Execution:
1
Stand with two dumbbells using a neutral grip (palms facing your body).
2
As you curl each rep, rotate your wrist so the palm faces up (supination).
3
Finish the curl at shoulder height, squeezing the biceps.
4
Lower under control and alternate to the other arm.
Tip: the wrist rotation happens during the lift, not at the end — that's what recruits more biceps fibers.