What is a Runner's High?
A runner's high is a pleasant psychological state experienced during or after endurance exercise, characterized by euphoria, reduced anxiety, pain relief, and sometimes an altered sense of time, mediated primarily by the endocannabinoid system rather than endorphins.
Neurobiological Mechanism
The runner's high phenomenon has been definitively linked to cannabinoid receptor activation, not opioid signaling as previously believed:
Endocannabinoids (specifically anandamide and 2-arachidonoglycerol) are the primary mediators of the runner's high, as demonstrated in both mouse models and human studies 1, 2.
In humans, opioid receptor blockade with naltrexone does not prevent the development of euphoria or reduced anxiety after 45 minutes of moderate-intensity running, while endocannabinoid levels (anandamide and 2-AG) remain elevated 2.
Mouse studies confirm that cannabinoid receptor 1 (CB1) receptors on forebrain GABAergic neurons mediate the anxiolysis, while peripheral CB1 and CB2 receptors mediate pain reduction 1.
The endorphin hypothesis, popularized since the 1980s, has been definitively disproven in recent high-quality research 3, 2.
Core Features
The runner's high manifests through several distinct components:
Euphoria: A sudden pleasant feeling of well-being and happiness that occurs during or after running 1, 2.
Anxiolysis: Significant reduction in anxiety levels, which depends on intact CB1 receptors 1, 2.
Analgesia: Pain reduction mediated by peripheral cannabinoid receptors 1.
Altered time perception: Runners may experience a lost sense of time during the experience 4.
Physiological Markers
Objective signs accompany the subjective experience:
Pupillary dilation (mydriasis) occurs in runners experiencing a runner's high compared to those who do not 4.
Hypothermia (reduced body temperature) is observed post-run in those experiencing the phenomenon 4.
Specific microRNA signatures (miR-194-5p, miR-4676-3p, miR-4254, miR-4425, miR-1273-3p, miR-6743-5p) show significant changes and target genes in opioid and GABA pathways 4.
Exercise Requirements
The runner's high typically requires specific exercise parameters:
Moderate-intensity endurance exercise lasting approximately 45 minutes or longer is most effective at inducing the phenomenon 2.
Long-distance running is the most commonly studied activity, though the effect likely extends to other sustained aerobic activities 1, 5.
The metabolic state during marathon running involves balanced steady-state metabolism with free fatty acid oxidation through the Krebs cycle, distinct from sprint metabolism 6.
Individual Variation
Not all runners experience this phenomenon:
In a study of 25 collegiate runners, approximately 52% (13 of 25) experienced a runner's high after long-distance running 4.
Typical runners experiencing this effect tend to be controlled, disciplined individuals who run substantial weekly distances (approximately 60 km per week) 5.
While motivated by physical health goals, runners derive significant emotional well-being benefits from their running practice 5.
Clinical Implications
Understanding the runner's high has therapeutic relevance:
The endocannabinoid-mediated anxiolysis and mood enhancement suggest potential applications for running as a therapeutic adjunct in mental health treatment 5.
The phenomenon represents a natural reward system that may contribute to exercise adherence and the psychological benefits of regular physical activity 1, 2.