Exercise Phys (12): Adaptations of Neuro-muscular system to exercise

Question 1

Most strength gains in the first few weeks of training are down to what?

Answer 1

Neural adaptation

Question 2

What is meant by neural adaptation and how does it lead to an increase in strength?

Answer 2

Normally motor units recruits asynchronously -> adaptation to synchronous recruitments = GAINS

Also greater motor unit recruitment -> more neural drive + frequency of neural discharge = GAINS

Training can decrease inhibitory impulses e.g. inhibition of muscle contraction at high tension via golgi tendon

Reduced co-activation of antagonistic muscles

Question 3

Types of muscle hypertrophy?

Answer 3

Transient - fluid retention / oedema (pump)

Chronic - increase in size of muscle fibres

Question 4

What happens to muscle myonuclei prior to hypertrophy? What happens to them in atrophy?

Answer 4

Increase in number prior to hypertrophy

Nuclei retain number for long periods of time after training, even after atrophy

Question 5

what is mTOR? function?

Answer 5

mechanistic target of rapamycin -> activation leads to elevated protein synthesis

activated by increases in amino acids, particularly leucine, arginine, increased activation by more aa’s, exercise, insulin

activated mTOR moves from cytoplasm to lysosome

Question 6

How does hyperplasia occur?

Answer 6

Intense strength training resulting in

• fibre splitting (2 new fibres grow to size of parent)
• fusing of satellite (myogenic stem) cells

may or may not occur in humans

Question 7

Role of myogenic stem cells?

Answer 7

Repair muscle fibres resulting in hypertrophy

May fuse together resulting in hyperplasia

Question 8

Are fibre type alterations possible?

Answer 8

Short/medium term training does not change fibre type

-> but type II and type I can become more aerobic/anaerobic depending on training stimulis

Question 9

Adaptations to muscle after aerobic training?

Answer 9

Main change in muscle fibres is hypertrophy of type I fibres

Increase in no. of capillaries supplying each fibre

increased myoglobin content 75% -> 80% (increased oxidative capacity)

increased no. of good mitochondria (new mitochondria via biogenesis, and more mitophagy = renewed mitochondria)