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 non-fatigued (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 three minutes throughout cycling. One-way ANOVA at baseline and exhaustion uncovered evidence of consistently smaller motor evoked potential (MEP) amplitudes (P = .011) and prolonged MEP latencies (P = .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; P = .037), and potentiated twitch force (HF: 35 ± 13%; LF: 50 ± 16%; CON: 47 ± 17% of pre; P = .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 R² = .389), elevated peripheral muscle fatigability (change in R² = .183), and depressive symptoms (change in R² = .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.

中文翻译：

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多发性硬化相关的疲劳：皮质脊髓反应受损和运动易疲劳性增加的作用。

目前尚不清楚运动疲劳和感知疲劳是否在多发性硬化症 (PwMS) 患者中具有共同的病理生理学。这项横断面调查探讨了骑自行车运动疲劳的机制与 PwMS 疲劳严重程度之间的关系。13 名高度疲劳 (HF​​) 和 13 名非疲劳 (LF) PwMS 以及 13 名健康对照 (CON) 在创新的自行车测力计上完成了一步测试，直到意志力耗尽。在整个骑行过程中每三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。基线和疲劳的单向方差分析揭示了 HF 中运动诱发电位 (MEP) 幅度始终较小 (P = .011) 和 MEP 潜伏期延长 (P = .041) 的证据，以及最大自主收缩力（HF：63 ± 13%；LF：75 ± 13%；CON：前的 73 ± 11%；P = .037）和增强的抽搐力（HF：35 ± 13%; LF: 50 ± 16%; CON: 47 ± 17% pre; P = .049) 在自愿衰竭的 HF 中。分层回归确定，疲劳严重程度量表上的疲劳严重程度是通过延长 MEP 延迟（R 的变化）来预测的² = .389)、外周肌肉易疲劳性升高（R ^{2 的}变化= .183）和抑郁症状（R ^{2 的}变化= .213）。这些发现表明，与 MS 相关的疲劳的特点是皮质脊髓反应性受损，这可能表明进行性病理，但全身运动的易疲劳和抑郁症状也会影响 PwMS 中对疲劳的感知。