Exercising during a heat wave: What you need to know

Extreme heat is more than just uncomfortable. According to the World Health Organization (WHO), an estimated 489,000 heat-related deaths occur worldwide each year.

As temperatures climb into the 90s and even reach triple digits across San Diego, many people wonder whether it's safe to continue their regular exercise routine.

While staying active is important for both physical and mental health, exercising in extreme heat can place additional stress on the body and increase the risk of heat-related illness. The good news is that you don't necessarily have to put your workouts on hold.

By understanding the risks and making a few smart adjustments, you can stay active while protecting your health.

How your body reacts to heat

When you exercise, your body naturally produces heat. To keep your temperature in a safe range, your body cools itself by sweating.

During a heat wave, however, high temperatures can make it harder for your body to regulate its temperature effectively. As your body works harder to stay cool, you may lose fluids more quickly and become dehydrated.

In some cases, prolonged exertion in extreme heat can lead to heat cramps, heat exhaustion or even heat stroke — a medical emergency that requires immediate attention.

What warning signs to watch for

Knowing when to slow down, take a break or stop exercising can help prevent serious complications. Early signs of heat-related illness may include:

• Excessive sweating

• Muscle cramps

• Headache

• Dizziness

• Nausea

• Unusual fatigue

If you begin experiencing any of these symptoms during a workout — or even simply while spending time outside — move to a cooler area, rest and drink water. More severe symptoms, such as confusion, fainting or a rapid heartbeat, may indicate heat exhaustion or heat stroke and should not be ignored.

Who is at greatest risk

While everyone should take precautions during extreme heat, certain groups face a higher risk of heat-related illness. Older adults, young children, people who are pregnant and people with chronic conditions such as heart disease or diabetes may have a harder time regulating body temperature.

Some medications can also affect how the body cools itself. If you have a medical condition or concerns about exercising in the heat, talk with your doctor before beginning or continuing an outdoor workout routine.

Why preparation is key

If you plan to exercise or spend time outdoors during hot weather, timing and preparation can make a big difference. Experts recommend exercising during the coolest parts of the day, such as early morning or after sunset.

Wearing lightweight, breathable clothing; seeking shade when possible; and staying well hydrated before, during and after exercise can also help reduce heat-related risks.

In addition to water, electrolyte-containing drinks help during prolonged exercise, heavy sweating or extended exposure to high temperatures. They can replace fluids and minerals lost through sweat.

"Listen to your body," says Dr. Mahi Trivellas, an orthopedic surgeon with Sharp Community Medical Group and affiliated with the Sharp Sports Medicine Clinic at Sharp Grossmont Hospital. "If you're feeling unusually fatigued, dizzy or lightheaded, those are signs that you need to slow down, rest or stop exercising altogether."

When to switch things up

She adds that when temperatures soar, it's often wise to reduce the intensity or duration of your workout. Taking your workout indoors may be the safest option.

Walking on a treadmill, riding a stationary bike, strength training at home or attending a fitness class can help you stay active without prolonged exposure to extreme heat. However, make sure your indoor environment is also cool and well-ventilated.

Not all homes have air conditioning, and indoor temperatures can still climb during a heat wave. If your home is hot, consider exercising in a climate-controlled setting, such as a gym, recreation center or other public facility.

How listening to your body can be lifesaving

One of the most important things to remember during a heat wave is that your body may not perform at its usual level.

Instead of focusing on pace, distance or personal records, shift your goal to staying active while minimizing your risk of heat-related illness. Shortening your workout, slowing your pace or taking rest breaks can reduce strain on your body while allowing you to maintain your routine.

"Consistency is more important than pushing through dangerous conditions," says Dr. Trivellas. "Missing one workout or modifying your routine for a few days is much better than ending up with a heat-related illness or injury."

Most importantly, listen to your body. If you feel dizzy, weak or unwell, stop exercising and move to a cooler environment. When temperatures soar, the best workout is one that supports your health, not one that puts it at risk.

Learn more about exercise and fitness; get the latest health and wellness news, trends and patient stories from Sharp Health News; and subscribe to our weekly newsletter by clicking the "Sign up" link below.