Inter-university Laboratory of Human Movement Biology, UJM-Saint-Etienne, University of Lyon, Saint-Etienne, FRANCE.
Faculty of Kinesiology, University of Calgary, Calgary, CANADA.
Med Sci Sports Exerc. 2022 Aug 1;54(8):1355-1363. doi: 10.1249/MSS.0000000000002919. Epub 2022 Apr 8.
Cancer-related fatigue (CRF) is a debilitating symptom that affects around one-third of people for months or years after cancer treatment. In a recent study, we found that people with posttreatment CRF have greater neuromuscular fatigability. The aim of this secondary analysis was to examine the etiology of neuromuscular fatigability in people with posttreatment CRF.
Ninety-six people who had completed cancer treatment were dichotomized into two groups (fatigued and nonfatigued) based on a clinical cut point for fatigue. Alterations in neuromuscular function (maximal voluntary contraction peak force, voluntary activation, potentiated twitch force, and EMG) in the knee extensors were assessed across three common stages of an incremental cycling test. Power outputs during the fatigability test were expressed relative to gas exchange thresholds to assess relative exercise intensity.
The fatigued group had a more pronounced reduction in maximal voluntary contraction peak force and potentiated twitch force throughout the common stages of the incremental cycling test (main effect of group: P < 0.001, ηp2 = 0.18 and P = 0.029, ηp2 = 0.06, respectively). EMG was higher during cycling in the fatigued group (main effect of group: P = 0.022, ηp2 = 0.07). Although the relative intensity of cycling was higher in the fatigued group at the final common stage of cycling, this was not the case during the initial two stages, despite the greater impairments in neuromuscular function.
Our results suggest that the rapid impairments in neuromuscular fatigability in people with CRF were primarily due to disturbances at the level of the muscle rather than the central nervous system. This could affect the ability to tolerate daily physical activities.
癌症相关疲劳（CRF）是一种使人虚弱的症状，大约三分之一的癌症治疗后患者会持续数月或数年出现这种症状。在最近的一项研究中，我们发现，治疗后出现 CRF 的患者的神经肌肉疲劳性更大。本二次分析的目的是研究治疗后 CRF 患者神经肌肉疲劳性的病因。
根据疲劳的临床切点，将 96 名已完成癌症治疗的患者分为两组（疲劳组和非疲劳组）。在递增式踏车测试的三个常见阶段评估膝关节伸肌的神经肌肉功能（最大自主收缩峰值力、自主激活、增强的抽搐力和肌电图）。疲劳测试期间的功率输出相对于气体交换阈值表达，以评估相对运动强度。
疲劳组在递增式踏车测试的常见阶段，最大自主收缩峰值力和增强的抽搐力下降更为明显（组间主要效应：P<0.001，ηp2=0.18 和 P=0.029，ηp2=0.06）。疲劳组在踏车过程中的肌电图更高（组间主要效应：P=0.022，ηp2=0.07）。尽管在踏车的最后一个常见阶段，疲劳组的踏车相对强度更高，但在前两个阶段并非如此，尽管神经肌肉功能的损害更大。
我们的研究结果表明，CRF 患者神经肌肉疲劳性的快速损害主要是由于肌肉水平而不是中枢神经系统的紊乱所致。这可能会影响患者耐受日常体力活动的能力。
