Primary Care in Rochester and Kasson

Exercising in summer heat? Play it safe

7/20/2023 by Denise Dupras, M.D., Ph.D.


Whether you're running, playing a pickup game of basketball or going for a power walk, take care when outdoor temperatures rise. 

Exercising in hot weather puts extra stress on your body. The exercise, plus the air temperature and humidity, can increase your core body temperature. Under normal conditions, your skin, blood vessels and perspiration serve as natural cooling systems. But these systems may fail if you're on certain medications, exposed to high temperatures and humidity for too long, you sweat heavily, you drink alcohol or you don't drink enough fluids. 

Pay attention to warning signs

During hot-weather exercise, watch for signs and symptoms of heat-related illnesses, including heat cramps, heat collapse, heat exhaustion and heatstroke. If you ignore these symptoms, your condition can worsen and result in a medical emergency.

Warning signs include:

  • Muscle cramps.
  • Nausea or vomiting.
  • Weakness.
  • Fatigue.
  • Headache.
  • Excessive sweating ― or in extreme cases, not sweating at all.
  • Dizziness or lightheadedness.
  • Confusion.
  • Irritability.
  • Low blood pressure.
  • Increased heart rate.
  • Rapid breathing.
  • Visual problems, including blurred vision.
  • Temperature of 104 degrees Fahrenheit or higher

If you develop any of these symptoms, stop exercising, get out of the heat and sun, lower your body temperature, and get hydrated immediately. Have someone stay with you to monitor your condition. If your temperature is higher than 104 F, seek emergency care immediately. 

To cool down:

  • Remove sports equipment and extra clothing.
  • Spray yourself with water from a hose or shower.
  • Place cool, wet towels or ice packs on your neck, forehead and under your arms. 
  • Sit in a tub filled with cold water. 
  • Drink fluids, such as water or a sports drink.

If you don't feel better within about 20 minutes, seek emergency medical care. 

Tips for avoiding heat-related illnesses

These commonsense tips can help you keep your cool and play it safe while exercising and enjoying outdoor activities this summer:

  • Watch the temperature. Pay attention to weather forecasts and heat alerts, and know what the temperature and humidity will be when you're exercising. 
  • Get acclimated. If you're used to exercising indoors or in cooler weather, it can take up to two weeks to adapt to the heat. As your body acclimates, gradually increase the length and intensity of your workouts. 
  • Know your fitness level. If you're unfit or new to exercise, be extra cautious when working out in the heat. Reduce your exercise intensity and take frequent breaks. 
  • Drink plenty of fluids. Dehydration is a key factor in heat illness. Don't wait until you're thirsty to drink fluids, including water and sports drinks, which are formulated to replace the sodium, chloride and potassium you lose through sweating. Avoid alcoholic beverages, as they only dehydrate you faster. 
  • Dress for the heat. Lightweight, loose-fitting clothing helps sweat evaporate and keeps you cooler. Avoid dark colors, which can absorb heat. If possible, wear a light-colored, wide-brimmed hat. 
  • Avoid midday sun. Exercise in the morning or evening when it's likely to be cooler outdoors. If possible, exercise in shady areas, or work out in a pool. 
  • Wear sunscreen. A sunburn decreases your body's ability to cool itself. 
  • Have a backup plan. If you're concerned about the heat or humidity, stay indoors. Work out at the gym, walk laps inside the mall or climb stairs inside an air-conditioned building. 
  • Avoid drinking alcohol. Alcohol can affect your body's ability to regulate temperature.
  • Understand your medical risks. Certain medical conditions, including heart or lung disease, or medications for blood pressure or mood disorders, can increase your risk of a heat-related illness. If you plan to exercise in the heat, talk to your healthcare clinician about precautions. 

By taking some basic precautions, your exercise routine doesn't have to be sidelined when the heat is on. 

Denise Dupras, M.D., Ph.D., is a general internist in the Division of Community Internal Medicine, Geriatrics and Palliative Care. She completed her medical and doctoral degrees at Mayo Clinic Alix School of Medicine and her residency in internal medicine at Mayo Clinic in Rochester. Her interests include medical education and LGBTI medicine.