An fMRI study on runner’s high and exercise-induced hypoalgesia after a 2-h-run in trained non-elite male athletes

While elite long-distance runners experience hypoalgesia and sometimes runner’s high after running, these phenomena are rarely explored in non-elite runners. Therefore, we examined the effect of a 2-h-run on mood and pain processing in 15 non-elite male runners using repeated painful and nonpainful pinprick stimulation and functional magnetic resonance imaging (fMRI). Pain ratings, pressure pain stimulus responses, and euphoria ratings were assessed immediately after a 2-h-run and at a run-free control day (RFC). Analysis of a half-standardized-interview indicates an improvement of mood. However, there was no elevation of euphoria. Neither in pain ratings nor in fMRI data, we observed less pain perception after the 2-h-run. However, endurance training increases the blood flow of the hippocampal formation. Furthermore, more pressure was required to evoke a clear pain sensation in highly trained athletes at post-run vs. RFC. In summary, we found behavioral and neuroimaging signs that underpin the positive effects of endurance exercise. However, the results also suggest that hypoalgesia and “runner’s high” experience are rather rare phenomena in non-elite endurance runners.