Adventure races like the Warrior Dash and Tough Mudder like to keep participants on their toes -- because jumping into freezing water or crawling through electrified fencing just isn't enough.

To do this, course designers and organizers of these team or individual races are constantly mixing up their venues with new and challenging obstacles each year. We dug into the mud to discover the newest, most challenging obstacles you'll find in your favorite adventure races -- and some grueling classics -- so you won't be caught by surprise. We also enlisted the help of Chris Frankel, head of human performance at TRX Training, for some tips on how to prepare for the any impediments thrown -- in some cases literally -- your way.

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