Cannabidiol (CBD) is a non-intoxicating cannabinoid derived from Cannabis sativa. CBD initially drew scientific interest due to its anticonvulsant properties but increasing evidence of other therapeutic effects has attracted the attention of additional clinical and non-clinical populations, including athletes [1].
Some professional athletes including golfers, rugby players, and more also appear to be using CBD.
This is despite there being no peer-reviewed research demonstrating beneficial effects on sport or exercise performance.
A wide range of low dose (e.g., 5–50 mg/day) CBD-containing “nutraceuticals” have become widely available online and over-the-counter in pharmacies or health food stores. This includes some varieties that are marketed specifically to recreational and elite athletes.
The use of these products is likely to become even more widespread if the World Health Organization’s recommendation that CBD no longer be scheduled in the international drug control conventions is adopted by the United Nations member states [2].
Cannabis has been prohibited in all sports during competition since the World Anti-Doping Agency first assumed the responsibility of establishing and maintaining the list of prohibited substances in sport 15 years ago [3].
In 2018, however, CBD was removed from the Prohibited List
This is presumably on the basis of mounting scientific evidence that the cannabinoid is safe and well-tolerated in humans [4], even at very high doses such as 1500 mg/day or as an acute dose of 6000 mg [5].
While several recent reviews have described the impact of cannabis on athlete health and performance, the influence of CBD alone has yet to be addressed.
In this article, we will review the available evidence on the effects of CBD and exercise both before and after working out.
Given the absence of studies directly investigating CBD and sports performance, our understanding today draws primarily on pre-clinical studies involving laboratory animals and a limited number of clinical trials involving human (non-athlete) populations.
Factor #1: As A Sleeping Aid
The importance of adequate sleep in facilitating optimal performance and recovery is increasingly recognized [6]. Yet, athletes and fitness enthusiasts often sleep less (e.g., ~6.5–6.7 hrs/night) and experience poorer quality sleep than non-athletes [7].
Factors that contribute to poor sleep among athletes include evening competitions and training sessions, pre-competition anxiety, use of caffeine, and long-haul travel that leads to jet lag and travel fatigue [6].
Several studies have investigated the effect of CBD on sleep in humans [8].
A study found that 160 mg CBD (but not 40 or 80 mg) increased self-reported sleep duration in individuals with insomnia; although time to sleep onset, number of sleep interruptions, and the likelihood of experiencing “good sleep” were unchanged [8].
Two case studies also indicated the benefits of CBD.
One study utilizing 75–300 mg/day for 42 days observed a reduction in symptoms of rapid eye movement sleep-behavior disorder in four individuals with Parkinson’s disease [9] and another found that ~25 mg/day of CBD improved subjective sleep quality in a young girl with post-traumatic stress disorder [10].
These studies are limited in that they rely on subjective measures of sleep and involve small sample sizes.
We can’t discount that the improvements observed could also be due to CBD attenuating other sleep-impairing comorbid conditions such as anxiety and post-traumatic stress disorder. Interestingly, a recent well controlled lab-based sleep study found no effect of 300mg CBD on sleep architecture in healthy adults [11].
While CBD seems unlikely to directly influence sleep in healthy humans [11] and may be “sleep-promoting” in those with certain comorbid conditions [10], research in rodents suggest that the cannabinoid could actually be “wake-inducing” [12].
One trial of healthy individuals [13] also found that a low-dose of 15mg of CBD counteracted some of the sedative effects of co-administered Δ9-THC (15 mg), which increased overnight wakefulness [14].
Differences in the doses of CBD given may explain this inconsistency.
A study on rats observed a biphasic effect of CBD on sleep, such that a lower dose decreased, and a higher dose increased (20 vs. 40 mg/kg), slow-wave sleep latency [15].
Collectively, the current evidence on CBD and sleep endorses the need for further research in clinical populations and athletes.
