Restitution of EMG spectrum after muscular fatigue.

Restitution of the EMG spectrum was studied in upper limb muscles. The subjects performed isometric and isotonic exercises until they refused because of fatigue. Force levels varied from 15 to 60% MVC. The mean frequency was used as an indicator of the modification of the spectrum. Restitution of the EMG spectrum was studied by recording for 10 min after the end of the fatigue experiment at intervals of 1 to 3 minutes. Recovery was rapid at the beginning, levelling off to a plateau in 2 to 5 min. The change was more regular in isometric experiments than in kinetic ones, although interindividual differences were large in both cases.