2025 Volume 74 Issue 3 Pages 171-179
Given that the long head of the biceps femoris (BFlh), semitendinosus (ST), and semimembranosus (SM) have hip adduction moment arm, this study aimed to clarify the influence of hip abduction angle on their shear modulus, measured by using shear wave elastography, to determine an effective stretching position where these muscles are more elongated and demonstrate higher passive tension. Twelve healthy young men participated in the study. The shear modulus of BFlh, ST, and SM at the middle point was measured using shear wave elastography. The shear modulus was measured at hip abduction angles of 0°, 15°, 30°, and 45°, with the hip and knee joint held at 70° and 0° flexion, respectively. The effects of hip abduction angle on the muscle shear modulus were analyzed using a Friedman test, followed by Wilcoxon signed-rank tests with Benjamini-Hochberg procedure for post-hoc analysis. Effect sizes were calculated using r. Significant differences in shear modulus were found between hip abduction angles for all muscles (p < 0.05). Post-hoc analysis showed that the shear modulus of the SM at 45° was significantly higher compared to 0° (p < 0.05, r = 0.62) and 15° (p < 0.05, r = 0.54). For ST, the shear modulus at 45° was significantly higher compared to 0° (p < 0.05, r = 0.58). The shear modulus in BFlh at 15° was higher than 0° (p < 0.05, r = 0.53). Adding to hip abduction in a position of hip flexion and knee extension increases the shear modulus of the medial hamstrings, particularly the SM.
