NEWS | June 26, 2019

Exercise safely this summer

UC Davis sports medicine expert talks about heat-related dangers and ways to avoid them

Editor's note:

Did you miss our Facebook Live on exercising safely during summer on July 2? You can still watch it at and post questions for Dr. Brandee Waite about how you should adjust your workout plan in higher temps.


Exercise is crucial to staying healthy, but it’s important to be careful in the summer to avoid heat stroke, dehydration and other consequences of overdoing it. Physical activity can become downright hazardous when temperatures soar.

With planning, awareness and a few adjustments, you can keep up your workout regimen during summer months. With planning, awareness and a few adjustments, you can keep up your workout regimen during summer months.

“People who exercise regularly often don’t consider the effects of heat on their performance and overall health,” said UC Davis Health sports medicine physician Brandee Waite.

“With just a few modifications and a lot of awareness of symptoms to be on the lookout for, you should be able to continue your work out plan,” Waite added.

Here are her tips for exercising in high temps:

Time it right

If possible, exercise indoors or during the cooler morning and evening hours. While right after work is a common time to exercise, this is typically the hottest time of day. Keep in mind that out-of-town visitors may not be accustomed to our temperatures and should especially take it easy the first few days, as it can take five to seven days to acclimate. Even pro athletes adjust their routines during their first days in new climates.

Take regular timeouts

This is especially important for youngsters who aren’t always aware that they need rest periods and water breaks. Schedule a minimum of 10 minutes in the shade for every hour of exercise. Children, older people and those who are less fit need more rest. Someone who’s fit but not acclimated may be even more vulnerable to heat issues because they are used to exercising hard and may overdo it. Of course, everyone should spend more time chilling out when it’s particularly hot. If you can splash water on yourself during exercise from a drinking fountain or a hose, that will have a large cooling effect.

Brandee Waite's top five tips for exercising when the weather is hot Brandee Waite
1. Exercise indoors or during cooler, early morning hours.
2. Drink plenty of water.
3. Supplement water with sports drinks or salty snacks if exercising longer than one hour.
4. Limit time in direct sun, and spend 10 minutes in the shade for every hour of outdoor activity.
5. If anyone is outside in the heat (exercising or not) and seems confused or shows signs of altered mental activity, call 911 and immediately initiate cooling measures.

Stay hydrated

Before any outdoor activity, have a big glass of your favorite cool drink. Make sure kids drink plenty of water since they don’t realize how important it is to stay hydrated. Competitive athletes should tank up with two big glassfuls of fluids at least two hours before an event. Anyone running or playing a sport in the heat should drink fluids early and often.

Plain water is adequate for most activities, but sports drinks to replenish carbohydrates and electrolytes and fruit juices are fine, too. Just avoid alcohol and caffeine, which contribute to dehydration. Whenever possible, drink during exercise as well to help the body with cooling and hydration needs. For people engaging in prolonged exercise over a period of more than an hour, it’s important to replace salts and add energy with sports drinks or snacks with salt and carbohydrates rather than plain water.

Current studies show that “drinking to thirst” with prolonged activities is recommended for exercise outdoors. Basically, if you feel thirsty, you should drink (though children likely need help with reminders). When someone has gotten dehydrated, it can take hours to days to get back to full hydration. Also, drink fluids as soon as possible after exercise — Tour de France riders pound water after each stage because they have to race the next day.

Dress for the occasion

Football players with bulky, tight-fitting uniforms will be at higher risk for heat-related problems than runners in shorts and tank tops. Coaches and athletes need to adjust fluid requirements and resting times with these factors in mind on hot days. Spectators also can get hot and tired sitting in the bleachers. Wearing a wide-brimmed hat and light-colored, loose clothing made of cotton or another light, breathable fabric is recommended, and applying sunscreen to all exposed areas every few hours will help prevent sun damage to skin.

Act before emergency

Heat-related illness can rapidly lead to a medical emergency, so it is essential to take action at the first warning signs. Conditions such as muscle cramps, heat exhaustion and heat stroke often occur in people working hard or exercising in hot weather, but they can happen to anyone on a hot day. People especially at risk are the elderly, children, overweight or obese individuals, and those with heart conditions or taking certain medications such as diuretics (also known as water pills).  

Be on the lookout for these heat-related conditions:

Muscle cramps typically occur in the legs or abdomen and are due to salt depletion from excessive sweating. The cramps are usually relieved by rest, stretching and rehydration. Tanking up on diluted fruit juice with a pinch of salt added or drinking sports drinks can help prevent salt depletion during hot weather.

man helping woman with heatstroke

Heat exhaustion is an early stage of heat stroke. The person feels excessively tired, weak, and nauseous, and may feel dizzy and even briefly pass out. The skin is cool and clammy, and may appear either flushed or pale. Have the person sit or lie down in a shady location and give cool drinks — the colder, the better. Try anything to cool the victim down: Loosen or take off extra clothes, sponge with cold water, and place him or her near a fan. If the person does not get better or symptoms get worse, seek medical care.

Heat stroke is a very dangerous condition. The body stops sweating and the internal temperature climbs to high levels, although you may get what feels like chills. The skin will be quite dry and hot. People with heat stroke may be confused, agitated and have blurry or double vision. Have the person lie down and call 911 at once while others continue efforts to cool the victim down.

Related stories and information

About the UC Davis Health Sports Medicine Program
Is it safe to go the distance?
Tips for avoiding sports injuries
Warning signs and symptoms of heat-related illness