Upper and lower extremity EMG correlations during normal human gait.

The purpose of the present study was to determine whether diagonal intersegmental interactions are present during normal human gait. The demonstration of consistently synchronous phasing would indicate the feasibility of utilizing an electromyographic (EMG) signal to control functional electrical stimulation to a paralyzed lower extremity muscle during gait. The EMG activity of several muscles of the upper extremity and of the tibialis anterior (TA) were monitored with surface electrodes in 8 women. Variability in both the frequency of occurrence and duration of EMG activity was found in all muscles of the upper extremity. No single arm muscle common to all subjects was phased similarly to TA. However, 6 subjects demonstrated at least 1 muscle of the upper extremity that was working at the same time as TA. It is postulated that differences in upper limb kinematics may mask the existence of intersegmental interactions during gait.