The study was of a particular non profit program called "Let Me Run." We love the following quote from the founder of the program.
"They found that the program significantly improves boys’ attitudes and behaviors associated with healthy masculinity. The ability to express their feelings led boys to have less physical altercations."
Read more at
http://running.competitor.com/2017/09/news/study-running-boys-healthy-behavior_167984#x7mxg1Jk4QJP0IV4.99