Pilates has a complete breathing system that most students and many teachers never fully learn .Each has a distinct purpose.

On March 17th, the American College of Sports Medicine published its first major update to resistance training guidelines since 2009. Seventeen years. That’s a long time in exercise science — roughly the same span that separated the first smartphone from the one in your pocket right now.

Here’s my little summary.

Every week, someone in class asks me some version of this question: “Should my lower back be flat on the mat or not?”

It’s a great question — and the answer isn’t as simple as most Pilates instructors make it sound. Because the real answer is: it depends on what we’re trying to accomplish and where you are in your practice.

During World War I, a German-born fitness trainer named Joseph Pilates found himself interned in a camp on the Isle of Man. His fellow internees were bedridden, deconditioned, and losing hope. He didn’t have a studio full of gleaming equipment. He had hospital beds.

So he took the beds apart.

Fifteen years into my dance career, I was sitting in an orthopedic surgeon’s office listening to him tell me—with the casual certainty doctors sometimes have—that he’d see me back for surgery after I tried physical therapy. My back injury had stopped me cold, and according to him, the knife was pretty much inevitable.