Should You Heat Up or Cool Down for a Better Summer Workout?

Summer is prime time to ditch cardio machines and get some al fresco exercise, but soaring temperatures can make it seem extra grueling. Looking for the best strategy to keep your cool so you can actually get a decent workout? Several studies have found that cooling off your body pre-sweat session in the heat can help—but conversely, new research has discovered that heating it up beforehand may actually be key. So what’s the best bet? Read on for a breakdown of the findings and to figure out which might work for you.

THE CASE FOR COOLING DOWN

There’s been much research about how chilling out (literally) pre-workout can improve your athletic performance in the heat. One of the most notable studies looked at the effects of ingesting cold drinks right before a run. Downing 16 ounces of a sweet frozen drink 20 minutes before a run helped people run 10 minutes longer than they were able to after sipping cold water without ice, a study published in Medicine & Science in Sports & Exercise found. The reason: It kept their core temperatures lower longer—a full half-hour longer, to be exact—which seems to be a crucial factor in helping to extend your performance when it’s hot out.

Other research has found that cooling yourself off before exercising with ice or by dumping cold water over your body before you head out to pound the pavement keeps your core temp down (and helps you move faster), too. In a study from the University of Brighton in England, putting their arms in icy water or wearing an ice vest or cooled underwear ahead of a 5K run in 90-degree heat helped athletes decrease their run times by nearly 4 percent.

HOW HEATING UP MIGHT HELP

But the same study also found that athletes' performance got an additional boost from spending time in warmed conditions. After riding a bike in the heat for five days in a row, runners were able to improve their 5K race times by an average of 6.6 percent. (And in fact, researchers suggest that taking a hot bath after training in the heat can amp up the effects.)

This might seem contradictory to previous findings about how cooling off is key, but it’s all about letting your body acclimate to the heat. When you’re better acclimated to hot weather, you’ll sweat more and sooner into your workout, which, in turn, keeps you cooler and going longer. Plus, acclimating to the heat improves your cardiovascular fitness—so your heart can handle pumping harder in high temps for an extended period of time, according to a report about heat-training recommendations published in the British Journal of Sports Medicine.

THE VERDICT

So should you guzzle a frosty drink or take a hot shower before heading out on a run? The verdict: Acclimation trumps pre-cooling—if you have at least a few days before an important hot run or workout to do it. Previous research has found it takes at least a few days to get your body used to training in higher temps, and you’ll notice bigger changes in adaptation after a couple weeks (no surprise to anyone who’s noticed it feels easier to exercise in the heat by the end of summer than it does during those first hot days in June).

To try heat acclimation, pedal in a hot group-cycling studio for an hour or take a hot yoga class, and then hop into a steamy shower afterward to reap the most rewards. But if you live in a cooler locale and have an unexpected heat wave or travel to a hotter city for a destination race, downing a slushie before you toe the start line might be the better choice for boosting your performance.