Some 10,000 participants took part in the Spartan Fenway Park Stadium Sprint over the weekend. For Heather McDonald of Brighton, it was her third time competing, but also her favorite.

On June 13, more than 5,500 competitors from across the nation (and the world) descended on Breckenridge for the mountain’s inaugural Spartan Race. They took on the Sprint, a 5.3-mile course ...