Effects of 4 Weeks of High-Definition Transcranial Direct Stimulation and Foot Core Exercise on Foot Sensorimotor Function and Postural Control

Abstract

Objective: This study aimed to examine the effects of 4 weeks of high-definition transcranial direct current stimulation (HD-tDCS) and foot core exercise (FCE) on foot sensorimotor function (i.e., toe flexor strength and passive ankle kinesthesia) and postural control.Methods: In total, 36 participants were randomly assigned into three groups as follows: HD-tDCS, FCE, and the control group. A total of 12 training sessions were performed over 4 weeks (i.e., three sessions per week) in the laboratory. The HD-tDCS group received 20-min HD-tDCS with a current density of 2 mA, and the FCE group completed short foot exercise, towel curls, toe spread and squeeze, and balance board training. Participants in the control group just maintained the activities what they usually did and did not receive any interventions. Foot muscle strength, passive ankle kinesthesia, and postural control were assessed at baseline and post-intervention.Results: HD-tDCS induced a greater decrease in the percentage changes in the passive kinesthesia thresholds of ankle inversion (p < 0.001) and eversion (p = 0.013) than the control group. Compared with the control group, a significant increase in the percentage change in the metatarsophalangeal joint flexor strength was found in the HD-tDCS group (p = 0.008) and the FCE group (p = 0.027), and a significant increase in the percentage change in toe flexor strength was observed in the FCE group (p = 0.015). Moreover, FCE induced a greater reduction in the percent changes in the medial–lateral average center of gravity sway velocity in one-leg standing with eyes open (p = 0.033) and the anteroposterior average center of gravity sway velocity in one-leg standing with eyes closed (p < 0.001) than control.Conclusion: This study demonstrated that 4 weeks of HD-tDCS and FCE induced distinct benefits on foot sensorimotor function and the standing postural control performance in healthy young adults. HD-tDCS could improve the metatarsophalangeal joint flexor strength and the passive kinesthesia thresholds of ankle inversion and eversion. Meanwhile, FCE could also enhance foot muscle strength and enhance postural control performance in one-leg standing.

Effects of tDCS on Foot Biomechanics: A Narrative Review and Clinical Applications

“…Furthermore, two sessions of bilateral tDCS were an effective method for improving jump height by modulating ankle and knee net energy [ 29 ]. In addition, 4 weeks of HD-tDCS and FCE induced distinct benefits on foot sensorimotor function and standing postural control performance in healthy young adults [ 22 ]. These findings suggest that tDCS, to some extent, can serve as an effective intervention for enhancing foot movement performance.…”

“…The latter also improved the visuomotor tasks induced by anodal tDCS targeting M1. More importantly, in terms of improving sensory function, HD-tDCS demonstrated more significant improvements in foot sensory function than FCE, particularly in significantly reducing the kinesthetic threshold of inversion and eversion [ 22 ].…”

Age-Related Dysfunction in Balance: A Comprehensive Review of Causes, Consequences, and Interventions

“…3) Standing on one leg: stand near a sturdy support and lift one foot off the ground. Hold this position for 10-30 seconds, then switch legs [133]. Gradually increase the duration as balance improves.…”