Adapting spatiotemporal gait symmetry to electrical stimulation during treadmill walking

Individuals with neurological impairments often exhibit asymmetrical gait
patterns. This study highlighted the potential of functional electrical
stimulation (FES) to improve gait symmetry during treadmill training and
investigated whether our proposed FES perturbation paradigm could induce
gait adaptation concerning spatial and temporal gait symmetry in healthy
subjects. In the FES perturbation paradigm, both legs received electrical
pulses at the same period as the subjects’ initial stride duration, and
the temporal gap between the two pulses for each leg was manipulated over
7 minutes. Following this, subjects continued to walk for another 5
minutes without FES. For the implicit trial (unconscious reaction to FES),
subjects were asked to walk comfortably in response to the stimulation.
For the explicit trial (conscious reaction to FES), subjects were asked to
explicitly synchronize their toe-off phase to the stimulation. To examine
the effects of the FES perturbation, we measured step length and stance
time and then analyzed changes in step length and stance time symmetries
alongside their subsequent aftereffects. In this study, regardless of
whether subjects adapted their gait patterns to the electrical pulses
explicitly or implicitly, a directional change was observed in stance time
(temporal) symmetry under both conditions, with the right stance becoming
longer than the left. The stance time asymmetry induced by FES
perturbation resulted in a slight residual effect. No consistent trend of
step length (spatial) symmetry changes was observed in either condition.
This indicates that subjects may adapt their spatial gait patterns through
diverse mechanisms. Our findings suggest that the applied FES perturbation
strategy can induce adaptations in subjects’ temporal gait asymmetry,
particularly while in stance. Further experiments would provide a deeper
understanding of the mechanism behind subjects’ response to FES
perturbations, as well as the long-term effects of these perturbations on
the spatial and temporal aspects of gait symmetry.