[Neurologic and muscular mechanisms of fatigue]

Fatigue of voluntary muscular effort is a complex phenomenon, influenced by peripheral and central nervous system factors. Peripheral mechanisms of fatigue include impairment in neurotransmission and impulse propagation down the sarcolemna, dysfunction within the sarcoplasmic reticulum involving calcium release and uptake, impairment in the actin-myosin cross-bridge interactions and substrate depletion or accumulation of metabolites. The central fatigue is associated with reduction of motor cortical excitability, failure to drive the motoneurons adequately, changes in neurotransmitter activity, etc. Is fatigue an unexplained disabling symptom or a protective mechanism to prevent muscle fiber degeneration?