Lecture 17 - Age And Exercise

Question 1

Define sarcopenia

Answer 1

Age related involuntary loss of muscle mass through decrease number of muscle fibres (hyperplasia) and decreased area of each muscle fibre (atrophy), leading to loss of strength (mainly less Type II fibres). It’s accompanied by increased fat and connective-tissue in the muscle

Question 2

What is the term for fat deposition?

Answer 2

Myosteatosis

Question 3

How are sarcopenia and myosteatosis accelerated?

Answer 3

Physical inactivity

Question 4

What are the mechanisms responsible for sarcopenia? (5)

Answer 4

Neuropathic process
Axonal sprouting from remaining motor neurons
Growth factor decrease with age
Nutritional changes
Infiltration of fat (myosteatosis) and connective tissue with age

Question 5

How is neuropathic process responsible for sarcopenia?

Answer 5

Loss of alpha motoneurons causing muscle denervation and loss of motor units
Loss of nerve innervation causing denervation muscle atrophy and irreversible decrease in muscle fibre number (apoptosis)

Question 6

How is axonal sprouting from remaining motor neurons responsible for sarcopenia?

Answer 6

Reinnervation of some denervated muscles creates giant motor units, which decreases fine control of motor unit recruitment when regulating force

Question 7

How is growth factor decrease with age responsible for sarcopenia?

Answer 7

1) Somatopause (progressive decrease in pituitary function) causes shift from low anabolic to high catabolic influence
2) Decrease of muscle size partly due to loss of satellite cell activation/proliferation
3) Type 2 more susceptible
4) Decreases capacity for motor unit remodelling (which involves selective denervation, axon sprouting and motor endplate regeneration)

Question 8

How are nutritional changes responsible for sarcopenia?

Answer 8

Decrease of food intake

Question 9

How is infiltration of fat (myosteatosis) and connective tissue responsible for sarcopenia?

Chronic inflammation is proposed to increase **

Answer 9

Increases load insert on specific muscle and increases proinflammatory adipokines which promotes sarcopenia

Insulin resistance

Question 10

Sarcopenia + obesity = very high *

Answer 10

Myosteatosis and circulating fatty acid

Question 11

What is the only known treatment for sarcopenia? (To stay above disability threshold)

• training can limit normal * of * power and * max

Answer 11

Exercise e.g resistance training, as fast twitch 2 atrophy lost more than type 1 with age

Endurance; loss; aerobic; VO2