Peripheral muscle fatigue involves the motor units, such as motor neurons, peripheral nerves, motor endplates, and muscle fibers. There are two different sites where repeated contractions may cause muscle fatigue. One is the transmission mechanism, which is basically the neuromuscular junction, muscle membrane, and endoplasmic reticulum. The other one is the contractile mechanism, which is the muscle filament. A muscle fiber's mechanical response declines with fatigue. Peripheral muscle fatigue is caused by changes in the internal conditions of the muscle. The changes can be biochemical, depletion of substrates, high-energy phosphate compounds in the muscle fibers, and acetylcholine in the terminal motor nerve branches, or they may be caused by the accumulation of metabolites. (Amussen)
Cnetral muscle fatigue involves motor