US heat wave doesn’t have to derail summer fun or fitness. Here are hydration tips, what to eat and when to exercise

By Jacqueline Howard, CNN

(CNN) — A widespread heat wave is building across the United States, and when the temperature is rising, how you eat, drink and exercise can all have an effect on your health.

Although it can be extremely dangerous to overexert yourself during a heat wave, your summer activities and workout plans don’t have to completely melt down.

An “extreme heat” weather event typically refers to a period of high heat and humidity with temperatures soaring above 90 degrees Fahrenheit for at least two or three days. When this happens, your body may need to work harder to maintain a normal temperature, which can lead to health risks such as heat-related illnesses. Older adults, children and people with certain illnesses or chronic conditions are especially vulnerable to heat risks.

But according to the American Red Cross, there are some steps many people can take before and during extreme heat to reduce these risks.

It’s also important to know the signs of heat-related illnesses, among which heat stroke is the most serious. It happens when the body’s temperature rises to 106 degrees Fahrenheit or above within 10 to 15 minutes, which can be life-threatening.

Symptoms of heat stroke include loss of consciousness, confusion, slurred speech, profuse sweating, hot or dry skin or seizures. In these cases, it is important to seek help by calling 911 and to work to cool the body quickly with cold wet cloths or ice bath. If possible, move the person to a cool, shaded area, remove any outer clothing and circulate the air around them.

Symptoms are especially important to watch for when exercising outdoors or competing in athletic events, particularly for young people. It’s estimated that about 9,000 high school athletes in the United States are treated for heat-related illnesses each year. And elite athletes aren’t exempt from the effects of heat: Research on the Tokyo 2020 Olympic and Paralympic Summer Games found that about 1 in 100 Olympic athletes developed heat-related illness.

Even people trying more typical outdoor activities or exercise can face similar risks and a familiar dilemma: Push through the heat or retreat indoors?

For people who may choose to venture out, things like exercising during cooler parts of the day, prioritizing hydration before thirst strikes, fueling with carbohydrates and replenishing fluids and electrolytes after workouts can help you train more comfortably and safely, said Dr. Kent Bradley, an Arizona-based preventive medicine physician and the chief medical executive of the fitness and precision medicine company 10X Health.

During summer months, “a couple of things is to recognize that the body is going to be depleted of not just hydration of water when we sweat, but electrolytes, and we’re going to be losing sugar as well,” Bradley said.

Therefore, what you eat and drink and when you exercise can play a role in your workouts and your overall health, he said, especially during high summer temperatures.

What to eat: easily digestible foods

What you eat can help make hot summer days feel easier, especially when you’re trying to stick with regular exercise.

Pre-workout

Before a workout, focus on easily digested carbohydrates that provide quick energy without sitting heavily in the stomach, and reach for hydrating foods, Bradley said.

“Consider something much more light, maybe something that has a lot of water content to begin with, like watermelon, and maybe add some sea salt,” he said. “A smoothie also would be OK. Or a frozen banana, and you could add a bit of protein with a nut butter.”

Carbohydrates, such as fresh fruits like bananas or berries, are important for supporting exercise because they provide the body with fuel before moderate- and high-intensity workouts. This can help delay fatigue and maintain stamina.

For fueling a summer workout, “I am a big fan of overnight oats with a little fruit and nuts or nut butter for a bit of protein. You could also do a hard-boiled egg with a rice cake and fruit,” Dana Santas, a certified strength and conditioning specialist and mind-body coach in professional sports and CNN Health contributor, said in an email.

“Also, because sodium helps your body retain fluid and delays dehydration, be sure to add a pinch of salt to your oatmeal or egg,” Santas said.

For workouts lasting longer than an hour, especially in hot conditions, sports nutrition experts recommend consuming about 30 to 60 grams of carbohydrates per hour of exercise, said Dr. Colby Genrich, sports medicine physician at Texas Tech Physicians of El Paso, who works with professional soccer players in the El Paso area.

But “try to limit dairy and high-fiber foods before exercise in order to avoid some of the gastrointestinal stomach issues,” Genrich said.

