Lower limb interjoint coordination in maximal successful snatch attempts during competition: a vector coding comparison of elite and sub-elite weightlifters

The snatch requires precise temporal coordination among multiple joints, yet technique is often assessed using individual-joint measures, which may not fully capture inter-joint coordination throughout the lift. We compared lower-limb inter-joint coordination and coordination-mode composition between elite and sub-elite weightlifters during competition snatch attempts. Successful 1RM attempts by ten elite and ten sub-elite 73-kg weightlifters were recorded using a dual-camera system. Three-dimensional kinematics provided sagittal-plane hip, knee, and ankle angles. Vector coding quantified coupling-angle trajectories and coordination-mode proportions for hip-knee, hip-ankle, and knee-ankle pairs across six time-normalised phases. Circular regression compared trajectories, PERMANOVA tested phase-specific mode composition, and coupling-angle mapping (CAM) characterised within-phase proximal-distal dominance. Significance was set at p ≤ 0.05. No between-group differences were found in coupling-angle trajectories across joint pairs or phases. However, knee-ankle mode composition differed during Transition (F = 3.389, p = 0.039) and Turnover under the barbell (F = 2.833, p = 0.048), but not in other phases or joint pairs. These findings suggest that performance-level differences are reflected in phase-dependent distal regulation and temporal reorganisation rather than overall coupling-trajectory patterns.