Running on empty: why are so many marathon runners so miserable?

One in four endurance runners displays ‘worryingly high’ levels of anxiety and depression, according to a study led by a man who has himself run more than 400 marathons. Isn’t exercise supposed to make you feel good?

Name: Marathons.

Age: The first modern Olympic marathon was run in 1896, inspired by the 490BC tale of Pheidippides and his 240km run to ask the Spartans for help battling the Persians.