Surface EMG profiles during different walking cadences in humans.

The ensemble electromyogram (EMG) patterns associated with different walking cadences were examined in 11 normal subjects. Five muscle groups were studied: the rectus femoris, vastus lateralis, lateral hamstring, tibialis anterior and soleus muscles of the right lower extremity. The myoelectric signals were telemetered, full-wave rectified and smoothed. Subjects walked at cadences of 115, 95 and 75 steps/min. Footswitches indicated the different phases of the stride. Six or more strides per subject were averaged for each cadence. Cadence-related changes in (1) mean EMG amplitude during stance, and during swing, and (2) the shape of the EMG patterns, were analyzed. One-way repeated-measures analyses of variance on the mean EMG amplitude in stance and in swing revealed significant changes with cadence (P less than 0.05) in all muscles examined. The magnitude of these changes could be related to the mechanical function of the muscles involved. The shape of the EMG patterns generally remained similar at the different cadences. The timing of EMG activity was closely related to the normalized stride time and remained invariant at different cadences.