I ran 100 miles in a day – this is what happened to my body

Ultra-marathon runner and exercise physiologist Nick Tiller describes what it's like to take part in an ultra-endurance event, and the consequences it had on his body.

The marathon race has long been considered the ultimate test of human endurance. But the last few decades have seen growing numbers of runners regularly tackling distances exceeding the traditional marathon. So-called “ultra-marathon runners” contest races from 35 miles (56km) to 100 miles (160km) – and occasionally further – in a single stage.