Starting Position: Grasp the cable / band handles with thumbs around the handles and palms facing the floor. Hands should be 6 - 12 inches apart. Stand in a split-stance position to stabilize your body. Position yourself to allow the cable / band to hang vertically in the starting position. Brace your torso by contracting your abdominal/core muscles. Pull your shoulder blades down and back. Your head and neck should be aligned with your spine. Maintain these engagements throughout the exercise.
Your upper arms should be parallel to, and close to, the sides of your torso. Your elbows are bent so that your forearms are parallel to, or near parallel to the floor. Keep the wrists in line with the forearm (neutral).
Downward Phase: Exhale. Slowly, press the bar down until your elbows are straight but not locked. Do not allow the upper arms to move. Keep your torso erect and your wrists neutral.
Upward Phase: Inhale. Bend your elbows, returning to your start position in a slow and controlled manner. Do not allow the upper arms to move. Keep your torso erect and your wrists neutral.
Proper form in performing this exercise is important to targeting triceps activity and for reasons of safety to prevent additional loading on your spine.