Placing back of arms on pad with one foot forward, grasp curl bar with shoulder width underhand grip.
Raise bar until forearms are vertical. Lower barbell until arms are fully extended. Repeat.
Body should be positioned to allow arm pit to rest near top of pad. Back of upper arm should remain on pad throughout movement. The long head (lateral head) of biceps brachii is activated significantly more than short head (medial head) of biceps brachii since short head enters into active insufficiency as it continues to contract.