Muscular System

Muscle Function

What is muscle fatigue?

Muscle fatigue results from strenuously exercising a muscle for a prolonged period of time. The muscle may lose its ability to contract due to interruption in the muscle’s blood supply (and therefore an interruption in the oxygen supply) or the lack of acetylcholine in motor neuron axons. However, muscle fatigue is most commonly associated with the accumulation of lactic acid in the muscle as a result of anaerobic respiration. During vigorous exercise, the circulatory system cannot supply oxygen to muscle fibers quickly enough. In the absence of oxygen, the muscle cells begin to produce lactic acid, which accumulates in the muscle. The lactic acid buildup lowers pH, and as a result muscle fibers no longer respond to stimulation.


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