research-bites.com February 2021

DEAL? IS CBD THE REAL

- Patrick McCarthy -

Narrative review of CBD for reducing pain and injury in athletes- Part I

Study Title: Cannabidiol and Sports Performance: a Narrative Review of Relevant Evidence and Recommendations for Future Research Study Author(s): McCartney, Benson, Desbrow, Irwin, Suraev & McGregor (2020) Study Journal: Sports Medicine Journal Impact Factor: 12.68

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BACKGROUND

WHAT WILL I LEARN?

• The proposed mechanisms underlying potential benefits of CBD

• An introductory overview of the evidence to date assessing CBD use in athletes

• Applications of CBD supplementation in athletes e.g. muscle soreness, pain relief

Cannabis Sativa, is a herbaceous plant that first originated in Eastern Asia, but is now cultivated across the globe. Whilst it provides a myriad of applications, the most popular is inexorably the intoxicating effects gained from smoking the herb. These psychoactive effects are attributable to its tetrahydrocannabinol (Δ9 - THC or THC) content, which is one of the many cannabinoids found in the plant. Another of these cannabinoids is Cannabidiol (CBD), which is non-psychoactive (does not have intoxicating effects such as THC). The authors of this study mention that CBD, unlike THC, has become widely popularized and even removed from the prohibited list by the World Anti-doping Agency (WADA). Yep! Olympians and professional athletes can now consume this compound without risk of testing positive in a doping test.

What piece of the puzzle is this?

As the authors mention, not only is CBD legal for use is supplements, it can now be purchased over the counter. I can say from personal experience that most stores will have some CBD-containing product on their shelves including but not limited to, skin creams, gummies, oils, energy drinks, sprays, drops and gums. The reason that the availability and appearance of these products has become so rampantly widespread, is for the same reason that you’re reading this article today; the potential benefits sound too good to be true! Pair those benefits with the publicized use of the compounds by famous athletes and sports stars, you’d be crazy not to consider it right?! This is when marketing and influencer sponsorship really can mystify the general understanding and perceptions of such a supplement or compound. With that said, I am coming into this article completely unbiased, and it is not an area I am particularly versed on. It is a narrative review, which means there was no systematic search or strategy,

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What did this study do?

How does CBD work in the body?

Does CBD improve muscle soreness?

This requires only a small little paragraph because, well, the search strategy was very relaxed and non-systematic. This is known as a narrative review, which serves to dip the reader’s toes in, so to speak, to the larger, unknown ocean of evidence out there. It is usually something you will see before there have been exhaustive and systematic reviews conducted. In this study, the researchers used the major databases (PubMed, Web of Science and SCOPUS) were searched for studies including ‘CBD’, ‘Cannabidiol’ and ‘Cannabis’. The authors make special mention that they tended to look at pre-clinical (animal, before humans) in vivo (in the body) studies and not so much at the mechanistic, biochemical in-vitro studies. What does this mean? Well, it means that we can’t make any conclusions without having definitive proof from both types of studies. Mechanistic studies provide the biological rationale, whilst in vivo studies show the clinical relevance on the ground level. For example, CBD may have a biochemical effect in tissue cultures, but it might be so small when you take into account the 1000’s of interactions that occur in our body every day. Ya get me?! A small paragraph I said…

THE STUDY The authors briefly outline some of the ‘molecular targets’ of CBD in the body to provide some of potential mechanisms by which it could benefit athletes. First and foremost, CBD in the body acts supports the actions of the endocannabinoid system, which prevails over a series of important biological processes. CBD is believed to act as an agonist (Stimulates a response), but not to the intensity of THC, on several important cell receptors. Once activated, these receptors can stimulate the activity of their accompanying cells. This is known as the endocannabinoid system which consists of enzymes, other proteins and receptors involved in a series of reactions that play a role in cognition (thinking), sensations of pain, appetite, immune function, inflammation and mood (Source: NCBI). Interestingly, CBD also prevents some receptors from becoming overly activated during stress responses (Sources: Examine & NCBI). Finally, CBD is known to act directly as an antioxidant, which if you are not aware, is a compound that reduces oxidative stress in the body, caused by free radicals.

