Exercise execution guide
Stand in front of the cable machine and grasp the handle with an underhand (supinated, palm facing up) grip, elbows tucked in and bent at a bit less than a 90° angle.
Extend the forearms until your arm is completely stretched. In this position, squeeze your triceps, pause, and then slowly come back to the starting position. Keep the elbows tucked in throughout the movement. Repeat for desired reps and then repeat for the other arm.