Exercising in the heat is serious business. For obvious reasons, overheating is not good. Your body fatigues faster, you might feel nauseated or dizzy, your head might start to ache, and, in the most serious cases, your organs might even begin to shut down.
But, over the years, a lot of misinformation has seeped into the general consciousness about how to prepare the body for enduring a hot outdoor workout. In fact, studies have shown that training in high temperatures is more effective than training at more standard temperatures.
Below, we dispel five of the more common myths and, where possible, offer some tips on what to do instead.
By all means, you do you, but know that you’re not beating the heat by losing a shirt (or more). If anything, you’re actually making yourself hotter, because your skin will absorb the sun’s heat, while a light (emphasis on light) layer of clothing reflects that heat away from your body. Wear light colors and light fabrics, even a light hat to keep the sun off of your face, and you’ll fare better.
Humid heat is different from dry heat. Key factors in differentiating heat include the levels of pollution, smog and, especially, the humidity. (Certain running events use a system of colored flags to warn participants. Yellow flags mean you might want to reconsider whether to participate.) In fact, if the humidity is high enough, the body might not be able to evaporate moisture safely — even when the temperature is lower. Check the forecast for the heat index — a more accurate indicator of how the air will feel on your body — before you head out. If there’s a heat advisory, you’ll want to stay indoors. (Which is a bummer, we know.)
While hydrating is generally a good idea, there is a recent body of research that suggests overhydrating can hinder performance as much as underhydrating. Researchers instead recommend drinking to thirst, which should help keep your body’s fluid loss to roughly 2% of body weight. Losing more or less is shown to coincide with a decrease in performance. To put it another way, if your body is dehydrated, you’ll slow down, rather than overheat. If you’re overhydrated, you’ll slow down, too. The body, being the amazing thing that it is, will probably tell you how much water is enough.
Actually, pouring cold water on your head and body does keep you cool. Precooling can help your body better regulate its temperature. (Indeed, more extreme versions like donning a cooling vest or packing ice into your underwear before you exercise are especially helpful.)
But… a recent study shows soaking in long, hot baths in the days before you train is even more helpful, especially when part of a full-on heat acclimation process. Athletes performed even better after practicing heat acclimation than after pre-cooling, but both practices improved performance versus doing zero preparation for the heat. This might all be a bit too intense if you’re a weekend or even weekday warrior, but if you’re going for that late-summer Ironman, you should definitely prepare your body for the heat.
If you’re exercising in a heated, outdoor pool, you’re just as vulnerable to overheating as you are outside of water. Be smart — use sunscreen or seek a shaded pool instead. And again, hydrate according to thirst.
One final thing: More than anything, listen to your body. If you’re feeling unwell — dizzy, nauseated, unusually tired — stop and seek shade immediately. Hydrate if possible, and call for help if you’re concerned. Be safe out there.