Coxal-femoral Rhythm and Difference in Left and Right Hip Retroversion in Hip Flexion Exercises

Abstract

[Purpose] The purpose of this study was to investigate the posterior tilt of the hip and whether or not there are disparities between the left and right sides in hip flexion exercises in the standing position. [Subjects and Method] The subjects were 15 healthy males (average age, 21.8±1.8 years). We measured the angle the line connecting the anterior and superior iliac crests made with the horizontal in the sagittal plane on the left and right sides as the angle of hip posterior tilt at 0˚, 45˚, 90˚ and maximum hip flexion when the subjects performed active hip flexion on the right side in the standing position. [Results] Flexion of the hip joint was accompanied with significant posterior tilt of the hip bone. The ratio of the right side posterior tilt to the left side was 2:1. Also, the ratio of the flexion movement of the hip joint to the hip posterior tilt was 7:1 at 45˚, 6:1 at 90˚, and 4:1 at maximum flexion. As the angle of hip joint flexion increased, the relative pelvic posterior tilt increased. [Conclusion] The results suggest that hip posterior occurs in hip flexion exercises, and we conjecture that movements of the left and right sacroiliac joints are involved. The results also suggest that for the coxal-femoral rhythm, the relative hip posterior tilt increases as the angle of hip joint flexion increases.