Single-Arm Reverse-Grip Pushdown (Cable)
Also called One-Arm Underhand Cable Pushdown
How to do it
Stand facing a high cable and hold a single handle in one hand with a supinated, palm-up grip and your elbow tucked to your side. Extend your elbow to press the handle down to full lockout, squeeze the triceps, then return slowly without letting the upper arm move. Complete the reps on one side before switching.