Heat Illness

Edward D. Snell, M.D. Head Team Physician, Pittsburgh Pirates West Penn Allegheny Health System

Heat illness and dehydration is a dangerous and sometimes misunderstood problem that athletes often do not think about in the heat of participation. Conditions such as heat syncope, cramps, exhaustion and stroke are manifestations of the body’s inability to effectively respond to an increased thermal load. These conditions can be defined as follows:

Heat Syncope: This occurs while a person is standing still following exercise in the heat and experiences a benign brief fainting episode. Core body temperature is normal and recovery is typically rapid.

Heat Cramps: Typically, this condition involves painful contractions of the large muscle groups of the legs following vigorous activity.

Heat Exhaustion: This is recognized as the most common form of heat intolerance in athletes. Dehydration plays an important role in heat exhaustion. Athletes frequently report dizziness, headache, fatigue, chills, goose bumps, nausea and vomiting. Body temperature is usually normal.

Heat stroke: With a 50-70 percent fatality rate, heat stroke is the second most common cause of deaths in athletes in the United States. Heat stroke represents a true medical emergency and results from prolonged vigorous exercise in hostile thermal environments. A spectrum of signs/symptoms may be present including arrhythmias, nausea, vomiting, paradoxical shivering, irritability, delirium, seizures and coma. Sweating may or may not be present.

The body attempts to protect itself from illness such as these by maintaining its core temperature through a process called thermohomeostasis, which creates a balance between heat produced and heat lost. As exercise increases, the body’s metabolic rate rises along with subsequent heat production. When the body’s normal thermohomeostatic mechanisms are unable to compensate for an increased thermal load during exercise, a person may experience heat intolerance/illness.

A well-conditioned athlete has a more effective sweat mechanism and dissipates heat more readily than poorly conditioned athletes. Precautions include gradual acclimatization to local weather conditions, appropriate clothing, adjusting practice schedules to avoid exposure to excessive heat and promotion of frequent fluid intake to ensure adequate hydration. Hydration is the key to preventing disorders of heat intolerance. Thirst is not triggered until an athlete is 5 percent dehydrated, so a program of calculated fluid consumption is important.

Environmental factors should also be assessed as a means of preventing heat intolerance/ illness. The risks of heat illness secondary to excessive exercise based on the Heat Index are as follows:

• Low risk < 65 degrees F
• Moderate risk 65 - 73 degrees F
• High risk 74 - 82 degrees F

Since the NCAA has instituted guidelines about football practices, there has been a significant decrease in the number of heat related deaths and illnesses during football practices in the summer. Guidelines are available at www.ncaa.org under the education- heat stroke section.

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