Whether it’s a training plan or optimised nutrition – athletes use various strategies to improve their physical performance and achieve training goals. CBD is also increasingly coming into focus: cannabidiol (CBD) has anti-inflammatory, pain-relieving and neuroprotective effects and can support the healing process of sports injuries. Athletes can also benefit from anxiety-relieving and sleep-promoting effects and, for example, alleviate stage fright.
The non-psychotropic CBD, together with other cannabinoids such as the psychotropic tetrahydrocannabinol (THC), was long considered an illegal doping substance in competitive sports. In 2018, the World Anti-Doping Agency (WADA) removed CBD from the doping list and has since allowed competitive athletes to use the cannabinoid.
What is doping?
Doping athletes use prohibited substances or methods to gain unfair advantages over other participants. According to the World Anti-Doping Agency (WADA), inclusion on the Doping List occurs when a substance or method meets three criteria :
- Increasing athletic performance
- Health risks
- Violation of the spirit of sport (e.g. fair play, team spirit)
Anti-doping rules are important to preserve the spirit of sport and thus ensure fair and healthy competition. It is about values such as fair play, health, team spirit, community and solidarity . However, health risks and moral concerns do not deter some athletes from doping.
Anti-doping rules can change over time. For example, caffeine used to be considered a doping substance, but may now be used in professional sports without restriction .
Prohibited substances and methods in competitive sports
Some doping substances and methods are strictly forbidden in professional sport, i.e. they are not allowed in competition or training. The best-known example is anabolic steroids, which are misused to build muscle. For example, blood doping, which increases the oxygen supply, is one of the prohibited methods. Since, in addition to the unfair advantage, health is also at risk, the athletes are disqualified.
Other groups of substances, on the other hand, are only prohibited in competition, i.e. they are allowed during leisure time and training. This group includes THC and other psychotropic substances such as stimulants and opiate painkillers. However, the limit values in the urine must be observed on the day of the competition.
For some groups of active substances, there are exceptions that allow their use in competitive sports if prescribed by a doctor. For example, athletes suffering from asthma can use inhaled beta-2 agonists (e.g. salbutamol). In the case of skin diseases, glucocorticoids can be applied externally to the skin.
The doping substances and methods banned by WADA in competitions and/or training are :
Cannabis in competitive sports
All cannabinoids – with the exception of CBD – are on the doping list and are therefore prohibited in competitive sports. Out-of-competition THC is allowed as long as the limits are respected in competition .
Cannabis products prohibited in competition are :
- Phytocannabinoids (except CBD) in the form of cannabis flowers and cannabis resin
- Natural or synthetic tetrahydrocannabinol (THC)
- Synthetic cannabinoids with THC-analogue effect (e.g. nabilone)
THC is detected in urine as the water-soluble degradation product THC-carboxylic acid (THC-COOH) . The permissible limits vary depending on the organisation conducting the doping tests .
In 2013, WADA relaxed the limits for THC-COOH: Whereas previously a maximum of 15 nanogrammes per millilitre of urine was permissible , the current limit is 150 nanogrammes per millilitre . THC degradation products can be detected in urine for a long time, as cannabinoids accumulate in fatty tissue due to their pronounced fat solubility. If fat is burnt during exercise, the cannabinoids are released again and appear in blood and urine .
Tetrahydrocannabinol (THC) in competitive sports
In 2017, an Australian research team analysed 15 studies that dealt with THC in sports in a review paper: In none of the studies did THC increase aerobic performance (endurance) and strength. While THC was shown to alleviate exercise-induced asthma, some studies found negative effects on cardiac function: In two studies, attacks of angina pectoris (chest tightness) occurred during low levels of exercise. Some athletes also felt too impaired to perform their training .
Although THC does not enhance performance, the psychotropic cannabinoid can have a sedating effect and increase risk-taking , which can increase the risk of injury for all participants in certain sports.
Cannabidiol (CBD) in competitive sports
In 2018, WADA removed the non-psychotropic cannabidiol (CBD) from the doping list . Since then, CBD can also be used in professional sports such as the Olympic Games.
