Foot-ground interaction and clubhead speed: impulse-based energy transfer as the key mechanism in the golf swing

Clubhead speed is a primary determinant of golf performance, typically linked to the kinetic chain. Although foot-ground interaction variables such as plantar pressure and center-of-pressure behavior associate with performance, the mechanisms linking these factors to clubhead speed remain unclear. This study investigated whether foot-ground interaction influences clubhead speed directly or through intermediate mechanisms, such as segmental sequencing and energy transfer.

Thirty right-handed golfers (15 professionals, 15 high-level amateurs) performed maximal swings using a driver and a 7-iron. Data from both club types were pooled to identify generalized biomechanical mechanisms across equipment. Kinematics, ground reaction forces, and plantar pressure were recorded. Impulse-based energy transfer efficiency-defined as the effectiveness of mechanical impulse transmission from proximal segments to the club head-was computed. Principal component analysis-derived constructs for hierarchical regression and serial mediation models, controlling for skill level.

Foot-ground interaction variables explained 35.5% of the variance in clubhead speed. Adding trunk sequencing and impulse-based energy transfer efficiency increased the explained variance to 75.4% (adjusted $R^2=0.715$ ). Mediation analysis revealed that early-phase center-of-pressure behavior did not directly influence clubhead speed. Instead, a significant indirect pathway through impulse-based energy transfer efficiency was found (accounting for 55% of the total variance in the mediation model); trunk sequencing did not independently mediate this relationship, while skill level remained a significant covariate.

Foot-ground interaction enhances clubhead speed primarily by facilitating efficient impulse-based energy transfer along the kinetic chain rather than through direct mechanical effects. These findings support integrating foot-pressure and energy-flow analyses for performance assessment and evidence-based training.