Indices to describe different muscle activation patterns, identified during treadmill walking, in people with spastic drop-foot

This study was concerned with individuals who were unable to effectively do rsiflex their ankle when walking, as a result of a lesion of the central ne rvous system (CNS). Indices that categorise and quantify different patterns of calf and anterior tibial muscle activation patterns during treadmill wa lking have been derived from a sample of fifteen individuals with establish ed hemiplegia following stroke and twelve age-matched individuals without i mpairment. As subjects walked on a treadmill, force sensitive foot-switches under the heel and first metatarsal head allowed EMG signals from the calf and anterior tibial muscles to be related to phases of the gait cycle. Nor mal activation periods for each muscle group were identified as percentiles of the gait cycle and indices for muscle activation periods were derived u sing ratios of integrated EMG during selected periods. Indices were derived that identified statistically significant differences, between normal and hemiplegic subjects, in calf activation during both pus h-off phase (P <0.001) and early stance phase (P < 001), but not activation of tibialis anterior during swing (P=0.325) Observation suggested that int egrated tibialis anterior activity during swing phase in hemiplegic subject s was not dissimilar to normal subjects, but the profile in hemiplegic subj ects tended to lack the normal second peak of activity at initial foot cont act. The reasons for drop-foot were shown to be varied and complex. The indices defined may be useful for directing therapy and measuring outcome. (C) 2001 IPEM. Published by Elsevier Science Ltd. All rights reserved.