Welcome to Men's Health Survival of the Fittest 2010 - the Tri Nations Challenge. 2009 saw the action spread to the cities of Cardiff, Nottingham and Edinburgh and we once again invite racers from England, Scotland and Wales to front up to these tough urban assault courses and battle it out to become Survivors. Packing a challenging 10km route in each host city, with tough and engaging obstacles every kilometre, you will pit your wits against 1000s of fellow "Survival" competitors in a test of stamina, grit, speed and guts. Possibly the UK's toughest obstacle course? Maybe. Possibly the UK's most action-packed 10k. Maybe. The must-do events of this year? Definitely.