Factor #2: Sports performance anxiety
High levels of pre-competition stress, or sports performance anxiety [16], can be detrimental to athletic performance. This impairment has been attributed to both the direct (i.e. anxiety causing) and indirect (e.g. decreased nutritional intake, increased energy expenditure, loss of sleep) effects of sports performance anxiety [17].
While behavior therapies such as cognitive behavioral therapy are the preferred method of treatment, a combination of pharmaceutical and psychological interventions may be indicated in some cases [16].
There are quite a few clinical trials that have investigated the effects of CBD on subjective anxiety in healthy individuals [18] and in individuals with social anxiety disorder [19] and high trait paranoia [20] under both standard (i.e. “low stress”) and “stress-inducing” (e.g. simulated public speaking) [19] conditions.
Overall, results suggest that CBD has little influence on anxiety under “low stress” conditions in healthy participants [18].
However, several studies have demonstrated anxiety reducing effects of CBD (300–600 mg) under “stress-inducing” conditions in both healthy participants and those with social anxiety disorder [19].
In fact, CBD (300 mg) had comparable efficacy to a pharmaceutical medication during a simulated public speaking test in one study [21]. On the other hand, some research (involving similar “stress-inducing” stimuli) show no effect of CBD [20].
These inconsistencies could be due to differences between individuals in baseline anxiety levels and the magnitude of the stress-response to the stressor enforced, small sample sizes, and differences in the dose and formulation of CBD provided.
Taken together, the evidence indicates that moderate doses of CBD mat reduce anxiety in stressful situations and in individuals with social anxiety disorder.
Therefore, research investigating the effect of CBD (in conjunction with behavior therapies) on pre-competition anxiety, as well as nutritional intake, energy expenditure, symptom perception during exercise (e.g., ratings of perceived exertion), and sleep in athletes who are negatively impacted by sports performance anxiety are needed.
Factor #3: Cognitive Function
A small number of clinical trials have investigated the effects of CBD on cognitive and psychomotor function in healthy individuals. Overall, results suggest a minimal influence of CBD on cognitive or psychomotor function. A recent investigation observed an improvement in emotion recognition with 16mg of vaporized CBD, however, this “ability” may have limited relevance to the sporting context [22].
More applicable to athletes and those involved in fitness, research found no effect of 150 μg/kg of vaporized CBD on balance or coordination (which is a product of both cognitive and motor function) [23].
A more recent investigation likewise found no effect of oral or vaporized CBD (100 mg) on cognitive performance between 30 minutes and 8 hours post-treatment [24].
Therefore, with only a narrow range of doses and relatively few discrete cognitive functions researched to date, the available data suggest that CBD is unlikely to impact cognitive or psychomotor function on healthy individuals.
Factor #1: Recovery, muscle soreness, and inflammation
Strenuous, unfamiliar, and/or exercise involving an eccentric component, can cause ultrastructural damage to skeletal muscle. This exercise-induced muscle damage impairs muscle function and initiates an inflammatory response [25].
While inflammation is integral to muscle damage repair, regeneration, and adaptation [25], excessive inflammation may contribute to prolonged muscle soreness and delayed functional recovery.
CBD modulates inflammatory processes [26].
In preclinical models of acute inflammation, CBD has been reported to reduce immune cell accumulation [27], stimulate production of anti-inflammatory cytokines [28] and inhibit production of pro-inflammatory cytokines [29], and reactive oxygen species [30].
Anti-inflammatory effects are generally observed at higher doses in vivo (e.g. ≥ 10 mg/kg); although, lower doses (e.g. ~1.5 mg/kg) have indicated efficacy in some studies [31].
Research investigating the effects of CBD on inflammation in humans is limited and inconclusive.
In terms of muscle-specific inflammation, one preclinical study has investigated the effect of high-dose CBD (60 mg/kg/day) on transcription and synthesis of pro-inflammatory markers in the calf muscle and diaphragm of dystrophic MDX mice (a mouse model of Duchenne muscular dystrophy) [32].
In this investigation, CBD reduced gene expression of each marker and reduced plasma concentrations of pro-inflammatory markers.
