By Gerald Cleveland, M.A.

If it’s not the heat, it’s the humidity. Together they are a one-two punch that can send even the most dedicated fitness buff in Southeast Texas running for cover. However, your exercise plans don’t have to go down for the count just because of the weather. 

According to fitness experts, you don’t have to forgo exercise or the beautiful outdoors. You just have to exercise caution — heat stroke is not part of a sensible fitness regimen.

It’s good to know the basic guidelines if you want to be active outside. A great place to start is with the heat index.

Developed by the National Weather Service as a guide, it’s kind of the reverse of the wind chill temperature used up north. The heat index links air temperature and relative humidity, giving you a more accurate idea of what the temperature actually feels like and its impact on your body.

For example, an air temperature of 90 degrees and relative humidity of 90 percent give a heat index of 122 degrees, which, if you’re exposed to it for extended periods, can lead to heat cramps, exhaustion and stroke.

That’s when one should consider exercising in the gym or at home, with the A/C cranked up. Wait for the heat index to go below 90 degrees before taking your fitness routine outdoors, and keep the following guidelines in mind:

• Wear loose, lightweight clothing that facilitates sweat evaporation
• Early morning and later evening may be cooler times to exercise outdoors.
• Know the effects of any medication you take. For example, antihistamines may decrease sweating. That means your allergy or cold medicine could make you more prone to dehydration and overheating
• Drink fluids. Thirst is an unreliable indicator of hydration levels — a 1 percent loss in body weight due to loss of fluids causes an elevation in core body temperature
• Fluid and salt replacement — most experts agree two quarts (eight 8-ounce glasses) of non-alcoholic liquid are recommended for an average non-exercising person per day. As activity levels increase, two to four glasses per hour of fluid should be consumed
• Your body absorbs fluid the best when consuming cool fluids frequently and in smaller amounts. Adding a small volume of a sports drink or even a pinch of sugar or salt will also increase absorption

Physical activity in hot and humid climates is possible, you just need to use caution and listen to your body. Watch the heat index, stay hydrated and wear sunscreen.

If all else fails, you can pop those Tae Bo tapes into the VCR and discover the joys of an air-conditioned workout.

Gerald Cleveland is director of health promotion and associate faculty within Preventive Medicine and Community Health at the University of Texas Medical Branch at Galveston.

The Your Health column is written by health and medical experts at the University of Texas Medical Branch at Galveston. The column focuses on topical health issues that we believe are of interest to your readers. It is e-mailed every Tuesday. If you have any questions about the column, or would like to suggest topics, please contact John Koloen, media relations specialist, at (409) 772-8790 or email

Heat Index