Our bodies, which create a tremendous amount of internal heat, are normally cooled through sweating and radiating heat through our skin. Under certain circumstances, such as unusually high temperatures, high humidity, or vigorous exercise in hot weather, this natural cooling system may begin to fail, allowing internal heat to build up to dangerous levels. The result may be heat illness, which can result in heat cramps, heat syncope, heat exhaustion, or heatstroke. The following information will describe what signs and symptoms to look for if you suspect heat illness, and also inform you on how to respond to these situations. Heat illness is more likely in hot, humid weather but can occur in the absence of hot and humid conditions.
Exercise-associated muscle (heat) cramps represent a condition that presents during or after intense exercise sessions as an acute, painful, involuntary muscle contraction.
Signs and Symptoms: dehydration, thirst, sweating, transient muscle cramps, fatigue
Treatment/Prevention: stop activity, replace lost fluids with sodium-containing fluids, and begin mild stretching with massage of the muscle spasm. A high-sodium sports product may be added to the rehydration beverage to prevent or relieve cramping in individuals who loose large amounts of sodium in their sweat.
Heat syncope, or orthostatic dizziness, can occur when a person is exposed to high environmental temperatures. It often occurs after standing for long periods of time, immediately after cessation of activity, or after rapid assumption of upright posture after resting or being seated.
Signs and Symptoms: dehydration, fatigue, tunnel vision, pale or sweaty skin, decreased pulse rate, dizziness, lightheadedness, fainting
Treatment/Prevention: Move the individual to a shaded area, monitor vital signs, elevate the legs above the level of the head, and rehydrate.
Exercise (heat) exhaustion is the inability to continue exercise associated with any combination of heavy sweating, dehydration, sodium loss, and energy depletion. It occurs most frequently in hot, humid conditions.
Signs and symptoms: Normal or elevated body-core temperature, dehydration, dizziness, lightheadedness, syncope, headache, nausea, diarrhea, decreased urine output, persistent muscle cramps, pallor, profuse sweating, chills, cool, clammy skin, intestinal cramps, weakness, hyperventilation
Treatment/Prevention: This condition can be prevented by matching fluid intake with sweat and urine losses and by rehydrating with fluids that contain sufficient sodium. If the individual’s temperature is elevated, remove his or her excess clothing; cool the individual with fans, ice towels, or ice bags; remove the individual to a cool or shaded environment if possible; start fluid replacement; transfer care to a physician if needed (911 or emergency room).
Exertional Heat Stroke
Exertional heat stroke is an elevated core temperature with signs of organ system failure due to hyperthermia.
Signs and Symptoms: High body-core temperature, central nervous system changes, dizziness, drowsiness, irrational behavior, confusion, irritability, emotional instability, hysteria, apathy, aggressiveness, delirium, disorientation, staggering, seizures, loss of consciousness, coma, dehydration, weakness, hot and wet or dry skin, tachycardia (100 to 120 beats per minute), hypotension, hyperventilation, vomiting, diarrhea
Treatment/Prevention: This condition is life threatening and can be fatal unless promptly recognized and treated. Call 911. Lower the body-core temperature as quickly as possible. The fastest way to decrease body temperature is to remove clothes and equipment and immerse the body (trunk and extremities) into a pool or tub of cold water.
Non-enviromental risk factors for heat illness
- Heavy or dark colored athletic equipment
- History of heat illness
- Increased body mass index
- Poor physical condition
- Lack of heat acclimatization
- Electrolyte imbalance
Tips for preventing heat illness
- Drink more fluids
- Stay away from liquids that contain alcohol or sugar
- Stay indoors, or in the shade if outdoors
- Take a cool shower/bath after activity
- Wear lightweight, light colored, loose fitting clothing
- Limit outdoor activity to morning and evening hours
Information provided by the National Athletic Trainers Association’s Position Statement on Exertional Heat Illnesses