Electromyographic gait assessment, Part 2: Preliminary assessment of hemiparetic synergy patterns.

The electromyographic (EMG) gait patterns of both lower limbs in 12 hemiparetic patients were studied during the early and late recovery periods. The linear envelopes of surface EMG were ensemble averaged to represent performance. The patients' stride parameters and EMG envelopes were compared to those of normal individuals measured at very-slow walking speeds. Both limbs could have normal or abnormal synergies. The abnormal synergy exhibited by the contralateral limb was almost always a cocontraction. Three different groups of synergies were defined depending on the change in synergy type exhibited by the contralateral limb. Patients who walked at less than a normal very-slow speed during the early recovery period never achieved a normal synergy in either limb. Seventy-five percent of the patients whose walking speed was at least 0.6 meters per second during the early recovery period improved or maintained their gait performance for at least one year.