title: Upright LBPP application attenuates elevated postexercise resting thresholds for cutaneous vasodilation and sweating.
abstract: We evaluated postexercise venous pooling as a factor leading to previously reported increases in the postexercise esophageal temperature threshold for cutaneous vasodilation (ThVD) and sweating (ThSW). Six subjects were randomly exposed to lower body positive pressure (LBPP) and to no LBPP after an exercise and no-exercise treatment protocol. The exercise treatment consisted of 15 min of upright cycling at 65% of peak oxygen consumption, and the no-exercise treatment consisted of 15 min upright seated rest. Immediately after either treatment, subjects donned a liquid-conditioned suit used to regulate mean skin temperature and then were positioned within an upright LBPP chamber. The suit was first perfused with 20 degrees C water to control and stabilize skin and core temperature before whole body heating. Subsequently the skin was heated ( approximately 4.0 degrees C/h) until cutaneous vasodilation and sweating occurred. Forearm skin blood flow and arterial blood pressure were measured noninvasively and were used to calculate cutaneous vascular conductance during whole body heating. Sweat rate response was estimated from a 5.0-cm2 ventilated capsule placed on the upper back. Postexercise ThVD and ThSW were both significantly elevated (0.27 +/- 0.04 degrees C and 0.25 +/- 0.04 degrees C, respectively) compared with the no-exercise trial without LBPP (P < 0.05). However, the postexercise increases in both ThVD and ThSW were reversed with the application of LBPP. Our results support the hypothesis that the postexercise warm thermal responses of cutaneous vasodilation and sweating are attenuated by baroreceptor modulation via lower body venous pooling.
authors.affiliation: University of Ottawa, Faculty of Health Sciences, School of Human Kinetics, Human Performance and Environmental Medicine Research Laboratory, Ottawa, Ontario, Canada K1N 6N5.
authors.forename: Dwayne N
authors.initials: DN
authors.lastname: Jackson
authors.forename: Glen P
authors.initials: GP
authors.lastname: Kenny
mesh_terms: D000328:Adult; D001794:Blood Pressure / Q000502:physiology; D001831:Body Temperature / Q000502:physiology; D004947:Esophagus / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008297:Male; D010101:Oxygen Consumption / Q000502:physiology; D011187:Posture / Q000502:physiology; D011312:Pressure; D012018:Reflex / Q000502:physiology; D012867:Skin / Q000098:blood supply*; D013546:Sweating / Q000502:physiology*; D014664:Vasodilation / Q000502:physiology*