Exercise duration and thermoregulatory responses following whole
body pre-cooling.
Lee, Dae Taek, Emily M. Haymes.
Exercise Physiology Laboratory, Department of Nutrition, Food, and
Movement Sciences, Florida State University, Tallahassee, FL
32306
APStracts 2:0317A, 1995.
Whole body pre-cooling was hypothesized to reduce thermoregulatory and
metabolic responses, thereby enhancing running time. Fourteen male
runners completed two high-intensity running tests consisting of
resting in either 24 C (normothermic condition; NC) or 5 C
(hypothermic condition; HC) for 30 min followed by 10-16 min rest at
24 C and then an exercise bout (24 C) at 82% VO2max to exhaustion.
Rectal temperature before exercise was lower (by 0.37 C; p <
0.005) and exercise duration was longer (by 121 +/- 24%; p <
0.05) in HC than NC. Rectal (Tre), mean skin (Tsk) and mean body (Tb)
temperatures remained lower during HC exercise (p < 0.01). Pre-
and post-exercise changes for Tsk, Tb, thermal gradient (Tre-Tsk) and
heart rate (HR) were larger in HC than NC (p < 0.05). Final Tre,
Tre-Tsk, HR, and blood lactate were similar between HC and NC. While
exercising, heat storage was greater (p < 0.01) in HC (173 +/-
46 W.m-2) than NC (143 +/- 38 W.m-2) and subjects sweated more in NC
than HC (p < 0.01). Oxygen consumption was lower initially in HC
exercise than NC (p < 0.05) while oxygen pulse was not
different. It was concluded that pre-cooling results in greater
exercise endurance with enhanced heat storage rate and less stress on
metabolic and cardiovascular systems.
Received 2 December 1994; accepted in final form 30 June 1995.
APS Manuscript Number A1231-4.
Article publication pending Journal of Applied Physiology.
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 30 July 1995.