decrease in force output
-decrease in velocity of contraction and hence power

Question 9

What does the reinnervation of muscle fibres cause?

Answer 9

Increased size of motor unit
preserves some muscle mass

Question 10

What changes occur to the excitation-coupling process?

Answer 10

-decrease in calcium release from SR
-changes in SR function- decrease in calcium reuptake
-slowing of myosin molecules- decrease in intrinsic speed of shortening
-reduced acto-myosin cross bridge- decrease in force output per muscle fibre