Why do we run until it hurts? Researchers might have some answers

During the Ultra Gobi in 2016, I felt more aware of my own body as it gradually disintegrated. According to scientists, this might be partly why I enjoyed it

Why would anyone want to run 400km across a desert? It's a good question and one that I confronted last year when I completed the Ultra Gobi, a single stage, self-navigated 250-mile footrace in China. This year I face an even harder question: Why would anyone do it again?

In moderation, running improves both your health and physique; in extremes, it does quite the opposite. The feet blister and swell to the point where multiple pairs of shoes in ascending sizes are required. Toenails turn black and fall off or, worse, fill with fluid and require puncturing. Some runners even choose to strike pre-emptively and have theirs surgically removed.