Improvements in muscle strength and coordination, as well as reductions in tissue degeneration, were also reported at this dose. Lower, but still relatively high, CBD doses (20–40 mg/kg/day) had no functional benefits [32].
It’s important to recognize that exercise-induced muscle damage and muscular dystrophy differ in their pathophysiology, and so the effects observed in MDX mice may involve mechanisms less relevant to exercise-induced muscle damage [32].
While CBD could potentially aid in muscle recovery
However, other anti-inflammatory agents, such as ibuprofen (a non-steroidal anti-inflammatory drug) have been reported to reduce exercise-induced skeletal muscle adaptation [33].
The precise mechanism(s) underpinning these effects have not been fully explained, although it may be that the prevention of inflammation inhibits the formation of new blood vessels and skeletal muscle hypertrophy [33].
Human trials also suggest that ibuprofen may not influence exercise-induced muscle damage, inflammation, or soreness [34].
Therefore, if CBD exerts its effects via similar mechanisms, it could possibly reduce the benefits of training without influencing muscle function or soreness. This is clearly not what we ultimately want from our time spent in the gym.
Despite the widespread inclusion of strength training amongst high-level athletes, studies investigating the effects of CBD supplementation on resistance exercise are extremely limited.
To date, only two preliminary studies are available with varying research designs, and ambiguous findings.
A study utilizing 150 mg/day of oral CBD (2 × 75 mg doses given immediately post, 24 and 48 hrs following a muscle-damaging protocol) had no beneficial effects on either muscle function or perceived soreness in untrained males [35].
The only other available data on CBD and muscle soreness in an athletic context are limited to a single abstract from a conference communication [36].
This study assessed muscle damage (via the blood marker creatine kinase) following a single bout of resistance exercise and suggested that 60 mg/day of CBD supplementation reduced the acute increases in creatine kinase.
However, alongside the proposed reduction in muscle damage, there were also reductions in strength within 24 hrs of supplementation.
It’s really important to acknowledge that neither of these studies assessed blood or urine cannabinoid concentrations and the ambivalent data could be related to the efficacy of the supplementation protocols with major differences in the actual dose of CBD, number of days supplemented, and route of administration.
Collectively, the evidence to date on the effects of CBD on muscle function following damaging exercise could be, at best, described as ‘in its infancy’ and, therefore, it is not possible to reach any form of conclusion as to the efficacy of CBD for muscle recovery. Research is now required, including pharmacokinetic data, measures of blood cannabinoids, and dose–response data to fully explore if CBD is able to reduce muscle damage and/or enhance recovery following exercise.
Factor #2: Relieving muscle pain
Persistent pain is common in athletes. Nociceptive pain, which includes inflammatory pain, typically occurs with tissue damage; whereas neuropathic pain typically results from a lesion or disease in the somatosensory nervous system [37].
Neuropathic pain is common among para-athletes with spinal cord injuries and can also arise with surgery (e.g., to treat an existing injury) or if there is repetitive mechanical and/or inflammatory irritation of peripheral nerves such as those that occur in endurance sports [37].
Clinical trials investigating the combined effects of Δ9-THC and CBD (e.g., Sativex®) on chronic neuropathic pain have yielded promising initial results [38].
However, the therapeutic effects of CBD administered alone have received limited clinical attention.
Despite some inconsistencies in methodology (e.g. the pain model, period of treatment, route of delivery), most preclinical studies appear to have observed a significant analgesic effect of CBD [39], albeit somewhat less pronounced than the effects of Δ9-THC [40], a commonly used agent for treating neuropathic pain.
It is important to note that the analgesic effect of CBD likely depends on several factors, including the treatment dose and the type of pain involved. Low doses of CBD (e.g. ≤ 1 mg/kg) do not consistently reduce pain [40], while higher doses are sometimes found to be more [40], and other times, less [41], efficacious than moderate doses in preclinical studies.
This highlights the importance of determining a therapeutic dose for CBD in analgesia.
