It's summertime and you head out for a run. Before you even finish the first mile, your body feels as though it might ignite from the heat. It's not your imagination. Fifteen minutes into your run and your body temperature could be as high as 5 degrees F above normal. If you were to continue at this pace, fatigue and heat illness would no doubt take over.

The above scenario doesn't have to happen. Drinking enough fluid, whether it be water or a sports drink, is imperative for exercising in hot or humid weather. Maintenance of body fluids is essential to maintaining proper body temperature. Sweat dispels heat through your skin. The harder and longer you exercise in the heat, the more fluid you lose through sweat. If you let your body become dehydrated, you'll find it much more difficult to perform even the lightest of workouts. But don't wait until you're thirsty to start, replenishing those fluids. Chances are, by the time you actually feel thirsty, your body is well on its way to becoming severely dehydrated.

The following strategies will help you protect yourself from the onset of heat illness:

Fluid replenishment before, during and after exercise is essential to avoid progressive dehydration. Always consume more fluids than you think you need before and after exercise, and strive to drink six to eight ounces of fluid every 15 to 20 minutes during exercise.

Physical training and heat acclimation can increase your blood volume, helping to regulate body temperature more effectively. Interestingly, the acclimatization process can be completed in 7 to 14 days of repeated heat exposure. However, you must continue to drink fluids before, during and after this acclimatization process.

You should probably reduce the intensity of your workout, particularly the first few times you are exposed to higher temperatures.

Wear minimal clothing to provide greater shin surface area for heat dissipation. Your clothing should be lightweight, loose fitting, light colored to reflect the sun's rays, and of a material that absorbs water, such as cotton.

Exercise caution-- when the mercury rises above 85 degrees F, you may want to consider postponing your exercise session until later in the day. Or, plan ahead, and beat the day's heat by working out early in the morning.

Know when to say "no" to exercise. Using common sense is your best bet for preventing heat stress when Mother Nature turns up the heat. Inadequate sleep, food or fluids will make exercising in any conditions, let alone extreme temperatures, difficult. Be sure you've had plenty of all three before heading out.