Lie face-down, arms overhead at a 45° angle (Y shape), thumbs up. Lift the arms a few inches off the floor. Activates lower trapezius — the muscle nobody trains, which holds the scapula down and back.
Secondary muscles
shoulders
rotator cuff
Form cues
1Thumbs UP — turns on the lower trap
2Lift slowly, hold 2 seconds at the top
3Small range — 5 cm off the floor is plenty
Common mistakes
⚠Thumbs neutral or down (recruits the upper trap instead)