There is also research that demonstrates the selectivity of the response, indicating that CBD is only effective in reducing the development of neuropathic pain induced by certain chemotherapeutic agents [27].
Thus, placebo-controlled trials of CBD in treating pain in clinical populations and athletes are warranted.
Factor #3 Dietary Intake and Feeding
An adequate intake of energy and nutrients is essential to support optimal athletic training, recovery, muscle growth and performance [42].
Various preclinical studies have investigated the effect of CBD on feeding behavior in animal models [43], with results suggesting that higher doses may influence food intake several hours post-treatment.
Indeed, while CBD, at doses of 3–100 mg/kg in mice) [44] and 1–20 mg/kg in rats [45], failed to influence food intake during a 1 hour ad libitum (i.e., as much as desired) feeding period, moderate to high doses of CBD (4.4 mg/kg [43] and 50 mg/kg [46]) suppressed food intake (in rats) during longer ad libitum feeding periods (i.e. 4–6 hrs).
In line with these results, chronic CBD treatment of 2.5 and 5 mg/kg/day for 14 days reduced body mass gains in growing rats [47].
A recent systematic review of human trials also reported that individuals with epilepsy receiving CBD (5–20 mg/kg/day) were more likely to experience decreased appetite than those receiving placebo ([48].
The mechanism behind these effects of CBD on feeding behavior remains to be established.
Other cannabinoids (e.g. Δ9-THC, AEA, cannabinol) reliably induce hyperphagia (i.e., increased appetite) when administered exogenously [43]; but CBD lacks such an effect. A role for gastrointestinal side effects in affecting appetite therefore cannot be ruled out [48].
Further preclinical research is needed to clarify the mechanisms underlying these functional effects on feeding.
Controlled trials are also needed to determine whether CBD influences appetite and dietary behavior in humans, particularly during the pre- and post-exercise period, where
nutrient provision is critical.
References:
1. McCartney, D., et al., Cannabidiol and Sports Performance: a Narrative Review of Relevant Evidence and Recommendations for Future Research. Sports Med Open, 2020. 6(1): p. 27.
2. Organization., W.H. 2019.
3. Huestis, M.A., I. Mazzoni, and O. Rabin, Cannabis in sport: anti-doping perspective. Sports Med, 2011. 41(11): p. 949-66.
4. Taylor, L., et al., A Phase 1, Open-Label, Parallel-Group, Single-Dose Trial of the Pharmacokinetics and Safety of Cannabidiol (CBD) in Subjects With Mild to Severe Hepatic Impairment. J Clin Pharmacol, 2019. 59(8): p. 1110-1119.
5. Taylor, L., et al., A Phase I, Randomized, Double-Blind, Placebo-Controlled, Single Ascending Dose, Multiple Dose, and Food Effect Trial of the Safety, Tolerability and Pharmacokinetics of Highly Purified Cannabidiol in Healthy Subjects. CNS Drugs, 2018. 32(11): p. 1053-1067.
6. Malhotra, R.K., Sleep, Recovery, and Performance in Sports. Neurol Clin, 2017. 35(3): p. 547-557.
7. Hausswirth, C., et al., Evidence of disturbed sleep and increased illness in overreached endurance athletes. Med Sci Sports Exerc, 2014. 46(5): p. 1036-45.
8. Carlini, E.A. and J.M. Cunha, Hypnotic and antiepileptic effects of cannabidiol. J Clin Pharmacol, 1981. 21(S1): p. 417S-427S.
9. Chagas, M.H., et al., Cannabidiol can improve complex sleep-related behaviours associated with rapid eye movement sleep behaviour disorder in Parkinson's disease patients: a case series. J Clin Pharm Ther, 2014. 39(5): p. 564-6.
10. Shannon, S. and J. Opila-Lehman, Effectiveness of Cannabidiol Oil for Pediatric Anxiety and Insomnia as Part of Posttraumatic Stress Disorder: A Case Report. Perm J, 2016. 20(4): p. 16-005.
