Don’t Work Up a Heatstroke

2020 Mankato Marathon

It’s that time of year when the temperature is continuously rising and the scenery gets more and more beautiful every day. A daily outdoor workout allows you to get quality physical activity while enjoying your environment. But overworking your body in the heat can cause you to become incapable of exercising due to cramping, feeling nauseated or, in the worst case scenario, losing consciousness. When you overheat during exercise, effects can range in severity from mild heat cramps to heat exhaustion to potentially life-threatening heatstroke.

Here’s what you need to know about exercising properly in warm-weather conditions:

Heat exhaustion cycle. The first phase in the heat exhaustion cycle is having heat cramps. This is the least serious phase and consists of painful, involuntary spasms that usually occur in muscles during exercise. The second phase is heat exhaustion. Due to the lack of fluids in the body, this is more serious than heat cramps. It results in rapid heart rate, low blood pressure, low-grade fever, and hot, red, dry or sweaty skin. Heatstroke is the third and most dangerous form of heat exhaustion; it can be life threatening. Signs of heatstroke include rapid heartbeat, unusually high or low blood pressure, lack of sweating, fainting, rapid and shallow breathing, confusion, irritability and loss of consciousness. Progression through the stages of heat exhaustion can occur very quickly, so you need to be aware of the signs and take immediate action.

Preventive measures. Anyone who is involved in strenuous outdoor physical exercise in warm weather should drink eight to 16 ounces of water an hour before beginning the workout. Once you begin to feel thirsty during the activity, your body has already become dehydrated. The key is to maintain fluid intake before thirst begins. Also, avoid exercising in the hottest part of the day — afternoon — and wear loose clothing to allow for circulation.

The heat index. When the heat index, which calculates how heat and humidity interact, is above 105 degrees or the dew point is above 70, exercise or practice at a cooler time of day in light sport clothing.

Individuals at higher risk. This includes people who:

  • Have diabetes, asthma, heart disease or other chronic diseases
  • Have recently been ill with a fever
  • Have previously experienced heat illness
  • Are hard chargers who might ignore the warning signs
  • Are not in good physical condition or are overweight
  • Haven’t become acclimated to warmer outdoor temperatures or higher humidity
  • Are elderly or very young
Mayo Clinic Health System

About the author:
Katy Anthony is a physician assistant practicing family medicine at Mayo Clinic Health System, a network of community-based health care providers committed to health and wellness.