Dehydration and Exercise – Cerebrovascular Control and Orthostatic Tolerance - Prof. Rickards скачать в хорошем качестве

Dehydration and Exercise – Cerebrovascular Control and Orthostatic Tolerance - Prof. Rickards

Invited Session at ECSS Vienna 2016 "Physical activity and brain vascular function" Dehydration and Exercise – Cerebrovascular Control and Orthostatic Tolerance Rickards, C. University of North Texas Health Science Center Exercise represents a physiological stressor that challenges the maintenance of cerebral blood flow and oxygenation as a result of increased metabolic demand (cerebral and systemic), elevated perfusion pressure (arterial pressure), changes in arterial PO2 and PCO2, dehydration, and heat stress. These interrelated factors play a role in the regulation of cerebral blood flow and oxygenation during exercise, and can also affect subsequent tolerance to orthostasis following the exercise bout, particularly when combined with post-exercise hypotension. In particular, dehydration due to environmental/situational conditions (heat stress, lack of adequate hydration fluids, exercise intensity and duration) or purposeful dehydration (fluid restriction for weight loss) can further exacerbate the exercise-induced impairments in cerebral blood flow regulation, placing the athlete at greater risk of orthostatic intolerance. The modality (aerobic vs. resistance) and duration (endurance vs. sprint) of exercise influences the magnitude of dehydration, the timing and magnitude of cerebral blood flow impairment, and risk of subsequent orthostatic instability. This presentation will explore the independent and combined effects of exercise (aerobic and resistance), dehydration, and heat stress on cerebral blood flow and cerebral oxygen regulation, highlighting recent advances in the examination of cerebral oxygen metabolism, and regional cerebral blood flow responses. The implications of these responses on the risk of orthostatic intolerance will be examined. Knowledge gaps in this field of investigation will be presented, and future research directions will be discussed.