The two students in Kim Bigelow`s Tuesday afternoon advanced class at Core Wisdom Pilates studio shift into a new position in their exercise sequence, exhaling with every other movement.

Their instructor alternates between padding lightly around the room -- offering advice and correcting posture -- and sitting on the sidelines, observing the way they curl their backs and shape their bodies.

What is Pilates?

"Pilates is a form of exercise, developed by Joseph Pilates, that emphasizes the balanced development of the body through core strength, flexibility, and awareness in order to support efficient, graceful movement. The six core Pilates principles are Centering, Control, Flow, Breath, Precision, and Concentration."

Source: About.pilates.com

Pointing from her crouched position on a Pilates chair, Bigelow indicates the slight quiver in her students` stomachs.

That`s how you can tell that this is more than a surface exercise, she says. The deep, core muscles are being activated and strengthened.

This deep muscle workout is what Bigelow said is the primary concentration of Pilates. Each exercise is designed to increase body awareness and core strength, which can help students improve posture and flexibility as well as counterbalance the everyday strain they put on their bodies.

"Pilates is a very diverse method of movement and exercise," Bigelow said. "It`s more of a lifestyle -- it`s something that you choose to do to really make a change."

Mind, body, spirit

Rachel Segel, co-owner of the Pilates Center, said that Pilates exercises the body, mind and spirit, effectively creating a healthier individual. A lot of times, she said, people put everything they have into work, school or their other daily tasks. They come home, exhausted, and feel the weight of a very imbalanced life.

By doing Pilates, Segel said that people can become invigorated and energized, making more time to simply be happy.

"Joseph Pilates was hoping that if people did his work, they would actually have a lot of energy left after their job," Segel said. "Therefore their lives would be much richer and fuller."

Segel said that Pilates instructors concentrate on educating their clients to eventually become autonomous enough to do the work on their own. It is an exercise, she said, that can be as gentle as is needed for someone rehabilitating an injury or as advanced and as challenging as would be required for an Olympic gymnast.

It all depends on how the student chooses to use it.

"You can`t get bored, because you can always make it harder and more complicated, whether it`s mentally more challenging, or physically, or both," Segel said.

Lindsay Ross, a Pilates instructor at Body Dynamics, said that Pilates is a good activity for people who don`t normally enjoy working out, because it`s a more low impact exercise that operates well for injury prevention, cross-training, muscle toning and stress relief.

Bigelow said that students don`t necessarily shed the pounds in Pilates classes because it`s not a cardio-based exercise. What they do tend to see is the development of longer, leaner muscles, she said, as the body reorganizes itself and tones them in a different way.

'Another tool`

Patrick Grace, a 39-year-old Longmont resident and student at Core Wisdom, said that he does Pilates in addition to going to the gym because, while the gym helps him with specific areas that he wants to improve upon, Pilates provides an overall balance for his body. He said that it also opens up his joints and decreases compression, which has been instrumental in helping with his back issues.

"It helps me add another tool in trying to keep my back in shape," Grace said.

Segel said that Pilates is very vast, and has phenomenal potential, but that clients should be cautious and educate themselves on what makes a good teacher. She said that they should shop around for someone who is certified and has a good training program behind them.

"The body is our most complicated instrument," Segel said. "We take our car to a good mechanic -- we need to think of our body that way. We need to take our body to someone who is really good."