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Flashcards in Lecture 16 Deck (11)

What is weakness?

Weakness is an inabiliy to develop an initial force appropriate for the circumstances..


How does the CNS influence muscle fatigue?

Supraspinal mechanisms affect how much force is generated at the muscle level. decreasing the CNS drive decreases muscle exertion.


What are the 2 thoughts as to what central fatigue is?

Sense of effort due to collateral pathway reaching a conscious centre. (telling the muscle what to do)

Sense of effort due to muscles' sensory information. ("weight feels heavy i should stop")


Which plays a bigger role; central or peripheral factors of fatigue?

Evidence indicates that central factors play a lesser role in fatigue.


What happens to muscle's force during fatigue?

In fatigued muscle force is decreased

Force develops more slowly

Relaxation takes longer.


Do neurotransmitters at neuromuscular junctions deplete during exercise?

No evidence that neurotransmitter supply at neuromuscular junction depletes during exhaustion.


How does fatigue occur at the T tubule?

T tubule can influence fatigue by release of potassium and making it difficult to generate an action potential at the T tubule


What are the 2 types of fatigue how are they different?

High frequency fatigue is fast onset fas recovery.

Metabolic fatigue is slow recovery and is induced by submaximal contractions repetitively taking place. This phenomenon includes acidosis and phosphocreatine depletion.


Do ATP levels cause fatigue?

ATP loss is not indicated to be a cause of fatigue.


How do lactic acid and lactate affect fatigue?

lactic acid increases amount of H+ in muscles decreasing pH. At low pH muscle performance is impaired.

Lactate, however, is not the same and it could delay onset of fatigue by taking up a H+ atom.


How does calcium affect force and fatigue in muscles?

more calcium = more force
during fatigue muscle is less sensitive to calcium