Pin the pulley height on a cable to its highest setting and pin a suitable weight. Your feet are planted firmly and your core is tight as you take position in front of the cable rack. Take an overhand-grip on the bar, just outside of shoulder width. You elbows are locked to your sides and when you take the weight, your forearms will be angled up toward the cable pulley. This is the starting position.
Commence the movement by squeezing the triceps and extending your arm in a large arc from the chest around to the groin. The elbow acts as a hinge joint - the upper arms should remain stationary, elbows pinned to the sides and the movement comes only from the forearms. You should feel a large contraction through the triceps. Exhale through the movement.
When the arms are fully extended and the bar approaches your groin, reverse the movement by returning the arms back to the starting position without lifting your elbows, inhaling as you do.