Department of Biomechanics, Performance Analysis and Strength & Conditioning, Olympic Training and Testing Center Westphalia, Dortmund,Germany.
Institute of Movement and Neuroscience, German Sport University, Cologne,Germany.
J Sport Rehabil. 2023 Jun 20;32(7):782-789. doi: 10.1123/jsr.2022-0372. Print 2023 Sep 1.
Different resistance exercise determinants modulate the musculotendinous adaptations following eccentric hamstring training. The Nordic Hamstring Exercise (NHE) can be performed 2-fold: the movement velocity irreversibly increases toward the end of the range of motion or it is kept constant.
This cross-sectional study aimed to investigate if the downward acceleration angle (DWAangle) can be used as a classification parameter to distinguish between increasing and constant velocity NHE execution. Furthermore, the kinetic and kinematic differences of these 2 NHE execution conditions were examined by analyzing the DWAangle in relation to the angle of peak moment.
A total of 613 unassisted NHE repetitions of 12 trained male sprinters (22 y, 181 cm, 76 kg) were analyzed.
The majority of analyzed parameters demonstrated large effects. NHEs with constant velocity (n = 285) revealed significantly higher impulses (P < .001; d = 2.34; + 61%) and fractional time under tension (P < .001; d = 1.29; +143%). Although the generated peak moments were significantly higher for constant velocity (P = .003; d = 0.29; +4%), they emerged at similar knee flexion angles (P = .167; d = 0.28) and revealed on average just low relationships to the DWAangle (Rmean2=22.4%). DWAangle highly correlated with the impulse (Rmean2=60.8%) and δ (DWAangle-angle of peak moment; Rmean2=83.6%).
Relating DWAangle to angle of peak moment assists to distinguish between significantly different NHE execution, which will potentially elicit different musculotendinous adaptations. These insights are essential for coaches and athletes to understand how to manipulate eccentric hamstring training to change its purpose.
不同的抗阻运动决定因素会调节离心腘绳肌训练后的肌腱-肌肉适应。北欧式腘绳肌训练（NHE）可以进行 2 次重复：运动速度在运动范围的末端不可逆地增加或保持不变。
本横断面研究旨在探讨向下加速度角（DWAangle）是否可用作区分增加和恒定速度 NHE 执行的分类参数。此外，通过分析与峰值力矩角度的关系来研究这 2 种 NHE 执行条件的动力学和运动学差异。
分析了 12 名训练有素的男性短跑运动员（22 岁，181cm，76kg）共进行的 613 次无辅助 NHE 重复运动。
大多数分析参数显示出较大的影响。恒定速度（n=285）的 NHE 显示出明显更高的冲量（P<.001；d=2.34；+61%）和张力下的分数时间（P<.001；d=1.29；+143%）。尽管恒定速度产生的峰值力矩明显更高（P=0.003；d=0.29；+4%），但它们出现在相似的膝关节弯曲角度（P=0.167；d=0.28），并且与 DWAangle 的平均关系较低（Rmean2=22.4%）。DWAangle 与冲量高度相关（Rmean2=60.8%）和δ（DWAangle-峰值力矩角度；Rmean2=83.6%）。
将 DWAangle 与峰值力矩角度相关联有助于区分明显不同的 NHE 执行，这可能会引起不同的肌腱-肌肉适应。这些见解对于教练和运动员理解如何操纵离心腘绳肌训练以改变其目的至关重要。
