A better athlete than his brother. Not than everyone. Each valid was designed by the parents for something, or in the case of his brother just generally enhanced because they weren't filthy rich.
I guess my point is that the valids could have been 100x better athletes than all the invalids which wasn't the case in the movie. For example, they could have retractable fins and could breathe under water.
Something which would make them swim a lot faster and the point of the movie would be lost.
Something which would make them swim a lot faster and the point of the movie would be lost.