I also advise my clients to be sensible about exercising in the heat and this includes Hot Yoga. In my opinion (in some circles, a not very popular one) it is NOT ok to do Hot Yoga controlled temp or not. The room may be controlled but the individual’s body’s ability to deal with that heat is not. Muscles can overstretch in an environment where everything is too warm and there is no emphasis on honoring when you feel too hot. It’s just supposed to be “good for you” or “a great detox when you know you’re hot”. Unless teachers or studios can be 100% sure that their students don’t have hypertension, are drinking enough water or any number of other factors, they better understand the liability they may be signing themselves up for. Now, I do practice yoga and prefer to have my room warm but I don’t purposely heat it to an unnatural temp. It’s supposed to be the internal heat that is raised, not external.