Remember that extreme heat conditions most commonly affect the very young & the elderly. However, anyone working out in these conditions can become a victim of a heat-related illness. Medications and medical conditions can alter your reaction to excessive heat.
Remember that effects of heat can be cumulative – with temperatures not dropping very much during evening hours, your recovery time to heat stress will be increased.
Symptoms of heat illness include heavy sweating, muscle cramps, weakness, dizziness, nausea, weak but rapid pulse, and headaches. People with these symptoms should find shade, drink water slowly and make sure there is good ventilation.
In the course of a day’s work in the heat, you may produce as much as 2 to 3 gallons of sweat. Because so many heat disorders involve excessive dehydration of the body, it is essential that water intake during the workday be about equal to the amount of sweat produced. Most workers exposed to hot conditions drink less fluids than needed because of an insufficient thirst drive. Therefore, you should not depend on thirst to signal when and how much to drink. Instead, drink 5 to 7 ounces of fluids every 15 to 20 minutes to replenish the necessary fluids in the body. Water and/or sports drinks are preferred. Avoid drinks containing caffeine (caffeine is a diuretic & will cause you to lose more fluids).
If fluids are not replaced soon enough, heat stroke can follow causing extremely high body temperature, red and dry skin, rapid pulse, confusion, brain damage, loss of consciousness and death. To help a person showing severe symptoms, get the victim into shade, call for emergency medical services and start cooling the person immediately with cool water, cool towels or by fanning.