Contribution of muscle activity at different gait phases for improving walking performance in chronic stroke patients with hemiparesis

[Purpose] The aim of this study was to clarify the optimal timing for increasing muscle activity in the paralyzed lower limb of stroke survivors by evaluating the relationship between gait muscle activity patterns and gait parameters. [Participants and Methods] Electromyography of the tibialis anterior, soleus, rectus femoris, and biceps femoris on the paralyzed side and spatiotemporal gait parameters were evaluated in 40 chronic post-stroke patients as they walked at a comfortable speed. The normalized average amplitude and asymmetry indexes of each gait phase were calculated. The correlations between gait velocity or asymmetry indexes and the activity amplitudes of various muscles during each gait phase were analyzed. Multiple regression analysis was performed with gait velocity or asymmetry indexes as the response variable and the muscle activity amplitudes in the various gait phases as explanatory variables. [Results] The major determinants of gait velocity were the tibialis anterior activity (β=−0.35) and biceps femoris activity (β=0.45) during the swing phase. In addition, the biceps femoris activity during the swing phase was the major determinant of the asymmetry index for the swing phase duration (β=−0.41). [Conclusion] For patients with hemiparesis, increasing the biceps femoris activity during the swing phase is considered optimal, which may lead to improvement in walking performance.