One-arm overhead work for a balanced triceps horseshoe.
Pin your upper arm in place so only your forearm moves.
With one dumbbell held overhead, lowering behind your head takes the triceps into a deep stretch that arms rarely see in pressing or pushdowns, and the long head is the fibre doing most of the complaining. Pinning the upper arm in place means only the forearm travels, so every rep is elbow extension and nothing else. It earns its place as pure stretch-loaded triceps work, one arm at a time so the strong side cannot carry the weak one.
Deep in the back of the upper arm, especially at the bottom stretch. If the elbow itself is complaining, the weight is likely too heavy or the upper arm is drifting instead of staying pinned.
Because the moment it moves, the shoulder starts helping and the triceps loses its stretch. The upper arm is the anchor, the forearm is the only moving part.
Both, for different reasons. Pushdowns load the shortened triceps and let you go heavier, while the overhead position loads the muscle at full length. The stretch position is the one most lifters skip.
