Differences in hip, knee, and ankle joint moments during squats across load intensities, gender classes, and performance level in elite powerlifters

This study investigated how joint dynamics and kinematics change with increasing squat intensity in elite powerlifters performing the powerlifting-style low-bar back squat. Twenty-nine national- and international-level Austrian athletes (13 women, 16 men) executed single-repetition squats at 70–90% of their estimated one-repetition maximum (1-RM) according to International Powerlifting Federation standards. A three-dimensional motion capture system and two force plates recorded full-body kinematics and ground-reaction forces. Inverse kinematics and inverse dynamics analyses were used to quantify joint angles and hip, knee and ankle flexion/extension moments. Absolute and relative joint flexion/extension moments were compared across intensities using repeated-measures ANOVA and Statistical Parametric Mapping (p < 0.05). As the load increased, hip joint flexion/extension moments increased significantly (p < 0.001) during the concentric phase, while knee and ankle flexion/extension moments remained unchanged. Relative joint flexion/extension moments shifted from the knee and ankle towards the hip, indicating a more hip-dominant strategy. No significant gender × intensity interaction was observed. These results demonstrate that during near-maximal squats in elite powerlifters, the hip joint endures the highest flexion/extension moments among the primary lower limb joints. Our findings can help inform coaching strategies for high-level athletes.