Very true. Some form of combat could be incorporated into it, or maybe there are less rules to protect contestants.
The stadiums could feature an inner lava moat separating the spectators and the players, which could be used for the lava surfing competitions. No need to give it its own unique name, since multiple events happen in Ignalu. The lava moat would also function as an out-of-bounds or disqualification zone for other events.
I would add more, but I think now someone should make a topic dedicated to this specific conversation so that we can free up space for future brainstorming. I'll link it to the initial post after it's been created.