Runner's high



The runner's high is a transient state of euphoria coupled with lessened feelings of anxiety and a higher pain threshold, which can come either from continuous moderate physical exertion over time or from short bursts of high-intensity exercise. The exact prevalence is unknown, but it seems to be a relatively rare phenomenon that not every athlete experiences. The name comes from distance running, and it is alternatively called "rower's high" in rowing.

Mechanism of action
Current medical reviews indicate that several endogenous euphoriants are responsible for producing exercise-related pleasurable feelings, specifically phenethylamine (an endogenous psychostimulant), β-endorphin (an endogenous opioid), and anandamide (an endogenous cannabinoid). However, more recent studies suggest that endorphins have a limited role in the feelings of euphoria specifically related to the runner's high due to their inability to cross the blood-brain barrier, placing more importance in the endocannabinoids instead, which can cross this barrier.