Abstract
Introduction
Age-related declines in lower-limb somatosensory function may contribute to impaired motor control and increased fall risk in older adults. Although plantar sensory stimulation has been reported to improve postural control, its effects on neural processing remain unclear. This study investigated whether repeated plantar electrical stimulation modifies lower-limb somatosensory processing in older adults using somatosensory evoked potentials (SEPs).
Methods
83 older adults aged ≥65 years were assigned to either a plantar electrical stimulation group (PES,
n
= 37) or a non-intervention control group (CON,
n
= 46). The PES group performed home-based plantar electrical stimulation for 8 weeks (30 min/session, ≥2 days/week). SEPs elicited by tibial, peroneal, and median nerve stimulation were recorded before and after the intervention. SEP latencies and amplitudes were analyzed using mixed-design ANOVA, and ANCOVA was performed for components showing baseline group differences.
Results
In the PES group, P37 latency elicited by tibial nerve stimulation and P37 and N50 latencies elicited by peroneal nerve stimulation were shorter at Post than at Pre, whereas no significant changes were observed in the CON group. ANCOVA confirmed that the group effect remained significant for P37 latency during tibial and peroneal nerve stimulations after adjustment for baseline values. Significant negative correlations were observed between baseline latencies and intervention-related changes, although these findings should be interpreted cautiously because change scores include baseline values. No significant intervention effects were observed for SEP amplitudes during lower-limb stimulation, and median nerve SEPs showed no comparable latency shortening.
Conclusion
Repeated plantar electrical stimulation was associated with shortened early SEP latencies elicited by lower-limb nerve stimulation. No comparable latency shortening was observed in median nerve SEPs, suggesting that the observed changes were more prominent in lower-limb than in upper-limb somatosensory processing. These findings suggest that repeated plantar electrical stimulation may be associated with changes in the temporal characteristics of lower-limb somatosensory processing in older adults. Further studies should determine whether these neurophysiological changes are associated with improvements in balance, mobility, and other functional outcomes.