Position a preacher bench so that it faces a cable machine.
Grasp the straight bar of the cable machine with an overhand (pronated) grip and sit on the preacher bench.
Rest your upper arms on the padded surface, in line with your shoulders.
Exhale as you slowly curl the straight bar up towards your shoulders.
Hold for a count of two and squeeze your biceps.
Inhale as you slowly lower the straight bar 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.
Adjust the seat to ensure that your upper arms lie flat on the padded surface.
Keep your reps slow, steady, and controlled to get the most out of the cable reverse preacher curl. By taking out any momentum, you will better isolate, and increase the tension on, the muscles being worked.
The outer (long) head of your biceps brachii is activated more than the inner (short) head is because, at the top of the movement, the inner head develops slack (i.e. enters into active insufficiency). This is true with all preacher curl exercise variations.
The reverse preacher curl can also be done using an EZ bar, dumbbells, a barbell, or resistance bands.