Adaptations To Strength Training // and fatigue Flashcards
What are the 3 proposed primary mechanisms for training adaptations?
Mechanical tension, metabolic stress, muscle damage
What neural adaptations occur to strength training in the first 8-20 weeks?
Motor learning,
increased MU recruitment,
Preferential recruitment of high threshold MU,
lowered threshold of MU recruitment,
Sync so increase RFD,
Increased firing freq and therefore summation
What muscular adaptations occur to strength adaptations?
Hypertrophy, Hyperplasia, Satellite cells, Growth factors, increased protein synthesis, Cellular adaptations, Changes in fibre type, Muscle architecture - increased pennation angle
Why is leucine (a BCAA) a good nutritional supplement for protein synthesis?
It’s a precursor for myofibrillar PS, regulator of intercellular signalling pathways involved in PS, helps balance protein turnover by suppressing muscle proteolysis and reducing protein oxidation and maintains the integrity of the muscle cell membrane
How do anabolic steroids work?
The steroid hormone enters the membrane of the target cell and binds to receptor,
The complex translocates to nucleus,
The complex binds to DNA regulatory site,
Transcription occurs,
Translation occurs.
Why do people take anabolic steroids for PS?
Steroids induce larger fibres with more myonuclei,
Myonuclei are not lost after removal of drug,
When muscles are overloaded they grow much faster with the steroids,
How would you assess fatigue in peripheral nerves?
Place electrode over the nerve,
Supra-max stimulation of nerve activated the muscle (eg. Femoral nerve to quads),
Then compare the peak force from pre and post exercise.
Fatigue would show a lower force produced
What is peripheral muscle fatigue?
This occurs downstream of the NMJ and involves changes in the muscle that cannot be overcome despite MVC.
What are the main causes of peripheral muscle fatigue?
Neural fatigue - limitations of a nerves ability to generate a sustained signal
And metabolic fatigue - the reduced ability of the muscle fibre to contract
What peripheral factors contribute to muscle fatigue?
Conc of H ions, NH4 ions, Pi,
Glucose, glycogen, PCr, Ca release and actin myosin cross bridge formation
Why does an increased conc of H ions contribute to fatigue?
The increased H ions leads to decreased Ca2+-troponin binding and decreased glycolytic enzyme activity (PFK).
How does Pi contribute to fatigue?
It interferes with cross bridges, decreases Ca2+ sensitivity and reduces Ca2+ conc as a Ca-Pi precipitate forms so there is reduced SR Ca2+ release
What protective mechanism is there in the muscle to prevent complete exhaustion?
The depletion in cellular ATP levels leads to a reduction in Ca2+ release. This decreases ATP usage by reducing cross bridge cycling and SR Ca2+ uptake. This reduces power output. It prevents complete exhaustion and cellular damage.
