A new twist on the cardiac response to physiological stress in humans

耐力训练是在运动条件下增强心脏功能的一种行之有效的方法。然而，出现了一个悖论，这些适应似乎使受过训练的人更容易发展低血压，以应对姿势位置的变化（如迅速站起来）。通过一系列NSERC资助的研究，我们发现这些对生理压力的独特反应（部分）是由于心脏左右两侧之间的相互作用减少。在这项研究中，我们还使用了新的心脏成像工具，以获得对心脏左右两侧功能的前所未有的观察。特别是，我们开始更好地理解心脏左侧扭转和解旋在最佳心脏功能中的重要性。我们推测，在某些情况下（如运动），心脏左侧扭曲和解旋的适应可能是非常有益的;然而，在其他情况下，这些相同的适应可能是有害的，因为血液回流到心脏（如快速站立）。因此，拟议的研究计划将利用一系列新颖的实验设计和方法，以评估在不同的生理应激条件下，心脏左侧的扭转和解旋对心血管功能，血流和有氧运动的影响。这项研究将对训练有素的运动员和易受低血压影响的体位变化的条件（例如，献血，从太空返回）。

Endurance training is a well-established means of enhancing cardiac function during exercise conditions. However, a paradox emerges where these adaptations appear to make endurance-trained individuals more susceptible to developing low blood pressure in response to a change in postural position (such as standing up quickly). Through a series of NSERC-funded studies we revealed that these unique responses to physiological stressors are (in part) due to a reduced interaction between the right and left sides of the heart. During this research we also made use of new cardiac imaging tools to gain an unprecedented view into the function of the right and left sides of the heart. In particular we are beginning to gain a greater understanding of the importance of the twisting and untwisting of the left side of the heart in optimal cardiac function. We have speculated that adaptations in the twisting and untwisting of the left side of the heart may be of great benefit during certain conditions (such as exercise); however these same adaptations may be detrimental under other conditions where there are sudden reductions in blood returning to the heart (such as standing up quickly). Accordingly, the proposed research program will utilize a series of novel experimental designs and methodologies to evaluate the effects of the twisting and untwisting of the left side of the heart on cardiovascular function, blood flow, and aerobic performance during diverse conditions of physiological stress. This research will have important implications for highly trained athletes and conditions that are susceptible to low blood pressure with changes in postural position (e.g., blood donation, returning from space).