This link doesn't really answer the question but it's a theory about how intelligence and athletic ability may be correlated. Seems that according to this theory, since high athletic ability (e.g., speed, strength) at one point was highly associated with
survival, it is not likely to be highly correlated with high levels of intelligence (i.e., people of average intelligence were just as likely to procreate as people with high intelligence). Lower levels of intelligence, though, are definitely correlated with athletic ability because brain damage often affects both types of abilities.
http://paulcooijmans.lunarpages.com/psy/gdef.html
