Preventing heat illness in athletes.

Although not generally appreciated, heatstroke is the third leading cause of death in athletes. (1) Fortunately, in the past few years there has been an increase in the awareness of heat-related illnesses in both the medical community and the population in general. This is likely due to the heat wave that swept Europe in the summer of 2003, as well as the recent high profile heat-related deaths of professional and collegiate athletes.

The tragedy regarding heatstroke, particularly in athletes, is that it is preventable. Contributing to this problem is the fact that to date, there is no valid or reliable method to predict which athletes are at risk for heat illness, including heatstroke.

In this issue of the Southern Medical Journal, a team of researchers report preliminary findings of a prospective observational pilot study entitled "Heat Illness Symptom Index (HISI): A Novel Instrument for the Assessment of Heat Illness in Athletes." (2) This scale is designed to alert health care personnel (physicians and certified athletic trainers) to athletes who may be at risk for heat illness, including heatstroke, so that early interventions may be undertaken to avert catastrophe.

The mechanism behind heat related-illness is the body's inability to disperse heat produced by metabolic activity, most often in relation to an increase in the ambient temperature. Athletes, particularly those competing in collision sports that are required to wear heat-trapping protective gear, are at particular risk. However, it is important to understand that even athletes without such heat-trapping equipment may also be at risk. For example, marathoners have developed core temperatures as high as 105.8[degrees]F while running in 77[degrees]F weather. (3) The "take home message" is that the prevention of heat illness requires vigilance in all athletes regardless of activity.

A number of factors may place an athlete at increased risk for heat illness. (4) This includes the use of antihistamines and decongestants (common in the spring and summer), alcohol consumption, dehydration, and obesity (mainly seen in lineman who play football). Modification of these and other risk factors is essential in minimizing the risk of heat illness. The missing piece, however, is the ability to monitor athletes and detect subtle changes in physiology so that interventions may be made proactively to prevent mild forms of heat illness from progressing to heatstroke. The HISI scale provides a good foundation in addressing this possibility.

It is already understood that dehydration is a major risk factor in developing heat illness. The body's main mechanism of thermoregulation is the evaporation of sweat during exercise, and is the primary thermoregulatory mechanism when ambient temperature is greater than 68[degrees]F. (5) The HISI scale has been validated for correlation to: 1) weight loss during the practice session; 2) percent of body weight lost during the practice; 3) weight loss relative to the athlete's baseline weight; 4) percent body weight lost relative to the athlete's baseline weight; 5) the athlete's perceived physical exertion during the practice, and 5) the environmental heat index. All of these parameters are directly related to hydration status.

The ability to assess an athlete's risk based on reported symptoms (HISI) in relation to hydration status will be invaluable in reducing the risk athletes face for heat illness. It will be an important tool for those responsible for the care of the athlete. This preliminary report of a novel method for detecting athletes at risk for heat illness is a good start toward achieving that goal.

References

1. Lee-Chiong TL Jr, Stitt JT. Heatstroke and other related illnesses: the maladies of summer. Postgrad Med 1995;98:26-36.

2. Coris E, Walz S, Duncanson R, et al. Heat Illness Symptom Index (HISI): a novel instrument for the assessment of heat illness in athletes. South Med J 2006;99:340-345.

3. Pugh LG, Corbett JL, Johnson RH. Rectal temperatures, weight losses, and sweat rates in marathon running. J Appl Physiol 1967;23:347-352.

4. Mellion M, Shelton G. Thermoregulation, heat illness, and safe exercise in heat. In: Mellion M, ed. Office Sports Medicine. Philadelphia, PA, Mosby, 1998, pp 45-47.

5. Luke A, Micheli L. Sports injuries: emergency assessment and field-side care. Pediatr Rev 1999;20:291-301.

Randy Wexler, MD, MPH, FAAFP 

From the Department of Clinical Family Medicine, The Ohio State University, Columbus, OH.

Reprint requests to Randy Wexler, MD, MPH, FAAFP, Assistant Professor of Clinical Family Medicine, The Ohio State University, B0902B Cramblett Hall, 456 West 10th Avenue, Columbus, OH 43210. Email: [e-mail]

Accepted January 12, 2006.