Exercise execution guide
Stand in front of the cable machine and grasp the straight bar with an underhand (supinated, palms facing up) grip, hands about shoulders width apart, elbows tucked in and bent at a bit less than a 90° angle.
Extend the forearms until your arms are 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.