Week 9- Factors affecting human performance Flashcards
What are the factors that affect performance?
-strength and skill
-energy demands
-environment and/or diet
-psychological component
What is fatigue?
inability to maintain power output of force during repeated muscle contractions, which is reversible with rest
What controls central fatigue?
central nervous system
What control peripheral fatigue?
-neural factors
-mechanical factors
-energetic of contraction
What is central fatigue characterised by?
motor unit activated
-motor unit firing frequency
How can arousal alter the state of fatigue?
-by facilitating motor recruitment
-increasing motivation
-physical or mental diversion
-excessive endurance training
-reduced performance, prolonged fatigue
-related to brain serotonin activity and its ratio to dopamine
-central governor model
-conscious and subconscious brain, not spinal cord and or motor unit
What is the site of peripheral fatigue?
-sarcolemma and transverse tubules
What is a cause of peripheral fatigue?
-inability of sodium potassium pump maintaining action potentials amplitude and frequency
-an action potential block in teh T tubules
What does cross-bridge cycling and tension development depend on?
-Arrangement of actin and myosin
-Ca binding to troponin
-ATP availability
How does high Hydrogen concentration contribute to fatigue?
-reduce the force per cross-bridge
-reduce the force generated at a given calcium concentration
-inhibit calcium release from the SR
What does the accumulation of Pi cause?
-inhibits maximal force
-reduced cross-bridge binding to actin
-inhibits calcium release from SR
What effects does lowering the rates of ATP utilisation below the rate of ATP generation cause?
-maintains ATP concentration
-the cell doesn’t run out of ATP
What fibres are recruited up to 40% VO2max?
Type I
When are Type IIa fibres recruited?
40-75% VO2max
When are Type IIx fibres recruited?
> 75% VO2max
