Two of the biggest OCR series in the U.S., and around the world for that matter, are Spartan Race and Tough Mudder. Both of these race series have dozens of events around the world each year, and both brands are growing at a rapid pace. There are a lot of similarities between Spartan Race vs Tough Mudder, such as average field sizes and number of race length options. But, the key differences are what will make or break your experience at these events, whether you are new to OCR or you’ve looking to advance your way through the sport…