Schaefer Laura V, Carnarius Friederike, Dech Silas, Bittmann Frank N
Neuromechanics Laboratory, Regulative Physiology and Prevention, Department Sports and Health Sciences, University Potsdam, Potsdam, Germany.
Front Physiol. 2023 Feb 22;14:1020954. doi: 10.3389/fphys.2023.1020954. eCollection 2023.
The Adaptive Force (AF) reflects the neuromuscular capacity to adapt to external loads during holding muscle actions and is similar to motions in real life and sports. The maximal isometric AF (AFiso) was considered to be the most relevant parameter and was assumed to have major importance regarding injury mechanisms and the development of musculoskeletal pain. The aim of this study was to investigate the behavior of different torque parameters over the course of 30 repeated maximal AF trials. In addition, maximal holding vs. maximal pushing isometric muscle actions were compared. A side consideration was the behavior of torques in the course of repeated AF actions when comparing strength and endurance athletes. The elbow flexors of = 12 males (six strength/six endurance athletes, non-professionals) were measured 30 times (120 s rest) using a pneumatic device. Maximal voluntary isometric contraction (MVIC) was measured pre and post. MVIC, AFiso, and AF (maximal torque of one AF measurement) were evaluated regarding different considerations and statistical tests. AF and AFiso declined in the course of 30 trials [slope regression (mean ± standard deviation): AF = -0.323 ± 0.263; AFiso = -0.45 ± 0.45]. The decline from start to end amounted to -12.8% ± 8.3% ( < 0.001) for AF and -25.41% ± 26.40% ( < 0.001) for AFiso. AF parameters declined more in strength vs. endurance athletes. Thereby, strength athletes showed a rather stable decline for AF and a plateau formation for AFiso after 15 trials. In contrast, endurance athletes reduced their AF, especially after the first five trials, and remained on a rather similar level for AFiso. The maximum of AFiso of all 30 trials amounted 67.67% ± 13.60% of MVIC ( < 0.001, = 12), supporting the hypothesis of two types of isometric muscle action (holding vs. pushing). The findings provided the first data on the behavior of torque parameters after repeated isometric-eccentric actions and revealed further insights into neuromuscular control strategies. Additionally, they highlight the importance of investigating AF parameters in athletes based on the different behaviors compared to MVIC. This is assumed to be especially relevant regarding injury mechanisms.
适应性力量（AF）反映了在保持肌肉动作过程中神经肌肉适应外部负荷的能力，类似于现实生活和体育运动中的动作。最大等长AF（AFiso）被认为是最相关的参数，并且假定在损伤机制和肌肉骨骼疼痛的发展方面具有重要意义。本研究的目的是调查在30次重复的最大AF试验过程中不同扭矩参数的行为。此外，还比较了最大等长保持与最大等长推的肌肉动作。一个附带的考量是在比较力量型和耐力型运动员时，重复AF动作过程中扭矩的行为。使用气动装置对12名男性（6名力量型运动员/6名耐力型运动员，非专业运动员）的肘屈肌进行了30次测量（休息120秒）。在测量前后测定了最大自主等长收缩（MVIC）。针对不同的考量因素和统计测试，对MVIC、AFiso和AF（一次AF测量的最大扭矩）进行了评估。在30次试验过程中，AF和AFiso均下降[斜率回归（平均值±标准差）：AF = -0.323±0.263；AFiso = -0.45±0.45]。AF从开始到结束的下降幅度为-12.8%±8.3%（P<0.001），AFiso为-25.41%±26.40%（P<0.001）。与耐力型运动员相比，力量型运动员AF参数下降更多。因此，力量型运动员的AF呈现出较为稳定的下降，AFiso在15次试验后形成一个平台期。相比之下，耐力型运动员的AF下降，尤其是在前五次试验之后，而AFiso保持在相当相似的水平。所有30次试验的AFiso最大值相当于MVIC的67.67%±13.60%（P<0.001，n = 12），支持了两种等长肌肉动作（保持与推）的假设。这些发现提供了关于重复等长-离心动作后扭矩参数行为的首批数据，并揭示了对神经肌肉控制策略的进一步见解。此外，它们强调了根据与MVIC相比的不同行为来研究运动员AF参数的重要性。这被认为在损伤机制方面尤其相关。
