Regular participation in yoga, regardless of the style or level, will identify and help strengthen weak points in your body, and it will help reawaken muscles that tend to be underused in even active people. Above, students practice at the Kula Yoga Project in New York City earlier this year.

The New York Times / Christian Hansen

WASHINGTON — Yoga may have a soft and peaceful reputation, but the theme at Willow Street Yoga on a recent Monday evening was fear. A large theme, to be sure, but in this case it was focused on issues such as: If I collapse from a handstand, what happens to my face?

The students in Batya Metalitz’s advanced class were no strangers to the handstand or other difficult poses, but she still encouraged them to acknowledge that some of the things she would ask them to do in the two-hour session would be unnerving.

“I want you to be okay being in that fear. Fear will encourage you to engage those muscles,” Metalitz told the group.

With yoga, tai chi and other Eastern practices moving more fully into the mainstream, the question comes up: What do they actually do? Is yoga just a nice stretch, or will it make you stronger? What about cardiovascular health? How does it stack up to the activities more commonly associated in the West with aerobic endurance, such as running or biking?

As with most forms of exercise, the answer is, it depends — on what goals you set and on how you organize your training. Watching the students in Metalitz’s class, there was little doubt that yoga practiced at such an advanced level involved serious strength. It also takes a pretty single-minded commitment. For anyone not ready to go that route, the relevant issue is whether there is value in a less intense relationship with these disciplines, referred to as “mindful exercise” because of their mental and sometimes spiritual aspect.

My own sense, buttressed in talks with Willow Street owner Suzie Hurley and others, is that regular participation in yoga, regardless of the style or level, is going to produce at least two surefire benefits: It will identify and help strengthen weak points in your body, and it will help reawaken muscles that tend to be underused in even active people.

Whether the issue is strength or flexibility, your body’s weaknesses become obvious when you start working through yoga poses, even seemingly simple ones.

Clearly, you can’t stand on your head unless a whole bunch of things are working right, but even a simple backbend can be revealing.

Which brings us to the other benefit of yoga: learning to use the right muscles at the right time. This might sound like something the brain takes care of without a lot of conscious planning on our part, but not necessarily. An overly sedentary life leads, unwittingly, to bad habits: We unlearn how to do things that ought to be natural: standing, sitting, walking, moving properly. The wrong muscles get used, the train of motion gets out of rhythm and problems ensue.

Yoga, as well as such disciplines as Pilates that require similar precision, forces you to concentrate on which muscles are engaged for each posture or exercise, and leads to more awareness of how we move in daily life.

Working through the body’s weak points, retraining muscles, building flexibility, teaching balance: All these flow from yoga practice, even if it’s limited to the less intense styles, said Ralph La Forge, an exercise physiologist at Duke University Medical Center’s Division of Endocrinology. There are other widely accepted psychological and physiological benefits as well: Yoga’s emphasis on controlled breathing and its meditative aspect, for example, can help lower blood pressure and reduce stress.

What’s missing?

“It is not intense cardio,” Hurley said of her studio’s anusara style, a more recent offshoot of the methods developed in the past few decades by B.K.S. Iyengar.

Hurley says she still goes for regular “vigorous” walks and swims to mix up her workouts and supplement her yoga.

Different styles of yoga will involve comparatively more or less motion. Some of the more dynamic, like ashtanga and vinyasa, provide “a hell of a workout,” La Forge said. But in general, he said, yoga won’t produce the same elevated heart rate or intense energy expenditure as more-standard aerobics.

And although yoga does develop underlying fitness (particularly important as we age), La Forge said there can be limits when it comes to strength training.

The styles that involve holding poses for a longer time build static strength, for example, as opposed to other sorts of exercise that require muscles to move weight through a range of motion or that build endurance by repeating motions under weight. In general, the gains in strength from yoga are limited by the type of resistance being used: namely, your body weight.

That can be plenty strong, as the students in Willow Street’s advanced class demonstrated. It depends on what you are trying to accomplish, as Hurley noted. If you decide yoga is your focus, be sure to find a studio that progresses from beginner to advanced levels; otherwise, you’re limiting yourself from the start.