Yoga certainly seems like it's more than just stretching. I mean, just try standing on your hands for a few minutes a day. And take a look at people who do yoga--Rodney Yee, Madonna, Christy Turlington--they're looking pretty strong with their lean muscle tone. That may be true, "but I would venture to say that those bodies didn't just happen from yoga and good genetics. It's the increased awareness of their bodies--what they eat, how they eat, other fitness activities and general lifestyle--that's what creates those lean, fit-looking 'yoga bodies,'" says Lewis Maharam, M.D., a physician specializing in sports medicine and the medical director of the New York City Marathon.
But don't run to the yoga studio just yet. The problem is that people who practice yoga may be short-changing themselves into thinking they have all angles of fitness covered. "I think it's human nature to hope for a quick fix--one simple thing you can do to stay healthy--but yoga is not a magic bullet. In order to achieve a total body workout, you still need to have all the components of fitness," says Erika Dillman, fitness enthusiast and author of The Little Yoga Book (Warner Books).
"Although there are strength training benefits from practicing yoga, it's foolish to think that you can substitute yoga for strength training. Once you master a specific yoga pose and your balance is really good, then you are no longer taxing yourself. In order to get true strength training results, you have to continuously tax your body," says Dr. Rice.
Dr. McCall tends to disagree, arguing that "you're not going to develop enormous muscles, but you can develop strength and build functional muscles--and from my experience, people tend to develop muscle strength more quickly than flexibility while practicing yoga."
And what about yoga as a cardio workout? Again, most experts agree that it isn't a substitute for a brisk walk, jog or bike ride. To investigate this issue, we sent a woman to both a yoga class and a spinning class to compare how long she was in her target heart rate range during each activity. A person's target heart rate is the rate at which the heart should pump during exercise--experts say it should be between 60 percent and 90 percent of your maximum heart rate for optimal cardiovascular fitness.