Somatosensory augmentation has sustained effects on mediolateral foot placement modulation while walking in people...

Many people with chronic stroke (PwCS) exhibit reduced mediolateral foot placement modulation while walking, a deficit linked with poorer walking balance. Applying hip abductor vibration to augment the available somatosensory feedback can elicit immediate increases in foot placement modulation.

The purpose of this study was to test whether such somatosensory augmentation can also cause sustained increases in foot placement modulation among PwCS after the vibration ceases, a beneficial characteristic for rehabilitation applications.

44 PwCS performed a series of treadmill walking trials, with some trials including hip vibration designed either to augment sensory feedback (Augmentation group; n = 22), or to follow a random distribution (Noise group; n = 22). We quantified foot placement modulation using the partial correlation between foot placement and mediolateral pelvis displacement (ρ_FP), accounting for pelvis velocity. ρ_FP was compared between a baseline walking period without vibration, periods when vibration was applied, and interspersed minute-long catch periods in which the vibration ceased.

In the Augmentation group, foot placement modulation increased significantly both while the vibration was applied (p < 0.0001) and during the subsequent catch periods (p = 0.007), providing evidence for short-term sustained effects of somatosensory augmentation. In contrast, no changes in foot placement were observed in the Noise group, either while the vibration was applied (p = 0.21) or during the catch periods (p = 0.36).

These results provide initial evidence that somatosensory augmentation via hip vibration has effects on foot placement modulation that persist after the augmentation ceases, possibly due to sensory reweighting.