Exercise Physiology: Theory and Application to Fitness and Performance 9th Edition by Scott Powers, Edward Howley

Exercise 9

What is the heat stress index, and why is the wet bulb temperature weighed so heavily in the formula?

Step 1 of 3

The heat stress index is a quantitative measure of overall heat stress associated with any environment. The index includes measurement of temperature and relative humidity which are the important contributing factors for risk of heat injuries. For quantification of heat stress, the Wet Bulb Globe Temperature (WBGT) guide was developed. The heat stress index includes measurement of the following:

• Dry bulb temperature - temperature of air is measured in the shade

• Black globe temperature - In this, radiant heat is measured under direct sunlight

• Wet bulb temperature - In this method, the mercury bulb of thermometer is covered with wet cotton and air temperature is measured. Since the evaporation of water on the cotton wick depends on relative humidity of the air, this method gives an idea on the ability to evaporate sweat