Abstract
[Purpose] The purpose of this study was to clarify the relationship between pelvic lateral tilt during lateral body weight shifting in the upright sitting position and the hip joint abductors on the weight-shifted side, and to investigate the influence of the unilateral gluteal region load on the integrated electromyographic activity of each muscle. [Subjects] This study recruited 16 healthy male volunteers (mean age, 27.1 ± 6.6 years). [Methods] With the subjects sitting upright, different weight loads were randomly applied on the unilateral gluteal region during unilateral weight shift. The electromyographic activities of the upper fibers of the gluteus medius, tensor fascia latae, and gluteus maximus muscles on the weight-shifted side were recorded under each load. The relative values of the integrated electromyographic activities of the muscles were compared among the different loads. [Results] Each muscle showed a significant increase in the relative value of the integrated electromyographic activity at weight loads of up to 85%. However, significant decreases were observed in the gluteus medius and tensor fascia latae muscles at weight loads of 90% or higher. [Conclusion] Participation of the hip joint abductors on the weight-shifted side is important for the promotion of pelvic lateral tilt with lateral weight movement in the upright sitting position.
