Mud runs are starting to catch on like fire. They are fun, you get dirty and you push yourself to do things you would never do normally. I think of them as an obstacle course for adults. I love love love them. I have done an all women's and a coed mud run and both are fun. The coed seems to be more challenging but all are great fun and even more fun when doing it with friends. I have been met some great people while doing them. Most keep time, but really I think as long as you finish the course, who cares about your time!
If you want to start training Lozilu has a great couch to 5k plan that incorporates more than just running to help you get ready for those upper body obstacles.
Good luck and remember to have fun!!!
Have a very fit day!