Eight51, Inc (Mud Factor, Run to Rave), Maybee

Mud Factor races are hardly races at all. Runners won't find any chip-timed competitiveness or awards for those who finish first. Instead, when competitors line up with thousands of fellow runners, they sprint toward a mud-filled playland where getting dirty beats winning any day.

Designed with Fun in Mind

• Each obstacle-filled 5K goes easy on the intimidation factor
• Obstacles include a rope swing, water slide, and wire crawl, not to mention wall jumps
• Participants are encouraged to run with friends and family members willing to don their most outlandish costumes or uniforms