Sit on a stability/birth ball, feet flat, knees at 90°. Roll the ball forward and back via the pelvis (NOT the whole body), then in circles. 5 minutes total. Late-pregnancy mobility for the SI joint + opens the pelvic outlet — same drill midwives recommend for early labor.
Secondary muscles
glutes
hip flexors
Form cues
1Pelvis leads the motion — torso stays relatively still
2Feet stay flat on the floor as anchors
3Small circles both directions for full SI release
Common mistakes
⚠Rolling with the whole body (defeats the SI focus)
⚠Ball that's too small or too inflated — sit so knees are at 90°