Brain Blood Flow Responses at Rest and During Exercise

Tight regulation of brain blood flow is integral for delivery of oxygen and energy for survival. During childhood, the brain has a twofold higher metabolic requirement, thus requires greater blood flow to match this. Despite this knowledge, brain blood flow responses and the mechanisms of regulation during maturation are largely unknown. Thus, we are trying to understand what happens to blood vessel function and the mechanisms of regulation at rest and during handgrip exercise. This will give us valuable information on brain blood vessel responses, which will help future interventions aimed at improving blood vessel function in youth, for future disease prevention. Utilizing the pubertal transition will provide insights into the influence of sex hormones on brain blood flow regulation. The goal of this cross-sectional observational study is to examine the influence of age and maturation on cerebral blood flow regulation, achieved through exploring the responses to increases in carbon dioxide concentrations, and static handgrip exercise in children (7-10 years), adolescents (12-16 years) and young adults (19-35 years). The main questions the study aims to answer are: * Investigate the brain blood flow responses to increases in carbon dioxide concentrations in children, adolescents and adults. * Investigate brain blood flow responses to handgrip exercise with and without increases in carbon dioxide concentrations in children, adolescents and adults. During all protocols, participants will have their end-tidal gas concentrations measured and/or altered using prospective end-tidal gas targeting using a computer controlled gas blender system in which we have obtained Health Canada approval for.