In the summertime many of us are itching to ditch the gym and go for a run outside or take an outdoor yoga class — but it's just so damn hot and humid. Right now, as many parts of the country are riding out a hellish heat wave, you might be wondering whether working out in the heat is a good idea? Exercising in the heat can be dangerous, because it puts you at risk for heat-related illness, so it's important to know when to take things indoors.
The two most important factors to consider are temperature and humidity, because while sweating in a hot yoga class can be relaxing, exercising in heat and humidity is a brutal combination. During any type of exercise, it's normal for your body temperature to rise between 2-3 degrees, according to the American Council on Exercise. Usually, sweat cools you down and regulates your body temperature. But in a humid environment, it's harder for sweat to evaporate on your skin, so your body has to work even harder.
The National Weather Service has a handy chart called the heat index that you can use to tell how hot it feels relative to humidity and temperature. Basically, the hotter it is and the higher the percentage of relative humidity, the riskier it is to work out. For example, if the temperature is 88 degrees, and the relative humidity is 85%, you can look at the chart and determine that it'll feel like it's 110 degrees out. The heat index chart also clearly lays out at what point you need to be worried about heat-related illnesses (it's broken down into: caution, extreme caution, danger, and extreme danger). In this example, the temperature and humidity would put you in danger, so it'd be wise not to work out in the heat.
While this might seem simple enough to follow, it's easy to misjudge the conditions and then realize that it's too hot in the middle of a workout. It's always better to err on the side of caution and listen to your body if it feels like you need to stop. There are a few symptoms of heat-related illness that you should be aware of, like heat cramps, nausea or vomiting, weakness, fatigue, headache, and dizziness, according to the Mayo Clinic. If you experience any of those, then you should stop exercising immediately, find a cool place, and grab someone to stay with you until you cool down.
Of course, the best way to prevent heat-related illness is to just stay out of the heat and work out in a gym where the air-conditioning is blasting. (If you don't belong to a gym, see if a local community center is hosting any indoor workout classes.) But if you're committed to exercising outdoors for whatever reason, then just be careful.
Plan your workout for the early morning or wait until the evening, when the sun is lowest, according to the Mayo Clinic. Start slow, and keep in mind that it takes most people 7-10 days to acclimate to the heat. Dress in loose, lightweight, breathable clothing, and avoid dark colors or thick fabrics. And please, please, please hydrate. A few hours before you work out, drink 17-20 ounces of water, then drink 7-10 ounces every 10-20 minutes during your workout. When you're done, keep drinking water to replace the fluids you've lost.
The thing is, while many of us are basking in the summer weather, it can get dangerous fast. But with these tips you'll hopefully know when to GTFO of the heat. And hey, you could always wait until fall to work out outside.