THE EFFECT OF STANCE WIDTH AND ANGLE ON THE ROTATIONAL RANGE OF MOTION OF PELVIS AND TRUNK

Abstract

[Background] In golf, snowboarding, etc., the distance between both feet (stance width), the angle of the foot (stance angle) are considered as an important factor for its performance. Those position of the legs (stance) are the empirically coached in the sports field. The purpose of this study was to investigate the influence of stance width and angles on the trunk range of motion and the laterality of the load. [Methods] Eleven healthy males participated as subjects in this study. To measure the maximum trunk rotational range of motion in the posture in which the standing to straightened the leg. In the experimental setting, the stance width was set to 42cm, 52cm wide and the stance angle was varied 5 conditions; the central angle (Odeg), the central angle+-15deg and +-30deg. The central angle was defined as the average of the maximum internal- and external-rotation of hip joint in a static standing. Measurement was used an optical motion capture and the force plate, including 12 units infrared camera. The local coordinate systems were set in the spine (TI, T4, T7, and L1)I). [Result] In the stance angle -30deg, the rotational range of motion of the pelvis and trunk decreased significantly in the stance width 42cm compared to the stance angle Odeg. Effect due to the difference in the stance was not observed. SI (Symmetry Index) of the load increased on the rotation side in accordance with the stance angle increased. The load on the leg of the rotational side in the stance angle +30deg was significantly greater than that in the stance angle -30deg. [Conclusion] It was suggested that the difference in the stance angle changed the trunk rotational range of motion in a static standing.