Human Performance Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
J Electromyogr Kinesiol. 2013 Jun;23(3):673-8. doi: 10.1016/j.jelekin.2013.01.007. Epub 2013 Feb 12.
Rhythmic fluctuations (Piper rhythm) have been resolved in surface electromyography (sEMG) recordings. For a long time this periodic signal could only be detected in isometric contractions, where the innervation time is much longer than the oscillation period. However, recently a periodic signal could also be resolved in cyclic movements like running, using non-linear scaled wavelets. The purpose of this study was to characterise the rhythm for different running velocities. A rhythmic signal (the Piper rhythm) was found in the EMG signal of both bellies of the gastrocnemius muscle with a frequency range of 20-35Hz. A decrease of the Piper frequency could be observed for all of the 13 subjects when increasing the running speed from 1.3 to 4.9m/s. The time and frequency analysis indicated that the origin of the periodic signal is from the activation of the muscle and is not likely resulting from muscle vibrations. No correlation between the medial and the lateral part of the muscle bellies could be found indicating that the two muscle compartments are fine tuned by two distinct processes. According to the literature, the signal might be the manifestation of a cortical rhythm, which has been shown for isokinetic movements.
在表面肌电图（sEMG）记录中已经解决了节律性波动（派珀节律）。长期以来，这种周期性信号只能在等长收缩中检测到，因为神经支配时间比振荡周期长得多。然而，最近，使用非线性缩放小波，也可以在跑步等周期性运动中解析周期性信号。本研究的目的是描述不同跑步速度的节律特征。在腓肠肌两个腹部的肌电图信号中发现了一个节律性信号（派珀节律），频率范围为 20-35Hz。当 13 名受试者的跑步速度从 1.3 米/秒增加到 4.9 米/秒时，所有受试者的派珀频率都有所下降。时频分析表明，周期性信号的起源是肌肉的激活，而不是肌肉振动引起的。无法在肌腹的内侧和外侧部分之间找到相关性，这表明两个肌肉间隔由两个不同的过程进行微调。根据文献，该信号可能是皮层节律的表现，这种节律已经在等速运动中得到证实。
