Thermoregulation, pacing and fluid balance during mass participation distance running in a warm and humid environment.

Autor:	Lee, Jason K. W., Nio, Amanda Q. X., Chin Leong Lim, Teo, Eunice Y. N., Byrne, Christopher, Lim, Chin Leong
Předmět:	BODY temperature regulation FEVER HYDRATION BODY fluid disorders PHYSICAL diagnosis OXYGEN RUNNING BASAL metabolism BODY temperature COMPARATIVE studies FATIGUE (Physiology) HEART beat HEAT HUMIDITY RESEARCH methodology MEDICAL cooperation RESEARCH TIME WATER-electrolyte balance (Physiology) EVALUATION research PHYSIOLOGY
Zdroj:	European Journal of Applied Physiology; Jul2010, Vol. 109 Issue 5, p887-898, 12p, 1 Diagram, 3 Charts, 2 Graphs
Abstrakt:	Deep body temperature (T(c)), pacing strategy and fluid balance were investigated during a 21-km road race in a warm and humid environment. Thirty-one males (age 25.3 +/- 3.2 years; maximal oxygen uptake 59.1 +/- 4.2 ml kg(-1) min(-1)) volunteered for this study. Continuous T(c) responses were obtained in 25 runners. Research stations at approximately 3-km intervals permitted accurate assessment of split times and fluid intake. Environmental conditions averaged 26.4 degrees C dry bulb temperature and 81% relative humidity. Peak T(c) was 39.8 +/- 0.5 (38.5-40.7) degrees C with 24 runners achieving T(c) > 39.0 degrees C, 17 runners > or = 39.5 degrees C, and 10 runners > or = 40.0 degrees C. In 12 runners attaining peak T(c) > or = 39.8 degrees C, running speed did not differ significantly when T(c) was below or above this threshold (208 +/- 15 cf. 205 +/- 24 m min(-1); P = 0.532). Running velocity was the main significant predictor variable of T(c) at 21 km (R(2) = 0.42, P < 0.001) and was the main discriminating variable between hyperthermic (T(c) > or = 39.8 degrees C) and normothermic runners (T(c) < 39.8 degrees C) up to 11.8 km. A reverse J-shaped pacing profile characterised by a marked reduction in running speed after 6.9 km and evidence of an end-spurt in 16 runners was observed. Variables relating to fluid balance were not associated with any T(c) parameters or pacing. We conclude that hyperthermia, defined by a deep body temperature greater than 39.5 degrees C, is common in trained individuals undertaking outdoor distance running in environmental heat, without evidence of fatigue or heat illness. [ABSTRACT FROM AUTHOR]
Databáze:	Complementary Index
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