Set the weight on the barbell to accommodate your fitness level and goals. As a small muscle group, biceps don't need heavy weight for growth. Only attempt to lift as much weight as you can while still maintaining form.
Adjust the seat on the preacher curl bench. Rest your arms comfortably on the pad. The back of your arms must press firmly against the bench with your armpits at the top.
Reach down and grab the bar with a loose underhand grip, palms facing up. Straighten your back and relax your shoulders. Contract your abdominal muscles to support your back.
Lift the bar slowly up until it reaches your chin. Your arms must stay firmly planted against the pad. Contract your bicep muscles at the top of the motion as your arms reach your shoulders.
Lower the bar slowly down to the starting position, arms extended. Elbows must stay loose, not locked. Maintain a straight back, relaxed shoulders and contracted abs during the exercise.
Repeat the preacher curls for a designated number of repetitions and sets based on your fitness goals and level.