Use caution when exercising in heat of Texas summer

As we move deep into the North Texas summer, you may be pursuing physical fitness or simply enjoying recreational physical activity. In either case, if your exercise takes you outdoors over the next couple of months, you should consider some of the following exercise guidelines.

Avoid exercising in high heat and humidity because "it's not just the heat; it's the humidity!" The higher the humidity, the more difficult it is to evaporate the sweat you have generated; therefore your most important heat-dissipation mechanism is less effective. Instead of evaporating to provide a cooling effect, sweat just drips off of your skin, wasting your body's valuable fluid reserves.

Because of the effect of humidity, we consider both the environmental temperature and the relative humidity in calculating the heat index (how the temperature actually feels). For example, exercising in 80 degrees with 90 percent humidity would be just as challenging as exercising in 85 degrees when the humidity is only 50 percent. These temperature-humidity combinations are actually good upper limits to keep in mind while exercising (and require extreme caution) if you want to minimize heat stress and the risk of heat illness, especially if you're not accustomed to exercising outdoors. Use some caution even when the temperature is 10 degrees lower than these limits.

Be alert to and respect heat illness danger signs. If you sense muscle cramping, lightheadedness, headache, nausea or weakness, you could be dehydrated. Stop the activity and replenish your fluids; if you've developed a cramp, gently stretch and massage the muscle. Do not allow your condition to progress to heat exhaustion, which often includes dizziness and skin that is pale, cool and clammy. People with heat exhaustion require medical treatment. Heat exhaustion can lead to heat stroke, which can be fatal.

Acclimate your body to the heat. Over a period of approximately two weeks, gradually increase the time you spend exercising outdoors. If you have already been training indoors, this may take less time.

Maintain a high fluid intake to sustain your sweating capacity. Without getting bloated, drink as much water or diluted sports drink as you can about a half hour before exercise and also immediately after exercise. During exercise, drink a cup of water or sports drink (8 ounces) every 10 to 15 minutes. Don't wait until you feel thirsty. Also, avoid caffeine and alcohol because they are diuretics and can cause you to lose body fluids more rapidly.

Select light-colored, lightweight clothing. Expose plenty of skin for better evaporation, but do not forget to use sunblock. Wet your shirt and exposed skin surface, contributing external fluid to the cooling process to save your body fluid.

For those of us who enjoy the outdoors and want to do it safely, these exercise precautions are worth following.

L. Perry Koziris (koziris@coefs.coe.unt.edu) is an assistant professor of kinesiology, health promotion and recreation.

Other featured articles in this issue:

• Craft named to Board of Regents
• System Center expansion adds rooms, technology
• UNT impact expected to reach $1 billion
• Recent System Center donations exceed $1 million
• UNT recognized for fund-raising efforts
• Students select catalog design concept
• Conference on access is planned
• Photos document pollution effects
• UNT helps Intel train teachers
• A fond farewell: 1999-2000 retirees
• Chancellor's statement on Dallas City Council action

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