Biomechanical Determinants of Ceiling-Tempo Double-Under Performance in World and Junior National Champions: Implications for Training and Injury Prevention.

Double-under jump rope performance requires rapid force production and precise coordination under extreme temporal constraints; however, the biomechanical determinants of elite high-speed performance remain unclear. This ceiling-performance biomechanical study examined speed-dependent motor control in world champions (n = 3, 19.7 years) and junior national champions (n = 5, 14.0 years) during double-under performance at 120 double-unders/min, 140 double-unders/min, and individualized ceiling tempo. Three-dimensional motion capture (300 Hz) synchronized with force plates (1500 Hz) quantified kinetic and kinematic adaptations across tempo conditions. Compared with junior national champions, world champions demonstrated shorter contact times, greater rates of force development, reduced center-of-gravity height and oscillation, more compact posture control with widened upper-limb positioning, smaller rope-foot clearance heights, and an increasingly ankle-dominant coordinative pattern between wrist-hand control and lower-limb movement under ceiling-tempo conditions. Collectively, these findings indicate distinct expertise-dependent differences in force-production, postural-control, and rope-coordination characteristics under ceiling-tempo conditions. In contrast, junior national champions demonstrated less pronounced temporal compression, maintained a comparatively extended posture, and appeared to approach a performance plateau beyond 140 double-unders/min. The findings provide biomechanical benchmarks for understanding ceiling-tempo performance and may inform training, movement retraining, and injury-prevention strategies in high-speed cyclic movement tasks.