[Purpose] Support moment was defined as the sum of ankle plantar flexion, knee and hip extension moments. There are some mechanical relationships among the 3 joints. If these relationships were understood, it might be possible to determine which joint should be strengthened to improve gait. The aims of this study were to examine the mutual relationship among kinetic variables of the 3 joints during different phases. [Subjects and Methods] Twenty-five healthy subjects volunteered for this study. They were asked to walk on a platform at a self-selected speed. Correlation coefficients between support moment and vertical ground reaction force were calculated for each subject. Pearson correlation analysis was performed among the 3 joint moments and between each joint moment and vertical ground reaction force. [Results] Knee and hip extension moments showed negative correlation throughout the stance. Ankle moment had a positive with hip but a negative correlation with knee moment except in the initial contact and pre-swing. Hip moment in the initial contact, knee moment in the loading response, and ankle moment from the terminal stance to pre-swing had a high correlation with vertical ground reaction force. [Conclusion] The results may indicate which joint should be strengthened to improve gait pattern.
Keywords: Biomechanics; Gait analysis; Motion analysis.