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Exercising When It Is Hot: How To Prevent Heat Stress

By Beth Jennings, PT, MPT

The summer sun is a welcomed sight after a Pacific Northwest winter, am I right? Rising temperatures pose a challenge to keeping up your exercise program and even a risk of injury from the heat. FYZICAL – Forest Grove wants you to stay safe while you stay fit year-round. 

The Body’s Response in Hot Weather

A normal body temperature is about 98.6F, and your body tries to maintain this through hot and cold exposures. 

The two ways your body stays cool are sweating and an increased heart rate. Sweat evaporates, cooling the skin. Increasing your heart rate delivers blood to the skin faster to allow more heat to release.

Add in exercise where active muscles produce heat and the demand on these two methods becomes greater. When the body can’t keep up, heat injury or stress will occur. Simple adjustments and recognizing early symptoms of overheating can keep you safe all summer long.

Let’s Talk Specifics on Heat Injuries

When your body can’t keep up with cooling and your temperature exceeds 102.2F, stress or injury can occur. Nausea, muscle cramps, dizziness, or heavy sweating are signs to slow it down, cool off, and hydrate. 

Heat cramps: Muscle spasms, moist and cool skin, normal body temperature.  

Action: Rest in the shade. Hydrate with a sports drink or drink water and eat some food.

Heat Exhaustion: Heavy sweating, dizziness, weakness, nausea or vomiting, fainting, muscle cramps. 

Action: Move to a cool location. Use cold cloths or ice packs if available. Hydrate. Seek medical attention if symptoms continue.

Heat Stroke: Confusion, throbbing headache, red/hot skin, sweating that has stopped, rapid pulse, unconsciousness, seizures, coma. 

Action: This is an emergency. Call 911 and seek immediate care. Cool quickly by moving to a cool place, remove excess clothing, cool with ice or water, but more effective cooling measures at a hospital is critical.


Who is at Risk for Heat Illness?

Everyone. Especially when the outside temperature is over 80F and 75% humidity. But those most at risk include:

  • Younger than 15 and older than 65
  • Males more than females
  • Military personnel
  • Outdoor workers
  • Athletes
  • Low-income population
  • Overweight
  • Sedentary or deconditioned
  • Those with chronic illnesses such as diabetes, cardiac conditions, and sickle cell trait

Let’s Talk Prevention

Drink! Staying well hydrated before and during an exercise session helps the body produce sweat to keep you cool. Consider drinking two glasses of water two hours before you work out. 

If you are exercising for longer than an hour, consider sports drinks to replace electrolytes, the salts you lose when you sweat. Otherwise, the natural salts in your food are usually sufficient. 

Low urine output or dark urine are signs you aren’t drinking enough. Don’t count on thirst to tell you when to drink.

Avoid alcohol or sugary drinks as a way to hydrate.

Wear clothes that breathe well and are light in color. When clothes breathe well, your sweat evaporates quickly, cooling your skin.

Reduce your workout intensity. Give your body a chance to acclimatize or adapt to the heat. It takes 8-14 days of regular exposure to heat for this to occur.

Consider exercising in the morning or late evening when temperatures are cooler.

Exercise in cooler locations such as on shady trails or at the gym if you know they keep it cool. Consider a cycling or running route where you could stop in a cool building like a grocery store or library if needed.

When working outside or playing team sports, take note of shady or cooler places and have plenty of cold water available. Keep an eye on each other for signs of heat stress.

More Information

Do you want to read more about preventing heat injuries? Check out what the Centers for Disease Control has to say about it.

Don’t know how much water to drink? Everyone has an opinion on this. Here’s what the Mayo Clinic thinks.

Do you know someone who could use this information? Forward it via email, Facebook, or Twitter through the links at the top of this page. 

Beth Jennings, PT, MPT is a freelance writer and a physical therapist.

Disclaimer This blog is provided for informational purposes only. The content is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or another qualified healthcare provider with any questions you may have regarding a medical condition.


Gauer R, Meyers BK. Heat-related illnesses. Am Fam Physician. 2019;99(8):482-489.