Effects of high-definition transcranial direct current stimulation on muscle strength, proprioception, cutaneous sensitivity and their relationship with balance in older adults with a history of falls

This study aims to investigate the effects of High-Definition Transcranial Direct Current Stimulation (HD-tDCS) on muscle strength, proprioception, cutaneous sensitivity and their relationship with static/dynamic balance in older adults with a history of falls. In this randomized, double-blind trial, 30 older adults with a history of falls were assigned to an active (a-tDCS, n = 15) or sham (s-tDCS, n = 15) group. The 4-week intervention consisted of 12 sessions (three times weekly). The a-tDCS group received 2 mA of continuous stimulation targeting the sensorimotor cortex for 20 min per session, whereas the s-tDCS group received current only during the initial and final 30-second ramp-up/down periods. Balance, muscle strength, proprioception and cutaneous sensitivity were assessed pre- and post-intervention. Significant interactions were identified in RMS ML ( p = 0.009, \(\:{\eta}_{\text{p}}^{\text{2}}\) = 0.222), DC scores ( p = 0.046, \(\:{\eta}_{\text{p}}^{\text{2}}\) = 0.134), peak hip abduction torque ( p = 0.007, \(\:{\eta}_{\text{p}}^{\text{2}}\) = 0.231), and ankle inversion proprioception threshold ( p = 0.038, \(\:{\eta}_{\text{p}}^{\text{2}}\) = 0.144). Post-hoc analyses revealed that the a-tDCS group demonstrated a significant reduction in RMS ML ( p = 0.034, d = 0.577) and ankle inversion threshold ( p = 0.010, d = 1.040), alongside significant increases in DC scores ( p = 0.002, d = 0.863) and hip abduction torque ( p = 0.008, d = 0.740) compared to baseline. No significant improvements were observed in cutaneous sensitivity ( p > 0.05). Correlation analysis in the a-tDCS group revealed a significant negative correlation between the change in RMS ML and the change in peak hip abduction torque ( r = -0.649, p = 0.009). A 4-week HD-tDCS intervention significantly improves static and dynamic balance, hip strength, and ankle inversion proprioceptive in older adults with a history of falls. Improved static balance is positively correlated with increased hip abduction strength.