In the olden days children would learn that they need to calm themselves down when back in the classroom environment.
It was probably called self-control or something like that.
It's an important behaviour to learn.
Do any parents on here routinely massage their kids after they've been playing outside with their friends?
Do any parents on here routinely do things with their kids that are designed to calm them down after they've been playing?
Yes obviously, everyone does. Stories and quiet time before bed being the most obvious example, but lots of times in the day when kids need a bit of a pause. Any idiot knows that you can't take a kid straight from full on running around play, dump them in bed without any calm down time, and expect them to go to sleep straight away and painlessly.
Kids benefit from time to calm down after they get excited. That much is bleeding obvious to anyone who has ever put a kid to bed, taken them to the park, or generally looked after kids at all.
Whether massage is the right thing to calm kids down, I don't know, but it seems pretty harmless, and I imagine that if it didn't work they'd stop doing it pretty quick.