Exercise and vascular adaptation in asymptomatic humans

Beneficial effects of exercise training on the vasculature have been consistently reported in subjects with cardiovascular risk factors or disease, whereas studies in apparently healthy subjects have been less uniform. In this review, we examine evidence pertaining to the impact of exercise training on conduit and resistance vessel function and structure in asymptomatic subjects. Studies of arterial function in vivo have mainly focused on the endothelial nitric oxide dilator system, which has generally been shown to improve following training. Some evidence suggests that the magnitude of benefit depends upon the intensity or volume of training and the relative impact of exercise on upregulation of dilator pathways versus effects of inflammation and/or oxidation. Favourable effects of training on autonomic balance, baroreflex function and brainstem modulation of sympathetic control have been reported, but there is also evidence that basal vasoconstrictor tone increases as a result of training such that improvements in intrinsic vasodilator function and arterial remodelling are counterbalanced at rest. Studies of compliance suggest increases in both the arterial and the venous sides of the circulation, particularly in older subjects. In terms of mechanisms, shear stress appears to be a key signal to improvement in vascular function, whilst increases in pulse pressure and associated haemodynamics during bouts of exercise may transduce vascular adaptation, even in vascular beds which are distant from the active muscle. Different exercise modalities are associated with idiosyncratic patterns of blood flow and shear stress, and this may have some impact on the magnitude of exercise training effects on arterial function and remodelling. Other studies support the theory that that there may be different time course effects of training on specific vasodilator and constrictor pathways. A new era of understanding of the direct impacts of exercise and training on the vasculature is evolving, and future studies will benefit greatly from technological advances which allow direct characterization of arterial function and structure.

在有心血管危险因素或疾病的受试者中，运动训练对血管系统的有益影响一直有报道，而在表面健康的受试者中的研究结果则不太一致。在这篇综述中，我们研究了与运动训练对无症状受试者的传导血管和阻力血管功能及结构的影响相关的证据。体内动脉功能的研究主要集中在内皮一氧化氮扩张系统，一般来说，训练后该系统会得到改善。一些证据表明，益处的大小取决于训练的强度或量，以及运动对扩张途径上调的相对影响与炎症和/或氧化作用的对比。有报道称训练对自主神经平衡、压力反射功能和脑干对交感神经控制的调节有有利影响，但也有证据表明，训练会导致基础血管收缩张力增加，以至于在休息时内在血管扩张功能和动脉重塑的改善相互抵消。顺应性的研究表明，循环的动脉和静脉侧都有增加，特别是在老年受试者中。就机制而言，剪切应力似乎是血管功能改善的关键信号，而运动期间脉压的增加和相关的血流动力学变化可能会引起血管适应，即使是在远离活动肌肉的血管床中也是如此。不同的运动方式与独特的血流和剪切应力模式相关，这可能对运动训练对动脉功能和重塑的影响程度有一定影响。其他研究支持这样一种理论，即训练对特定的血管扩张和收缩途径可能有不同的时间进程影响。一个理解运动和训练对血管系统直接影响的新时代正在发展，未来的研究将极大地受益于能够直接表征动脉功能和结构的技术进步。