Lower-limb coordination during the rear-leg roundhouse kick in competitive taekwondo: a vector-coding analysis

To investigate whether differences exist in coupling angle (CA)-derived joint coordination pattern characteristics and coordination variability between the dominant side (DS) and non-dominant side (NS) during successful scoring rear-leg roundhouse kick (RLRK) in competitive taekwondo athletes.

Twelve male taekwondo athletes were recruited to perform RLRK with both the DS and NS. Lower-limb kinematic data were collected using a Vicon three-dimensional motion capture system. Signals from the Daedo electronic protector and a Kistler force platform were used for valid trial selection and movement event identification. Custom-written MATLAB code was used to calculate CA trajectories and coordination variability for lower-limb joint couplings. CA data were analyzed using circular statistics, with mean CA used to characterize CA-derived joint coordination pattern characteristics, and coordination variability was compared using paired-samples t-tests.

No significant bilateral differences in mean CA were observed during the knee-lift phase. The bilateral differences in mean CA were mainly observed during the kicking and recovery phases, reflecting side-related differences in coordination characteristics represented by CA. Specifically, significant bilateral differences were found in the frontal-plane hip-ankle coupling and sagittal-plane knee-ankle coupling during the kicking phase (p = 0.037; p = 0.026), and in the sagittal-plane knee-ankle coupling during the recovery phase (p = 0.016). Significant side-related differences in coordination variability were observed across all three movement phases. During the knee-lift and kicking phases, significant differences were found in the sagittal-plane knee-ankle coupling (p = 0.002; p = 0.015). During the recovery phase, significant bilateral differences were observed in the frontal-plane hip-ankle coupling (p = 0.008), sagittal-plane hip-knee coupling (p = 0.027), and sagittal-plane knee-ankle coupling (p = 0.044).

Competitive taekwondo athletes exhibit side-specific lower-limb joint coordination control strategies when executing RLRK. These differences were reflected in mean CA-based coordination pattern characteristics and coordination variability. Lower coordination variability in certain joint couplings on the DS during the knee-lift and kicking phases suggests that the DS may adopt a relatively more stable coordination control strategy during the key output stages of the movement. In the recovery phase, bilateral differences were mainly reflected in joint-specific coordination organization and in the distribution of coordination variability.