Your body should form a completely straight line ... This exercise is fantastic for isolating the triceps. Stand facing the machine and grasp the bar overhand with your palms facing down.

Bend at the elbows, slowly lowering the bar ... your triceps (B) before pressing back up explosively. Repeat. Jump up on two parallel bars with your palms facing inward and your arms straight ...

Why it rocks: This variation hits the long head of your triceps hard while simultaneously working your core as long as you keep your spine straight and ribs from flaring forward. Why it rocks ...