Motion Analysis of Load Lifting at Defined Stance Widths

Abstract

[Purpose] This study aimed to clarify the characteristics of movement when lifting loads at defined stance widths, and the associated mechanical stress in the lumbar region. [Subjects and Methods] Eight healthy, male university students lifted a 10 kg load placed on the floor using three stance widths. High-speed cameras and surface electromyography were used to measure body movements and muscle activities. [Results] Anterior tilt angle of the trunk and activity of the lumbar paraspinal muscles were significantly decreased when using a wide stance. There were no significant differences in the activities of the lower extremity muscles. [Conclusion] These results suggest that use of a wide stance while lifting loads decreases the anterior tilt angle of the trunk and the activity of the lumbar paraspinal muscles, which would decrease mechanical stress on the lumbar region.