In the shot put the arm is the last thing that matters

Distance comes from bracing the front side hard enough to stop the whole body, and almost nobody watching sees it happen.

Watch a shot putter and your eye follows the arm. That is the visible part, the extension and the flick of the wrist at release, and it is the part every casual explanation of the event fixes on. It contributes remarkably little to how far the implement travels.

The real work is done by the front side stopping. A right handed thrower arrives at the front of the circle with the whole body rotating and travelling forward, and the left leg goes down as a brace. If that leg holds, everything moving behind it has to go somewhere, and where it goes is up through the trunk and out along the arm. The technical term is a blocking action and the everyday version is simpler. You hit a wall on purpose, and the implement keeps going because you stopped.

If the brace leg gives, even slightly, the energy leaks into the ground and the arm is left trying to throw a heavy object on its own. It cannot. This is why a thrower who has been strong all season suddenly loses two metres when a knee is sore, while every measurement of upper body strength stays exactly where it was.

There is a live argument in coaching about the rotational technique against the older glide, and I lean rotational for most athletes even though it is harder to learn and more likely to fail under pressure. The reason is that rotation lets a thrower build speed over a longer path before hitting the block. More speed arriving at the brace means more to redirect, provided the brace can take it. Gliders arrive with less and lose less. Rotators risk more and, when it works, throw further.

Which sets up the interesting selection question. A rotational thrower with an average front side is a worse athlete than a glider with a magnificent one, regardless of what either can do in the weight room.

Next time the camera lingers on a thrower's shoulder, look down at the left knee instead. It has already told you the answer before the shot has left his hand.