Department of Internal Medicine and Infectious Diseases, European Hospital in Marseille, Marseille, France.
Department of Internal Medicine and Infectious Diseases, European Hospital in Marseille, Marseille, France.
Clin Biomech (Bristol). 2023 Aug;108:106055. doi: 10.1016/j.clinbiomech.2023.106055. Epub 2023 Aug 3.
Myalgic encephalomyelitis is an invalidating chronic disease often associated with exercise-induced alterations of muscle membrane excitability (M wave). No simultaneous measurements of maximal isometric force production and sarcolemma fatigue in the same muscle group have been previously reported. We hypothesized that M wave alterations could be partly responsible for the reduced muscle force present in this invalidating disease.
This retrospective study compared two groups of patients who presented (n = 30) or not (n = 28) alterations of M waves evoked by direct muscle stimulation during and after a cycling exercise bout. The maximal handgrip strength was measured before and after exercise, concomitantly with electromyogram recordings from flexor digitorum longus muscle. The patients also answered a questionnaire to identify eventual exacerbation of their clinical symptoms following the exercise test.
The M wave amplitude significantly decreased in muscles and the M wave duration significantly increased in the group of patients with M wave alterations after exercise. Resting values of handgrip were significantly lower in patients with exercise-induced M-wave alterations than in patients without M-wave abnormalities. In patients with exercise-induced M-wave alterations, handgrip significantly decreased after exercise and the changes in handgrip and M wave were positively correlated. The frequency of post-exertion malaise, increased fatigue, myalgia, headache and cognitive dysfunction was significantly higher in patients with M-wave alterations and variations in handgrip after exercise.
These data suggest that post-exercise sarcolemma fatigue often measured in patients with myalgic encephalomyelitis could be the cause of muscle failure.
肌痛性脑脊髓炎是一种使人丧失能力的慢性疾病，常伴有运动引起的肌肉细胞膜兴奋性改变（M 波）。以前没有同时测量同一肌肉群的最大等长力产生和肌膜疲劳。我们假设 M 波改变可能是导致这种使人丧失能力的疾病中肌肉力量下降的部分原因。
这项回顾性研究比较了两组患者，一组在进行踏车运动时和运动后（n=30），另一组在进行踏车运动时和运动后（n=28）直接肌肉刺激时出现 M 波改变。在运动前后同时测量握力的最大强度，并从指深屈肌记录肌电图。患者还回答了一份问卷，以确定运动试验后他们的临床症状是否恶化。
运动后 M 波振幅在有 M 波改变的组的肌肉中显著降低，M 波持续时间在有 M 波改变的组显著增加。与无 M 波异常的患者相比，运动引起 M 波改变的患者的静息握力明显较低。在运动引起 M 波改变的患者中，握力在运动后明显下降，握力和 M 波的变化呈正相关。运动后出现不适、疲劳加重、肌痛、头痛和认知功能障碍的频率在有 M 波改变和运动后握力变化的患者中显著升高。
这些数据表明，在肌痛性脑脊髓炎患者中经常测量的运动后肌膜疲劳可能是肌肉衰竭的原因。
