Posture is a strength problem more than a habit problem

Telling someone to sit up straight fails because the position they are being asked to hold requires mid-back endurance they do not have. Within minutes they return to the position their body can actually sustain.

The route to lasting change is building the capacity to hold the better position, which means loading the mid-back and mobilizing the thoracic spine so the position is available in the first place.

The sequence

Mobilize first, then strengthen in the new range. Strengthening a range you do not have simply reinforces the existing pattern.

  • Arc or spine corrector over the carriage — 2 minutes of supported thoracic extension
  • Breaststroke prone on long box — 1 spring, 8 reps
  • Pulling straps 1 and 2 — 1 spring, 8 reps each
  • Seated rowing — 1 spring, 8 reps each variation
  • Chest expansion, kneeling — 1 spring, 10 reps
  • Standing roll-down at the footbar — 3 slow repetitions

Where the ribs sit

The single most useful cue for posture work is keeping the lower ribs down over the pelvis rather than flaring forward. Most people who "stand up straight" do it by lifting the chest and flaring the ribs, which trades one compensation for another.

On the reformer, watch for rib flare in any overhead or extension work. If it appears, that is your working range boundary for now.