I could have probably used a qualifier, such as marathon runners or some such (blanketing all of athleticism is always dangerous). And no scientific documentation, merely statistics from events such as the Olympics. Also, I could have said that Asians are generally smaller than Caucasians, and thus tend to be better at gymnastics. It's not meant to be offensive, merely a statistical look at biology and culture.
You're right though, I could have phrased it better.
;-)