Bikram yoga – also known as "hot" yoga – was created in 1971 by Bikram Choudhury, an Indian entrepreneur based in Los Angeles, who still travels the world to teach it. Bikram yoga is called "hot" for good reason: classes are held in rooms with the temperature set at 105 degrees Fahrenheit and the humidity controlled at 60 percent. It consists of 26 yoga poses (asanas) designed to warm and stretch muscles, ligaments, and tendons in a specific order. On his website, Choudhury claims that these 26 poses "systematically work every part of the body, to give all the internal organs, all the veins, all the ligaments, and all the muscles everything they need to maintain optimum health and maximum function." He maintains that the high heat is necessary for protection of muscles and to "allow for deeper stretching, to detoxify the body (by opening pores to let toxins out), to thin the blood to clear the circulatory system, to increase heart rate for a better cardiovascular workout, to improve strength by putting muscle tissue in an optimal state for reorganization, and to reorganize lipids (fat) in the muscular structure."
It's true that warmer muscles are more flexible and better able to stretch. But I have concerns about exercising in high heat since it can be particularly stressful on the body (even for those who are very fit). It is also easier to overstretch muscles in a hot environment without being aware of it at the time. If you do overstretch, you may suffer for it later with muscle strains or even damage to joints. If you have heart disease or are pregnant, I advise you to choose other types of yoga.
If you decide to try Bikram yoga, be sure to drink plenty of water throughout the routine and pay close attention to how you feel. Take a break if you find the poses too strenuous and stop immediately if you feel dizzy, lightheaded, overheated or experience chest pain. In general, I suggest avoiding Bikram yoga if you're sensitive to heat and have experienced heat stroke or dehydration in the past. If you have arthritis or any type of joint problem or high (or low) blood pressure, be sure to check with your doctor before taking a Bikram yoga class.
Although I have reservations about this particular variant, I believe that yoga is one of the best forms of nonaerobic exercise. It can improve muscle tone, flexibility, and balance. And whether you practice it for this reason or not, yoga may also make you calmer and more balanced, emotionally and spiritually.
Andrew Weil, M.D.