There is an increasing amount of research that shows regular physical activity can do wonders for reducing symptoms of Alzheimer's (http://www.ncbi.nlm.nih.gov/pubmed/24652914) and does wonders for children and test scores (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2748863/).

Thanks Dan! appreciated

Physical exercises enhances health which in turn allows one work longer (thus allows to apply one's intelligence longer).

“a sound mind in a healthy body”

I don't know this paper can help you. In  2012 a research group of Institute Karolinska, they studied how the general executive functions can predict the success of a soccer player. 

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0034731