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Exercising outside can be one of the great pleasures of summer. But a sweaty body and racing pulse may be signaling more than your performance -- it could be a sign of life-threatening heatstroke.
Heatstroke can strike with scant warning, even after as little as a half hour if you are exercising hard, doctors say. Although drinking plenty of water can help, you can still get heatstroke even if you aren't dehydrated, particularly while exercising. Complicating matters, experts have sharply divergent guidelines on how to treat a person suffering from the condition.
Heatstroke hits when exertion or external heat, or both, overwhelm the body's ability to regulate its temperature. As internal temperatures climb, cells of the body can be damaged -- causing organ failure, brain dysfunction and, potentially, coma or death.
'It's like you are in an oven and your cells are being roasted,' says Douglas J. Casa, a professor of kinesiology at the University of Connecticut and a co-author of the American College of Sports Medicine's guidelines for treating heatstroke.
Athletes are at special risk, and the bulk of heatstroke deaths in high-school and college sports are in football, where heavy gear and sometimes insufficient breaks during practice contribute to overheating, researchers say.
The American College of Sports Medicine advocates cooling athletes first and transporting them to a hospital later. In its 2007 guidelines, the group recommends immersion in a cold or ice-water bath to cool the body as fast as possible. Survival 'comes down to the number of minutes that you are above the critical threshold for cell damage, which is around 105 degrees Fahrenheit,' says Dr. Casa. Most people survive if you can adequately cool them in 30 minutes, he says.
The next best options are dousing with a garden hose, putting the person in a cold shower and applying ice packs to the groin, head and neck, says William Roberts, a professor of family medicine at the University of Minnesota in Minneapolis and a co-author of the 2007 guidelines.
By contrast, the American Heart Association favors slower, gentler cooling of heatstroke victims. The AHA's First Aid guidelines for heatstroke recommend calling 911 and then fanning and sponge-bathing the person, or misting with cool, not cold, water.
'If you use ice water such as plunging into ice cold bath, you may induce shivering, which causes muscles to produce more heat,' says Monica Kleinman, chairman of the AHA's Emergency Cardiac Care committee.
A 2005 article in the British Journal of Sports Medicine reviewed 17 studies on cooling methods used in heatstroke and concluded that the current evidence suggests that ice water is the 'most effective' cooling method.
The article acknowledged methodological flaws with the underlying work that could have skewed the results: Many of the studies either used just one cooling method, or if they did compare one method to another, did not randomly assign patients to a specific group.
Spotting heatstroke as fast as possible is key. In adults, confusion or irrational speech or behavior is often the most obvious sign, Dr. Kleinman says.
Other symptoms can include red, hot and dry skin, rapid strong pulse, throbbing headache, dizziness, nausea and unconsciousness, according to the Centers for Disease Control and Prevention. Sometimes a person stops sweating when heatstroke hits.
Infants and children may exhibit lethargy and reduced interaction with others, says Dr. Kleinman. Context is important -- a half hour in a hot car could be a bigger risk than a day at the beach with good hydration, she adds. 2011-08-19
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