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The Informed Parent

Heat Related Sports Illnesses

by Louis P. Theriot, M.D., F.A.A.P.
Published on Aug. 19, 2002
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It was a warm, balmy September night, approaching the middle of the third quarter of a closely contested high school football game. The star wide receiver streaked up the sidelines leaving the defender, who obviously misread the head fake, frozen in space. The receiver was a good ten yards behind any defender. It was sure to be an easy six points. Then, in mid-stride, for no apparent reason, the receiver pulled up lame and fell to the ground grabbing his calf. The ball spiraled past him as the shocked crowd watched it insignificantly hit the ground and bounce around. He had a severe cramp that the trainers immediately tried to stretch out. Within ten minutes the same thing happened again.

Three hours into a local marathon, a twenty-three year old female runner is found at a water station at the 19 mile mark...the proverbial “wall”. She is bent over, hands on her knees. She is having a difficult time maintaining her balance, as if she were intoxicated. Up until the 18 mile point she had an excellent time. But then her stride took a sudden change. Instead of the fluid and effortless pace maintained for the past three hours, all of a sudden she seemed to be awkward and stiff, arms flailing by her side. She stopped at the water station and looked around as if in a daze. The support staff immediately came to her assistance, but she became a bit combative. Her color was ashen and gray, skin was cold and clammy. She complained of a headache and reported being dizzy before vomiting numerous times. She was taken to the medical tent with a diagnosis of heat exhaustion.

As summer is coming to an end, once again the fall sports programs will be getting underway. The two-a-day workouts of football’s hell week will be in full swing before classes even begin. Cross-country programs will be stepping up their workouts to get an edge on the competition. 5-K’s, 10-K’s and marathons will be more numerous. And one can anticipate an increased number of heat related illnesses as a result.

Heat related illnesses can be divided into three major categories: 1) muscle cramps 2) heat exhaustion and 3) heat stroke. Muscle cramps are the most benign heat syndrome. They are characterized by severe and painful spasms of the voluntary muscles usually during or after strenuous exercise. They tend to occur primarily in individuals who are in good physical shape, and respond quite well to re-hydration and stretching.

Heat exhaustion, or heat prostration, is by far the most common of the heat related syndromes. The symptoms include weakness, dizziness, nausea, headache, vomiting, and even collapse. The onset is usually very sudden, and the period of collapse is brief. The patient is ashen-gray in color, and the skin is cold and clammy. The pupils may be dilated, and the core temperature may be normal or low.

Heat stroke, or sunstroke, is the most severe form of heat syndrome that can even be fatal. High humidity seems to be implicated in the genesis of heat stroke, far more than actual direct exposure to the sun. Patients who suffer a heat stroke usually have stopped sweating before the actual onset of symptoms which include headache, vertigo, faintness, confusion, loss of consciousness, delirium and shock. The skin is hot and dry, the muscles are flaccid and the tendon reflexes are absent. The rectal temperature can be as high as 106 degrees, and internal body temperatures as high as 112 degrees have been reported. Heat stroke is a medical emergency.

There have been an increased number of heat related deaths reported in the recent years, some of which have gained wide publicity because they have involved professional athletes. Five high school football players died of heat stroke in the United States in 1995...three college football players died in 2001...in 1997, three collegiate and one high school wrestler died from heat related illnesses. Heat stroke is the third most common cause of exercise related death in high school sports. It follows head injuries and heart disorders. No one is certain why there is an increased number of cases recently, but some authors feel that the increased use of steroids, ephedrine and nutritional supplements may play a role in this.

The pediatric athlete is more susceptible to heat related problems with exercise for a number of reasons. Children produce more heat relative to body mass for the same amount of exertion when compared to an adult. Children are less able to dissipate heat. One of the factors for this is that they have less lung volume which is an important way to increase the evaporative losses of heat. Relatively speaking, children sweat less than larger individuals. They tend to develop higher body temperatures with the same amount of dehydration when compared to adults. Children have a slower rate of heat acclimatization than adults.

The act of muscle contraction is a very inefficient process. When energy sources are converted to muscle activity, only around 20-25% of the energy is used for work...the remaining 75 - 80% is converted to heat that must be dissipated by the body. The best way for this to occur is through sweating which causes an evaporative loss of heat. When a person becomes dehydrated, there is a loss of circulating blood volume in the blood vessels. To insure that the blood continues to flow to the vital organs of the body, the blood vessels constrict and blood is shunted away from the muscles and sweat glands which results in a decrease in sweat production in the face of an increasing body temperature. This is why proper hydration is critical before any exercise.

Thirst is a poor indicator of dehydration, as one needs to be around 3% dehydrated before the sense of being thirsty kicks in. As a result, when an athlete “feels thirsty” it is already too late. It is critical for an athlete to hydrate BEFORE an event. The fluid should contain sodium rather than just plain water, and most of the commercially available sports drinks are excellent. Plain water is adequate for events lasting less than an hour, but for sporting events that will last beyond this, the hydrating solution should contain 4 - 8% glucose, sodium and potassium.

A good rule of thumb for athletes is drink 1/2 liter (approximately 16 ounces) of fluid two hours before the event. This will allow for hydration as well as excretion. Then drink 300 ml (10 ounces) of fluid twenty minutes before the event. This should keep one properly hydrated going into an event. It is still critical for the athlete to drink regularly DURING the game or event.

Sports medicine has come a long way from the 60’s and 70’s when water was forbidden during football practice...”only sissies drank water”. Those were the days when, if a player was caught “cheating” by sneaking a drink, the whole team was punished by making them all run laps. Those were the days when each locker room had an industrial sized bin full of orange salt tablets by the door leading to the football field. Each player was expected to take two before heading out to practice.

Yet, during those times, there weren’t reports of heat related sudden deaths like there are today. Is it merely that the incidents occurred in the same number, but were not sensationalized as they are today? Or, are there in fact MORE today, and if so, why? This needs to be looked into, as does the role of steroids, ephedrine and supplements such as creatine. It seems odd that during the 60’s and 70’s, when everything was done wrong in high schools across the country by today’s standards, no one seemed to hear about this problem.




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