Ultramarathon runners train for months, sometimes years. But what happens when they don’t finish a race?

September 1, 2026

In ultramarathons, where attrition commonly runs 15–40% (and higher in extreme conditions), “DNF” is a frequent outcome shaped by both physical and psychological factors. Injuries, electrolyte errors, GI distress, and life stress can derail months of preparation, yet these non-finishes are normal—even among elites—and the training still counts as progress rather than a pass/fail verdict. Many runners treat a DNF as part of the journey and return to try again. The Guardian