Background: Studies involving animals and older adults suggest that physical activity (PA) might lead to improved cognitive ability in general, and enhanced intelligence scores (IQ) in particular. However, there are few studies involving young persons and none controlling for the possibility that those with better cognitive skills are more likely to engage in PA. Methods: Data are from the Mater–University of Queensland Study of Pregnancy. We measured IQ at the 14-year follow-up and IQ and PA at 21 years. Mean IQ scores are presented at the 21-year follow-up adjusted for IQ at 14 years, and PA and other variables. Results: Measures of vigorous exercise, less vigorous exercise, walking, and vigorous activity apart from exercise, produced inconsistent results. Increased levels of less vigorous exercise were associated with higher IQ, but neither higher levels of vigorous exercise nor walking were associated with IQ. For vigorous activity at work or in the home, the associations are curvilinear, with more and less activity both associated with lower IQ. Conclusions: While there is an association between some indicators of PA and IQ, there was no consistent evidence that higher PA levels might lead to increased IQ scores.
Keywords: adolescents, exercise, IQ, prospective study, young adults