Coates Kyla D, Aboodarda Saied Jalal, Krüger Renata L, Martin Tristan, Metz Luanne M, Jarvis Scott E, Millet Guillaume Y
Neuromuscular Fatigue Laboratory, Faculty of Kinesiology, University of Calgary, Calgary, Alberta, Canada.
Unité Mixte de Recherche-S 1075 Comete Moblites: Vieillissement Pathologies Santé, Institut National de la Santé et de la Recherche Médicale, Normandy University, Caen, France.
J Neurophysiol. 2020 Oct 1;124(4):1131-1143. doi: 10.1152/jn.00165.2020. Epub 2020 Sep 2.
It is unclear whether motor fatigability and perceived fatigue share a common pathophysiology in people with multiple sclerosis (PwMS). This cross-sectional investigation explored the relationship between the mechanisms of motor fatigability from cycling and fatigue severity in PwMS. Thirteen highly fatigued (HF) and thirteen nonfatigued (LF) PwMS and thirteen healthy controls (CON) completed a step test until volitional exhaustion on an innovative cycle ergometer. Neuromuscular evaluations involving femoral nerve electrical stimulation and transcranial magnetic stimulation were performed every 3 min throughout cycling. One-way ANOVA at baseline and exhaustion uncovered evidence of consistently smaller motor evoked potential (MEP) amplitudes ( = 0.011) and prolonged MEP latencies ( = 0.041) in HF as well as a greater decline in maximal voluntary contraction force (HF: 63 ± 13%; LF: 75 ± 13%; CON: 73 ± 11% of pre; = 0.037) and potentiated twitch force (HF: 35 ± 13%; LF: 50 ± 16%; CON: 47 ± 17% of pre; = 0.049) in HF at volitional exhaustion. Hierarchical regression determined that fatigue severity on the Fatigue Severity Scale was predicted by prolonged MEP latencies (change in = 0.389), elevated peripheral muscle fatigability (change in = 0.183), and depressive symptoms (change in = 0.213). These findings indicate that MS-related fatigue is distinguished by disrupted corticospinal responsiveness, which could suggest progressive pathology, but fatigability from whole body exercise and depressive symptoms also influence perceptions of fatigue in PwMS. The etiology of fatigability from whole body exercise was examined for the first time to accurately elucidate the relationship between fatigue and fatigability in multiple sclerosis (MS). Compromised corticospinal responsiveness predicted fatigue severity, providing a novel, objective indicator of fatigue in MS. Although the impaired corticomotor transmission did not aggravate muscle activation in this group of people with multiple sclerosis (PwMS) of lower disability, heightened muscle fatigability was seen to contribute to perceptions of fatigue in PwMS.
目前尚不清楚多发性硬化症患者（PwMS）的运动疲劳和感知疲劳是否具有共同的病理生理学机制。这项横断面研究探讨了PwMS患者骑行运动疲劳机制与疲劳严重程度之间的关系。13名高度疲劳（HF）的PwMS患者、13名非疲劳（LF）的PwMS患者和13名健康对照者（CON）在一台创新型自行车测力计上完成了一项阶梯测试，直至自愿力竭。在整个骑行过程中，每隔3分钟进行一次涉及股神经电刺激和经颅磁刺激的神经肌肉评估。基线和力竭时的单因素方差分析发现，HF组存在运动诱发电位（MEP）波幅持续较小（P = 0.011）和MEP潜伏期延长（P = 0.041）的证据，并且在自愿力竭时，HF组的最大自主收缩力下降幅度更大（HF：63±13%；LF：75±13%；CON：73±11% of pre；P = 0.037），以及强直后增强肌力（HF：35±13%；LF：50±16%；CON：47±17% of pre；P = 0.049）。分层回归分析确定，疲劳严重程度量表上的疲劳严重程度可由MEP潜伏期延长（ΔR² = 0.389）、外周肌肉疲劳性升高（ΔR² = 0.183）和抑郁症状（ΔR² = 0.213）预测。这些发现表明，与MS相关的疲劳的特征是皮质脊髓反应性受损，这可能提示存在进行性病变，但全身运动引起的疲劳和抑郁症状也会影响PwMS患者的疲劳感知。首次对全身运动引起的疲劳的病因进行了研究，以准确阐明多发性硬化症（MS）中疲劳与疲劳性之间的关系。皮质脊髓反应性受损可预测疲劳严重程度，为MS中的疲劳提供了一种新的客观指标。尽管在这组残疾程度较低的多发性硬化症患者（PwMS）中，皮质运动传导受损并未加重肌肉激活，但肌肉疲劳性增加被认为会导致PwMS患者的疲劳感知。
