L10.3 Muscle plasticity 2

Question 1

Muscle adaptations to exercise

Answer 1

• Muscles adapt optimally to ex → exceed capacity
• Gradual progression maximises performance
• But have physiological/anatomical limitations

Question 2

General adaptation syndrome

Answer 2

• Alarm phase: Present challenge to system
• Resistance phase: Growth from the challenge (reaches a plateau)
• Exhaustion phase: challenged system excessively (overtraining)
  
  • System no longer capable of responding to challenge

Question 3

Differences b/w voluntary & electrical stimulation.

Adv of electrical stimulation

Answer 3

• Voluntary recruitment:
  
  • Recruited MU according to task → allows fine smooth movements
  • Asynchronous activation
• Electrical simulation:
  
  • All MU recruited
  • Synchronous activation & same pattern/impulse generation
• Advantages
  
  • Allows a clean way of measuring modification of patterns
  • Max adaptive potential response

Question 4

Definitions: Overload & specificity

Answer 4

• Overload: Muscle challenged with intensity/duration/frequency of exercise which it is unaccustomed to (will adapt overtime)
• Specificity: Muscles adapt specifically to exercise (SAID principle)
  
  • Endurance: Mito & Capillary adaptations
  • Resistance: Constructive proteins adaptations

Question 5

Effects from endurance training

Answer 5

• Changes to central & peripheral circulation
• CO, muscle BF improved
• ↑ muscle metabolism
• ↑ respiratory capacity
• Fibre types:
  
  • Little or no change in fibre size & type
  • Subtle change among fast type (2B → 2A)
• O2 delivery → by ↑capillarisation (↑15% in 2 weeks) - also improves gas exhange and waste removal
• Energy production: ↑mito capacity (↑# & size & activation of oxidative enzymes - SDH/MDH/CPT)
• ↑Release of FFA → Shifts to reliance on fats for fuel

Question 6

Effects from resistance training

Answer 6

• Hypertrophy, size generally correlates with strength
• Chronic hypertrophy
  
  • ↑size following long term training → ↑size of individual muslce fibres (true hypertrophy)
  • ↑# muscle fibres (hyperplasia) (less likely)
  • ↑ myfibrils & or connective tissues
• All muscle fibres adapting (both slow & fast fibres recruited)

Question 7

Why is there a lag from the change in size of fibres?

Answer 7

• Neural adaptations: altered neural drive → recruit larger MU → initial ↑ in str after training (early training)
  
  • From improvement of technique, etc…
• Advance training → can only ↑ str from hypertrophic response
  
  • New ex/new approaches → able to ultilise neural factors and cycle back to neural adaptations
• Performance will plateau depending on adaptive potential
  
  • However, can be enhanced by using growth promoting agents

Question 8

2 possibilities of hyperplasia

Answer 8

• 2 possibilities:
  
  • Splitting of hypertrophied fibres (muscles become too big to get a good blood supply)
  • Sat cells proliferate following muscle exercise

Question 9

Why is there a specificity of exercise?

Answer 9

• Each person has differing responses for different training programs
• Genetic adaptive potential for change is different
• Need variation to provide neural stimulation and response (but don’t overload)

Question 10

What is periodisation? (beginniners)

Answer 10

• Gradual cycling of specificity, intensity & vol of training to achieve peak performance
• Training divided into cycles → prompt variety & continual adaptations
• Beginners:
  
  • Gradual decrease in quantity of training whilst gradually increasing intensity
  • Improvement of technique corresponds to increase of intensity

Question 11

Periodisation (advanced)

Answer 11

• Advance:
  
  • Steadily high quantity and intensity
  • Gradual decrease in quantity and further increase in intensity progressing to peak
  • Gradual improvement of technique