Cable Skull Crusher

Set a low cable pulley and lie back on a flat bench positioned so the cable lines up with your head, holding a rope or bar with arms extended over your shoulders. Keeping your upper arms fixed and elbows pointing toward the ceiling, bend only at the elbows to lower the attachment toward your forehead. Extend your elbows to press the attachment back up, squeezing the triceps at the top. The cable keeps constant tension on the triceps through the entire range, even at lockout.