Sharon, a 36-year-old fashion designer who began doing the class as a way to open parts of her body that felt "locked up," says the exercise is complementary to yoga. Yoga, she explains, gradually leads up to twisting and stretching movements, whereas you dive right into them in the Gyrotonic system.

For some women, Gyrotonic acts as a form of physical therapy. Becky had consistent complaints of lower back pain that led her friend to suggest the new workout as a possible cure. For her, the class's emphasis on "opening your body and increasing flexibility" has allowed her more physical freedom, such as being able to turn her body in directions it could not have gone before.

No matter the reason women get into Gyrotonic, Sharon explains they love it because "it feels so good." Even first-timers can walk out of a session feeling lighter in their joints and more energetic.

Additionally, Gyrotonic comes with a hefty price tag. Because of the unique machinery used in the class, it cannot be performed at home without buying the equipment, and even in the gym, you must be trained on the machines before going at it solo. Private sessions typically cost $50 to $85 each. Many women take only one class a week, but if the cost were less, they say, they would come more often.