Reverse-Grip Triceps Extension

Attach a straight bar to the high pulley of a cable station. Grab the bar with an underhand, shoulder-width grip and pull it down until your elbows are bent 90 degrees. Stand straight with your upper arms tucked against your side. Your feet should be hip-width apart, knees slightly bent.
 
Push the handle down until your arms are straight, while keeping the rest of your body in the starting position.
 
Pause, then slowly allow the handle to rise until your elbows are bent at 90 degrees.