3.. 2..1.. GO!

The gun fires, ten people rush forward in a burst of adrenaline-fed speed. Two in the back of the pack get too close together - first elbows fly, then one foot gets in front of the other sending two bodies sprawling. On the way down one of them reaches out to break the fall and catches the back of a shirt on his little finger. The gun fires a second time. They will all have to start again.