I assume there has probably been at least one story done on this at some point

One assumes that people like the Flash or whoever have better things to do than cheat at a marathon or whatever

People my understanding in both universes is that you also have people with much lower powered superpowers

Some guy from West Virginia got bit by a magic greyhound and now he can sprint at like, 45 miles per hour

how do you screen for that?

I'm sure there's a lot of anti-mutant sentiment in Marvel's sports

Do exception "mundane" people get falsely accused of having superpowers?

Michael Phelps getting accused by bitter competition of being Aquaman's cousin

nerdiethings: oh fr sure

yeah. Northstar has a story about his mutation and how it banned him from sports

in my superhero tabletop campaign, the party have real mixed feelings about having detected an NHL player as superpowered

This is the whole Wild Cards series, excepting the High Drama parts.