If you’re just headed out for a short hike or run near your house this summer, bring water and wear sunscreen. If you’re planning a longer epic, you’ll need to be more careful. For advice on hot-weather mistakes and helpful gear to stay cool, I called up four professional ultrarunners—people accustomed to running stupid-far distances in unbearable heat—who gave me a host of smart, surprising ideas. Here are the six mistakes they see most often.
#1. Stripping Down
It’s tempting to take off your shirt to stay cool, but that can actually make you hotter. “That radiation from the sun is going to heat your core temperature up more than if you have a light layer and a hat that will give you a little shade,” says Salomon pro Max King. He suggests a breathable white layer that will let you vent and also reflect the sun. My pick is Patagonia’s Capilene Lightweight Crew. Also make sure your lid breathes: trucker hats with a brim and mesh back are an easy, cheap solution.
#2. Drying Out
During the winter, you want your clothes to stay dry. During the summer, you want them to stay wet. “I want my top to stay as wet as possible,” says Nike runner David Laney. Cotton T-shirts are great at holding onto moisture, so that’s what Laney suggests for the hottest days. I personally like the cheapest cotton T-shirts I can find at places like Walmart and Target. He also suggests dunking your shirt in a river or pouring water onto your head and chest every chance you get.
#3. Ignoring Your Core
Many of us just pay attention to how our skin feels under the sun. But when it’s dangerously hot, you also need to pay attention to your core temperature. Dean Karnazes, who has run the Badwater ultramarathon through California’s Death Valley ten times, says temperatures creep up to an astounding 130 degrees. When it’s this hot, he likes to place ice around major arteries so that it can cool his blood. For example, he’ll tie a bandana around his neck and fill it with ice to cool his carotid. (A Buff would work equally well.) He also recommends RecoFit arm sleeves, which can hold ice on your radial arteries.
#4. Soaking Your Feet
You do want a wet core, but you don’t want wet feet. “Wet socks in hot shoes and hot ground conditions is a recipe for blistering,” Karnazes says. When you’re dumping water over your head, spread your legs to avoid your feet. Also, avoid waterproof shoes. No waterproof liner can vent sweat fast enough in hot conditions to keep you from getting wet feet and possible blisters. On hot days, I like to run in the Hoka Speed Instincts because of their lightweight uppers.
#5. Poor Water Planning
On long hikes or runs, you can’t realistically carry enough water to drink and pour over your head. So you’ll need to carefully plan to stop by water sources along the way, whether that’s a mountain stream or a 7-Eleven. King also suggests that you plan for your terrain. You’ll get much hotter running or hiking up hills, of course, and so you’ll need more water to cool off.
#6. Not Acclimating
“The biggest mistake that I think people make is heading out early in the summer thinking that they can do the exact same [distance and speed] that they could do at the end of the summer last year,” King says. “It takes time to acclimate to the heat.” One acclimation tip from King: overdress in the spring. When you head out for a run on a 60-degree March or April day, wear a thick midlayer like the OR Deviator Hoody instead of a just a running shirt, which can simulate hotter temperatures. King also suggests spending time in a dry sauna for 30 minutes a day to get your body ready for the heat.
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