As the long, hot days of summer slide into Indian summer, heralding the beginning of a new school year, many sports activities are underway. Baseball is becoming interesting as teams are in the hunt for a spot in the playoffs. The end of summer is full of races for all ages and levels of competence: 5 K’s, half-marathons, full marathons and triathlons. Football teams across the country are conditioning and practicing diligently as the first game is just weeks away. At the high school level, late August marks the beginning of “hell week” which is aptly named because of the “two-a-day” sessions that the football players must endure.
While watching these various endeavors, we’ve all heard reference to heat stroke, getting overheated, or heat exhaustion. It seems as if these terms are used interchangeably. The blue chip running back who has carried the ball 29 times in the game is cramping miserably late in the fourth quarter. The announcer emphatically states, “Well, it’s no wonder he is cramping so. It is 103 degrees on the field and he MUST be suffering from heat exhaustion!” Every summer or fall one reads about a football player who collapses during practice. He is said to have succumbed to heat exhaustion. One may be watching a marathon on TV when in the later stages of the race a runner may be bent over with hands on knees vomiting by the side of the road. The announcer explains that because of the heat and humidity the runner probably has a heat stroke. What is the difference, if any, between these terms that get used so commonly?
The various forms of heat related illness represent a spectrum from the mildest form of heat stress, to heat exhaustion and finally to heat stroke. Heat stress refers to the feeling of discomfort and sluggishness when one exercises in unusually hot conditions. By definition, the body core temperature is NOT elevated, and the only negative effect is that one’s performance may be very well below normal.
Heat Exhaustion is more serious than heat stress. This represents a state of mild dehydration whereby the body core temperature is between 100.4 and 104 degrees. Athletes suffering from heat exhaustion usually are sweating profusely, feeling faint or may have collapsed. They are extremely thirsty but may complain of nausea and could be vomiting. Very likely they may seem dazed or confused and often complain of a headache. Other than being a bit confused, there are not any serious neurological symptoms. This is what differentiates exhaustion from heat stroke.
Heat stroke is a serious medical emergency that carries a 12% mortality rate in adults. By definition, the core temperature in heat stroke exceed 104 degrees. The person is severely dehydrated and the skin may be hot, flushed and dry as sweating has ceased because of the dehydration. The neurological symptoms of dizziness, confusion, disorientation and delirium followed by unconsciousness and shock may rapidly evolve. Heat stroke is a medical emergency. It affects multiple organs such as the brain, intestinal tract, liver, kidneys and bone marrow where the blood products are made. It is known that if the core temperature exceeds 105.8 degrees for longer than a brief time, thermal injury to individual cells in the body takes place. Proteins are broken down and injured cells die and necrose, resulting in an irreversible state. It is also known that the severity of the injury is accumulative. This means that a brief exposure to a very high temperature for a brief time (107.5 degrees) may produce the same harmful effects as one exposed to a lower temperature for a longer period of time.
The treatment of a person suffering from heat stroke involves multiple disciplines and is far beyond the scope of this article. What is of practical importance, however, is the proactive measures one can employ to prevent this from happening. Obviously the coach or person in charge of the practice session must be mindful of the conditions, such as temperature AND relative humidity, and adjust the practice accordingly.
One cannot stress the importance of proper hydration BEFORE the event of practice. If it is particularly hot one may want to drink fluids containing electrolytes in order to replace what is lost in their sweat and not be at risk to suffer electrolyte imbalance (especially low sodium). While there are no guidelines for the pediatric athlete, the recommendations for adults are that they drink 500 ml. (one half a liter) two hours before exercising , followed by drinking 250 ml. every 20 minutes during practice. It is reassuring to watch a high school football practice and have the coach blow the whistle every 20 minutes for a water break. Long gone are the days of salt tablets and two hour practices without water, because “water is for sissies!” It took a while and unfortunately the lesson was learned at a high cost.
While it may seem like a mute point, heat exhaustion and stroke are specific terms that mean very specific things relative to a person’s medical condition. As the symptoms of the heat related illnesses represent a spectrum or continuum from the less serious to life threatening, one must be very precise in the terminology they use to convey information to a member of the medical team.