Summary: Too much of one exercise, like running, can be unhealthy. That's why sports medicine physician <a href="http://healthcare.utah.edu/fad/mddetail.php?physicianID=u0053747">Dr. Nick Monson</a> says runners should do other exercises in addition to running, like biking, swimming or weightlifting. He says people who have a balanced exercise regime experience fewer injuries. Learn some specific things that runners can do to keep themselves balanced.
