How to Identify and Treat Heat-Related Illnesses

by Kevin Gray

During warmer months, we tend to spend more time outdoors, running, cycling, frolicking on the beach and otherwise enjoying the sun. But with all that time in the heat comes the risk of developing heat exhaustion or heatstroke, illnesses that can be extremely harmful and even deadly. It’s important to take measures to avoid these conditions, but if they do occur, you must recognize the symptoms and take appropriate action.


There are several factors that contribute to heat exhaustion and heatstroke. “Exercising in a warm or hot environment when not acclimatized to that environment can predispose one to heat exhaustion or heat injury,” says Dr. Mike Clark, a preventive medicine physician at Cooper Clinic in Dallas. He notes this is markedly worsened if the environment has high humidity, and risks are also greater with high-intensity exercise and poor physical fitness. Equipment, uniforms and clothing that prevent heat loss impact your body’s ability to cool itself. And other factors like sleep deprivation, dehydration and fever also increase your risk of developing heat-related problems.

A third condition to note is heat cramps. These can also occur during exercise and may result in painful, involuntary muscle spasms, but Dr. Clark says these do not appear to be related to high ambient temperature. “They are not life-threatening and should respond to hydration, stretching and massage.”

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“Heat exhaustion is not uncommon in warm climates and can be extremely serious and life-threatening,” says Dr. Clark. He notes exertion-related heat illness is a leading cause of death in young athletes, and it also affects laborers, firefighters, military personnel, and others who are required to exert themselves in the heat.

Signs and symptoms of heat exhaustion may include increased heart rate and breathing, mild to moderate dehydration, nausea, vomiting, fatigue and weakness. Dizziness and mild confusion may also occur, and one can even experience a brief loss of consciousness.

If you or someone you know is suffering heat exhaustion, it’s important to take steps to cool the body. Remove equipment and excess clothing, and if cold water is available, immerse the athlete in a tub of water, ideally at a temperature between 35–60°F (2–16ºC). If ice water immersion is not possible, “rapidly initiate an alternative method of cooling,” advises Dr. Clark. For example, apply ice packs to areas of the body where large blood vessels are located, like under the arms and near the groin. “You may also spray water over the patient’s body and use fans to blow air over the moist skin, which will result in evaporative cooling. Water should be continually reapplied as needed, and fanning performed continuously.” Monitor vital signs and mental status to track improvement, and if improvement does not occur, medical assistance may be necessary.


A dangerous step up from heat exhaustion, heatstroke occurs when the body temperature rises to 104°F (40ºC) or higher. Dr. Clark says only a rectal thermometer can accurately test this condition. “This is a medical emergency and in-hospital treatment is required,” he adds. However, until help arrives, you should employ the same cooling techniques utilized for heat exhaustion.

Symptoms of heatstroke can range from slurred speech and delirium to hallucinations and coma. Rapid breathing, fast heart rate and low blood pressure are common, and moderate to severe dehydration should be anticipated, which vomiting or diarrhea exacerbates. Dr. Clark says dry skin is common with classic heatstroke, when a body cannot properly cool itself (for example, among infants or the elderly), while excessive sweating is more common in exertional heatstroke.


  1. Hydrate. Take breaks and drink plenty of water, says Jennifer Conroyd, a certified fitness trainer and founder of Fluid Running. “If you are outdoors running, run for one mile and then walk the next mile to drink water and to allow yourself to cool down.”
  1. Timing is everything. “Try exercising in the early morning or late evening,” says Conroyd. “The heat is less intense before 10 a.m. and after 4 p.m.”
  1. Location, location, location. “If possible, do a water workout in the pool or exercise in a shady area,” she adds.
  1. Pick your outfit strategically. Wear loose-fitting, lightweight clothing to help keep you cool and evaporate sweat. “Light-colored clothing will also reflect the heat, as opposed to dark colors that absorb it.”
  1. Take it slow. “Make sure to also acclimate yourself to hot weather if you are used to exercising indoors,” advises Conroyd. “First, reduce your exercise intensity when beginning to work out in the heat. Then, gradually increase the intensity and length of your workouts as your body adapts to the heat.”
  1. Pay attention to your body. “If you begin to feel nauseous, light-headed or dizzy, stop exercising immediately,” says Conroyd.


Heat illnesses are dangerous and possibly deadly. If you exercise in warm environments, take precautions: Drink plenty of water, wear loose-fitting clothing, take breaks and attempt to avoid the hottest part of the day. If you or someone you know does experience heat exhaustion or heat stroke, act quickly to cool the body and don’t hesitate to seek medical attention.

Make progress every day while you work on fitness and nutrition goals, like walking more steps. Go to “Plans” in the MyFitnessPal app for daily coaching and easy-to-follow tasks to keep you motivated. 

Tagsfitnessinjury preventionwellness

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