Sand Sports

 Most of Eastern America enagages in the the typical medieval style jousts, with tournees, melee et. al (albeit with a seasonal cycle akin to today's professional football.) For most of the Plains and its surroundings, the big thing is the rodeo. However California, and some of the Deep South, they enagage in game and sport that harken to sun-sokaed decadence. California, with beach and desert, and its high (for Middle Ages) urbanization and massive infrastracture, sets the the standard for athletics in the Sun Belt. That said, the Gulf Coast, a mirror in many ways, also engages in these events, a little more hardscabble, a little more more makeshift. It should also be said the Caribbean some of these traditions have taken hold. Think a legacy of NASCAR, amusement parks, Pro-Wrestling, and strip clubs, their hubs, with the spectacle we associate with the Ancient world. And generally speaking, the sports gravitate towards with the best sand. Think Venice, Daytona, Myrtle, Penescola, Bahamas. (Note: New Orleans, like Miami today, has to import sand. But they are not going to sit back and let another city have something they don't. To really show everyone up, they have Battleship, not dissimilar to the Roman sport of Naumachia). And yes, it's very ofen many of these athletes are slaves, usually from debt or conflict.

Dueling: A little bit fencing, a little UFC, and a little Gladitorial games. Blades locked in the most theatrical, corloful manner possible. A bad actor might as well be a bad swordsman. Likewise, Wrassling, the Medieval equivalent to Pankration. Most of the time, these these two events are held separately, but sometimes the audience craces escalation, and the best Fencer and the best Wrassler are pitted together like an argument in a bar made into reality.

Smelting: A mixture of Muscle-Beach style bodybuilding with the ancient art of Calisthentics. The balance between form and function exists firstly because a pre-Industrial society has to be a more practical one by nature. Secondly, they just don't have the technology or supplements to get as shredded today. In the heart of California, the might even diversify into genres. Your big hulking frames, your swimmers' bodies. Women don't necessarily get involved as much, and usually not as shredded as the men, but it happens. More than one governor has liked himself a muscle mommy. 

Chariot Racing: Chariots for the most part have not made a comeback in Medieval America, largely because the continuity wasn't there. (there is harness racing, but that was mostly a Northern/Canada  niche thing, and thus was abandoned when civillization collapsed) But in California, the memory of Formula 1 and street drag racing, a culture of spectacle and decadence, and an extollation of old Sword and Sandals yarns brought them back (it also didn't hurt that chuck wagon racing was experimened with at rodeos), and to be honest, chariots aren't the most difficult things to engineer. In the east, this is the most modified, hippodromes can be fairly intensive, and the chariots are more like that of Boudica's Britain (plainer, just two) than the Circus Maximus.

Beast-fights: As the chariot racing has shown, there's no animal, humane society in Medieval America. Hell, there's not really a human humane society. So fighting an animal to the death is a pretty common sport. More often bull-fighting in the west (Again, a Rodeo variant exists, although they try not to kill the bull unless everyone is planning on eating it) while alligator wrestiling is huge on the Gulf, and they do in fact enjoy some good eating.

Pre Games

As mentioned the Sun Belt overall is a realm of spectacle and sensuality, and in many ways it can be a more liberal, permissive society, and women are generally allowed to display their skills and charms, although California and Florida from ethoses in the opposite direction. These are skills of atheleticism they're often allowed to show in the arenas (great on the beach, but also adaptable for indoors) as a sort of palate cleanser for the bloodsport.

Volleyball: Perhaps the team sport that has most thrived into the the close of the third millennium, this largely because it's incredibly easy to set up. Heck, a fishing net and a goat's bladder and you have yourself a homegame. Actually, while it is supposed to be a much softer display than swordplay, the ball is heavier and the game is a little more agressive, and the game that's supposed to pretty may not be pretty for long.

Pole-dancing: One of the most popular and prestigous sports in the Olympic games is gymnastics. Howver, it is something of a very intensive game to set up, and without television it loses some of its oomph. That said, it combines with acrobatics and yes, some nightclub showmanship and then you have one of the most popular and engaging display of atheleticis in Medieval America. It's sort of the equivalent to belly-dancing. Not not sensual, but an undeniable display of skill and actually quite prestigous. An overlord who does not have an expert in his harem is seen as a second rater.