Proceed with caution when working out in the summer heat

During mid-summer, athletes throughout most of the United States face the challenge of keeping up with their outdoor workout routines despite high temperatures and humidity.

Normally the skin, blood vessels, and sweat glands work together as a cooling system. The heart serves as a circulatory pump. In extreme heat, blood vessels direct more blood flow to the skin where cooling takes place. This diverts circulation from muscles and leads to muscle cramps – an early sign of heat illness. Anytime ambient conditions reach 70% humidity and 70 degrees simultaneously, this system is at risk to fail.

The dangers of heat-related illness, such as heat exhaustion and heat stroke, include permanent neurologic impairment, heart attack, and death.

Symptoms of heat exhaustion include:
• Heavy sweating; cold, clammy skin
• Dizziness or fainting
• Muscle cramps
• Fast, shallow breathing

Symptoms of heat stroke include:
• Warm, dry skin; no sweating
• Confusion or loss of consciousness
• High fever
• Throbbing headaches

Nausea and vomiting are early symptoms of both conditions.

Potential catastrophe can be avoided by not working out during the hottest part of the day; wearing lightweight clothing that keeps moisture away from the skin and drinking plenty of fluids before, during and after working out.

Some innovative methods of keeping cool during competition include the use of a cooling vest. This was originally developed for Olympic athletes participating in the 2004 games in Greece where average temperatures exceeded 90 degrees. Athletes put on a vest that contains a gel material that is pre-cooled. It is worn until the time of competition. Consider it the opposite of “warm-up.”

Some athletes immerse their hands in buckets of cold water to cool the circulating blood. Wristbands containing a cooling substance are also effective.

Hot, humid weather should not halt your exercise regimen, but it is wise to proceed with caution.

Anthony G. Alessi, MD, is Chief of Neurology at The William W. Backus Hospital and in private practice at NeuroDiagnostics, LLC, in Norwich. E-mail him at If you wish to learn more about sports health topics, listen to the podcast or go to the Healthy Sports blog at

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