STARTING POSITION:
Select the appropriate weight of the dumbbells. Get on your knees on a incline bench (around 30º) and place your chest on the backrest. The arms should be perpendicular to the floor and the palms should face each other. Retract your shoulder blade.
MOVEMENT:
Contracting your biceps, fully bend your elbows supinating your hands while you exhale. Return to the starting position in a smooth movement while you inhale.
TIPS: While your are doing the exercise, move only the elbow joint, make sure you don't move any other part of your body. The exercise key is quality over quantity. The trick is to perform the exercise using proper form.