Ripley Nicholas, Fahey Jack, Comfort Paul, McMahon John
School of Health and Society, University of Salford, Salford M5 4WT, UK.
School of Medical and Health Sciences, Edith Cowan University, Joondalup 6027, Australia.
Muscles. 2024 Sep 18;3(3):310-322. doi: 10.3390/muscles3030027.
The Nordic hamstring exercise (NHE) is effective at decreasing hamstring strain injury risk. Limited information is available on the in vivo mechanics of the bicep femoris long head (BF) during the NHE. Therefore, the purpose of this study was to observe kinematic, neuromuscular and in-vivo mechanics of the BF during the NHE. Thirteen participants (24.7 ± 3.7 years, 79.56 ± 7.89 kg, 177.40 ± 12.54 cm) performed three repetitions of the NHE at three horizontal planes (0°, 20° and -20°). Dynamic ultrasound of the dominant limb BF, surface electromyography (sEMG) of the contralateral hamstrings and sagittal plane motion data were simultaneously collected. Repeated measures analysis of variance with Bonferroni post hoc corrections were used on the in vivo mechanics and the kinematic and sEMG changes in performance of the NHE. Likely differences in ultrasound waveforms for the BF were determined. Significant and meaningful differences in kinematics and in vivo mechanics between NHE variations were observed. Non-significant differences were observed in sEMG measures between variations. Changes to the NHE performance angle manipulates the lever arm, increasing or decreasing the amount of force required by the hamstrings at any given muscle length, potentially changing the adaptive response when training at different planes and providing logical progressions ore regressions of the NHE. All NHE variations result in a similar magnitude of fascicle lengthening, which may indicate similar positive adaptations from the utilization of any variation.
北欧绳肌练习（NHE）在降低绳肌拉伤风险方面是有效的。关于NHE期间股二头肌长头（BF）的体内力学的信息有限。因此，本研究的目的是观察NHE期间BF的运动学、神经肌肉和体内力学。13名参与者（24.7±3.7岁，79.56±7.89千克，177.40±12.54厘米）在三个水平面（0°、20°和-20°）进行了三次NHE重复动作。同时收集优势侧肢体BF的动态超声、对侧绳肌的表面肌电图（sEMG）和矢状面运动数据。对NHE执行过程中的体内力学以及运动学和sEMG变化采用带有Bonferroni事后校正的重复测量方差分析。确定了BF超声波形可能存在的差异。观察到NHE不同变体之间在运动学和体内力学方面存在显著且有意义的差异。在不同变体之间的sEMG测量中未观察到显著差异。改变NHE的执行角度会操纵力臂，在任何给定肌肉长度下增加或减少绳肌所需的力量大小，这可能会改变在不同平面训练时的适应性反应，并为NHE提供合理的进阶或退阶方式。所有NHE变体导致的肌束拉长幅度相似，这可能表明使用任何变体都会产生相似的积极适应性变化。