Effects of CBD in sports are [4,5]:
- Anti-inflammatory, analgesic (e.g. for injuries)
- Improved healing for sports injuries
- Anxiety-relieving (e.g. before competitions)
- Neuroprotective (for head injuries such as concussion)
- Prevention of inflammatory gastrointestinal complaints
- Sleep-inducing (for sleep disorders)
In 2020, scientists from the University of Sydney compiled a review of the state of research on the effect of CBD on athletic performance. The research team looked at the physiological and psychological effects of the cannabinoid that are important in sport. Since only a few clinical studies with athletes have been published so far, the research team compiled results from preclinical studies and clinical studies with cannabis patients in the context of other diseases .
Anti-inflammatory effect and promotion of bone health
The anti-inflammatory effect of CBD promotes healing in muscle injuries and supports regeneration. Compared to other anti-inflammatory drugs, CBD has some advantages : For example, non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen can interfere with the adaptability of the muscles during sports . Another side effect of (NSAIDs) is stomach problems: As the digestive organs are less supplied with blood during sporting activity in favour of the heart, lungs and skeletal muscles, the gastric mucosa of athletes is particularly sensitive to the side effects of ibuprofen. CBD has an anti-inflammatory effect without affecting the muscles or causing gastritis .
Exercise promotes bone health, but injuries impair it. A preclinical study published in 2015 showed that CBD promoted healing of femur fractures in rats. Eight weeks after fracture, the bones showed improved mechanical properties. It is possible that CBD inhibits the proteins RANK and RANK-L, which means that osteoclasts, which normally break down bone, are not activated. On injured bone, CBD also has an anti-inflammatory effect, resulting in the release of fewer pro-inflammatory cytokines. Based on the promising results of the preclinical studies, further investigations into the effect of CBD in acute injuries such as fractures and sprains are desirable .
The neuroprotective effect of CBD in neurodegenerative diseases (e.g. Alzheimer’s disease) is known from numerous studies. CBD can also be helpful in cases of minor head injuries such as concussion . In Germany, about 44,000 cases of mild craniocerebral trauma resulting from sports accidents are diagnosed every year , which manifest themselves in the form of neurological and cognitive disorders. Possible consequences are cerebral oedema (fluid accumulation in the brain) and increased intracranial pressure. In 2019, the effects were investigated in a mouse model for head injuries: CBD regulated the disturbed balance of messenger substances such as glutamate and GABA (gammaaminobutyric acid) after injuries.
This reduced excitotoxicity, which experts understand as the death of nerve cells due to stimulus overload as a result of overactivity of excitatory neurotransmitters (e.g. glutamate) .
Exercise-related gastrointestinal complaints
During sport, organs such as the heart and lungs as well as skeletal muscles are challenged and are therefore supplied with more blood. In turn, the digestive organs are less supplied with blood. Especially during long training sessions such as marathons, the sensitive mucous membrane of the stomach and intestines can be damaged by a lack of oxygen: This can lead to complaints such as nausea, vomiting or diarrhoea. In preclinical studies, CBD improved tissue damage through antioxidant and anti-inflammatory effects. Studies on intestinal cells also showed that CBD can restore the normal permeability of the intestinal wall, which has been damaged by bacterial toxins (Clostridium difficile toxin A), for example. Anti-inflammatory painkillers from the group of non-steroidal anti-inflammatory drugs (NSAIDs) such as ibuprofen additionally reduce mucosal blood flow and can worsen tissue damage. CBD, on the other hand, poses no risk of stomach damage and also has an anti-inflammatory effect. The effect of CBD on gastrointestinal complaints in sport should be researched in more detail .
Pain relieving effect
Many athletes benefit from the pain-relieving effects of CBD. Sports injuries can cause nociceptive and neuropathic pain :
- Nociceptive pain is caused by tissue damage and has an inflammatory component.
- Neuropathic pain (nerve pain) is caused by injured or diseased nerves. In particular, para-athletes with spinal cord injuries are affected by nerve pain.
