What You Should Know About Heat Illness and Exercise

When considering the degree of risk involved for heat related illness during exercise, special attention must be paid to not just the temperature, but rather ambient temperature, which also takes into account the degree of humidity.

The best method of determining ambient temperature is the use of Wet Bulb Globe Temperature (WBGT). Although recommendations differ depending upon which source is used, on average, any day that the WBGT is above 82 degrees Fahrenheit should be considered high risk and outdoor exercise should be avoided or at least modified to limit risk of injury.

Training should follow the same regimen as in any other form of athletic preparation. The length and intensity of each exercise bout should be increased on a gradual basis with proper time being allowed for recovery. On days with higher ambient temperatures lower intensity and shorter duration events should be planned. During these high risk days it is necessary to take multiple breaks (preferably in a shaded area) from exercise.

Proper hydration is of utmost importance as research has shown that as little as 2 percent of body weight loss during exercise can predispose an athlete to exertional heat illness. Core body temperatures have shown to rise .25 to .35 degrees Fahrenheit for every percent of body weight loss during exercise.
Since hydration needs are individualized and vary from one athlete to another, steps need to be taken to determine how an athlete must hydrate in order to avoid the risk of heat related illness. It must be kept in mind that dehydration can occur in a single bout of exercise or accumulatively over several days.

One method to measure hydration needs is pre- and post-exercise weighing. For every pound lost during exercise, the athlete should have consumed 16 to 20 ounces of fluids. This may equate to drinking approximately 8 ounces of fluids every 20 minutes. The fluids taken should generally consist of a 50/50 mix of water and sports drinks. Additional electrolyte replenishment may be necessary in higher temperatures.

Furthermore, an athlete must begin to hydrate for an exercise bout in higher temperature two to three days prior to the event. An easy method of self-regulating proper hydration is checking the color of one's urine during exercise days. It should normally be a very light yellow color. If darker, it could indicate possible dehydration.

Management of heat illness follows some basic rules that apply to almost all levels of this injury. Keep in mind that heat stroke is a true medical emergency and the athlete must be treated by medical staff. Heat cramps can be the easiest to manage. Once activity ceases, the cramps will generally subside. As for heat syncope and heat exhaustion, the athlete should be moved to a cool shaded area. Wet clothing should be replaced by dry ones. Ice packs can be placed on the forehead and under the armpits to help decrease body temperature. Both these stages may and often do require intravenous hydration. Vital signs should continuously be monitored paying special attention to body temperature, heart rate and blood pressure.

Following these tips can help prevent very serious and possibly fatal injuries which can result from exercising in high temperatures.

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Dr. Hamid Sadri is a sport chiropractor from Atlanta, Georgia, with over 24 years of experience. He holds certifications from the American Chiropractic Board of Sports Physicians, National Academy of Sports Medicine, National Strength & Conditioning Association, Graston Technique and Active Release Techniques. He has worked with national and international athletes of all levels and was selected as one of America's Top Chiropractors by the Consumer's Research Council. Contact:

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