As a massage therapist I can't tell you how many clients I treat in recovery from hot yoga-related injuries. The heat allows for greater stretching of tissues than they should be allowed to stretch, and of course slipping on sweaty mats also does damage. Bikram in particular has a dogmatic approach that in my view contradicts the gentle, receptive, yin-focus yoga is supposed to engender, and in fact has a violent and antagonistic regard for an individual body's limitations. None of my personal objections matter if a person enjoys this kind of yoga and engages in it carefully, and I applaud whatever anyone likes. That said, when clients ask me about it, I honestly explain my concerns and hopefully help prevent injury, via awareness, should they pursue this practice. As an aside, I also do not practice Thai yoga massage, which is a recognized and valued therapeutic modality, because only a small segment of the population has joints that can tolerate it safely. The main thing to be aware of is one's ego, which overrules the sense of what our bodies can or cannot do at any specific time. To me, the very fact of hating doing something just for the sake of feeling great once it's done is a red flag. To me that's ego pushing the body beyond its capacity and past its needs. Sorry for the diatribe but I just hate to see those injuries sustained from what should be a practice that loves and honors the body rather than defies it.