Bikram Yoga is a system of yoga that Bikram Choudhury synthesized from traditional hatha yoga techniques and popularized beginning in the early 1970s. All Bikram Yoga classes run for 90 minutes and consist of the same series of 26 postures, including two breathing exercises. Bikram Yoga is ideally practiced in a room heated to 40 °C (104 °F) with a humidity of 40%. All Bikram classes are officially only taught by Bikram certified teachers, who have completed nine weeks of intensive training endorsed by Bikram. Bikram certified teachers taught a standardized dialogue to run the class, but are encouraged to develop their teaching skills the longer they teach.