Intramuscular Coherence of the Lower Flexor Muscles During Robotic Ankle-assisted Gait

Abstract Background: A close-fitting assisted walking device (RE-Gait) designed to assist ankle movements might be a novel approach for acquiring the forefoot rocker function in the gait cycle. The purpose of the present study was to investigate the effects of using RE-Gait by evaluating the intramuscular coherence (IMC) of the two parts of the tibialis anterior muscles (TA) in the initial, mid, and terminal swing phase, which could indicate whether the common synaptic drive of motor neurons was populated.Methods: Seventeen healthy volunteers walked on a treadmill at a comfortable speed before, during, and immediately after 15-minute RE-Gait intervention (pre / RG / post). RE-Gait supported plantar flexion at toe lift-off in the terminal stance phase and dorsiflexion in the initial swing phase. Electromyograms of the right lower leg and gait parameters were analyzed for each session.Results: After RE-Gait intervention, the step length was significantly increased. IMC of the two parts of the TA muscles in the beta frequency band in the initial swing phase was significantly enhanced during RE-Gait intervention compared with pre session. In addition, IMCs in the beta and low-gamma frequency bands were significantly correlated with the enhancement ratio of the step length.Conclusions: These results suggest that robotic ankle planter flexion and dorsiflexion assistance in the pre- and initial swing phase would be effective for learning adaptively modified walking by activating corticospinal tracts. RE-Gait will be a useful tool for re-learning of gait with smooth switching with appropriate forefoot rocker function.