Vascular responsiveness and oxygen transport during exercise in children and adolescents

儿童的自由生活活动是高度零星的，需要近乎瞬时的新陈代谢调整。支持这些运动模式所需的血流快速调整最好从动态反应剖面和动力学来评估。对儿童的研究很少使用动态方法进行运动测试，很少考虑机械途径或性别，而且往往缺乏对关键发育阶段的准确评估。这个研究项目将克服传统方法在研究儿童运动方面的一些局限性，通过对运动开始时脑血流量如何适应新陈代谢的快速变化产生新颖和综合的见解。在目标1中，我们将定义不同强度急性运动的脑血管动力学反应及其与性别、年龄和成熟度的关系。在目标2中，我们将进一步了解青春期早期和晚期女孩、男孩以及成人对急性运动适应的调节机制。最后，在目标3中，我们将确定参与运动训练是否会以发育方式改变脑血管动力学反应，以及性别和训练时间是否重要。总的来说，这个研究项目的长期目标是更好地了解年龄、性别和成熟度如何影响运动中控制脑血流的因素。

Free living movement in the child is highly sporadic, requiring near instantaneous adjustments in metabolism. The rapid adjustment in blood flow needed to support these movement patterns is best assessed from the dynamic response profile and kinetics. Studies in children rarely use dynamic approaches to exercise testing, seldom consider mechanistic pathways or sex and the accurate assessment of key developmental stages is often absent. This research program will overcome some of the limitations of traditional approaches to studying exercise in children by creating novel and integrative insight into how brain blood flow accommodates rapid changes in metabolism at the onset of exercise. In Objective 1, we will define the kinetic cerebrovascular response to acute exercise of varying intensities and the relationship to sex, age, and maturation. In Objective 2, we will develop an understanding of the regulatory mechanisms underpinning adaptations to acute exercise in early-and late-pubertal girls and boys and in adults. Finally, in Objective 3 we will determine whether participation in exercise training alters the cerebrovascular kinetic response in a developmental manner and if sex and duration of training are important. Overall, the long-term objective of this research program is to better understand how age, sex and maturations influence the factors that govern brain blood flow during exercise. SCIENTIFIC APPROACH: Studies conducted to address these objects use cross-sectional, experimental and longitudinal designs with healthy pre-pubertal and pubertal children and adolescents (8-16 years old; 50% boys) and healthy adults (20-25 years old; 50% male). Our experimental approach incorporates exercise protocols designed to systematically alter the metabolic responses in the child and we evaluate brain blood flow responses using non-invasive ultrasounds measures. Importantly we assess biological age using a minimally invasive technique. NOVELTY AND SIGNIFICANCE: This research programme will provide new information about the factors that regulate brain blood flow during the energetic challenges of exercise in the child, how this differs between girls and boys and how this changes as the child ages and matures. The results from these studies will significantly advance our knowledge of the influence growth and have on cerebrovascular function and has the potential to influence current theories of brain blood flow regulation in the child and adolescent. This work will create a better evidence base from which effective intervention can be designed, establishing whether or not exercise training results in adaptations of cerebrovascular function. Importantly the physiologic factors that determine the cerebrovascular response to exercise and the degree to which these can be altered will be key to developing future research investigating impaired cerebrovascular function due to disease or environment.