STARTING POSITION:
Select the appropriate weight on the machine preacher curl. Grab the handles with a neutral grip and sit on the bench. Your chest and your upper arms should be positioned against the pads. Hold the handles in front of you with your elbows extended. Contract your pelvic floor and core.
MOVEMENT:
Contracting your biceps, fully bend your elbows while you exhale. Return to the starting position with a smooth movement, preventing moving weights from touching the rest of the stack.
TIPS: While your are doing the exercise, move only the elbow joint, make sure you don't move any other part of your body.