Clinical trials with cannabis medicines containing THC and CBD, such as the cannabinoid spray Sativex®, have shown good results for nerve pain. Even though THC is attributed with a stronger pain relief, many animal models also prove a significant pain-relieving effect for CBD . A clinical trial conducted in 2021 showed significant pain relief in diabetic neuropathy of the legs with sublingual CBD tablets . The pain relief is mediated, at least in part, by the effect of CBD on TRPV1 channels, which studies have shown to be involved in increased pain sensitivity (hyperalgesia) in muscle inflammation. Further studies are needed to determine the optimal dosage for pain .
Anxiety-relieving effect (especially for competition anxiety)
Stage fright can limit athletic performance. Competition anxiety manifests itself, for example, in a lack of appetite and sleep. Anxiety can be treated with cognitive behavioural therapy and medication. Some small studies investigated the effect of CBD in anxiety situations – consisting of a speech in front of a public audience – with healthy participants and anxiety patients. CBD was found to be similarly effective to the anti-anxiety antidepressant Ipsapirone, a 5HT1A agonist. However, other studies showed no efficacy for CBD on similar “anxiety-provoking” situations. Dosage also plays a role in the effect, with less sometimes being more: studies showed that medium doses of CBD best reduced anxiety in stressful situations and social anxiety disorders. Small and high amounts of CBD, on the other hand, were less effective .
Sufficient sleep is important so that the body can regenerate after peak athletic performance. Many competitive athletes struggle with sleep disorders. Evening training sessions, caffeine and travelling to sporting events can disrupt sleep patterns. Last but not least, competition anxiety can also cause sleepless nights. According to a double-blind study with healthy people published in 2018, CBD probably has no influence on the sleep-wake rhythm of healthy people, as measurements in the sleep laboratory (polysomnography) showed.
However, for patients with co-occurring disorders such as anxiety and post-traumatic stress disorder (PTSD), CBD can improve sleep as it can alleviate underlying symptoms . Clinical studies have shown a dose-dependent effect of CBD on sleep: for example, a study published in 1981 found that high-dose CBD increased total sleep time in healthy individuals . Another study from 2004 with healthy subjects showed wakefulness effects of low-dose CBD, whereby it also counteracted the sedative effect of THC .
Can CBD affect athletic performance?
According to current research, CBD only minimally affects mental and motor abilities. An older American study in 1976 showed that CBD does not interfere with the ability to maintain balance or coordination. In a more recent study from 2020, oral or inhaled CBD also had no effect on mental performance. Experts therefore assume that CBD does not impair athletic performance .
Which CBD-containing cannabis products are suitable for competitive athletes?
A problem with over-the-counter CBD-containing food supplements is that, in contrast to prescription drugs (e.g. Epidiolex®), no pharmaceutical quality is prescribed . According to an American study from 2017, only one third (31 %) of all CBD products sold on the internet are correctly labelled. About half of the CBD extracts examined were underdosed and a quarter overdosed. THC was detected in every fifth sample. This brings with it the risk of positive drug or doping tests . A recent study examined 25 CBD preparations purchased in Mississippi: Only three preparations were +/- 20 percent of the declared CBD content. Buyers cannot rely on claims like “0 percent THC” .
Competitive athletes should avoid full-spectrum products: CBD extracts made from the whole cannabis plant contain residual amounts of THC and other phytocannabinoids that are on the doping list . Professional athletes should only use pure CBD products that are free of other cannabinoids in competition.
The World Anti-Doping Agency (WADA), founded in 1999, added all cannabis products to the doping list in 2004. Due to the increasing international liberalisation of medicinal and recreational cannabis, the ban has been increasingly relaxed. In 2018, non-psychotropic CBD was removed from the doping list. The 2020 Summer Olympics in Tokyo were the first Olympic Games where CBD was allowed. This means that competitive athletes can use CBD specifically in training to alleviate associated complaints such as pain, sports injuries or stage fright, as well as to support regeneration.
The regulations for the psychotropic THC have also been increasingly relaxed. After the limit for THC-COOH was lowered in 2013, the status of cannabis as a doping substance, including THC, is currently under scrutiny. WADA announced a scientific review. In 2022, cannabis and thus THC will remain banned in competition .
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