Obstacle races have absolutely exploded in popularity in recent years. Perhaps you have seen ads for some of the most popular races like Spartan or Run For Your Lives. Everyone is covered in mud and looking tough by jumping over fire or crawling under barbed wire. But what's the exact definition of an obstacle course, anyway?

Though there isn't any kind of formal body that regulates the sport, an obstacle course race is a race/event where contestants have to complete a course that has many obstacles for the racers to traverse. And oftentimes at least one of the obstacles will include muddiness.

But beyond this very broad definition, there are many variations on this theme. Some runs are very extreme and last for 24 hours or more. In these events, the obstacles are extremely difficult and require a great deal of training.

Other obstacle course races are crafted with the average person in mind who just wants to pursue a fitness goal or who is looking for a fun weekend challenge. Obstacle course races like this are about 5 kilometers with obstacles that most individuals can complete as long as they are in decent shape. Participants may have to climb cargo nets, walk over a balance beam or crawl under barb wire. Generally participants will have the option to participate with a team in these events.

Every state hosts at least one mud run every year, and big states like Texas host up to 40. The three most popular companies that put on these events are the Warrior Dash, the Tough Mudder and Spartan. However, there are many other companies that organize races on a national level, as well as some that operate on a local or regional level. Some of these companies have also adopted themes for their mud runs. For example, in Run For Your Lives, in addition to normal obstacles, participants escape a Zombie Apocalypse.

Only a few events penalize participants who are not able to complete every obstacle. In these events, the runners may not be eligible for awards or they might have to wait for a few minutes before being allowed to proceed. For most of the events, it is perfectly acceptable to skip obstacles that may be too difficult.

In many of the competitions, obstacle racers do not take themselves too seriously. Many events encourage whacky costumes, and almost all of them attract participants by promoting a big after-party at the end of the race. Free beer to all participants!

Obstacle course races have attracted many people who hadn't previously cared about fitness interested in pursuing new fitness goals. Want to get your feet wet? Try it out!