Integration of coordination and kinetic analysis reveals mechanisms of upper limb joint loading and technique-specific strategies in female gymnastics

This study aimed to identify differences in upper-limb coordination by integrating vector coding with joint kinetics across three round-off (RO) techniques to better explain potential injury mechanisms. Twelve female gymnasts performed six trials of each RO technique (Parallel, Reverse, T-shape). The kinematic and kinetic data were collected. All analyses focused on the contact phase of the second hand. Elbow and Wrist joint flexion/extension (E -W ) and rotation (E -W ) couplings were assessed using modified vector coding to determine coupling angle (CA) and variability (CAV). Elbow joint adduction/abduction moments (M ) and joint power (JP ) were calculated using inverse dynamics. Joint kinetics and CA were overlaid on the same plots to visualise how kinetic patterns corresponded with coordination dynamics. Results showed decreased M using the T-shape technique ( < 0.001) with E -W in-phase, while Reverse and Parallel techniques exhibited anti-phase with increased M ( < 0.001) and lower CAV using Reverse technique. Furthermore, E -W coupling revealed technique-specific control strategies; notably, the T-shape technique exhibited a different transition from anti-phase to in-phase motion, indicating a potentially more effective transfer from JP absorption to generation. The result provides new insights into the underlying mechanism of these differences through integration of coordination analysis with traditional biomechanics.