Set the bar at shoulder level and sit in an upright chair directly beneath it, with your face close to the bar.
Take the bar with an overhand grip, 3-4 inches wider than your shoulders on each side. Keep your forearms perpendicular to the bar throughout the exercise.
Unlock the bar. Press it straight upward until it is directly above your shoulders. Do not lock your elbows.
Lower the bar directly downward, until it is against your chin or on your upper chest.