These mud and trail events such as the Major Series, Spartan and Tough Mudder see competitors run, jump and leap over a variety of obstacles and they've become hugely popular in the UK and around the world - both as fun days out and also at the elite level.
But combining a run with obstacles can be a daunting to beginners and seasoned runners alike and requires a varied training approach.
That's why we've enlisted the help of some of the very best obstacle course racers (OCR) to help you get the most out of your next event.
Found yourself signing up to Tough Mudder, the Royal British Legion Major Series or a Spartan race with no idea what you’re letting yourself in for? Then check out these expert tips.
Combining a run with obstacles that can range from a cargo net or a mud crawl to a giant slide takes an all-round set of skills.
Failure at an obstacle in a Spartan Race leads to the dreaded 30 burpees - follow this advice from Race Director Karl Allsop to give yourself the best chance of avoiding a penalty.
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