Effects of Hip Abductor Fatigue on Neuromuscular Control During Single-Leg Side-Jump Landing in Different Gender Groups / 医用生物力学

Objective To compare the effects of hip abductor fatigue on postural stability and neuromuscular control in different gender groups during single-leg side-jump landing. Methods Twenty male and twenty female adults were required to execute single-leg side-jump landing before and after hip abductor fatigue protocol. The center of pressure (COP), ground reaction force (GRF), lower extremity kinematics, joint moment, muscle activity were compared. Results For both males and females after fatigue, the maximum displacements and average velocities of COP decreased, and the peak angles of hip abduction and ankle eversion increased, and the peak torques of ankle inversion increased. At 200 ms pre-landing, the activiation of rectus femoris, biceps femoris, tibialis anterior, peroneus longus were lower in male than that in female. At 200 ms post-landing, the activiation of biceps femoris in male was lower than that in female after fatigue. Conclusions The postural stability in frontal plane decreased after hip abductor fatigue. The frontal plane control of hip joint and ankle joint was weakened, which might increase the risk of joint injury. There are differences in postural strategies for different genders, indicating that gender difference in the mechanism of lower limb joint injury is worth of further investigation.

Gluteus Medius and Tensor Fascia Latae muscle activation levels during multi-joint strengthening exercises

Aim: To compare the activation of GMed and TFL in four multi-joint exercises in strength training protocols and to verify if the level of muscle activation is indicated for strength gains in resistance training protocols. Methods: Eleven recreational lifters had normalized muscle activation of GMed and TFL assessed during ten maximal repetitions of four multi-joint exercises: (1) bilateral supine bridge (BiBRG); (2) bilateral supine bridge with hip abducted (BiBRG-AB); (3) unilateral supine bridge (UniBRG) and (4) single-leg squat (SLS). Results: A load of exercises was significantly greater for the BiBRG and BiBRG-AB compared to the UniBRG and SLS (p<0.001). We observed that GMed activation was significant greater compared to TFL among the four exercises (p=0.004) [BiBRG: Δ=26.2%; BiBRG-AB: Δ=27.3%; UniBRG: Δ=24.5% and SLS: Δ=18.8%]. Additionally, GMed activation was classified as moderate (<40%iMVC) and TFL activation was classified as low (<20%iMVC) in all exercises. Conclusion: Our results demonstrated that GMed is more active than TFL in all analyzed exercises. However, the level of activation observed for GMed was below that recommended to strength gain in resistance training programs.(AU)

Comparisons of Test-Retest Reliability of Strength Measurement of Gluteus Medius Strength between Break and Make Test in Subjects with Pelvic Drop

PURPOSE: The purpose of this study was to compare the reliability of unilateral hip abductor strength assessment in side-lying with break and make test in subjects with pelvic drop. Hip abduction muscles are very important in the hip joint structures. Therefore, it is essential to evaluate their strength in a reliable way. METHODS: Twenty-five subjects participated in this study. Unilateral isometric hip abductor muscle strength was measured in side-lying, with use of a specialized tensiometer using smart KEMA system for make test, of a hand held dynamometer for break test. Coefficients of variation, and intra class correlation coefficients were calculated to determine test-retest reliability of hip abductor strength. RESULTS: In make test, maximal hip abductor strength in the side-lying position was significantly higher compared with break test (p<0.05). Additionally, Test-retest reliability of hip abductor strength measurements in terms of coefficients of variation (3.7% for make test, 16.1% for break test) was better in the side-lying position with make test. All intraclass correlation coefficients with break test were lower than make test (0.90 for make test, 0.73 for break test). CONCLUSION: The side-lying body position with make test offers more reliable assessment of unilateral hip abductor strength than the same position with break test. Make test in side-lying can be recommended for reliable measurement of hip abductor strength in subjects with pelvic drop.