Recognizing and Preventing Heat-Related Illnesses


When you're active outdoors, it's important you take steps to stay safe in the heat.


UW Health Sports Medicine Athletic Trainers in Madison, Wisconsin explain the dangers of heat-related illnesses and how to recognize the symptoms. 


In mid- to late-summer heat and humidity tend to be at their highest. In order to stay safe, athletes – whether they are competitive or recreational – need to be aware of how environmental factors can affect their health and athletic performance and develop a plan for playing in the heat.


The Heat and Our Bodies


Our bodies cool off through the evaporation of sweat. As the heat rises, we produce more sweat to keep cool. But, as humidity rises, it becomes more difficult for the sweat to evaporate, hampering the body’s ability to keep cool. There are two main concerns for exercising in the heat – dehydration and heat-related illnesses such as heat exhaustion or heat stroke.




Because our bodies are working harder and producing more sweat, we lose fluids rapidly, which is why it is important for athletes to stay hydrated. When we don’t, we can become dehydrated, a condition that can be potentially life threatening. Early symptoms of dehydration include:

  • Headache
  • Dizziness
  • Thirst
  • Feeling less alert
  • Muscle cramps
  • Decreased urine output
  • Urine that is dark in color

Drinking water while out on the practice field or during a run isn't enough to keep the body hydrated. The American Council on Exercise recommends the following guidelines to help:

  • Before activity drink 17-20 oz of fluid within the 2 hours before exercise
  • During activity drink 7-10 oz every 10-20 minutes during your workout
  • After activity drink 16-24 oz per pound of body weight lost during exercise

While everyone's body is different and the demands vary by sport or activity, it's particularly important for individuals over 50 to monitor their hydration, as well as children and young athletes. 


Ways you can help maintain hydration include:

  • Don't wait until thirsty to drink.
  • Drink water throughout the day. To remain hydrated it is important to drink fluids throughout the day and not only during activity.
  • Eat foods with high water and electrolyte content such as fruits and vegetables, especially within 2 hours post-activity
  • After exercising, consume water and possibly an electrolyte replacement drink
  • Avoid beverages that contain alcohol and caffeine. These are diuretics and will add to the dehydration of the athlete.

Heat-Related Illnesses


When the body’s cooling systems are overworked, we can experience heat-related illnesses. When we start to experience any symptoms, it’s important to pay attention so we can seek immediate treatment to cool off and rehydrate. Note that not all symptoms may be present, but it’s still critical to stop all activity and move to a cool area out of the sun for treatment.


Heat Exhaustion


Heat exhaustion isn’t necessarily life-threatening, but can be a precursor to heat stroke. Symptoms include:

  • Heavy sweating
  • Nausea
  • Confusion
  • Vomiting
  • Goose bumps
  • Extreme fatigue
  • Incoordination (e.g. weaving, staggering, etc.)
  • Weak and rapid pulse

If you experience these symptoms, seek medical treatment. If you are with someone who has these symptoms, remove excess clothing, provide cool fluids and cool the body with ice or a damp cloth to the neck, armpits and groin area while you wait for medical assistance.


Heat Stroke


Heat stroke occurs when the body can no longer cool itself and the core body temperature reaches very high levels. When the body’s ability to cool itself off breaks down, the body’s core temperature can increase 1.8 degrees Fahrenheit every five minutes. If left untreated, this can cause permanent damage to major organs and possibly even death. Heat stroke can occur rapidly and is a medical emergency that requires immediate care and rapid cooling.


Keep in mind you may not experience symptoms of heat exhaustion prior to experiencing heat stroke. Symptoms of heat stroke do include those of heat exhaustion, as well as:

  • Bizarre behavior
  • Significant confusion
  • Lack of consciousness
  • A strong and fast pulse
  • Red skin
  • Either heavy sweating or a cessation of sweating
  • A temperature great than 104 degrees (common methods of taking the temperature – orally, under the armpit, across the forehead – may not be accurate)

When someone is experiencing a heat stroke, they need to be cooled immediately. Cold water immersion is the most effective, but if that’s not possible, move the person to an air-conditioned room; place ice packs on the neck, armpits, and groin; use fans; and if conscious, provide cool liquids until he or she can be transported to a medical facility for further care.


UW Health Services


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