To the uninitiated, Pilates might not even look like something in the realm of fitness. In fact, the first time you see someone doing a Pilates class or workout, you'll probably have some questions. Are the participants doing some sort of physical therapy? What's that weird, Ikea-coffee-table-looking thing they're using? How exactly does one Pilate? And most broadly, what is Pilates? That's where we can help.

What is Pilates?

In short, it's a low-impact, resistance-based fitness system invented by German citizen Joseph Pilates while he was interned in Britain during World War I. It uses a combination of gravity and the user's bodyweight to challenge muscles and bring about a slew of benefits.

There are actually two types of Pilates classes, mat Pilates and Reformer Pilates. Mat Pilates excercises are performed on, you guessed it, a mat—basically a thicker version of a yoga mat. Moves include scissor kicks and dynamic core planks, and these classes are often recommended for beginners. Reformer Pilates classes, what most people think of when they think of Pilates, take place on the fitness method's trademark contraption.

What's a Pilates Reformer?

To better understand the central piece of equipment at Pilates studios, here's a breakdown of its six key parts:

1. Footbar: It's used as a footrest for many—but not all—moves.
2. Carriage: The platform that glides along the reformer's tracks; this is where most of the user's weight rests.
3. Straps: The ends of these are connected to stirrups, which can be looped around the hands or feet.
4. Longbox: This leather-wrapped box can be used as a seat or prop during exercises.
5. Springs: Connected to the footbar and carriage, these add resistance to exercises.
6. Shoulder rests: Similar to the footbar, these nubs sit above the user's shoulders during some exercises, but they're not necessary for all moves.

What does a Reformer do?

A Reformer takes the mat version of Pilates—where all resistance comes courtesy of gravity during upward movements—and turns it up a notch. Its straps and springs are more versatile than gravity, not only resisting movement in all directions, but also providing support during tougher exercises to offset gravity's effects. So what exactly can you on a Reformer in terms of exercises? Just about anything: lunges, squats, side bends, and leg circles, to name a few.

What are the benefits of Pilates?

It builds core strength.

All Pilates classes build core strength, but a Pilates Reformer especially challenges your core. From one-legged bridge poses to awkwardly lying on your side, the Reformer targets not just the muscles that make up a six-pack, but all of those in your entire midsection, from your back muscles to your obliques.

It improves your balance (without you having to fall and get back up).

Since it lies on a track, the Reformer's carriage isn't a totally stable surface. Its ability to roll back and forth tests your balance right away, especially on moves like the lunges seen in here. Even with this added wobbly challenge, though, it's basically impossible to fall. If you do find yourself slipping, you're usually close enough to a piece of anchored equipment to help brace yourself. Mat classes also help improve balance through such core-bolstering exercises as leg-lift side circles.

It can give you better posture.

Whether you intended to or not, you'll leave your first Pilates class with a better understanding of your body and how it works. Whether it's with regard to the spine (many instructors advise students to "peel" their spine up one vertebra at a time during exercises like the rollup) or to the pelvis (some instructors liken it to a filled bowl: keeping it from tipping too far one way puts it in a nice, neutral position), or to some other body part, you'll almost certainly leave being more conscious about how you sit, stand, and lie down throughout the day. That knowledge alone can lead to a stronger body and fewer thrown-out backs.

How much do Pilates classes cost?

If you have a regular gym membership, chances are you'll be able to find either a free or discounted Pilates class there. However, not everyone has a gym membership, and depending on the type, Pilates classes can sometimes reach upward of $100 a pop. If you find yourself in the latter situation, though, we have you covered. Groupon's inventory is constantly stocked with Pilates class deals that often slash that $100 in half.

What to wear to Pilates?

Comfortable exercise clothes you'd normally wear to the gym should be fine. You don't want your garmets to be too loose, since they could bunch up during leg raises and other exercises, and it's probably best to avoid clothes with a lot of extra detail, like buttons, zippers, or cargo pockets, since they can rub against you during mat and Reformer workouts. Wicking fabric will help keep you cool, and if you have to run errands before or after your class, it's worth learning how to wear athleisure wear (check out our picks here for a complete athleisure wear outfit for under $110.)

Pilates Reviews

Here's what Groupon customers are saying about Pilates:

"Did some floor work followed by invigorating Reformer exercise. Love the jumping and psoas stretches at the finale!" – from Kelly S.'s review of IM=X Pilates in New York City

"Stephanie made sure to provide adjustments to suit the various levels of the Reformer class participants. Challenging but not overwhelming. Exactly the workout I was looking for!" – from Kristina M.'s review of My Thrive Pilates in DC

"Non-intimidating for someone who's been out of commission for a year...Totally feel the pain the day after, in all the right places!" – from Ethel L.'s review of Natural Pilates Silver Lake in Los Angeles

"Loved the class. Warning this might become your new obsession."— from Amy F.'s review of Joie de Vivre Pilates in Denver

"Intro class is great - you get familiarized with equipment and correct posture, both of which are important to know before taking actual classes" – from Erica S.'s review of Pilates Reforming NY in New York City

"It was such a great experience that I've signed up for more sessions. The instructors are great, very accommodating to a beginner. The women in the classes I've taken have been super welcoming and supportive. Can't say enough great things about the experience." – from Frenchie K.'s review of Ultimate Pilates in Plano, TX

Looking for other ways to change up your workout routine?

Check out some of the Groupon Guide's other fitness articles to learn more about how you can add a fun, new challenge to your fitness regimen:

• 10 Types of Yoga, Explained: Whether you're looking to find your zen or boost your core strength, this article will help you find the type of yoga that's right for you.

• The Top 10 Martial-Arts Styles: Stressed out? Take it out on a punching bag or sparring partner's mitts in one of these classes, many of which hide effective cardio elements.
• What a Sword-Fighting Class Is Really Like: Find out how you can reach a knightly level of fitness in a medieval-inspired sword-fighting class.
• Pilates Exercises for New Moms: Learn about the best Pilates exercises for new moms jumping back into an exercise routine.