PURPOSE This study explored foot angle control’s influence on lower extremity joints’ kinematic variables during bodyweight squats in adult women. The study compared correlation variances among kinematic variables to evaluate foot angle control’s impact on knee stability and movement performance. METHODS Participants included 29 healthy adult women over 20 years old. Each participant completed three sets of five repetitions under two conditions: foot angles of 0° and foot external rotation angle of 30°. Data analysis used Cortex 8.0 software. A paired sample t-test compared lower limb joint angles and center of mass (COM) height of the pelvic region based on foot angle. The Pearson correlation coefficient was calculated to assess correlations between each dependent variable; to analyze differences, Fisher’s Z transformation was applied to significantly correlated pairs. Statistical significance was set at p < 0.05. RESULTS Findings indicated that, compared to 0° (p < 0.05), at a foot external rotation angle of 30°, hip joint abduction, knee joint flexion, and ankle external rotation angles significantly increased, whereas the knee valgus angle significantly decreased (p < 0.05). Moreover, at the foot external rotation angle of 30° (p < 0.01), pelvic COM’s vertical movement range increased, resulting in deeper squats. Correlation analysis among lower extremity joint kinematic variables under different foot angle conditions showed no significant differences. CONCLUSIONS At a foot external rotation angle of 30°, adult women performed bodyweight squats with reduced knee valgus angle and potentially decreased knee joint loading, indicating lower risk of injury and increased squat depth due to enhanced lower extremity joint freedom. Thus, adjusting the foot angle to 30° during adult women’s bodyweight squats can be recommended to enhance knee stability and movement performance.
