Heat exhaustion is the second in the triad of heat-related injuries, more serious than the muscle spasm contraction known as heat cramps, and less dangerous a condition than heat stroke. All three injuries have a similar causation mechanism.
Each injury is most commonly precipitated by the combined effects of heat and dehydration. Heat exhaustion is physical fatigue that is made more pronounced by the effect of heat on the body. Younger athletes, or athletes less experienced with the effects of heat on their systems, are prone to heat exhaustion. The common symptoms of the heat-related injury are similar to those that accompany muscle cramps: dizziness and a somewhat disoriented affect, nausea and vomiting, and a tendency to faint. Heat exhaustion also tends to elevate the core body temperature to the range of 101°F to 102°F (39°C to 40°C).
In mild cases of heat exhaustion, the symptoms may be alleviated by removing the person from the warm environment, ensuring that he or she rests and consumes fluids for hydration. In more severe cases, it may be necessary to have the person receive medical attention, including treatment such as intravenous fluid replacement, particularly when the person has vomited to a significant degree and the ingested fluids do not stay within the system.
Heat exhaustion can bring down any athlete, irrespective of the level of fitness, experience with hot weather competition, or personal training regimen. Heat-related injuries of all types tend to occur more frequently with athletes that are in lesser degrees of fitness. The key aspect to the prevention of heat exhaustion is proper hydration.
Hydration has a number of components. It is such an important aspect of athletic performance that hydration must be approached through strategy, as opposed to that of an afterthought. Pre-hydration is the period leading up to an event; an athlete can tailor the daily consumption of fluids with the upcoming event in mind. A healthy person will consume approximately 64 oz of fluids daily. An athlete may adjust this consumption as the event approaches. Pre-hydration will also include the fluid consumed on the day of the event prior to competition. Hydration is the process of consuming fluid during the competition, usually either water or sport drinks with specialized electrolyte or carbohydrate elements. Rehydration is the equally important process of returning fluids of the body to their optimal levels.
Hydration goes to the root of the mechanism of how the body keeps itself cool. Heat is generated by the body in every instance of energy production; warm weather and humid conditions make the elimination of heat from the body even more important. The body produces perspiration through the combined functions of the cardiovascular system bringing warm blood from the core of the body to the extremities and the release of fluids. Consequently, the amount of water in the body decreases, along with lesser amounts of electrolytes, which are minerals such as sodium, potassium, and calcium. The combined effect of electrolytic and fluid loss is the cause of muscle cramps. Heat exhaustion is primarily related to fluid loss. The onset of dehydration is a problem for the body that is progressive: as more water is lost, the less efficient is the cardiovascular system, as the fluid loss directly affects the blood volume available to the system. As fluid levels decline, the body cannot produce as much cooling perspiration. Humid weather compounds this problem as the perspiration, once produced, cannot evaporate as readily into the air, leaving the body temperature elevated.
While the most effective preventative of heat exhaustion is water, the intensity and the duration of the exercise will also be a significant factor. Athletes that exceed their own training limits in a competition are vulnerable to heat-related injury. Athletes from temperate climates who compete in warm weather sporting events are particularly vulnerable to heat exhaustion. These individuals must consider a period of acclimatization to bridge the accustomed temperature and humidity to that of the competitive venue.
In some circumstances, the athlete may ingest sufficient quantities of water and yet not combat the effects of heat exhaustion. In such circumstances, the proportion of sodium relative to the volume of water present in the body may fall to a stage in which the body is no longer in equilibrium. In addition to the consequences of heat exhaustion, the body becomes subject to a condition known as hyponatremia, in which the water ingested cannot be used to perform its intended cooling function.
heat ex·haus·tion (also heat pros·tra·tion) • n. a condition caused by prolonged exposure to heat during activity and characterized by weakness, profuse sweating, dizziness, and nausea. Also called heat prostration.