Skull Crusher

Lie down on a bench or on the floor and grab the bar with an overhand grip, hands shoulder width apart. Bring the bar down to your forehead while keeping the elbows pointing up. Extend the arms and bring the bar back to starting position. Don't let your elbows move. Inhale on the way down and exhale on the way up.

Dig your heels into the floor to keep the core tight and stable.