Training adaptations - muscle Flashcards
What are the 3 ways skeletal muscle adapts to anaerobic training?
Increases size, within fibre transitions, enhances its biochemical and ultra structural components
Define hypertrophy
Muscular enlargement from an increase in cross sectional area
What is sarcoplasmic hypertrophy?
Muscle bulk but no increase in strength or myofibril hypertrophy
What 2 things does the process of hypertrophy involve?
- Increase in the synthesis of actin and myosin
- increase number of myofibrils
Which fibre type has greater increases as well as hypertrophy sooner?
Type II
Which fibre type hypertrophy increases synthesis and which one decreases degradation?
Type II increases synthesis
Type I decreases degradation
TRUE or FALSE. synthesis >degradation in 48hr window post resistance exercise
TRUE
What is the nuclear domain theory?
Satellite cells donate nuclei to hypertrophied new myofibrils
How do satellite cells cause muscle hypertrophy?
After damaged muscle, satellite cells activated and migrate. They multiply and donate nuclei to muscle fibre for regeneration. With more myonuclei the fibre can continue to grow.
How does mechanical stress lead to protein synthesis?
Integrins sense mechanical stress which cascade intracellular signalling to muscle fibre cytoplasm
What pathway is stimulated by mechanical stress?
The P13K/mTOR/Akt pathway.
What 2 things does Akt accumulation do to help towards cell growth?
Blocks FOXO proteins and activates mTOR which stimulates protein synthesis in nucleus
What 5 factors does metabolic stress cause which stimulate hypertrophy?
- Increased fibre recruitment
- elevated hormonal response
- Altered myokine production
- Accumulation of ROS
- Cellular swelling
What growth hormone does stress stimulate?
IGF1
How does cell swelling induce hypertrophy?
Stimulates P13K pathway
Satellite cell migration
Why does acute exercise cause muscle to swell?
- Blood outflow from veins is stopped
- Pressure higher in arteries so blood flow to muscles
- Fluid moves from plasma to interstitial spaces
Muscle damage stimulates growth factors, what growth factors are stimulates which increase satellite cell division?
Insulin like GF
Fibroblast like GF
Interleukin 5 and 6
What growth factor helps satellite cells migrate to site of repair?
Hepatocyte like GF
What three hormones are increased post exercise by the stimulation of muscle damage?
Growth hormone
Cortisol
Testosterone
How might cortisol inhibit hypertrophy?
By blocking protein synthesis
What does current evidence suggest about concurrent aerobic exercise?
It blunts the hypertrophic response to resistance exercise
What happens with AMPK activation with endurance exercise and how does this effect resistance training hypertrophy?
Increased AMPK from endurance exercise which blocks mTOR and this decreases protein synthesis
What is the term used for muscle fiber formation?
Myogenesis
What is myogenesis?
Replacement of old/damages muscle fibres in tissue remodeling