A heat stroke (heat injury) can occur when you work out or compete on a hot and/or humid summer day, don’t drink enough fluids, or push yourself too hard, while your skin temperature rises. Heat strokes can be fatal and have a higher death rate than many expect. People preparing for their first marathon or triathlon are especially at risk. Find more track and field topics at Track and Field Main and sports injury information at the Injuries Main page.
Description: Heat Stroke & Summer Workouts
What Happens When You Work Out in the Midday Heat?
Your skin acts as your body’s natural cooler. Think of your muscles as a motor: when you exercise or compete, they generate a lot of heat. The skin helps cool your body by evaporating sweat. However, the human body is inefficient during exercise—more than 70% of the energy we use is lost as heat. The fitter and more acclimatized you are, the less energy is wasted.
During exercise in the sun or when dehydrated, your skin can become overstrained, impairing performance. One of the first symptoms is shortness of breath. High humidity makes things worse because sweat doesn’t evaporate efficiently. That’s why heat combined with high humidity is particularly dangerous for marathon runners and triathletes.
For safety, the air temperature should ideally be below body temperature. For most people, 34°C is manageable if humidity is moderate, but 42°C with 90% humidity is extremely dangerous. Wind, shade, or a brief cool shower can help reduce risk.
Symptoms: Heat Stroke & Summer Workouts
- Dizziness
- Blurred vision
- Loss of orientation
- Headache
- Pale, dry skin
- Decreased sweating
- Fatigue
- Throbbing headache, difficulty running straight
Who Is Susceptible: Heat Stroke & Summer Workouts
- Triathletes and marathon runners competing in hot, humid conditions
- People not acclimated before competition
- Beach volleyball players exposed to intense sun
- People doing heavy workouts during summer vacation
- Individuals with less skin surface per kilogram of body weight; heavier individuals are at higher risk than thin individuals
Treatment: Heat Stroke & Summer Workouts
- Rest in the shade
- Take a cold shower
- Lie down and raise your feet 20–30 cm (8–12 inches) to improve blood flow to the brain
- Drink cold water regularly for 30–60 minutes
- Loosen or remove clothing (avoid direct sun)
- Sponge exposed skin with cold water
- Use a fan or air conditioning
- Slow down or stop exercise if dizzy
- Seek medical help if necessary
Trainer Advice: Heat Stroke & Summer Workouts
- Run in the shade whenever possible
- Drink water every 20 minutes
- Protect your skin from direct sunlight with light clothing
- Slow down if you feel weak
- Acclimatize for 2 weeks before competing in the midday heat; this improves sweating and cooling efficiency
- Avoid alcohol
- Avoid large meals 2 hours before exercise or competition
- Pour water over your head or shoulders during long runs in hot weather to cool your skin—professional marathoners often do this
Related Topics
- Track and Field
- Jumper’s Knee
- Sprained Ankle
- Plantar Fasciitis
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