Physiological mechanisms underlying real-world dynamic cardiorespiratory and cerebrovascular control

点击翻译按钮获取中文摘要

For 40 years, my NSERC-supported research program has contributed to the training of exceptional HQP through exploring the complex dynamic physiological adaptations of the cardiorespiratory and cerebrovascular systems to challenges typical of daily life. Three major inter-related themes with 7 hypotheses provide details on our work for the next five years. Theme 1, involving PhD students, post-docs and undergraduate students, will extend recent work using wearable sensors and machine learning to predict the time course of change of aerobic metabolism during transitions in exercise intensity and during activities of daily living. We will extend the research to test the hypothesis (1.1) that these methods will extract indicators of aerobic system dynamics from higher intensities of exercise that require complex considerations of nonlinear system dynamics. These new models will have application to high intensity exercise such as athletic training, and to studies of astronauts. We have confirmed access to 8 astronauts over the next 5 years while they are wearing a Canadian-designed smart shirt allowing us to test the hypothesis (1.2) that our new methods of analysis will be sensitive to changes in fitness with spaceflight and recovery. Theme 2 experiments involving post-docs and training senior undergraduates will develop and apply coded hemodynamic imaging, a wide-field camera assessment of infrared signals from humans. This system monitors vascular pulsatility without contact of the skin surface. We will test the following hypotheses. (2.1) That we can track changes in central venous pressure and its pulsatility induced by changes in body position and central blood volume. (2.2) That arrival time of arterial pulsations at different locations on the body can provide a non-contact method to assess arterial stiffness. (2.3) That changes in regional tissue oxygenation measured without skin contact will track traditional near infrared spectroscopy during manipulations of muscle O2 delivery. Theme 3 experiments involving MSc students, post-docs and undergraduate students, will determine regulatory factors affecting arterial and cerebrovascular hemodynamics. We will test the hypothesis (3.1) that rapid drops in cerebral perfusion pressure will identify the point of zero flow coinciding with the theoretical construct known as critical closing pressure for the cerebral circulation under conditions that vary cerebral flow by changing arterial PCO2. Changes in arterial stiffness affect cerebrovascular pulsatility. We will test the hypothesis (3.2) that central artery stiffness is unaffected, but peripheral arteries will appear stiffer during acute interventions affecting neural control of the vascular system. These experiments provide outstanding opportunities to train HQP in an interdisciplinary environment linking key physiological questions to technological innovations.