One of the most popular reasons for athletes dosing CBD is for reducing exercise-induced muscle soreness and injury, right? When we exercise, inflammation and tissue damage will occur at the muscle site. While we want a certain degree of this inflammation (to engage the adaptive and recovery processes), we don’t want a whole bunch. CBD is believed to regulate inflammation and so may help here. OK, so the authors mention a bunch of studies here, but to save you the time and reading, CBD’s effects on muscle soreness can be boiled down to -

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Does CBD improve exercise-induced GI damage?

Does CBD reduce overall pain?

Here, the authors mention several pre-clinical studies (lab-based, non-human) that found evidence for a potential application of CBD for exercise-induced GI damage. They state that the these are mostly through the antioxidant and anti-inflammatory mechanisms of CBD, and it may help to reduce the tissue damage accrued (Source: NCBI). However, the authors then highlight the lack of evidence supporting CBD use by humans for GI conditions. One study tested the impact of CBD on reducing symptoms of Chron’s disease (Source: NCBI), while another assessed CBD’s impact on inflammatory markers of Colitis (Source: NCBI). Both of these failed to show improvements when compared to placebo. In summary, the evidence here is inconclusive and we need more before making some outlandish claims on labels.

three main mechanisms -

• Reduces the activity of immune (inflammatory) cells

• Increases activity of anti-inflammatory molecules

• Reduce the production of pro-inflammatory cells

So, as mentioned, there were mechanistic studies showing these effects in cell cultures or animal models. In rodent trials, the authors emphasize that anti-inflammatory effects are commonly observed at high doses of CBD (much higher than what you would consume in a store-bought product) but that the book isn’t closed for smaller doses. Finally, the authors draw attention to an important consideration here. They compare these proposed actions of CBD to NSAID’s (e.g. Ibuprofen) which because of their potent anti-inflammatory impacts, may offset the positive muscular adaptations to training. For example, imagine you’re a tennis player suffering from the infamous tennis elbow. Your coach recommends an elbow strap that you need to keep on until your match next week. BUT, it is so tight, you cannot even flex the elbow to practice. Yes, it protects your elbow, but to an extent that prevents you from improving. Just an insightful consideration, alluded to by the authors.

This one can be a f**ker, especially for endurance athletes. Runner’s tummy is a commonly-experienced phenomenon characterised by pain, bloating, inflammation and the need to defecate during exercise. But it can also become a chronic issue too.

Nociceptive pain, as the authors term it, is that caused by inflammation commonly experienced by athletes in response to tissue damage. They also mention neuropathic pain which is typically limited to those who have had a spinal cord injury such as para-athletes. There have been several clinical (human) studies, examining moderate-dose CBD + THC in athletes. The results of these, as authors mention, have been promising and shown positive results on pain management, but studies of CBD alone are lacking. In the few that do exist, it seems higher doses are required and even then, the results are mixed. They did highlight several pre-clinical (animal) trials that showed analgesic (pain-relieving) effects of CBD alone, however it was not to the magnitude of THC. This section is rounded out with a call for the need for placebo-controlled clinical trials to identify the optimal dose, frequency and timing, if any, for CBD’s analgesic role.

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TAKEAWAYS This is only part I of this series, where I discussed the aspects of the study pertaining to pain and inflammation. In the second part, we will look at CBD’s potential role in attenuating anxiety, stress, concussion/brain injury symptoms and improving sleep. For now though, what have we learned from this initial instalment? For me, it has been an eye opener that the majority of studies conducted thus far have been preclinical trials, in animals or isolated tissue. There do of course, exist several human trials, but the findings of these have not been persuasive. Here are some more takeaways:

• It appears that CBD may provide pain-relieving and anti-inflammatory benefits in muscle injury and damage, when consumed in higher doses. These doses are usually much higher than those provided in commercially-available products (Source: NCBI).

• Several human studies showing pain-relieving benefits of CBD, paired it with THC, which has been known to provide greater effects on pain management. Less is known about CBD alone.

• In pre-clinical studies, there does seem to exist the potential for CBD to help reduce the tissue damage and inflammation caused by GI distress during exercise. Definitive proof is not available however, and some human studies (with diagnosable conditions) showed little to no impacts.

• When it comes to pain-relief, CBD alone has repeatedly shown promise in preclinical studies, but randomized, placebo-controlled studies are needed before making any recommendations.

As I mentioned, stay tuned for part II, next week! I hope you enjoyed this article, and took something new away! Keep it classy, P