Execution:
1
Lie back on an incline bench with your back fully supported, arms hanging straight down for a max biceps stretch.
2
Start the movement by rotating your wrists from neutral to supinated (palms up) while flexing the elbows.
3
Bring the dumbbells toward your shoulders, squeezing the biceps at the top.
4
Lower under control, don't let the shoulders roll forward.
Tip: the stretch at the bottom is the whole point — don't cut the bottom range of motion short.