FAQ: What ball should I use for StrongPosture® exercises?
Dr. Weiniger’s preference and clinical reasoning behind it
People often ask me what size ball they should get. My strong position is that the numbers from ball manufacturers are too low for using the ball in the StrongPosture® MOTION track exercises.
Here’s why: Normally a proportion of people end up sitting with their hips below their knees, causing them to pitch the torso forward to compensate. In addition, a ball that places the hip joints at the less than 90° angle means the already shortened hip flexors (primarily the psoas) are unable to function and be trained towards stronger posture in a more normal lengthened state. This is the same muscle that is tight on most people who sit a lot, and which pulls the torso forward when we’re in a standing posture.
The Goldilocks issue of “too hard vs too soft” is another factor. To put another way, it’s the variable of the ball’s compliance and inflation. In order to get a ball adequately inflated to bring the hips even with or above the knees, it must be fully inflated. For many balls, this causes it to become uncomfortably hard (imagine sitting on a giant billiards ball), while for others it becomes too squishy (that is, not offering stable resistance to push against and train deep core muscle patterns).
Our recommendation for most people doing the StrongPosture® exercises is usually a 75cm ball, but inflated so that the thighs are parallel to ground when sitting just in front of top of ball, or a tad higher for comfort (e.g. hips higher than knees). My preference is the Theraband Pro series balls, but there are other good ones as well.