While physical activity is vital to maintaining optimal health, I do not recommend the growing trend of hot yoga which is not in line with Yogic philosophy of balance.
Being in these rooms with temperatures that range from 100-105 degrees is an extreme environment and with everyone profusely sweating, the air becomes full of the toxins that are being excreted. In yoga, you are to inhale and exhale fully yet as you do so, in this moist, hot space; the oxygen level is actually lower which leads to respiratory issues, dizziness and fainting.
These high temperatures also heat the head, which is not recommended in Ayurveda because it leads to agitation in the mind and hot headiness in our brain. From the Yogi point of view it activates the ego and can lead to being overly ambitious and thus causing us to push ourselves too far which can result in injuries.
Additionally, the body can become so depleted by a lack of water that muscles and tissues begin to tear due to being overly drained. This is not apparent during the class but later when the body cools down and stiffness sets in.
In the Yoga Sutras, this type of activity is described as rajas and it refers to a kind of intensity which can be compared to over stimulation. We don’t want to exist in these drastic situations as they mentally and physically tax us in severe ways, although they may seem enjoyable in the short term. Yoga should help us come to the middle, to be centered by calming our thinking and emotions. Yoga is the opposite of anything extreme. Remember your yoga practice is supposed to be a benefit to your whole life on the body, mind and spiritual levels.