In a small study sponsored by the American Council on Exercise, researchers put 20 men and women between the ages of 28 and 67 through a traditional Bikram yoga class, measuring participants’ core body temperature and heart rate throughout the session. They found that the heart rates generally went up and down with different poses, but the body temps of the participants slowly rose. At the end of 90 minutes, the average body temp was just above 103°; 104° is when you can expect to notice some of the early signs of heat stroke or exhaustion, like dizziness, lightheadedness, and nausea, says ACE chief science officer Cedric Bryant, PhD, who oversaw the study. MORE: The Surprising Way Gentle Yoga Can Help You Lose Serious Weight These study participants never got to the point of heat illness (a broad term for illnesses like heat exhaustion and the more serious heat stroke) but that’s probably because they were regular Bikram yoga practitioners, says Bryant. “Their bodies were already acclimated to the heat and humidity. If you’re just starting out, it’s going to take 4 of 5 sessions for your body to adjust.” So while it’s always important to maintain proper hydration before, during, and after a Bikram yoga session, it’s especially vital when you’re just starting. If you don’t drink enough water and become dehydrated, your body’s less able to regulate your temperature, says Bryant. He recommends drinking 16 to 20 ounces of water (about 2 cups) about an hour before class, and another 16 to 20 ounces afterwards. One way to make sure you’re properly hydrated before a session is to check out your pee. “If it has a color like apple juice, you’re going to need to drink some more water,” he says. “If it looks more like lemonade, you’re probably in good shape.” MORE: 7 Things Your Urine Says About You Of course, keep in mind that not all hot yoga is created equal: Researchers performed a similar study a few years ago in a Vinyasa yoga class, where the room temperature peaked at about 95°, says Bryant. “In that situation, the practitioners had lower body temperatures than the Bikram yogis.” MORE: The 10-Minute Easy Yoga Routine That Can Help You Lose Weight So if you’re sensitive to the heat, consider opting for a class that doesn’t feel like you’ve just walked into the Sahara the moment you open the door. And if you are going to practice in the heat, drink up and remember to listen to your body. If you start to feel light-headed, nauseous, or dizzy—rest on your mat, drink some water, and, consider leaving the room for a few minutes to take a break from the heat. “If you listen to your body, you’ll be just fine,” Bryant says.
