Immediate Effects of Force Feedback and Plantar Somatosensory Stimuli on Inter-limb Coordination During Perturbed Walking

Single-sided motor weakness, also known as hemiparesis, is the most prevalent gait impairment among stroke survivors, which often results in gait asymmetry. Studies on robot-assisted gait training (RAGT) have shown positive effects of force feedback on spatial symmetry; somatosensory stimulation is thought to facilitate recovery of temporal symmetry. Despite the known importance of sensorimotor integration for motor recovery, interventions that incorporate RAGT and somatosensory stimuli have been largely overlooked so far. In this paper, we explore how gait symmetry can be restored in healthy subjects following unilateral foot perturbations, using adaptive assistive forces and plantar vibrotactile stimuli provided by a bilateral powered ankle-foot orthosis. Results suggest that combined force feedback and vibrotactile stimuli may be more effective than force feedback alone in reducing spatial asymmetry. Further, force feedback did not produce significant improvements in temporal symmetry, unlike the combined modality. We discuss possible implications of these preliminary findings for future training paradigms for RAGT.