Neuromuscular Activation Patterns in Response to Windlass Stimulation and Biofeedback: A Surface EMG Study

Handball involves unilateral, high-demand actions that increase injury risk. The Windlass mechanism (WM) is a position-dependent plantar fascia tensioning system, activated by dorsiflexion of the first metatarsophalangeal joint, which increases medial longitudinal arch stiffness and contributes to foot stability. WM activation can be mechanically simulated using hallux wedges to induce controlled dorsiflexion, allowing graded engagement of the mechanism under standardized conditions. The primary aim of this study was to investigate how different wedge inclinations, with and without visual biofeedback, affect foot muscle activity during squats in elite female handball players.

Seventeen elite female handball players performed squats at 65% of one-repetition maximum under six conditions combining three wedge inclinations (0°, 10°, 30°) with the presence or absence of visual biofeedback. Electromyographic activity (RMS and %MVC) of intrinsic and extrinsic foot muscles was recorded.

A significant increase in left abductor hallucis activation with the 10° wedge without biofeedback. Visual biofeedback significantly increased RMS and %MVC in intrinsic foot muscles and increased RMS in the left gastrocnemius (p < 0.05). No significant interaction was observed between wedge inclination and biofeedback.

Controlled activation of the WM via hallux wedges and the use of visual biofeedback modulate foot muscle activity during squats. These strategies may be considered in training programs aimed at improving foot stability and reducing injury risk in elite female handball players.