Phase-specific lower limb kinematic differences during Taekwondo roundhouse kicks between elite and youth athletes revealed by 1D statistical parametric mapping

To delineate youth–elite differences in roundhouse-kick technique, we quantified kinematic gaps and defined youth joint-motion patterns to guide training. Twenty-three elite and 23 youth athletes performed roundhouse kicks recorded with a 12-camera Vicon system (200 Hz). Support- and kicking-limb hip, knee, and ankle angles (Cardan XYZ) were filtered (zero-lag 4th-order Butterworth, 15 Hz), time-normalised to 0–100% (101 points; four phases & five events), and compared using 1D-SPM independent t-tests (RFT, α = 0.05). Differences were phase-specific. Hip: elites were more extended at support 25–35% (p = 0.008) and 40–45% (p = 0.040), and kicking 0–14% (p = 0.005); more support abduction at 40–65% (p < 0.01) and 88–100% (p = 0.004), but more kicking adduction at 0–3% (p = 0.041); smaller hip internal rotation (support p ≤ 0.007; kicking p < 0.001). Knee: greater support flexion at 95–100% (p = 0.015) and smaller kicking internal rotation at 2–9% (p = 0.002), 43–47% (p = 0.003), and 90–100% (p < 0.001). Ankle: elites were more plantarflexed at support 16–22% (p = 0.040) and 58–100% (p < 0.01), and kicking 57–93% (p < 0.01); kicking ankle abduction–adduction differed at 0–8% (p = 0.008). Elites adopt a more stable support posture and tighter rotation and braking, enabling rapid re-stabilisation; these windows are actionable targets for youth technique training.