Contessa Paola, Puleo Alessio, De Luca Carlo J
Delsys Incorporated, Natick, Massachusetts; Department of Physical Therapy and Athletic Training, Boston University, Boston, Massachusetts
Delsys Incorporated, Natick, Massachusetts; Department of Mechanical and Aerospace Engineering, Politecnico di Torino, Turin, Italy; and.
J Neurophysiol. 2016 Feb 1;115(2):967-77. doi: 10.1152/jn.00889.2015. Epub 2015 Dec 9.
Exercise-induced muscle fatigue has been shown to be the consequence of peripheral factors that impair muscle fiber contractile mechanisms. Central factors arising within the central nervous system have also been hypothesized to induce muscle fatigue, but no direct empirical evidence that is causally associated to reduction of muscle force-generating capability has yet been reported. We developed a simulation model to investigate whether peripheral factors of muscle fatigue are sufficient to explain the muscle force behavior observed during empirical studies of fatiguing voluntary contractions, which is commonly attributed to central factors. Peripheral factors of muscle fatigue were included in the model as a time-dependent decrease in the amplitude of the motor unit force twitches. Our simulation study indicated that the force behavior commonly attributed to central fatigue could be explained solely by peripheral factors during simulated fatiguing submaximal voluntary contractions. It also revealed important flaws regarding the use of the interpolated twitch response from electrical stimulation of the muscle as a means for assessing central fatigue. Our analysis does not directly refute the concept of central fatigue. However, it raises important concerns about the manner in which it is measured and about the interpretation of the commonly accepted causes of central fatigue and questions the very need for the existence of central fatigue.
运动诱导的肌肉疲劳已被证明是损害肌纤维收缩机制的外周因素所致。中枢神经系统产生的中枢因素也被假定可诱发肌肉疲劳，但尚无直接的实证证据表明其与肌肉力量生成能力的降低存在因果关系。我们开发了一个模拟模型，以研究肌肉疲劳的外周因素是否足以解释在疲劳性自主收缩的实证研究中观察到的肌肉力量行为，这种行为通常归因于中枢因素。肌肉疲劳的外周因素在模型中表现为运动单位力颤搐幅度随时间的下降。我们的模拟研究表明，在模拟的疲劳性次最大自主收缩过程中，通常归因于中枢疲劳的力量行为仅由外周因素即可解释。该研究还揭示了将肌肉电刺激的插值颤搐反应用作评估中枢疲劳手段时存在的重要缺陷。我们的分析并未直接反驳中枢疲劳的概念。然而，它引发了对中枢疲劳测量方式、对其普遍接受的成因解释的重要担忧，并对中枢疲劳存在的必要性提出了质疑。
