Wrestling was a very common passtime in the Medieval Age, the 'jacket/belt wrestling' or 'folk wrestling' styles known as Cornish Wrestling, Devon Wrestling, Schwingen, Glima, etc all descend from what was traditionally practiced, and wrestling was part of a man-at-arms repetoir
The people who still do them basically look like what >>76288730 suggests
The accounts of how men-at-arms trained suggest they'd be up several times a day before sunrise to practice, primarily in their armor, what amounts to cardio: running, dancing jigs, vaulting fences, doing hand stands, etc - in up to 25kg of armor
They also still used Roman military manuals so it is possible they copied their weapons training technique of using lead sword and shields heavier than the real thing too