You can do all the close-grip bench presses and dips in the world, but neither of them put the long head of the triceps in a fully lengthened state. Remember, whatever muscle is loaded the most in a stretched position is the one that's going to have the greatest amount of tension distribution.
No exercise for triceps blasts the long head harder than this one. There isn't even a comparison.
The long head, which actually attaches to the lateral part of the scapula, acts as an extensor for the shoulder. You can't get the long head into a fully lengthened state without shoulder flexion. The PJR pullover puts the shoulder into 180 degrees of shoulder flexion, which in turn gets the long head as stretched as possible.
This is why, when someone tells me this version of the pullover is a lat movement, I know they simply don't understand how to execute it properly.
How To Do It
- From the top, let the shoulders go into 180 degrees of flexion, then drop the dumbbell straight down to fully lengthen the triceps.
- The initiation into the concentric (the lifting part of the rep) is done via elbow extension – which is the primary function of the triceps, of course – until completion.
This differs from a lat-specific pullover where the elbows tend to stay in "soft flexion" or even remain completely straight (again to emphasize lengthening the lats primarily) and remain in that position. With this pullover variation the elbows go into flexion, then extension emphasizing the triceps more than the lats.