One arm on a high cable for a strict, balanced triceps hit.
Keep your elbow pinned at your side, only your forearm moves.
With the pulley set high and one palm-down hand on the handle, this is a strict single-arm pushdown, the forearm swinging from stretch to lockout while the elbow stays welded to your side. The triceps works alone here, no secondary muscles listed and none needed. It earns its place for evening out arm imbalances and grooving a clean extension pattern, since one wandering elbow is much easier to spot and fix than two.
Same movement, one arm and a single handle instead of two hands on a rope. You lose the outward rope flick but gain a focused rep where one triceps does everything.
You are using your shoulder to shove the weight. Lighten the stack, pin the upper arm to your ribs, and treat the elbow like a hinge that does not move in space.
Until you feel a full stretch in the triceps with the elbow still pinned. Cutting the top half of the rep to keep the stack moving means leaving stimulus behind.
