A new study reveals extreme long-distance running boosts endocannabinoids. Learn how aging endurance athletes can safely manage load and recovery.
On September 1, 2026, BMC Medicine published a new open-access study examining how prolonged running impacts circulating endocannabinoids. These lipid signaling molecules interact with the body's cannabinoid receptors, specifically CB1 and CB2. A research team led by Michael Siebers tracked these molecules across both a standard marathon and ultramarathon events up to 230 kilometers. Their work clarifies the biochemical shifts that occur during extreme endurance efforts to move the conversation beyond the traditional focus on endorphins.
The primary conclusion of the paper, titled "Endocannabinoid dynamics across marathon and ultramarathon running," is that circulating anandamide rises progressively during a marathon. Anandamide, often referred to as AEA, is a key endocannabinoid linked to pain modulation and mood regulation. The researchers found that this molecule did not just spike at the start of the run and then plateau. Instead, it continued to increase throughout the event and remained elevated after a 45-minute recovery period.
Similar increases in AEA occurred following ultramarathons of 100, 160, and 230 kilometers. Another lipid compound, 2-AG, also increased during the latter stages of the marathon and immediately after the ultramarathon distances. Interestingly, the post-race levels of 2-AG were higher after the shorter ultramarathon events than after the longer ones. This suggests that relative intensity heavily influences the endocannabinoid response rather than sheer distance alone.
The study confirms a strong association between these biochemical changes and lower anxiety. The marathon condition was associated with higher reported euphoria and lower anxiety than walking. Meanwhile, ultramarathon running successfully reduced anxiety but did not produce a statistically significant post-race increase in euphoria. Ultimately, the paper shows that circulating endocannabinoid changes occur alongside changes in mood, but it does not prove that these specific molecules directly cause the elusive runner's high.
Dr. Michael Siebers emphasized that his team tracked endocannabinoid changes in unprecedented detail across these long distances. Professor Johannes Fuß added that the endocannabinoid system remained active during very long runs. However, Fuß cautioned that further work is needed to clarify the exact role these molecules play in euphoria, anxiety reduction, and pain perception. The authors clearly stated that no definitive mechanism can be inferred from the peripheral blood concentrations measured.
The authors describe the relationship between endocannabinoid signaling and calming effects as nonlinear. This biological relationship is strongly influenced by specific context and exercise duration. That nuance matters deeply for athletes who might experience a calm, focused state after one long run. Those same athletes may experience intense fatigue, irritability, or pain after another training session of similar duration.
The researchers divided their work into two distinct field studies to capture varied intensity and duration levels. The first study followed 19 experienced runners who completed a marathon and a duration-matched walking session. Blood samples were collected at baseline, after each 14-kilometer loop, and after a 45-minute recovery period. These participants had a mean age of 46.2 years and completed an average marathon distance of 42.94 kilometers.
The marathon condition was substantially more intense than the walking comparison. The marathon runners averaged 145 beats per minute, which is approximately 82.7% of their estimated maximum heart rate. The walking group averaged 102 beats per minute, or roughly 57.6% of maximum heart rate. The researchers highlighted this distinction because relative exercise intensity may influence endocannabinoid responses more strongly than total exercise time.
The second study evaluated 36 ultramarathon runners competing over distances of 100, 160, or 230 kilometers. This field testing took place in Germany's 2024 TorTour de Ruhr event. The participants were a highly experienced group with a mean age of 50.2 years. On average, they had previously completed 57 marathons and 41 ultramarathons.
The researchers relied strictly on blood measurements rather than direct tracking of brain activity to assess the resulting biochemical shifts. The authors also noted that the walking comparison in the first study was not a resting control. Walking produced its own physiological response, meaning the marathon findings represent differences between higher and lower intensity exercise. Additionally, they described the marathon versus ultramarathon comparison as exploratory since the extreme running intensity was not strictly standardized.
For the older endurance athlete, this research provides a clearer view of the psychological rewards and physical realities of long-distance training. The findings show that a post-run mood lift is a real biological response, but it is not a universal guarantee. Only 3 of the 19 marathon participants reported experiencing a runner's high during the study. Just 12 of the 36 ultramarathoners felt one during their races, proving that chasing extreme distances purely for psychological benefits is an inefficient strategy.
More importantly, increased endocannabinoid activity does not mean athletes become pain-free. Pain actually increased during prolonged running, specifically after approximately 28 kilometers of the marathon effort. In the ultramarathon group, 29 of the 36 participants reported pain during their race. Athletes managing their long-term structural health must remain vigilant, as pushing through escalating discomfort can compromise injury prevention and healthy movement patterns.
Endocannabinoid activity should never be used as an excuse to ignore worsening physical warning signs. Athletes must balance the calming effects of an endurance session against the heavy musculoskeletal costs of extreme distance. A separate case report highlighted that a 444-day running challenge of 30,300 kilometers resulted in skeletal-muscle remodeling and impaired contractile function. A post-exercise calm does not prove that your muscles, tendons, and connective tissues have successfully recovered.
Older athletes need to build sufficient rest into their programming, especially when prioritizing longevity or managing safe return protocols following an injury. To apply this research safely, athletes should use intensity and duration together to manage their internal training load. The study indicates that the relatively harder effort of a marathon produced a larger immediate biochemical response than a longer event at a sustainable pace. You do not need to run an ultramarathon to reap the calming biological rewards of endurance exercise.
It is wise to set an upper limit before the session begins. A practical plan might define a maximum duration, a heart rate ceiling, or specific fueling intervals. You can also establish turnaround points and a clear stop rule for worsening pain, dizziness, or loss of coordination. The clear evidence that pain commonly rises during extreme running makes such predefined safeguards particularly critical for older athletes.
Middle-aged and older endurance athletes must also consider long-term cardiovascular questions when planning extreme distance events. A recent review reported that structural cardiac findings, including atrial fibrillation and focal nonischemic fibrosis, have been observed more often in older endurance athletes. Even training guided by heart rate variability has not consistently shown a meaningful advantage for improving VO₂max or endurance performance in recent reviews. Therefore, qualitative subjective feedback remains a vital component of any balanced athletic strategy.
You can use modern wearable devices to monitor external and internal stress efficiently without relying on a subjective high. Sports-science monitoring guidance recommends tracking objective metrics like duration, power, and heart rate. You can pair these exact numbers with subjective feedback on sleep, fatigue, soreness, and daily mood. Integrating this data with circadian rhythm and fatigue monitoring will help you make smarter load management decisions as you age.
Reviews and recent science coverage commonly report increased endocannabinoid concentrations after roughly 30 to 60 minutes of continuous aerobic exercise. This typically occurs at moderate to vigorous intensity, translating to roughly 70% to 85% of maximum heart rate. You can effectively target these physiological responses during standard training blocks rather than risking the deep fatigue of an ultramarathon. Managing your effort intentionally ensures that strength training and performance objectives remain the priority throughout your athletic career.
While extreme endurance running clearly stimulates the endocannabinoid system to reduce anxiety, aging athletes must prioritize objective load management over chasing a biochemical high.
Follow ReEndure for practical insights on endurance training, recovery, nutrition and healthy aging. Stay connected for new articles, research led guidance and ideas to help you perform better for longer.
Read practical ideas on endurance training, recovery, nutrition and healthy aging to keep progressing for years to come.
Read the Blog