11. Linares, I.M.P., et al., No Acute Effects of Cannabidiol on the Sleep-Wake Cycle of Healthy Subjects: A Randomized, Double-Blind, Placebo-Controlled, Crossover Study. Front Pharmacol, 2018. 9: p. 315.
12. Murillo-Rodriguez, E., et al., Cannabidiol, a constituent of Cannabis sativa, modulates sleep in rats. FEBS Lett, 2006. 580(18): p. 4337-45.
13. Nicholson, A.N., et al., Effect of Delta-9-tetrahydrocannabinol and cannabidiol on nocturnal sleep and early-morning behavior in young adults. J Clin Psychopharmacol, 2004. 24(3): p. 305-13.
14. Ibeas Bih, C., et al., Molecular Targets of Cannabidiol in Neurological Disorders. Neurotherapeutics, 2015. 12(4): p. 699-730.
15. Monti, J.M., Hypnoticlike effects of cannabidiol in the rat. Psychopharmacology (Berl), 1977. 55(3): p. 263-5.
16. Patel, D.R., H. Omar, and M. Terry, Sport-related performance anxiety in young female athletes. J Pediatr Adolesc Gynecol, 2010. 23(6): p. 325-35.
17. Carvalho, R.K., et al., Chronic exposure to cannabidiol induces reproductive toxicity in male Swiss mice. J Appl Toxicol, 2018. 38(12): p. 1545.
18. Bhattacharyya, S., et al., Opposite effects of delta-9-tetrahydrocannabinol and cannabidiol on human brain function and psychopathology. Neuropsychopharmacology, 2010. 35(3): p. 764-74.
19. Bergamaschi, M.M., et al., Cannabidiol reduces the anxiety induced by simulated public speaking in treatment-naive social phobia patients. Neuropsychopharmacology, 2011. 36(6): p. 1219-26.
20. Hundal, H., et al., The effects of cannabidiol on persecutory ideation and anxiety in a high trait paranoid group. J Psychopharmacol, 2018. 32(3): p. 276-282.
21. Zuardi, A.W., et al., Effects of ipsapirone and cannabidiol on human experimental anxiety. J Psychopharmacol, 1993. 7(1 Suppl): p. 82-8.
22. Hindocha, C., et al., Acute effects of delta-9-tetrahydrocannabinol, cannabidiol and their combination on facial emotion recognition: a randomised, double-blind, placebo-controlled study in cannabis users. Eur Neuropsychopharmacol, 2015. 25(3): p. 325-34.
23. Dalton, W.S., et al., Influence of cannabidiol on secobarbital effects and plasma kinetics. Clin Pharmacol Ther, 1976. 20(6): p. 695-700.
24. Spindle, T.R., et al., Pharmacodynamic effects of vaporized and oral cannabidiol (CBD) and vaporized CBD-dominant cannabis in infrequent cannabis users. Drug Alcohol Depend, 2020. 211: p. 107937.
25. Fatouros, I.G. and A.Z. Jamurtas, Insights into the molecular etiology of exercise-induced inflammation: opportunities for optimizing performance. J Inflamm Res, 2016. 9: p. 175-186.
26. Booz, G.W., Cannabidiol as an emergent therapeutic strategy for lessening the impact of inflammation on oxidative stress. Free Radic Biol Med, 2011. 51(5): p. 1054-61.
27. Klein, M., et al., Effects of cannabidiol, a Cannabis sativa constituent, on oral wound healing process in rats: Clinical and histological evaluation. Phytother Res, 2018. 32(11): p. 2275-2281.
28. Weiss, L., et al., Cannabidiol arrests onset of autoimmune diabetes in NOD mice. Neuropharmacology, 2008. 54(1): p. 244-9.
29. Arruza, L., et al., Cannabidiol reduces lung injury induced by hypoxic-ischemic brain damage in newborn piglets. Pediatr Res, 2017. 82(1): p. 79-86.
