People have cited diverse reasons for the sudden popularity this type of race: the search for a run less boring was one; the urge to create an outstanding profile photo another; and the constant human urge to test the limits of mind and body is certainly up there. However, in an interview Guy Livingstone, the founder of Tough Mudder, said it was the feeling of teamwork and human connection you get at the event. You are pushed and pulled over obstacles and you push and pull in return, and come to the end triumphant having not only conquered an obstacle race, but helped fellow humans finish too. Regular footraces by comparison seem somewhat lonely... and easy.
Tough Mudder is brutal, but there are other challenges equal to it, or even tougher, out there. If you're prepared to test your mettle, charge headlong into these:
Total Warrior (Leeds, UK)
There's mud, as ever, but there's also fire, electricity, nets, swimming, climbing and diving. Yes, we said fire. Good luck.
You May Die: The Death Race (Vermont, USA)
Set for 24 hours, organisers claim the events have lasted up to 70. This obstacle course once again has the mud, but incorporates sleep deprivation and further mental and physical tasks, just to try and kill you. According to their website there is only around a 10% completion rate. This is the most extreme race of the kind we could find. If you think you've had a long enough life then sign up.
Jungle Marathon (Tapajos, The Amazon Rainforest, Brazil)
This is a little different and isn't strictly an obstacle race, but you can bet there are still obstacles - dangerous wildlife, vegetation and terrain mostly, and several large bodies of water. It is split into 63 miles over four days, or 150 miles in six. Pack your raincoat.