The kinematics of the lower leg in the sagittal plane during downward squatting in persons with pronated feet

[Purpose] This study aimed to examine changes in lower extremity kinematics in the sagittal plane during downward squatting by subjects with pronated feet. [Subjects and Methods] This study selected 10 subjects each with normal and pronated feet using a navicular drop test. The subjects performed downward squatting, in which the knee joints flex 90° in a standing position. We recorded the angles of the hip, knee, and ankle joint in the sagittal plane through motion analysis. For the analysis, the squatting phase was divided into phase 1 (initial squat), phase 2 (middle squat), and phase 3 (terminal squat) according to the timing of downward squatting. [Results] In the pronated foot group comparison with the normal group, the hip joint flexion angle decreased significantly in phases 2 and 3. The dorsiflexion angle of the ankle joint increased significantly in phase 3. The flexion angle of the knee joint did not differ between groups in any of the phases. [Conclusion] The pronated foot group utilized a different squat movement strategy from that of the normal foot group in the sagittal plane.