Ashley Olsen's trainer, Jessica Schatz, says the star does Pilates almost daily, and "is extremely strong"


One place you’ll find Ashley Olsen almost daily? Her favorite Pilates studio.

The fashion designer and former actress works out regularly with her trainer, Jessica Schatz, in Los Angeles.

“She is extremely strong and works incredibly hard,” Schatz tells PEOPLE.

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The trainer comes up with workouts that are a mix of Pilates and yoga, with a focus on core work.

“While the work is rooted in Pilates, I combine all of my expertise to offer her an incredibly strong workout based on core strength, core stability, and core control,” Schatz says. “I also combine my expertise in yoga and biomechanics to keep things tailored to her specific body.”

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Schatz runs Olsen through several different body positions on the reformer and other Pilates tools to work every muscle.

“We do a lot of planks and variations of planks, like reverse planks, and side body core and leg work,” she says.

Schatz will also occasionally train Olsen in New York City when the Elizabeth & James designer is there, but without Pilates equipment.

“We do solid floor work, whether it be from the classical Pilates mat series or my own methodology,” she says, adding that they work on “full body strength, functional movement, focused on core strength, core stability and core control.”

“Ashley is extremely disciplined, hard working and open to trying anything new.”