I'm pretty sure you can, because Athletic isn't all running and stuff, its also bench-pressing and what not. However, (being a clumsy person myself) I find it unusually funny to see them just stand there and lose their balance (then I normally reflect on how many times I've done that too.)
I've also seen them about to cast into a pond or something when they fall on their own butt. It was possibly one of the funniest and most realistic things my Sims do!