Cancer patients had lower baseline levels of the endocannabinoid anandamide compared to healthy controls, but 30 minutes of moderate exercise increased endocannabinoid levels in both groups — along with increased happiness.
Read this if you're interested in the biology behind exercise and mood, or if you're a cancer patient or oncology provider exploring the science of why exercise makes patients feel better.
What the researchers found
The 'runner's high' was long attributed to endorphins, but recent research has shifted the credit to the endocannabinoid system — specifically anandamide, the body's own cannabis-like molecule. This pilot study explored whether exercise-induced endocannabinoid changes differ between cancer patients and healthy adults.
At baseline, cancer patients had lower circulating levels of anandamide (AEA), OEA, and SEA compared to healthy controls across all time points. This suggests that cancer itself (or its treatment) depletes the endocannabinoid system — potentially contributing to the mood, appetite, and pain problems that cancer patients experience.
But the encouraging finding: just 30 minutes of moderate-intensity exercise (treadmill or cycling at 64-76% of age-predicted max heart rate) increased levels of anandamide, 1-AG, OEA, PEA, and SEA in both groups. Exercise activated the endocannabinoid system regardless of cancer status. Notably, 2-AG — the other major endocannabinoid — did not change with exercise.
On the mood side, happiness was the only one of 10 visual analog scales that significantly increased with exercise in the total cohort. The study also asked participants whether they experienced a 'runner's high,' connecting the subjective experience to the objective endocannabinoid changes.
The implication is that exercise may help replenish depleted endocannabinoid levels in cancer patients — offering a non-pharmacological way to activate the same system that cannabis targets.
Why it matters
This is one of the first studies to examine the endocannabinoid system's exercise response in cancer patients. If cancer depletes endocannabinoids (contributing to pain, mood, and appetite problems), and exercise restores them, it provides a biological rationale for exercise prescription in oncology that goes beyond general fitness — exercise may be directly addressing the neurochemical deficits that many cancer patients experience.
The numbers in context
Cancer patients had lower AEA, OEA, and log SEA vs controls across all timepoints (all p<0.06). Exercise increased AEA, log 1-AG, OEA, PEA, and log SEA (all p=0.05) in the total cohort. 2-AG did not change. Happiness was the only mood scale that increased with exercise (p=0.02). Exercise intensity: 64-76% age-predicted HRmax for 20 minutes plus warm-up/cool-down.
How the study worked
Pilot study comparing cancer patients and healthy controls. Participants did 30 minutes of quiet rest followed by 30 minutes of moderate-intensity exercise (64-76% age-predicted HRmax) on treadmill or cycle. Blood samples and 10 Visual Analog Scales collected before and after each condition. Blood analyzed for endocannabinoids (AEA, 2-AG, 1-AG) and endocannabinoid-like lipid mediators (PEA, OEA, SEA). 'Runner's high' query post-exercise.
Who was studied
Cancer patients and healthy controls (exact N not specified)
What this study cannot tell us
Pilot study with a small sample size (not specified in abstract but described as pilot). Acute exercise only — unknown whether chronic exercise training would produce sustained endocannabinoid changes. Cancer patients were heterogeneous (different cancer types, treatment stages). No control for anti-cancer treatments that might independently affect endocannabinoid levels. The mood assessment (only 1 of 10 scales changed) suggests the psychological effects of exercise are complex and not fully captured by endocannabinoid changes alone.
How to read the evidence
Pilot study with small sample size. The comparison between cancer patients and healthy controls is novel, and the objective endocannabinoid measurements are rigorous. However, the small sample limits generalizability and the acute design doesn't address chronic exercise effects.
When this study was published
Published in 2025. Exercise oncology and the endocannabinoid system are emerging research areas.
The bigger picture
This adds a cancer-specific dimension to the endocannabinoid science in the database. The basic endocannabinoid system studies (RTHC-00005 on anandamide discovery, RTHC-00072/73 on endocannabinoid-dopamine interactions) describe the system's normal function. This study shows what happens when cancer disrupts it, and that exercise can partially compensate. It also connects to the tolerance literature (RTHC-00100) — if cannabis use downregulates the endocannabinoid system, and exercise upregulates it, the two may work at cross-purposes or in complementary ways.
Replication
Not stated in abstract.
Funding
Not reported in abstract.
Conflicts of interest
Not reported in abstract.
Questions still open
- Would a chronic exercise program restore endocannabinoid levels in cancer patients to healthy baseline? Does the endocannabinoid depletion in cancer correlate with specific symptoms (pain, appetite loss, mood)? Could combining exercise with low-dose cannabinoid therapy produce synergistic endocannabinoid effects? Do different cancer types or treatments produce different endocannabinoid deficits?
Read the original research
Endocannabinoid system and mood responses to acute aerobic exercise in adult cancer patients versus healthy controls: a pilot study.
Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer, 33(12), 1162
Supportive Care in Cancer is a reputable journal focused on improving the quality of life for cancer patients.
Citation
Cheema, Birinder S; Low, Mitchell; Kay, Shelley; Stehn, Justine; Hall, Damian; Gourshettiwar, Abha; Wahlroos, Sara; Harrison, Michelle; Lacey, Judith. (2025). Endocannabinoid system and mood responses to acute aerobic exercise in adult cancer patients versus healthy controls: a pilot study.. Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer, 33(12), 1162. https://doi.org/10.1007/s00520-025-10221-5
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