Peripheral changes during muscle fatigue and their adaptation to training and disuse

Muscle fatigue has been studied in the human adductor pollicis during electrically evoked (30 Hz) contractions. The peripheral electrical and mechanical changes were compared during sustained (60s) and intermittent (sixty ls) contractions separated by 2.0, 1.0 and 0.5s intervals. The results indicate that the mechanical failure is not closely related to the electrical changes and it is proposed that intracellular processes dominate the force deterioration during fatigue. This point of view is discussed on the basis of data recorded from control, trained and disused muscles, during standard fatigue tests.