Synergists: Brachioradialis, Biceps Brachii (especially the outer head)
Sit on the preacher machine.
Rest the backs of your upper arms on the padded surface, in line with your shoulders.
Grasp the handles.
Exhale as you curl the handles up towards your shoulders.
Hold for a count of two and squeeze your biceps.
Inhale as you lower the handles until your elbows are almost fully extended.
Repeat for the prescribed number of repetitions.
Comments and tips
Keep your body still; only your forearms should move.
Keep your elbows in line with your shoulders.
To ensure that your upper arms lie flat on the padded surface, adjust the seat.
The outer (long) head of your biceps brachii is activated more than is the inner head because, at the top of the movement, the inner (short) head develops slack (i.e. enters into active insufficiency). This is true with all preacher curl exercise variations, not just the machine preacher curl.