So after years of believing that endorphins are the source of the runner’s high, new evidence shows (well in mice anyway) that maybe there’s something else at play.  Thanks to Stewart Forsyth, one of the attendees at my HRINZ presentation last week for pointing this shift in thinking!  A new study from the Central Institute of Mental Health at the University of Heidelberg medical school indicates that the euphoric feeling that runners experience is actually due to the body’s own endocannabinoids, the chemicals that, like the cannabinoids in marijuana, lighten mood. The New Source of the Runner’s High