During that time period, with regular exposure, physiological changes occur that help your body better deal with heat stress. For example, you get sweatier faster, and the evaporation of that fluid from your skin allows for better cooling. Other indications include keeping skin and core temperatures lower and heart rate and blood flow more stable.
All of this means that it’s important to start exercising when it’s hot out, Seely says; she wouldn’t have attempted hard interval training at the start of the summer.
Whatever your usual routine, take a couple of steps back the first few times you exercise in the heat, Seely suggests. Go for less time, fewer miles, or a lower intensity (perhaps more walking instead of running, for example). Over a period of a week or two, you’ll likely start to notice things feel easier, and you may gradually start to recover.
However, even after you’re acclimated, any given workout is likely to feel more difficult in the heat, Kylee Van Horn, RD, a registered dietitian, certified running coach, and ultrarunner in Carbondale, Colo., tells herself. That’s not necessarily a bad thing, just something to keep in mind, so adjust your expectations and don’t get hung up on hitting the same times or paces you might in cooler weather. Lastly, if you still want to push yourself hard and it’s really hot outside, do your training inside.
2. You feel hot when you don’t exercise.
Although it may seem counterintuitive, you can speed up the acclimatization process by spending time between workouts sweating too. In a study from the University of Birmingham, researchers asked 20 trained runners to jump into the sauna for 30 minutes after an easy run. After three weeks, they were more heat tolerant, as measured by core body temperature and heart rate in warm training, and what’s more, they ran faster in more moderate weather conditions.
When preparing for the 2021 Speed Project, a 300+ mile race from Los Angeles to Las Vegas, ultra runner Jes Woods used this method, adding 30 minutes in a sauna after each day’s run over a 10-day period. And Adidas Terrex athlete and ultrarunner Abby Hall goes to the sauna for 20 to 30 minutes in recent weeks before a big event like the Western States 100 (a 100.2-mile event with temperatures topping 100 degrees) or a race with the fastest known time in Death Valley.
No access to a sauna? Simply sitting in a steam room can also work, says Woods. However, as Howard points out, research suggests that the water should be around 104 degrees, a temperature that can be difficult to maintain for the 20 to 40 minutes required. (Also, the water temperature shouldn’t get any higher than that, according to the CDC.)
However, that is not to say that you cannot harvest some benefits without getting super intense with it. Simply spending 60 to 90 minutes in the heat doing some physical activity that isn’t as strenuous as your usual exercise (going for a walk, for example) might also stimulate some similar physiological changes. And just sitting outside with a book or a smoothie could also be beneficial, helping you change the way you think. “Sitting (hot temperatures) will probably give you more mental resources to endure and enjoy than any actual physical adaptation, but mental resilience is also very important,” Howard says.
3. Hydrate, hydrate, hydrate, even before your workout begins.
Preparation is key to hydration in the heat, hiker Natalie Smart, who owns a travel business called Destination Hike, tells SELF. while the hydration during every walk is essential; she advises her hikers to bring two liters of water for every warm-weather adventure, regardless of distance; It’s not something you can crave for. Instead, she gets a boost by staying on top of her fluids beforehand. “People don’t realize that it’s the day before that can set you up for success or failure,” she says.
