Hips drop — body sags
Core fails; hip flexors disengage from the plank position.
Overactive muscles
Hip flexorsErector spinae
Corrective work
Foam RollHip flexors↗StretchHalf-kneeling hip flexor stretch↗Core fails; hip flexors disengage from the plank position.
Rings stay neutral; infraspinatus and teres minor underactivate.