FACTORS AFFECTING PERFORMANCE Flashcards
(48 cards)
What factors affect performance?
Diet (carbs, water intake)
Energy Production
Aerobic sources (VO2 max, cardiac output, O2 delivery, [Hb], PO2, O2 extraction, mitochondria)
Environment (altitude, heat, humidity)
Strength/Skill (practice, natural endowment, body type, muscle fibre type)
CNS function (arousal, motivation)
What is fatigue?
Inability to maintain power output or force during repeated muscle contractions.
What is central fatigue?
Central nervous system.
What is central fatigue?
Central nervous system.
What is Peripheral fatigue?
Neural factors.
Mechanical factors.
Energetics of contraction.
Why is there
Uncertainty about exact causes of fatigue?
Due to differences in research methods.
Central fatigue characterized by reductions in?
Motor units activated.
Motor unit firing frequency.
Central fatigue characterized by reductions in?
Motor units activated.
Motor unit firing frequency.
How CNS arousal can alter the state of fatigue?
By facilitating motor unit recruitment.
Increasing motivation.
Physical or mental diversion.
What does Excessive endurance training (overtraining) cause?
Reduced performance, prolonged fatigue, etc.
Related to brain serotonin activity.
What is the “Central Governor” model?
Conscious and subconscious brain, not spinal cord or motor unit.
What is the “Central Governor” model?
Conscious and subconscious brain, not spinal cord or motor unit.
What part of muscle is Not the site of fatigue?
Neuromuscular junction
What happens in the Sarcolemma and transverse tubules?
Altered muscle membrane to conduction and action potentials.
Inability of Na+/K+ pump to maintain action potential amplitude and frequency.
Can be improved by training.
An action potential block in the T-tubules.
Reduced sarcoplasmic reticulum C a++ release.
Cross-bridge cycling and tension development depends on?
Arrangement of actin and myosin.
C a++ binding to troponin.
ATP availability.
What may High H+ concentration may contribute to fatigue?
Reduce the force per cross-bridge.
Reduce the force generated at a given C a++ concentration.
Inhibit C a++ release from SR.
Why is
Longer “relaxation time” is a sign of fatigue?
Due to slower cross-bridge cycling.
Imbalance between ATP requirements and ATP generating capacity causes?
Accumulation of P i.
Inhibits maximal force.
Reduces cross-bridge binding to actin.
Inhibits C a++ release from SR.
Why is the Rate of ATP utilization is slowed faster than rate of ATP generation?
Maintains ATP concentration.
The cell does not run out of ATP.
How does Muscle fiber recruitment in increasing intensities of exercise?
Type I -> Type IIa -> Type IIx
Up to 40-50% VO2 max type I fibers recruited
Type IIa fibers recruited at 40–75% VO2 max
Exercise >75-80% VO2 max requires IIx fibers
Results in increased lactate production and H+ ions
Increasing glycolysis
How does Exercise promotes muscle free radical production?
Radicals are molecules with an unpaired outer orbital electron.
Capable of damaging proteins and lipids in muscle.
Does exercise contribute to fatigue during exercise >30 min?
Yes it can
What are Damage contractile proteins (myosin and troponin)?
Limits the number of cross-bridges in strong binding state.
Why does exercise Depress sodium/potassium pump activity?
Disruption of potassium homeostasis