COMPARISON OF THE MOTION CHARACTERISTICS OF THE LUMBAR, LUMBOSACRAL, AND HIP JOINTS BETWEEN TRUNK FLEXION-EXTENSION IN STANDING POSITION AND DURING UNDERWATER DOLPHIN KICK MOTION / 体力科学

ABSTRACT

Low-back pain is one of the most common injuries in competitive swimmers. Therefore, the prevention of low-back pain would contribute to improved performance of swimmers. A biomechanical analysis is necessary to prevent the sports-related injuries. However, only lumbar movement has been analyzed in swimmers with low-back pain. Lumbar spine movement is closely associated with the pelvis and hip joint. Thus, not only the lumbar joint but also the pelvis and hip joint should be analyzed to determine the cause of low-back pain.The aim of this study was to investigate the relationship of the effect of underwater movement on the motion characteristics of the lumbar, lumbosacral, and hip joints with trunk flexion-extension in the standing position.Fourteen male competitive swimmers were recruited for this study. Trunk flexion-extension motion in the standing position and underwater dolphin kick motion were captured in the saggital plane on a digital video camera. A 2D motion analysis was performed to determine the lumbar, lumbosacral, and hip joint angles during these motions.The results demonstrated that the lumbar angle during the dolphin kick motion was associated with the angle in the standing position when the trunk was extended; and the lumbosacral angle during the same motion was associated with the angle in the standing position when the trunk was flexed.Additionally, the subjects who tilted their pelvis anteriorly while swimming exhibited a bit of pelvis motion during trunk movement in the standing position. Thus, the anterior tilting of the pelvis during swimming leads to low-back pain in swimmers.