Exercise Biology, Department of Public Health, Aarhus University, Denmark.
Centre for Innovative Medical Technology, Odense University Hospital, Denmark.
Neurorehabil Neural Repair. 2020 Jun;34(6):523-532. doi: 10.1177/1545968320920250. Epub 2020 May 12.
. Fatigue is one of the most frequent symptoms in persons with multiple sclerosis (MS). Distinction is made between subjective perceptions of fatigue and objective measures of fatigability. Fatigability can be measured by different protocols. Yet no studies have compared isometric and concentric contraction protocols of the lower extremities head-to-head. Therefore, the purpose of the present study was to (1) compare 2 such protocols head-to-head and (2) to investigate the association between fatigability evoked by the 2 protocols and measures of fatigue and walking. A total of 45 patients with MS had their walking capacity measured objectively by the 6-minute walk test (6MWT) and subjectively by the 12-item Multiple Sclerosis Walking Scale (MSWS-12). Fatigue was measured by the Modified Fatigue Impact Scale (MFIS) and fatigability by 2 knee extension protocols: sustained isometric and concentric. The sustained isometric protocol induced a higher degree of fatigability than the concentric protocol ( < .01). Regression analyses revealed that sustained isometric fatigability was not associated with either measures of fatigue or walking (all = 0.00; = .85-.99), whereas the concentric protocol was significantly associated with fatigue ( = 0.20; < .01), 6MWT ( = 0.09; < .05), and MSWS-12 ( = 0.16; < .01). Furthermore, after adjusting for maximal strength and sex, concentric fatigability remained a strong and significant predictor of fatigue (β = 0.49) and walking (6MWT: β = -0.26; MSWS: β = 0.37). This study provides the first evidence that a lower-extremity concentric fatigability protocol provides superior reflection of both fatigue and walking when compared with a sustained isometric protocol. We suggest that concentric protocols should be the focus of future studies investigating fatigability.
疲劳是多发性硬化症（MS）患者最常见的症状之一。区分疲劳的主观感知和疲劳能力的客观测量。疲劳能力可以通过不同的方案来测量。然而，没有研究将下肢等长和向心收缩方案进行头对头比较。因此，本研究的目的是：（1）头对头比较这两种方案；（2）探讨两种方案引起的疲劳能力与疲劳和步行的测量之间的关联。共有 45 名 MS 患者通过 6 分钟步行测试（6MWT）客观测量其步行能力，通过 12 项多发性硬化症步行量表（MSWS-12）主观测量。疲劳通过修改后的疲劳影响量表（MFIS）测量，疲劳能力通过两种膝关节伸展方案测量：持续等长和向心。持续等长方案引起的疲劳能力比向心方案更高（<0.01）。回归分析显示，持续等长疲劳能力与疲劳或步行的任何测量值均无相关性（所有=0.00；=0.85-0.99），而向心方案与疲劳显著相关（=0.20；<0.01），6MWT（=0.09；<0.05）和 MSWS-12（=0.16；<0.01）。此外，在调整最大力量和性别后，向心疲劳能力仍然是疲劳（β=0.49）和步行（6MWT：β=-0.26；MSWS：β=0.37）的强有力且显著的预测因子。本研究首次提供证据表明，与持续等长方案相比，下肢向心疲劳能力方案能更好地反映疲劳和步行。我们建议，向心方案应成为未来研究疲劳能力的重点。
