Yoga is associated with flexibility, increased range of motion and de-stressing. And at more advanced levels, yoga can certainly build strength, in addition to bestowing numerous other benefits, not the least of which are mindfulness and well-being. So there's little doubt that yoga is a good workout.
But is it a complete program for building muscle mass, weight loss and cardio health? The short answer is that yoga can be the centerpiece of a good fitness regimen, but it comes up a bit short in a department or two, mainly in cardiovascular health. But yoga's power to transform the body in other areas may surprise you.
Hatha yoga -- the kind of yoga most commonly taught in classes -- will substantially improve your strength, as well as your flexibility, endurance and balance. In a study funded by the American Council on Exercise, researchers found that one hour of Hatha yoga 3 days a week brought substantial gains in chest and abdominal strength. Gains in endurance were also particularly notable in chest and abdomen, with the yoga group able to perform six more push-ups and 14 more curl-ups at the end of the trial than the non-yoga group.
A big advantage of yoga is that builds real-life strength, developing along with flexibility, balance and endurance. However, if your main goal is to bulk up, you'll make faster progress with weights.
A couple of yoga classes per week fulfills the American College of Sports Medicine recommendation of 30 minutes, 2 to 3 days a week of neuromotor exercise and proprioceptive training, which can be described as the body's sixth sense regarding its position in space. In this way yoga lowers risk of injury while exercising and in daily life, falls in older adults and improves physical function.
Alas, aerobic activity is the one area where yoga comes up short. The ACE study found no notable changes in VO2 max -- the maximum amount of oxygen you can burn during intense activity -- in the yoga group over the 8 week period. While some types of yoga such as vinyasa will raise your heart rate up somewhat, getting an all-around cardio workout means you'll still want to hit the treadmill, the stairs or some other form of heart-pumping exercise.
Yoga does not turn your body into a calorie-burning furnace. According to the American Council on Exercise, doing yoga burns about 3 to 6 calories per minute, or 180 to 360 calories for a 60- to 90-minute class. How many calories you burn can depend on the type of yoga -- an intense Ashtanga class will be at the higher end of the spectrum while a mellow Hatha practice will burn less calories. By comparison, a rigorous kettlebell workout burns about 13 to 17 calories per minute, or 800 or more calories in an hour.
However, yoga may help people attain a healthy weight in other ways, especially when it comes to staving off the dreaded middle-aged spread. Between the ages of 45 and 55, most people gain an average of a pound a year. But a 2005 study funded by the Fred Hutchinson Cancer Research Center found that people who were of normal weight at the age of 45 and had a regular yoga practice gained about 3 pounds less in the ensuing 10-year period than average.
What's more, yoga had the biggest weight-loss impact on people who were overweight -- they lost about 5 pounds compared to the 14 pounds gained by people who didn't do yoga. Researchers concluded the benefits were likely derived from a more mindful approach to eating; because yoga practice imbues mental discipline by training the mind to stay focus when the body is under stress, chocolate cravings and other weight-gain bugaboos may hold less sway.