By my feet on the artificial turf of the ‘Human Performance Forge’, a 44,000 square foot gym, lie a mannequin on a stretcher, three fuel canisters, several ammunition cartons and a rusty pole attached to a weight.

“We are going to test your physical capabilities as well as your perseverance,” shouts a camouflage-wearing sergeant from the side of the track. I gingerly stretch out my hamstring.

Our job, on this annual open day for the US Special Forces at Fort Bragg army base, is to lug all the materiel to the other side of the track within eight minutes. “Are they going to quit or push through?” the sergeant bellows.

In the woods outside the gym, real Special Forces applicants are enduring ‘team week’, a series of grim, tendon-snapping challenges. They have already overcome individual training and land navigation. Only around 30 per cent will make the final cut.