Why do people run marathons? There is probably a bundle of physical, psychological and social motives. Many seek a borderline experience and want to test what their body can do with structured training and how intense exertion feels. Others pursue a concrete goal: to complete 42.195 km once in their life, to beat a certain time, or to redefine themselves after illness, a life crisis or professional upheaval. Marathons also promise intense emotions – from exhaustion and pain to euphoria and a powerful sense of self-efficacy at the finish line. Last but not least, community plays a role: running groups, shared routines and race-day atmosphere create a sense of belonging that extends beyond the event itself.

I am interested in what happens inside runners shortly before the finish – at kilometre 40. A point at which the body lays bare all its reserves and the will becomes the dominant force. Getting there means more than two hours of focused effort, countless small decisions, breaths, steps. Beyond this mark, running loses its lightness and becomes the elementary motion of hanging on. Runners’ gazes turn inward. Posture, facial expression and muscle tension speak of the narrow ridge between exhaustion and determination, of effort, concentration, pain, but also ecstasy and euphoria. The portraits in this volume are not images of defeat or victory, but reveal a state in which the answer to the question of one’s own limits is still open. In this closeness between utmost strain and the last remaining reserves on the one hand, and the prospect of the nearby finish and its satisfaction on the other, lies a peculiar beauty.

KM 40 is a long-term photographic project for which, since 2011, I have been accompanying the Cologne Marathon, held every October, and on which I will continue to work in the future.