Department of Physiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore, Singapore.
Scand J Med Sci Sports. 2018 Mar;28(3):807-818. doi: 10.1111/sms.13015. Epub 2017 Dec 13.
The central nervous system, specifically the brain, is implicated in the development of exertional fatigue under a hot environment. Diverse neuroimaging techniques have been used to visualize the brain activity during or after exercise. Notably, the use of magnetic resonance imaging (MRI) has become prevalent due to its excellent spatial resolution and versatility. This review evaluates the significance and limitations of various brain MRI techniques in exercise studies-brain volumetric analysis, functional MRI, functional connectivity MRI, and arterial spin labeling. The review aims to provide a summary on the neural basis of exertional fatigue and proposes future directions for brain MRI studies. A systematic literature search was performed where a total of thirty-seven brain MRI studies associated with exercise, fatigue, or related physiological factors were reviewed. The findings suggest that with moderate dehydration, there is a decrease in total brain volume accompanied with expansion of ventricular volume. With exercise fatigue, there is increased activation of sensorimotor and cognitive brain areas, increased thalamo-insular activation and decreased interhemispheric connectivity in motor cortex. Under passive hyperthermia, there are regional changes in cerebral perfusion, a reduction in local connectivity in functional brain networks and an impairment to executive function. Current literature suggests that the brain structure and function are influenced by exercise, fatigue, and related physiological perturbations. However, there is still a dearth of knowledge and it is hoped that through understanding of MRI advantages and limitations, future studies will shed light on the central origin of exertional fatigue in the heat.
中枢神经系统，特别是大脑，与在热环境下进行体力活动时产生的疲劳发展有关。多种神经影像学技术已被用于可视化运动过程中和运动后的大脑活动。值得注意的是，由于磁共振成像（MRI）具有出色的空间分辨率和多功能性，因此它的应用变得越来越普遍。本综述评估了各种脑 MRI 技术在运动研究中的意义和局限性——脑容积分析、功能 MRI、功能连接 MRI 和动脉自旋标记。该综述旨在提供关于体力疲劳的神经基础的概述，并为脑 MRI 研究提出未来的方向。进行了系统的文献检索，共综述了 37 项与运动、疲劳或相关生理因素相关的脑 MRI 研究。研究结果表明，在中度脱水的情况下，总脑容量减少，伴随脑室容积扩大。在运动性疲劳时，感觉运动和认知脑区的激活增加，丘脑-岛叶的激活增加，运动皮层的大脑半球间连接减少。在被动性体温升高下，脑灌注区域发生变化，功能脑网络中的局部连接减少，执行功能受损。现有文献表明，大脑结构和功能受运动、疲劳和相关生理干扰的影响。然而，目前知识仍然匮乏，希望通过了解 MRI 的优势和局限性，未来的研究将揭示热环境下体力疲劳的中枢起源。
