Task-dependent reorganization of digit forces in fencing.

Abstract

Effective weapon control in fencing requires precise coordination of forces across the fingers, yet the organization of digit-level grip forces during dynamic fencing actions remains largely unknown. We aimed to quantify finger-force distribution during fencing thrusts and determine whether it is influenced by spatial accuracy demands and temporal constraints. Thirty-four elite foil and épée fencers performed thrusts toward small and large targets under self-paced and reaction-time conditions. Digit contact forces applied by the thumb, index, middle, ring, and little fingers were recorded using an instrumented fencing handle, while muscle activity was assessed using surface electromyography. Relative finger contributions, percentage of individual maximum force, and the effective number of fingers were used to characterize finger-force organization. Finger-forces were distributed asymmetrically across the digits, with the index finger producing the largest share of total force. The thumb-index unit contributed more than half of total digit contact force. Despite this asymmetry, forces remained distributed across all digits. Temporal constraints influenced grip organization: reaction-time thrusts increased the contribution of the middle finger and shifted force distribution away from the thumb-index unit, accompanied by greater muscle activation; this pattern was absent when forces were normalized to individual digit maxima. In contrast, spatial accuracy demands had little effect on force distribution, though this conclusion is limited by the lack of trial-level accuracy measures. Present findings demonstrate that finger-force organization during fencing relies on a stable yet adaptable multi-digit strategy in which temporal constraints primarily influence how forces are redistributed across the hand.