[Evaluation of central and peripheral factors in muscular fatigue]

Muscular fatigue was investigated in 13 healthy people by employing a simple device which comprises a computer on line with a conventional EMG equipment able to automatically measure the frequency and duration of free-run EMG recording. The procedure was carried out in the extensor digitorum brevis muscle by using surface electrodes throughout 10 minutes of voluntary maximal effort. The maximal M wave as well as the muscle response to repetitive nerve maximal stimulation was also explored at the beginning and at the end of the experiment. It was observed a decrease of the potentials frequency discharge and an increase of their duration without major changes in the M wave amplitude neither in the muscle response to the repetitive nerve discharge. The findings pointed out to the central factors as the mean responsible for the development of muscular fatigue.