Modes of centripetal ground reaction force application in curved sprinting on an athletic track in male athletes

Curve sprinting requires a centripetal ground reaction force (GRF) impulse, causing biomechanical leg asymmetries. However, the strategies for modulating this impulse, its primary determinants (contact duration versus GRF magnitude), and specific joint kinetic and kinematic contributions remain unclear. This study investigated these impulse determinants and identified lower-limb factors associated with the magnitude of the GRF to elucidate asymmetrical leg modes in curve sprinting. Fifteen experienced male sprinters performed submaximal sprints on a 42-m-radius curve. Three-dimensional kinematic data and GRFs were recorded, joint torques were calculated, and partial least squares regression (PLSR) was used to assess key relationships. The centripetal impulse was strongly correlated with the mean centripetal GRF for both legs but not with the contact duration. Thus, the mean centripetal GRF, rather than the contact duration, was the primary determinant of the centripetal impulse during curve sprinting for both legs, supporting our first hypothesis. The PLSR results revealed functionally distinct asymmetrical modes: the left leg engaged in a complex turning and stability mode, defined by specific hip/ankle torques, and suppressed outward push. Conversely, the right leg relied on a dominant whole-limb inclination of the knee and ankle joint axis, along with a contribution from the ankle plantarflexion torque. These findings highlight distinct asymmetrical mechanisms of GRF application, thereby advancing our understanding of curve-sprinting biomechanics.