Postexercise hemodynamics and control of heat loss responses following exercise-induced hyperthermia

Title: Postexercise hemodynamics and control of heat loss responses following exercise-induced hyperthermia
Authors: Gagnon, Daniel
Date: 2007
Abstract: Purpose. The purpose of this thesis was to investigate the nonthermoregulatory control of cutaneous vascular conductance (CVC) and sweating during recovery from exercise-induced hyperthermia as well as to determine possible sex-related differences during the recovery period. It was hypothesized that an active and passive recovery would maintain mean arterial pressure (MAP), CVC and sweat rate at higher levels than an inactive recovery and result in a faster rate of esophageal temperature (Tes) decay. It was also hypothesized that changes in MAP, CVC and sweat rate would be sex dependent. Methods. Eighteen participants (9 males, 9 females) were rendered hyperthermic by exercise (i.e. Tes = 39.5°C) and recovered in one of three recovery modalities for 60-min: (1) active, (2) inactive or (3) passive. Tes, CVC, sweat rate, cardiac output, stroke volume, heart rate, total peripheral resistance, and MAP were recorded at baseline and 2, 5, 12, 20 and every 10-min until the end of recovery. Results. Both active and passive recoveries were equally effective in maintaining MAP, CVC and sweat rate at greater levels compared with an inactive recovery (p ≤ 0.05). A significantly lower Tes was subsequently observed during passive recovery at 20-min and for the rest of recovery compared to the active mode (p ≤ 0.05). Sex did not affect any of the measured variables at any time point during any recovery mode, with the exception of sweat rate which was significantly higher in males throughout the recovery period (p ≤ 0.05). Conclusion. We conclude that despite an important thermal drive, nonthermal input remains an important influence in the modulation of postexercise heat loss responses. Further, action of the muscle pump/mechanoreceptors is the main nonthermal determinant in the postexercise modulation of MAP, CVC and sweat rate irrespective of sex.
CollectionTh├Ęses, 1910 - 2010 // Theses, 1910 - 2010
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