Children climb over a six foot high wall with a cargo net as they compete in the Merrell Down & Dirty National Mud and Obstacle Series presented by Subaru, on Sunday, June 24, 2012, at the Aurora Sports Park, near Denver, Colo.. Michael Epstein Sports productions, MESP, will produce 10 Down & Dirty events this summer season alone. (Nathan Bilow /AP Images for Merrell)