Martial Art Institute

Author Wai-Po Tang, 1997. Webpublish Dec 2001

Thermoregulation

Introduction

Excessive heat stress during practice or competition can have direct result on the athlete's performance and it may even lead to death in extreme cases. Basically, when heat gain exceeds heat loss during intensive exercise in warm environment, the core temperature rises. Whereas, in a cold environment, the heat loss often exceeds heat production thus lead to reduced core temperature.

Thermal balance to maintain normal core temperature of 37°C depends on the regulatory factors of heat gain and heat loss. Heat gain is affected by Basal Metabolic rate, muscular activity, hormones, thermic effect of food, postural changes, and environment. Heat loss is affected by the physical mechanisms of radiation, conduction, convection and especially vaporisation of water from skin and the respiratory passages.

Exercise create metabolic heat and disrupt the homeostasis of the body due to the blood flow needed for the skin and the muscles. The muscles require blood flow for oxygen supply and the skin demands blood flow for heat dissipation.

Amussen, E. and Boje, O. (1945) stated that, "Research on the relationship between the rise in body temperature and exercise capacity has produced conflicting results." The argument is that increased core and muscle temperature signals a failing thermoregulatory mechanism that reduces exercise performance. However, other researchers argued that temperature increases might accelerate neuromuscular processes and thus increase exercise capacity.

Purpose
A subject is put under two conditions of free heat loss and restricted heat loss on separate days over a period of two weeks to provide data of thermoregulatory analysis. The data of the subject will be examined to determine the effects of heart rate, core temperature and effort. Thus, the results offer the opportunity to review or argue the theses and the hypotheses as mentioned above.