The Powerhouse Myth: What the 'Core' Is in Marketing, and What It Is in Anatomy

Every introductory Pilates class starts the same way: “engage your center.” The instruction sounds like anatomical fact, carrying the weight of science behind it. It’s actually a layer of marketing built on a term Joseph Pilates coined for very different reasons, and on a 1990s study whose conclusions science itself has been quietly revising ever since.

What Joseph Pilates Actually Meant by Powerhouse

Pilates never talked about “the core” or “the transversus abdominis.” He called a broad region running from the base of the ribs to the pelvis the powerhouse: abdomen, low back, pelvic floor, glutes, and hip musculature working as one. To him it was a principle for organizing movement, not a list of muscles to isolate — every gesture, he argued, should originate there. That’s consistent with the rest of his method, integration over isolation, but it was never meant as a precise anatomical description, and it isn’t one.

The Study That Launched a Thousand “Engage Your Abs” Classes

Anatomical precision arrived later, and with it, a simplification. In 1996, a team led by Paul Hodges found that the transversus abdominis — a deep muscle that wraps around the abdomen like a corset — activated late in people with low back pain compared with those who had none. The idea fit neatly with a biomechanical model published a few years earlier by engineer Anders Bergmark, which divided trunk muscles into a “local” deep-stabilizing system — transversus and multifidus — and a “global” system of large movement-generating muscles — rectus abdominis, obliques, erector spinae. Combined, the two studies were translated, in clinics and Pilates studios worldwide, into a simple cue: pull your navel toward your spine before you move, to “activate” the stabilizer that fails in a painful back.

The Uncomfortable Correction That Followed

Nearly three decades of further research have worn away much of that tidy story. Later biomechanical models show the transversus, on its own, has very limited capacity to stabilize the spine. A systematic review checking whether changes in transversus activation or thickness during treatment tracked with real clinical improvement found that, largely, they don’t — the link between “activating” the muscle more and hurting less is far weaker than the slogan suggests. There’s a second twist, this one with a name attached: biomechanist Stuart McGill demonstrated that “sucking in” — the hollowing maneuver taught as transversus activation — actually reduces the spine’s capacity to bear load, because it pulls the muscle closer to the spinal axis and shortens its lever arm. Bracing the entire abdominal wall at once — what he calls simply “bracing” — provides more stability than isolating a single muscle.

What the “Core” Actually Is

Current anatomy describes something closer to a coordinated cylinder than a belt: diaphragm on top, pelvic floor on the bottom, and a 360-degree muscular wall around the middle, where the activation order depends on the task, the direction of movement, and the individual — not on a fixed sequence that always starts with the same muscle. Pilates, as a method of coordinated movement and progressive loading through that whole cylinder, remains a reasonable way to train that full system. What doesn’t hold up is the mythology that turned one of Joseph Pilates’ organizing principles into an order to isolate and “switch on” a single muscle before any other movement: the science cited to justify it has moved on, and studio language hasn’t quite caught up.