Cardiovascular Physiology in the Extremes: Mechanisms of Adaptation

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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.