I'm just back from hot yoga class. This was the fourth time for me to try it so now I feel I've had enough experience to comment.
I'm taking the hot yoga classes at my gym, which is not a specialized hot yoga studio. They just crank up the furnace and portable heaters to heat the room. So, this is not official Bikram® yoga, but rather, a knock-off version. I decided to try hot yoga because I hadn't been particularly challenged by any of my workouts recently, and because it was something different. Also, I love the feeling of relaxing in a sauna - I thought the class might be similar.
Before my first class, I was nervous. I didn't know what to expect. I searched online and asked around for advice on how I should prepare. I heard that I should drink lots of water during the day before class but not for two hours before. I also heard that I shouldn't eat anything for four hours prior to prevent cramping up. I was advised to bring towels and to dress minimally. I did all of these things. It turns out that I needn't have been so concerned about getting a stitch from eating or drinking too soon before class although I wouldn't recommend eating a meal beforehand. I expected the studio to be sauna-level hot, but it wasn't. It was warm enough to bring out a damp glow, but I would not have minded a higher temperature. Perhaps the true hot yoga rooms are hotter than what I tried.
I've been taking yoga classes on and off since undergrad but I'm not all that good at it. Pose 5 in the chart is impossible for me (you should see my perfect 6 and 11, though!). From what I understand, hot yoga is supposed to make your muscles more stretchy, allowing you to improve your flexibility. For me, I felt that the heat made the poses more challenging which in turn required me to focus more. In most yoga classes, my mind wanders all over the place. In the hot yoga studio, I'm forced to really concentrate on my posture and my muscles - I think this makes the exercise more worthwhile.
Have you tried hot yoga? What do you think?