S2L4 Physiology of Strength and Power - Chronic Adaptations

Question 1

How does short and long term resistance training effect strength?

Answer 1

• Short term - increased strength rapidly even w/o visible increase in muscle mass
• Long term - increase in strength largely due to increase in muscle mass

Question 2

What things does RT cause to the motor unit?

Answer 2

1. increased firing rate of motor unit
2. threshold at which motor unit is recruited decreases - quicker recruitment

Question 3

What occurs in antagonist coactivation?

Answer 3

• exciting receptors inhibits antagonist
• increased inhibition of antagonist after training - coactivation lower
• increased activation of agonist - more force produced

Question 4

What is the key muscular adaptation and how does it occur?

Answer 4

Hypertrophy = increasing the no of contractile proteins in muscle tissue.
* myonuclei fill up with contractile proteins but limits capacity to grow muscle as can only take up so many
* satellite cells activiated, progress to a myonuclei so can fill up w/ more contractile proteins

Question 5

How is hypertrophy induced and what signalling pathways are involved in this?

Answer 5

1. mechanical tension
2. muscle damage
3. metabolic stress
   - IGF-1
   - Akt
   - mTOR
   leads to MPS and thus hypertrophy

Question 6

How does mechanical tension induce hypertrophy?

Answer 6

needed to maintain muscle mass
- at sarcomere level, I bands formed by thin filaments and H zone = where thick and thin filaments overlap when contraction produced
- when enough mechanical tension, rupture of Z-disk
- causes the repair process of muscle, involving protein synthesis

Question 7

How does muscle damage induce hypertrophy?

Answer 7

• distruption in extracellular matrix of muscle–> cascade process linked to inflammation
• this excites nociceotors in muscle, feel delayed soreness
• exercise decreases soreness over time
• repeated bout effect - protective ability of muscle - so less sore next time, less strength loss, recover quicker

Question 8

How does metabolic stress induce hypertrophy?

Answer 8

e.g. restriction of blood flow induces hypertrophy
- cannot isolate from mechanical tension - evidence not clear
- MECHANICAL TENSION = most important stimulus of hypertrophy