Also known as: Heat exhaustion, Heat cramps or Heatstroke
- Heat cramps. Muscle cramps, usually in the legs or stomach (caused by loss of salt from sweating). This may be the first sign of overheating.
- Heat exhaustion. Heavy sweating, cold and clammy skin, nausea and vomiting.
- Heatstroke. When the body temperature rises above 104°F (40°C). Heatstroke is a life-threatening condition.
- Drink plenty of fluids. Drink before, during, and after your workout. Drink even if you do not feel thirsty. You can tell you are getting enough if your urine is light or very pale yellow.
- DO NOT drink alcohol, caffeine, or drinks with a lot of sugar, such as soda. They can cause you to lose fluids.
- Water is your best choice for less-intense workouts. If you will be exercising for a couple of hours, you may want to chose a sports drink. These replace salts and minerals as well as fluids. Choose lower-calorie options. They have less sugar.
- Make sure the water or sports drinks are cool, but not too cold. Very cold drinks may cause stomach cramps.
- Limit your training on very hot days. Try training in early morning or later at night.
- Choose the right clothing for your activity. Lighter colors and wicking fabrics are good choices.
- Protect yourself from direct sun with sunglasses and a hat. DO NOT forget sunscreen (SPF 30 or higher).
- Rest often in shady areas or try to stay on the shady side of a walking or hiking trail.
- DO NOT take salt tablets. They can increase your risk of dehydration.
- Heavy sweating
- Muscle cramps
- Nausea or vomiting
- Cool, moist skin
- Dark urine
- Fever (over 104°F [40°C])
- Red, hot, dry skin
- Rapid, shallow breathing
- Rapid, weak pulse
- Irrational behavior
- Extreme confusion
- Loss of consciousness
Whether you are exercising in warm weather or in a steamy gym, you are more at risk for overheating. Learn how heat affects your body, and get tips for staying cool when it is warm out. Being prepared can help you safely work out in most conditions.
How Heat Affects Your Body
Your body has a natural cooling system. It is always working to maintain a safe temperature. Sweating helps your body cool down.
When you exercise in the heat, your cooling system has to work harder. Your body sends more blood to your skin and away from your muscles. This increases your heart rate. You sweat a lot, losing fluids in your body. If it is humid, sweat stays on your skin, which makes it hard for your body to cool itself.
Warm-weather exercise puts you at risk for heat emergencies, such as:
Children, older adults, and obese people have a higher risk of these illnesses. People taking certain medicines and people with heart disease also have a higher risk. However, even a top athlete in superb condition can get heat illness.
Stay Cool During Exercise
Try these tips to help prevent heat-related illness:
Signs of Heat Illness
Know the early warning signs of heat exhaustion:
Later signs may include:
Signs of heatstroke may include:
As soon as you notice early signs of a heat illness, get out of the heat or sun right away. Remove extra layers of clothing. Drink water or a sports drink.
When to Call the Doctor
Call your health care provider if you have signs of heat exhaustion and do not feel better 1 hour after getting away from heat and drinking fluids.
Call 911 or your local emergency number for signs of heatstroke.
Centers for Disease Control and Prevention. Keep Your Cool in Hot Weather. Updated June 29, 2015. www.cdc.gov/features/extremeheat. Accessed September 17, 2015.
Centers for Disease Control and Prevention. Tips for Preventing Heat-Related Illness. Reviewed June 1, 2012. emergency.cdc.gov/disasters/extremeheat/heattips.asp. Accessed September 17, 2015.
FamilyDoctor.org. Athletes: The Importance of Hydration. Updated March 2015. familydoctor.org/familydoctor/en/prevention-wellness/exercise-fitness/exercise-basics/athletes-the-importance-of-good-hydration.html. Accessed September 17, 2015.
- Review date:
- December 07, 2016
- Reviewed by:
- Linda J. Vorvick, MD, Medical Director and Director of didactic curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.
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