Turns Out, ‘Runner’s High’ Is Way More Literal Than You ThoughtCannabinoids. The same chemicals responsible (sorta, it’s complicated) for the high one gets from cannabis, or marijuana, and which the body produces naturally in the form of endocannabinoids, are actually what you’re chasing if you’re chasing a runner’s high. But, it turns out, endorphins can’t cross the blood brain barrier and therefore can’t affect mood. The study blocked the uptake of endorphins in the body of test subjects running on treadmills, but the subjects still reported feeling a runner’s high. Pretty cool, but raises even more questions, chiefly, did we evolve a runner’s high as a means of keeping us from stopping?