Looking back on my games, I haven't featured a lot of sports. Not even the sportified version of combat sports - touch duels, jousts, etc.
We've tried, but generally it's fizzled. We've had PCs fight in pit fights, but inevitably the same guys who want their PCs to fight in them also want to kill their opponents, kill anyone who doesn't want them killing their opponents, and then kill their way out of town. So it goes from "sport" to "murder" in a few turns of combat.
We have had forced competitions, with foot races, obstacle courses, and odd skill challenges.
Not much else.
The Dread Empire books featured "Captures," a game that's very much like a variant of Calcio Fiorentino. So is the Game of the Juggers, actually. They'd make good sporting events in a fantasy world.
I've just had trouble featuring them in a game and then getting players to treat them as something other than a lethal encounter with a thin veneer over the top. Anyone have any better luck with a game within a game?