30. Fouad, A.A., A.S. Al-Mulhim, and I. Jresat, Cannabidiol treatment ameliorates ischemia/reperfusion renal injury in rats. Life Sci, 2012. 91(7-8): p. 284-92.
31. Philpott, H.T., M. O'Brien, and J.J. McDougall, Attenuation of early phase inflammation by cannabidiol prevents pain and nerve damage in rat osteoarthritis. Pain, 2017. 158(12): p. 2442-2451.
32. Iannotti, F.A., et al., Effects of non-euphoric plant cannabinoids on muscle quality and performance of dystrophic mdx mice. Br J Pharmacol, 2019. 176(10): p. 1568-1584.
33. Machida, M. and T. Takemasa, Ibuprofen administration during endurance training cancels running-distance-dependent adaptations of skeletal muscle in mice. J Physiol Pharmacol, 2010. 61(5): p. 559-63.
34. Peterson, J.M., et al., Ibuprofen and acetaminophen: effect on muscle inflammation after eccentric exercise. Med Sci Sports Exerc, 2003. 35(6): p. 892-6.
35. Cochrane-Snyman, K.C., et al., The Effects of Cannabidiol Oil on Noninvasive Measures of Muscle Damage in Men. Med Sci Sports Exerc, 2021. 53(7): p. 1460-1472.
36. Isenmann, E., et al., Effects of Cannabidiol Supplementation on Skeletal Muscle Regeneration after Intensive Resistance Training. Nutrients, 2021. 13(9).
37. Hainline, B., et al., International Olympic Committee consensus statement on pain management in elite athletes. Br J Sports Med, 2017. 51(17): p. 1245-1258.
38. Hoggart, B., et al., A multicentre, open-label, follow-on study to assess the long-term maintenance of effect, tolerance and safety of THC/CBD oromucosal spray in the management of neuropathic pain. J Neurol, 2015. 262(1): p. 27-40.
39. De Gregorio, D., et al., Cannabidiol modulates serotonergic transmission and reverses both allodynia and anxiety-like behavior in a model of neuropathic pain. Pain, 2019. 160(1): p. 136-150.
40. Casey, S.L., N. Atwal, and C.W. Vaughan, Cannabis constituent synergy in a mouse neuropathic pain model. Pain, 2017. 158(12): p. 2452-2460.
41. Genaro, K., et al., Cannabidiol Is a Potential Therapeutic for the Affective-Motivational Dimension of Incision Pain in Rats. Front Pharmacol, 2017. 8: p. 391.
42. Thomas, D.T., K.A. Erdman, and L.M. Burke, American College of Sports Medicine Joint Position Statement. Nutrition and Athletic Performance. Med Sci Sports Exerc, 2016. 48(3): p. 543-68.
43. Farrimond, J.A., B.J. Whalley, and C.M. Williams, Cannabinol and cannabidiol exert opposing effects on rat feeding patterns. Psychopharmacology (Berl), 2012. 223(1): p. 117-29.
44. Wiley, J.L., et al., CB1 cannabinoid receptor-mediated modulation of food intake in mice. Br J Pharmacol, 2005. 145(3): p. 293-300.
45. Scopinho, A.A., et al., Cannabidiol inhibits the hyperphagia induced by cannabinoid-1 or serotonin-1A receptor agonists. Pharmacol Biochem Behav, 2011. 98(2): p. 268-72.
46. Sofia, R.D. and L.C. Knobloch, Comparative effects of various naturally occurring cannabinoids on food, sucrose and water consumption by rats. Pharmacol Biochem Behav, 1976. 4(5): p. 591-9.
47. Ignatowska-Jankowska, B., M.M. Jankowski, and A.H. Swiergiel, Cannabidiol decreases body weight gain in rats: involvement of CB2 receptors. Neurosci Lett, 2011. 490(1): p. 82-4.
48. Lattanzi, S., et al., Efficacy and Safety of Cannabidiol in Epilepsy: A Systematic Review and Meta-Analysis. Drugs, 2018. 78(17): p. 1791-1804.
