Spreading the risk of heat illness
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By JANE E. BRODY The New York Times - Published: September 25, 2005
Football players, while at greatest risk, are not the only ones who can encounter such trouble. Young tennis and soccer players, too, who often play multiple matches in a day in hot weather, can also suffer life-threatening dehydration and heat stress, according to Dr. Michael F. Bergeron, of the Medical College of Georgia in Augusta, a fellow of the American College of Sports Medicine.
The sports medicine group is trying to put an end to unnecessary deaths among young football players. In the August issue of its journal, Medicine & Science in Sports & Exercise — published, unfortunately, a month too late — an expert panel headed by Bergeron published an eight-page advisory on preventing heat stress.
"Mandatory preseason football practices generally begin in the late summer for the fall youth and high school football seasons," the journal stated. "With these physically demanding sessions being held during the hottest and most humid part of the year for many teams, it is no surprise that the high incidence of on-field heat-related problems is considered an expected 'part of the game.'"
The first few days of training, usually late July through early September, are the most dangerous. Many players start out with several problems. They are not used to the uniform, the intensity and duration of practice, and exercising in hot weather. And they get out of shape off season and start preseason training with a fluid deficit that often grows worse with each practice session, Bergeron's studies have shown.
He found that after a two-hour practice players typically lost at least 1 percent of their body weight (two pounds for a 200-pounder, the weight of a liter of water) despite having consumed two liters of water in the session. Typically, the players do not make up for this loss before the next practice session, the research showed.
"Large sweat losses, insufficient fluid intake and consequent fluid deficits could likely impair performance and may increase the risk of hyperthermia and heat injury," the journal reported.
Athletes, especially those less than optimally fit, who overexert themselves, can suffer muscle fiber damage that can be immediately fatal because of excessive potassium buildup in the blood or can lead to life-threatening kidney failure.
Those who are carriers of sickle cell trait, an inherited blood cell gene fairly common among American blacks, face an additional risk of exertional collapse or death from overheating, dehydration, sickling of red blood cells, inflammation and damage to muscles or vital organs.
The risk of heat stress for football players is increased by the need to wear helmets, body guards and uniforms, which increase the workload and impair the body's ability to cool itself.
With a short time to prepare teams, coaches are sometimes tempted to try to accomplish too much too quickly, scheduling practice sessions that are too long and too frequent, regardless of the weather. And players who try to enhance muscle mass by taking the dietary supplement creatine can make matters worse by temporarily shifting body water into muscle cells, depleting fluid around the muscles and increasing the risk of cramping.
Though the journal's suggestions may be late for this year, there is plenty of time to set up new rules and provide adequate training for next year. The preseason should start with a thorough medical exam that includes a review of medications and supplements taken and a check for hidden cardiac disease, sickle cell trait and a history of previous heat-related problems.
Participation in preseason practice should be postponed for athletes with a recent or current illness, vomiting, diarrhea or fever; all of them increase the risk of heat stroke.
And "coaches must accept that environmental conditions" can be "altogether too extreme for safe and effective football activity," the guidelines say. When temperature, humidity and solar radiation are extreme (above 91.5 as measured by the wet-bulb globe temperature index) practice should be canceled or taken indoors.
Athletes should begin each practice "well hydrated, well rested and well nourished and with a normal resting body temperature." Those who are not acclimatized to the heat or who are physically out of shape should start off slower and build up more gradually than others.
Only one practice session a day, with a maximum of 90 minutes of fitness activities, should be done during the first preseason week, and players should not practice more than six days in a row. If two practice sessions a day are done the second week, they should not be scheduled on consecutive days.
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