Division Regulative Physiology and Prevention, Department Sports and Health Sciences, University of Potsdam, Potsdam, Germany.
PLoS One. 2021 May 6;16(5):e0238331. doi: 10.1371/journal.pone.0238331. eCollection 2021.
In sports and movement sciences isometric muscle function is usually measured by pushing against a stable resistance. However, subjectively one can hold or push isometrically. Several investigations suggest a distinction of those forms. The aim of this study was to investigate whether these two forms of isometric muscle action can be distinguished by objective parameters in an interpersonal setting. 20 subjects were grouped in 10 same sex pairs, in which one partner should perform the pushing isometric muscle action (PIMA) and the other partner executed the holding isometric muscle action (HIMA). The partners had contact at the distal forearms via an interface, which included a strain gauge and an acceleration sensor. The mechanical oscillations of the triceps brachii (MMGtri) muscle, its tendon (MTGtri) and the abdominal muscle (MMGobl) were recorded by a piezoelectric-sensor-based measurement system. Each partner performed three 15s (80% MVIC) and two fatiguing trials (90% MVIC) during PIMA and HIMA, respectively. Parameters to compare PIMA and HIMA were the mean frequency, the normalized mean amplitude, the amplitude variation, the power in the frequency range of 8 to 15 Hz, a special power-frequency ratio and the number of task failures during HIMA or PIMA (partner who quit the task). A "HIMA failure" occurred in 85% of trials (p < 0.001). No significant differences between PIMA and HIMA were found for the mean frequency and normalized amplitude. The MMGobl showed significantly higher values of amplitude variation (15s: p = 0.013; fatiguing: p = 0.007) and of power-frequency-ratio (15s: p = 0.040; fatiguing: p = 0.002) during HIMA and a higher power in the range of 8 to 15 Hz during PIMA (15s: p = 0.001; fatiguing: p = 0.011). MMGtri and MTGtri showed no significant differences. Based on the findings it is suggested that a holding and a pushing isometric muscle action can be distinguished objectively, whereby a more complex neural control is assumed for HIMA.
在运动科学和运动科学中，等长肌肉功能通常通过对抗稳定的阻力来测量。然而，人们可以主观地进行等长握持或推动。有几项研究表明存在这些形式的区别。本研究旨在探讨在人际环境中，是否可以通过客观参数来区分这两种形式的等长肌肉活动。20 名受试者分为 10 对同性受试者，其中一组的一个搭档执行推等长肌肉动作（PIMA），另一个搭档执行持等长肌肉动作（HIMA）。搭档通过接口在远端前臂接触，接口包括应变计和加速度传感器。三头肌（MMGtri）、肌腱（MTGtri）和腹部肌肉（MMGobl）的机械振荡通过基于压电传感器的测量系统进行记录。每个搭档在 PIMA 和 HIMA 中分别进行三次 15 秒（80%MVIC）和两次疲劳试验（90%MVIC）。比较 PIMA 和 HIMA 的参数是平均频率、归一化平均振幅、振幅变化、8 至 15 Hz 频率范围内的功率、特殊功率-频率比以及 HIMA 或 PIMA 期间的任务失败次数（停止任务的搭档）。在 85%的试验中发生了“HIMA 失败”（p<0.001）。在平均频率和归一化振幅方面，PIMA 和 HIMA 之间没有发现显著差异。在 HIMA 期间，MMGobl 的振幅变化（15 秒：p=0.013；疲劳：p=0.007）和功率-频率比（15 秒：p=0.040；疲劳：p=0.002）显著更高，而在 PIMA 期间 8 至 15 Hz 范围内的功率更高（15 秒：p=0.001；疲劳：p=0.011）。MMGtri 和 MTGtri 没有显示出显著差异。基于这些发现，建议可以客观地区分握持和推动等长肌肉动作，其中 HIMA 假设了更复杂的神经控制。
