The summer months can be the perfect time to start training for fall races. But how does running in the heat and humidity impact your exercise routine? Should outdoor exercise, such as running, take a pause during times of high temperatures?
Jason Hageman, MD, a primary care provider at Mercy Health – Delphos Family Medicine in our Lima market, answers the questions below to keep you safe while working out.
Risks of running in the heat
Heat-related illnesses are often a result of your body’s core temperature rising too high. When it gets to unsafe levels, your sweat is no longer enough to cool it down. You are then more at risk for heat exhaustion or heat stroke.
Some symptoms of heat-related illness are:
- Headache
- Dizziness
- Heavy sweating or sudden chills
- Confusion
- Nausea
- Muscle cramps
- Rapid heart rate
- Fainting or loss of consciousness
Heat exhaustion and heat stroke are the two major heat-related illnesses people experience in the summer months. Heat stroke is more severe and can even be deadly. It’s characterized by elevated body temperatures that cause severe symptoms such as confusion, slurred speech, seizures, severe headaches, nausea or vomiting.
Heat stroke is a medical emergency that requires rapid cooling of the person affected. While heat exhaustion may have similar symptoms, such as headaches and nausea, the person will not be confused or disoriented.
“Running raises your body temperature, causing you to sweat during your workout. The harder you run, the more your body sweats to bring your temperature down,” Dr. Hageman says. “The sweat is then evaporated from your body to make you cooler. When heat and humidity are added to the mix, your body has a harder time evaporating the sweat from your body. The good news is that our bodies adapt to heat and humidity after roughly two weeks.”
What temperature is too hot for running?
While some people tolerate running in hot weather better than others, generally, avoiding running in temperatures above 95 degrees Fahrenheit is recommended. Additionally, humidity above 80 percent can also cause your body to take in as much oxygen, meaning your body doesn’t perform as efficiently and your heart and lungs have to work harder.
“An unsafe temperature and heat index varies from person to person. Personal factors including age, medical conditions, medications, heat acclimation and health all play a role in heat-related illnesses. Other factors, like the amount of clothing needed for an activity such as football pads, or length of exercise as well as the intensity of an activity, play a role in exercising safely,” Dr. Hageman adds.
Adjusting to the heat
While running in the heat is possible (with some precautions), don’t expect to head out for a run on the first warm day and feel fine. As the temperatures rise with the seasons, your body has to acclimatize to the heat.
As you get used to running in the heat, gradually increase your exposure to warm weather for seven to 14 days. As you do this, reduce the intensity and duration of your runs. As your body adapts, you will sweat more efficiently to keep you cooler and faster.
Hydration: The backbone of running in the heat
Proper hydration is crucial when running in the heat. Your body needs more fluids in hot and humid weather, even before you start feeling thirsty. Dehydration can impair your body’s ability to sweat and cool down, leading to faster overheating.
Here are some hydration tips:
- Pre-hydrate: Drink water throughout the day before your run. The ACSM recommends drinking 16 to 20 ounces of water at least four hours before exercising.
- Hydrate during the run: For long runs, sip 3 to 8 ounces of water every 15 to 20 minutes. For runs longer than 60 minutes, consider a sports drink to replace lost electrolytes, which are crucial for maintaining muscle and nerve function.
- Rehydrate post-run: Replenish lost fluids by drinking water or an electrolyte-containing beverage after your run. Weighing yourself before and after exercise can help determine fluid loss – drink 16 to 24 ounces of fluid for every pound lost during your run.
“Whether a sports drink is needed during activity depends on the duration and intensity of the activity,” Dr. Hageman says. “Consider using sports drinks when the duration of activity exceeds 45 minutes of being physically active to replenish electrolytes. It’s also important to remember to hydrate before and after exercising to prevent issues during exercising.”
More tips for running in the heat safely
Hydration isn’t the only thing you should do to ensure you are exercising outside safely on hot days. Some other precautions to take include:
- Timing: Running during the cooler parts of the day, such as the early morning or late evening when the sun’s intensity is lower, lowers your risk of heat-related illnesses. If you have to run during the hotter parts of the day, take water breaks often and try to find shaded areas to run.
- Clothing: Lightweight, loose-fitting, lightly colored and moisture-wicking clothes are essential to keeping your body cool when you run in the heat. They allow your body to breathe and sweat to evaporate, maximizing your body’s own cooling system. A hat can also protect your face from the sun and allow heat to dissipate from your head.
- Sunscreen: While it won’t keep you cooler, wearing sunscreen is still critical when you’re running. Use a waterproof sunscreen with an SPF of at least 30 to protect your skin from UV rays – including on cloudy days.
- Slow down: Your body doesn’t perform as well as it does in cooler weather. Slow your pace to account for the weather so you don’t overexert yourself.
- Cool down: It’s just as important to cool down after a hot run. Lower your core body temperature with cold towels, putting your feet in cold water or taking a cool shower.
- Listen to your body: Overall, you can follow these tips and still do too much in the heat. Pay attention to the signs of heat-related illnesses and never push through them. If you do notice them, stop running, find a cooler spot to rest and get some water.
“Drinking water is a start, but not the full picture. I recommend exercising in the cooler parts of the day, such as the mornings or evenings and with as much shade as possible. Wear cool, moisture-wicking clothes when exercising and limit caffeine as well as alcohol use to stay hydrated,” Dr. Hageman says. “Taking breaks or adjusting your intensity level while exercising can also keep you safe from heat-related illnesses. If the heat is too much, always remember that your health is more important than your workout.”
Learn about the health care services we provide at Mercy Health.