Throughout the day

Heavy, high-fat meals immediately before exercise can increase your digestive workload and contribute to feelings of sluggishness in the heat. Therefore, how you time your meals – before and after exercise – is important, said Dr. Dan Benardot, a professor at Emory University and a registered dietitian who has been the nutritionist for several Team USA athletes.

He recommends consuming several small meals throughout the day instead of three large meals. Aim for about “an hour and a half or two hours between your eating opportunities,” Benardot said.

After exercise, “a lot of athletes, they finish their activity, they go into the locker room, they shower, they change their clothes and they go have a group meal with people, but that’s maybe an hour and a half or two hours after they finish the activity,” he said. “They should really start recovering within 15 minutes of getting off the field.”

Post-workout

Recovery nutrition becomes especially important after training in hot weather. For post-workout meals, sports nutritionists and physicians recommend combining carbohydrates and protein to replenish glycogen stores and support muscle repair. Glycogen is the stored form of glucose in the body, a main source of energy that the body stores primarily in the liver and muscles. Carbohydrates in food are used to form glucose and glycogen.

“After exercise, especially in the heat, athletes should focus on the three Rs: rehydrate, refuel and repair,” Genrich said.

“Recent research supports consuming 20 to 30 grams of protein within the first few hours after exercise combined with a form of carbohydrate,” he said. “On the protein front, where you’re rebuilding the muscles, eat something that has 20 to 30 grams of protein – that can be peanut butter, yogurt or cottage cheese, or a protein smoothie – and then balancing that with some carbohydrate as well, so maybe a turkey sandwich with some wheat bread in order to replenish those carbohydrate stores.”

What to drink: electrolytes

After exercise, hydrating the body is equally critical and “don’t wait until you’re thirsty to start drinking,” Genrich said.

Drinking enough water remains important for everyone, and for most workouts lasting less than an hour, water is sufficient. But there are some cases in which adding electrolytes may be helpful.

“For longer or more intense workouts, especially those lasting over an hour, fluids containing electrolytes may be beneficial,” Genrich said. “Below an hour, it’s not completely necessary to replenish all those electrolytes. You’re probably not losing enough to have to replenish during the activity, but activities over an hour, you want to replenish.”

After longer workout sessions, watermelon, oranges, berries, cucumbers or other water-rich fruits and vegetables also can help hydrate.

“Sometimes people confuse feelings of dehydration with hunger. After a summer workout your fluid and electrolyte status is a priority,” Santas wrote.

“Replacing what you lost in your sweat is foundational to everything else your body needs to recover, including muscle repair and glycogen replenishment,” she said. “A protein shake made with fruit and a liquid base like coconut water is a great option — it covers your protein needs, gives you fast-digesting carbs and the coconut water provides additional electrolytes to support rehydration.”

Many people may not realize that hydration starts before your exercise, too – and for summer workouts, that could be the night before a workout.

“And make sure that you’re not drinking too much caffeine the morning of a workout,” Genrich said. “One or two cups of coffee is fine, but beyond that, caffeine can cause a lot of dehydration.”

There are ways to look for cues that you might need more hydration throughout the day. A simple hydration check can happen while using the bathroom: Urine appearing pale yellow is a sign that you are more hydrated, whereas dark amber urine can be a sign of dehydration.

When to work out: early or evening

It’s also important to choose your workout window wisely, especially when enjoying the outdoors in the summer.

The safest and most effective times for outdoor activity are generally early morning, before 9 a.m., or after the sun begins to set. These are times when air temperatures, pavement temperatures and solar radiation are significantly lower.

“I’d stay away from that 9 a.m. to 4 p.m. window – and definitely that peak window of 11 a.m. to 3 p.m. – that’s when it’s the hottest,” Bradley said.

Midday workouts expose athletes to the highest heat load and can dramatically increase the risk of heat exhaustion, he said. Humidity compounds the problem because sweat evaporates less efficiently, making it harder for the body to cool itself.

“Early morning is generally ideal because temperatures tend to be at their lowest,” Santas said. “If morning isn’t possible, later in the evening after sunset is your next best option.”

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