It exists only insofar as naive children internalize and ape what they see on TV. There is no reason whatsoever that a bright child shouldn't enjoy sports, except the Disney channel tells him he must choose between reading books or exercise, when there is plenty of time in the day for both. And insofar as it discourages smart kids from exercising, it's a clearly harmful stereotype which you should refrain from reinforcing.

Real life is not a 1980s teen comedy movie, no matter how comforting out of shape engineers may find the notion.