Since Pilates first popped up in the 1990s in group fitness programming at health clubs, it has developed a large following of dedicated students. In fact, Pilates participation has grown by 456 percent in the past 10 years, according to a 2010 study by the Sporting Goods Manufacturers Association.

However, as many instructors have discovered, those dedicated students now want more from their Pilates classes, and Pilates has become so mainstream that its core strength elements are being used in small traditional group cardio classes, and elements from other classes have seeped into Pilates classes. This fusing of Pilates was once controversial as some devotees worried it could dilute Pilates’ principles, but it is now commonplace in many fitness facilities.

To teach an effective and safe fusion Pilates class, though, instructors need to be well-trained in the other types of cardio exercises that they are blending with Pilates so that their clients can move smoothly through their exercises, many Pilates experts say. They also must keep in mind all of their Pilates training in addition to what other exercise group training they may have, says Portia Page, education project manager at Balanced Body, Sacramento, CA.

Pilates is still being fused with yoga, but it also is now being used in post-rehab programming, pre- and post-natal programming, and golf and athletic conditioning, says Stefania Della Pia, program director, education and master instructor trainer at Merrithew Health & Fitness (Stott Pilates), Toronto.

Some clubs are stepping even further outside the box, mixing Pilates with some of the latest programming trends to capitalize on their popularity.

“I call it Pilates on steroids because it takes Pilates to the next level of stability and conditioning,” says Dana Goodale, director of Pilates at Woodside Health & Tennis Club, Westwood, KS. She combines TRX suspension training with Pilates mat work or the Reformer on a rotating basis.

The TRX Pilates class is for more advanced Pilates students who already have a basic understanding of core stability and balance, says Goodale. Her classes are small—generally four people—but in the few months she’s offered the classes, it’s become so popular that she has a waiting list.

Meshing Pilates with other exercises expands programming options for certified instructors and trainers and broadens the type of workout members receive.

“By piecing together Pilates with more aerobic exercise, it sparks my clients’ normal routine,” says Page, who has been teaching Pilates and other group exercise classes for more than 20 years. She works with a small group of students two times a week at Propel Pilates and Fitness. “They don’t know what to expect. It shakes up their workout so they don’t hit a plateau.”

The fusion Pilates classes offered at clubs often depend on the type of equipment they have and how they choose to define and combine their fusion Pilates classes. Page typically has students warm up on a treadmill, bike or stability ball or by doing squats or lunges. She then instructs them in traditional Pilates moves so they become aware of their breathing and their core alignment. Then, she uses the CoreAlign method from Balanced Body along with other types of exercise.

Pilates fusion programs are a great opportunity for clubs and trainers to get creative, but that doesn’t mean anything goes, says Mara Braskin, owner of Vital Pilates, a boutique Pilates studio in Wilmington, DE. Regardless of what is added to Pilates, Braskin says it is important to remain true to Pilates’ core principles and to keep class sizes small so instructors can be hands on.