Even here in Vermont, heat-related illness can be a major issue for athletes. Consequences range from decreased performance to death. In fact, heat stroke is the third leading cause of death in athletes after cardiac disorders and cervical spine trauma.
It is important to recognize and treat heat illness before major complications arise. Equally important is learning how to prevent it from happening in the first place.
During any exercise, heat is produced. This occurs mainly in the muscles. The heat that is produced needs to be released from the body, or the body’s temperature will rise. Body heat is mostly released through evaporation. Temperature, wind and especially, humidity, affect the body’s ability to get rid of heat. Clothing also has an effect, as do body mass and amount of body fat. Prolonged, vigorous exercise on a still, hot and humid day is a recipe for heat illness. Lack of adequate hydration only makes the problem worse.
There are multiple forms of heat illness, ranging from minor to severe.
- Heat Edema: This presents as swelling in the legs and improves with simple elevation and rest.
- Heat Syncope “fainting”: This is due to low blood pressure from dehydration. The treatment is lying flat, elevating the legs, and rehydrating.
- Heat Cramps: This is very common during or after exercise. Treatment is rest, stretching, and hydration. Electrolyte (salt) replacement is often recommended.
- Heat Exhaustion: This is a more serious problem. It is characterized by inability to continue exercise. The athlete may or may not collapse. Findings include fatigue, dizziness, heavy sweating, nausea/vomiting, headache, chills, and irritability. Core temperature is less than 104° F. This is most accurately measured by rectal thermometer. Central nervous system changes are not present. Treatment is immediate cessation of activity, transfer to as cool a location as possible, removal of excess clothing, leg elevation, and rehydration. If the athlete’s condition worsens and/or temperature does not decrease with proper treatment, emergency medical attention should be sought.
- Heat Stroke: This is the most serious form of heat illness and can lead to death if not recognized and treated right away. The difference compared to heat exhaustion is that core body temperature is greater than 104° F and central nervous system changes (delirium, convulsions) are present. The skin may be dry or soaked with sweat. Risk factors include obesity, low fitness level, lack of heat acclimatization, dehydration, history of heat illness, loss of sleep, and certain medications like diuretics and stimulants. Heat stroke most commonly happens early in the season during the first few practices and can worsen from day to day. Treatment is rapid whole body cooling, preferable in an ice bath. Water soaked towels and fanning also works, but not as well. Once stable, an athlete suspected or diagnosed with heat stroke should always be taken to an emergency facility.
The key to heat illness is awareness and prevention. Here are recommended ways to prevent heat illness from occurring.
- Acclimatize to the conditions, especially if your fitness level is low. Don’t ride or run aggressively in hot weather if you’re not used to it or not in shape. This process of acclimatization can take 7 to 14 days.
- Maintain good hydration and electrolyte replacement. Be prepared especially on hot and humid days.
- If you take medications, be aware of what effect they may have on fluid loss and hydration.
- Wear appropriate clothing that allows for good heat transfer from the body.
- Be aware that certain medical conditions (obesity, diabetes, history of concussion) are risk factors for heat illness.
- Be aware of the outside temperature and humidity.
- Get adequate sleep before a vigorous workout in the heat.
Nathan Endres, MD, is an orthopaedic surgeon at and assistant professor at the UVM Medical Center. He is fellowship trained in sports medicine, shoulder surgery and orthopaedic trauma.
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Noonan B, Bancroft RW, Dines JS, Bedi A. Heat- and Cold- Induced Injuries in Athletes: Evaluation and Management. JAAOS 2012; 20:744-754.