1. The Vail Pass Half Marathon
Whist a half marathon is 13.1 miles worth of child’s play compared with some of endurance events on this list, stick that run 10,662 feet above sea level where there is roughly 21 per cent less oxygen and it quickly becomes a throat burning battle of the fittest.
One aspect of the annual Teva Mountain Games, hosted by the outdoor footwear company, a further 2,900 feet of elevation to tackle during the run, oxygen starved muscles become lead weights to drag you up the side of a snowy mountain. Oh, and did we mention the possibility of altitude sickness, nose bleeds and lung busting shortness of breath before you even cross the start line?
Your performance tracking watch and route mapping apps might give you the techy boost to churn out a few miles but for these races you need balls of steel...
Think you’re made of sterner stuff because you’ve jogged home a few times, or cycled through London in a pair of black tights with neon detailing? Think again. You’re nothing in our eyes till you’ve run three marathons on the trot. Through mud, whilst on fire.
Instead, why don't you test yourself against something really hardcore? We've got a few ideas, and some tech that will help to drag you through the blood, sweat and tears.