Role of the Cardiovascular System and the Brain in Determining Individual Tolerance to Exercise

个人对运动的感觉有多轻松可以决定他们是否愿意参加体育活动(对运动的耐受性)。体力活动是加拿大人生活质量的重要组成部分。因此，了解是什么对个人的运动耐量做出贡献是很重要的。众所周知，当一个人在氧气含量减少的环境中锻炼时，比如在高原，锻炼感觉更困难。这是因为在运动过程中提供给肌肉的氧气供应可以决定肌肉功能的好坏。这种供应依赖于锻炼肌肉内的小血管扩大以允许更多的血液流动，以及心脏增加对身体的血液输出。 目前的观点是，如果你是一个年轻而健康的成年人，在正常的氧气环境中，你的氧气输送与运动肌肉的需求紧密匹配，因此不会决定你的运动耐力。这一观点是基于一项研究，在研究中，一组人的平均反应被用来理解当一个人锻炼时，这种匹配是如何起作用的。然而，在我的实验室里，我们最近发现，在这种匹配下，一个健康的年轻人的心脏和血管反应可能天生就比另一个人更好或更差。不仅如此，这实际上可能是一个原因，为什么一个人觉得一定的运动量比另一个人更难。然而，目前对这一个体差异现象的了解很少。因此，我和我的HQP将追求的这项建议的具体目标是：A)确定运动肌肉血管和心脏对可持续运动的反应存在个体差异，B)证明这些差异与肌肉中的氧气水平密切相关，C)证明它们有助于个人之间的运动耐力差异，D)确定解释这种差异的个人不同机制。 运动感觉有多难(或不难)的另一个可能因素是大脑对运动的感觉。大脑的哪些区域参与了对劳累的知觉，以及如何改变这种知觉，这一研究才真正开始。研究人员面临的一个大问题是，监测大脑活动并确定活动强度和位置的最佳技术(磁共振成像)要求头部保持非常静止。这就要求研究人员在运动后立即观察大脑，而不是在运动过程中。我们正在开发一种可以克服这个问题的锻炼方式。通过这种方法，我和我的HQP将追求这些特定的目标：A)绘制运动过程中与努力感知相关的大脑反应图，以及B)确定当感知到的努力增加或减少时，大脑反应如何变化。

How easy exercise feels for an individual can determine their willingness to participate in physical activity (tolerance for exercise). Being physically active is an important part of quality of life for Canadians. Understanding what contributes to an individual’s exercise tolerance is therefore important to establish. It is known that when a person exercises in environments where there is a reduced amount of oxygen, such as at altitude, exercise feels more difficult. This is explained by the fact that the supply of oxygen provided to muscle during exercise can determine how well the muscle functions. This supply depends on the small blood vessels inside exercising muscle widening to allow more blood flow, and the heart increasing its output of blood to the body. The current view is that if you are a young and healthy adult in normal oxygen environments your oxygen delivery is tightly matched to the demands of the exercising muscles and therefore is not determining your exercise tolerance. This view is based on research studies where the average response of a group is used to understand how this matching works when a person is exercising. However, in my laboratory we have recently discovered that a healthy young individual’s heart and blood vessel response might be inherently better or worse than another's at this matching. Not only that, but this might actually be a reason why one person feels a certain amount of exercise as more difficult than another person. However there is currently a very poor understanding of this individual difference phenomenon. Therefore, the specific objectives of this proposal I and my HQP will pursue are to A) Establish the existence of individual differences in exercising muscle blood vessel and heart responses to sustainable exercise, B) Demonstrate that these differences are closely linked to the oxygen levels in the muscle, C) Demonstrate that they contribute to exercise tolerance differences between individuals, D) Identify what mechanisms are different across individuals that explain this. Another possible contributor to how difficult (or not) exercise feels is how the brain senses the exertion of exercise. Research into which areas of the brain are involved in the perception of exertion and how this perception can be modified is only really beginning. A big problem for researchers has been that the best technique to monitor activity of the brain and identify how much and where this activity is (magnetic resonance imaging (MRI)) requires the head to be very still. This has required researchers to look at the brain immediately after, rather than during, exercise. We are developing a way of exercising that will overcome this problem. With this approach I and my HQP will pursue these specific objectives A) Map the brain responses during exercise that are related to perception of effort and B) Identify how the brain responses change when perceived exertion is made to increase or decrease.