When I think of athletic, I think of people with coordination and the ability to be "naturals" at other sports. I do not believe that everybody is capable of being athletic, as that definition would suggest. My guess is, some nerd at Websters came up with that definition to make himself and his buddies feel better about being picked last for every team sport ever.
When I toss my keys to a buddy and he "air hugs" them, missing completely, and they nail him in the face, I can pretty much rule him out of the "athletic" category forever.
If it makes you feel better, I'll admit that being a world class powerlifter doesn't necessarily make you athletic either, as your definition would suggest.
Nobody will ever convince me that running marathons makes you athletic. I've seen way too many examples of the opposite.