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° F above normal. If you were to continue at this pace, fatigue and heat illness would no doubt take over.
Strategies to Protect Yourself From Heat Illness
The above scenario doesn’t have to happen. Drinking enough fluid, whether 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 cools your body by evaporating off your skin. Visible beads of sweat that don’t evaporate only dehydrate you without the beneficial cooling effect. 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 strive to drink 7 to 10 ounces of fluid every 15 to 20 minutes during exercise. Water isn’t the only thing your body loses in sweat. Electrolytes such as sodium, potassium and chloride are also lost in sweat. It is equally important to replace these with a sports drink during continuous exercise lasting longer than one or two hours.
2. Exercise Intensity
You should probably reduce the intensity of your workout, particularly the first few times you are exposed to higher temperatures.
High humidity prevents sweat from evaporating, and remember that sweat that does not evaporate does not cool the body. Use the heat stress index to determine the risk of exercising at various combinations of temperature and humidity. While a 90° F outdoor temperature is relatively safe at 10% humidity, the heat stress of 90° F at 50% humidity is the equivalent of 96° F. When the heat stress index rises above 90° 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.
4. Heat Stress Index
When you go outside to exercise, refer to the heat stress index and consider the associated risks:
- Below 80° F (27° C): Little or no danger under normal circumstances
- 80–90° F (27–32° C): Fatigue possible with prolonged exposure
- 90–105° F (32–41° C): Heat cramps and heat exhaustion are possible
- 105–130° F (41–54° C): Heat cramps and heat exhaustion likely, heatstroke is
- Over 130° F (54° C): Heatstroke is imminent
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 seven to 14 days of repeated heat exposure. However, you must always continue to drink fluids before, during and after exercise.
Wear minimal clothing to provide a greater skin surface area for heat dissipation. Your clothing should be lightweight, loose-fitting, light-colored to reflect the sun’s rays and of a fabric that absorbs water, such as cotton or other moisture wicking material.
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.