Last updated: Feb 09, 2012
Bettina Lewin/Folio-ID
Finding a yoga class used to be simple. Youd walk into your local gym and there would be The Class. Your choices were few because, well, there werent that many people looking to get their om on: In 2001, 4.3 million Americans were hitting the yoga mat; just over a decade later, that number has almost quadrupled to about 16.5 million. Studios, gyms, and rec centers now offer an estimated 800-plus styles to choose from, says Leigh Crews, a spokesperson with the American Council on Exercise. Some of it has to do with yogas (well-deserved) reputation for being an excellent stress reliever. But a big part of yogas popularity surge is its just plain good exercise. Virtually any type of yoga improves strength, flexibility, and balance, explains John P. Porcari, PhD, director of the clinical exercise physiology program at the University of Wisconsin–LaCrosse. "The more intense styles can also help you shape up and trim down."

Want to take full advantage of that powerful collection of benefits? Read on for everything you need to know, whether you are a first timer or a regular looking to take your poses to a whole new level.

If you are just beginning or want the best mind/body combo, try Hatha
Poses are straightforward, and the pace unhurried. "You do a pose, come out of it, then do another," explains Mark Stephens, author of Teaching Yoga: Essential Foundations and Techniques. "Its an excellent style for beginners." Props like blocks and bolsters are often used to help you get the right alignment. But its not just about the body, as your teacher will also encourage you to focus on breathing, relaxation, and meditation (which may involve chanting). And all of this mindfulness has a real-world benefit: A study in the journal Psychosomatic Medicine found that women who practice Hatha yoga once or twice a week recover from stress faster than those who dont.

If you want to get slim, try Ashtanga Power Yoga
These two provide all the regular benefits of yoga with the fat-blasting bonus of a killer cardio session. Both styles focus on flowing from one pose to the next without rest—making for a terrific calorie burn (about 500 per hour). "The practice is meant to generate heat in your body," says Mandy Ingber, the yoga instructor behind Jennifer Anistons ageless body. So, yes, you will sweat. A lot.

In Ashtanga, the more traditional of the two, youll begin with chanting, then follow a sequence of poses ("asanas") that never changes. In a Power yoga class, the poses vary each time and theres usually none of the spiritual aspect.

A large study in the journal Alternative Therapies in Health and Medicine confirmsthat women get lean in these classes: Practicing yoga of any kind at least once a week for four years or more stavesoff middle-age spread.

If you want to chill out, try Yin Yoga
Named for the calm half of yin-and-yang, this style requires you to move slowly into poses (most of them seated or lying down), then stay there for up to five minutes to allow for a xdeeper stretch and time to just, well, be.

Not surprisingly, Yin yoga is particularly good at activating the part of your nervous system that helps you bounce back from pain and stress, says Sara Gottfried, MD, an integrative physician in Berkeley, California, and author of the forthcoming book The Hormone Cure. Expect meditative music and lots of attention to breathing, as well as those centers of spiritual energy known as chakras—all elements that add to the serene allure of the practice.

If youre prone to aches, try Iyengar
As in many types of yoga, the poses youll do in an Iyengar class are traditional. The difference is in how those poses are done. Iyengar teachers are trained in biomechanics, so they understand which positions are most likely to cause injuries—and how to modify them by tweaking your form and showing you how to use props to make them less intense, says Stephens. Plus, a pause between poses (as opposed to flowing from one to the other) allows you to perfect your position, so youre less likely to strain something.

Iyengar may even help you recover from injury. A study in the Archives of Internal Medicine found that a similar style of yoga, Viniyoga, worked wonders on chronic low back pain in just 12 weeks.

Find the right class
The truth is, you can find a great instructor and class in a church basement, and a questionable one in a fancy yoga studio. Just keep in mind this rule-of-thumb: Your teacher should be properly trained, with at least a 200-hour certification
A More Flexible You in 5 Minutes
Treat your body to this stretch-you-all-over mini-routine from yoga instructor and DVD star Seane Corn, who teaches at Exhale at Sacred Movement in Venice, California.  Read more
from Yoga Alliance, the main yoga education organization in the United States. Below, the scoop on your options:

Yoga studio

The coaching: Most require teachers to have Yoga Alliance certification. Some also require additional in-house training so teachers can learn the studios specific style.
The classes: Practice rooms are zen-like and class options abound. Studios that are part of national chains may also offer lockers and showers.
The crowd: Morning classes tend to be smaller (10 to 20 people), but post-work classes may be packed. "In big classes theres usually additional help from yoga instructors who are being mentored by the main teacher," says KayKay Clivio, head of teacher training at Pure Yoga.
The cost: $12 to $20 per class; $100 to $190 per month for unlimited classes. Ask about free trial classes.

The gym

The coaching: Teachers are usually certified by Yoga Alliance, but since many gyms dont pay well, you may end up with a teacher whos certified but less experienced, says Timothy McCall, MD, author of Yoga as Medicine.
Getty Images
The classes: Most gyms provide props and a variety of classes, including yoga hybrids (though the benefits of pure yoga often get lost); atmosphere is less serene than a studios. Then again, you get to hit the steam room after class.
The crowd: After-work classes average 25 to 40 people—usually without additional teaching help—and classmates may be less serious about yoga.
The cost: Usually free with gym membership.

The rec center

The coaching: Teachers sometimes have group-fitness (as opposed to yoga-specific) certification, which is not ideal.
The classes: Usually a few styles with BYO props.
The crowd: Classes tend to be crowded.
The cost: Many charge by the class, others by the year. Discounts are often available for residents.

In the end, what matters is that youre comfortable in the class. If that first one isnt a good fit, try a different style, a different teacher, or both. And once you find that perfect combination, stick with it, says Dr. McCall: "Youll get the most benefits from yoga if youre a regular."