Cardiovascular Physiology in the Extremes: Mechanisms of Adaptation

问题陈述*耐力训练是一种公认的增强心血管功能的方法。一般认为，体力活动/锻炼与心血管功能之间存在剂量-反应关系，因此更多的活动/锻炼会带来更大的益处。然而，这些信息通常不考虑身体活动连续体的极端情况(例如，超耐力运动员)。关于常规参加大运动量运动对心血管功能的影响以及对运动成绩和日常生活活动的影响，信息相对有限。最近的研究(包括我们自己的研究)挑战了“运动越多越好”这一广为流传的公理。我们已经证明，极端的体力活动参与可能会使耐力运动员容易出现一系列适应不良，使他们容易出现运动后低血压、立位不耐受和表现不佳。因此，提出的研究计划将进一步探索极限运动参与对心血管功能的影响。我们假设有一个增强心血管功能的最佳水平，超过这个水平就会有递减的回报。*方法*我们将采用机械方法研究高强度运动对心血管功能的急性和长期影响，以及对健康成年人立位耐力和运动后低血压的影响。拟议的研究计划将涉及一系列调查，以检查健康的未经训练的个人、受过耐力训练的运动员、从事对身体要求很高的职业的工人，以及从事长期剧烈运动的个人(不同健康水平)的心血管功能。我们将利用先进的技术和方法(如心电图、质谱仪、超声、血管顺应性、神经血管偶联和认知)和方法来探索大运动量对心脑血管和认知功能的急性和长期影响。*研究结果的意义和新颖性*本研究计划将有助于阐明大运动量对健康成年人的心血管、脑血管和认知功能的影响。这项研究将对最佳运动表现和预防(或治疗)立位不耐受和运动后低血压具有重要意义。

STATEMENT OF THE PROBLEM***Endurance training is a well-established means of enhancing cardiovascular function. Generally, there is thought to be a dose-response relationship between physical activity/exercise and cardiovascular function such that more activity/exercise leads to greater benefits. However, this information generally does not consider the extremes of the physical activity continuum (e.g., ultra-endurance athletes). Relatively limited information exists regarding the effects of routine participation in high volumes of exercise on cardiovascular function and the implications for sport performance and activities of daily living. Recent work (including that of our own) has challenged the widely held axiom that "more physical activity is better." We have demonstrated that extremes of physical activity participation may make endurance athletes prone to a series of maladaptations that make them vulnerable to post-exercise hypotension, orthostatic intolerance, and suboptimal performance. Accordingly, the proposed research program will further our exploration of the effects of extreme exercise participation on cardiovascular function. We hypothesize that there is an optimum level for enhancing cardiovascular function, beyond which there are diminishing returns. ******METHODS***We will take a mechanistic approach to examine the acute and long-term effects of high volumes of exercise participation on cardiovascular function and the implications for orthostatic (in)tolerance and post-exercise hypotension in healthy adults. The proposed research program will involve a series of investigations that examine cardiovascular function in healthy untrained individuals, endurance-trained athletes, workers from physically demanding occupations, and individuals (of varying fitness levels) that engage in prolonged strenuous exercise. We will utilize advanced technologies (such as electrocardiography, mass spectrometry, ultrasonography, vascular compliance, neurovascular coupling, and cognition) and methodologies to explore the acute and long-term effects of high volumes of exercise on cardiovascular, cerebrovascular, and cognitive function. ******SIGNIFICANCE AND NOVELTY OF FINDINGS***This research program will help elucidate the effects of high volumes of exercise on cardiovascular, cerebrovascular, and cognitive function in healthy adults. This research will have important implications for optimal exercise performance and the prevention (or treatment) of orthostatic intolerance and post-exercise hypotension.