If you've watched any of the World Cup being held in Brazil's Amazon, you know that heat and humidity are playing a huge part in this year's games. Soaring temps and muggy conditions in the rainforest prompted officials to institute a mandatory water break during Sunday’s game between the U.S. and Portugal—and by the looks of the sweat-drenched players, it was much appreciated. There's even been speculation as to how much advantage teams from warm-climate countries have over those from milder ones and what affect it could have on the outcome of the tournament.
While you may never play fútbol (and probably never in a jungle), heat and humidity can be just as dangerous to your exercise. Here’s how to keep your cool and have a safe, successful outdoor summer workout.
Pay Attention to Both Numbers
It's not just the temperature you should pay attention to when considering whether to hit the outdoor track versus the indoor (and air-conditioned) treadmill. High humidity can make a hot day even more unbearable, says Bret Nicks, M.D., associate professor of emergency medicine at Wake Forest Baptist Medical Center. "Sweat evaporating off our skin is what helps keep us cool and regulates our internal temperature," he explains. "If it's humid, sweat can't evaporate as easily, and you'll be at higher risk of heat-related illness." If perspiration is literally dripping off you, you may need to take a break and find yourself a cool spot until your inner thermostat can recover, he cautions.
There are plenty of things you can do before you walk out the door to make a hot-weather workout more enjoyable: Dress in light-colored, wicking clothing (choose breathable synthetics over cotton), wear sunscreen and a hat or visor (sunburn reduces your skin's ability to cool itself), and avoid peak midday heat by working out in the morning or evening, if possible. Also check with your doctor before you do any strenuous endurance training outdoors: Certain medications and health conditions can increase the risk of overheating.
Hydrate Before, During, and After
"One thing we don't do well is drink enough water before we go out for vigorous exercise in the heat," Nicks says. "If you wait until you're sweating and thirsty, you're already several liters behind and it's very difficult to catch up." For workouts less than an hour long, sipping water frequently is probably sufficient, but for longer training, choose a sports drink with electrolytes like sodium and potassium to replace what's lost through perspiration. Be sure to drink plenty once you've finished too. Cool drinks can taste refreshing, but Nicks cautions against chugging anything frozen or very cold immediately after a hard workout. "For some people, the extreme temperature difference can cause vomiting."
The World Cup players don’t only drink water, they’re also squirting their faces or pouring it over their heads. This trick works, Nicks says, as it helps your sweat evaporate so your body can regulate temperature more effectively. He recommends splashing yourself and then standing in front of a fan for a few seconds, which can help speed up the process. (Lots of sporting events and road races held in the summertime have "cooling stations" set up for this purpose.)
Obey Your Body
There’s no magic number when it comes to being too hot to work out outside, Nicks says, as everyone is different. People who spend a lot of time outdoors in hot temps will likely be more conditioned—mentally and physically—to keep their cool, which is why some soccer teams seem to be especially struggling in the heat while others aren't phased by it. According to Nicks, the best rule of thumb is to listen to your body. Take it easy if you notice that a workout seems exceptionally tough, and stop if you start to experience cramps, headache, nausea, or trouble catching your breath. And use common sense about where and when you work out, he adds. "I always tell people, if you're running on blacktop and your shoes are sticking, you probably shouldn't be out running."