Cannabis in endurance sport

TL;DR

• Prevalence studies (Colorado): up to 82% of cannabis-using athletes use it around training.
• Subjective effects: focus, monotony tolerance, pain detachment.
• Objective: mild VO2max drop, higher heart rate (Renaud 1975).
• Bottom line: no ergogenic edge — mostly subjective motivation.

Why do trail runners report effects?

Cannabis neurologically overlaps with the endogenous runner's-high signal (anandamide, 2-AG). Reports describe deeper immersion and warped time perception — useful in ultras, but no substitute for fitness (Kennedy 2017).

Physiological strain and recovery phase

The acute effect of tetrahydrocannabinol (THC) on the cardiovascular system limits athletic performance during intense endurance exercise. Since THC increases the heart rate even at rest, the body reaches its performance limit faster under submaximal load. Oxygen uptake becomes less efficient, which reduces aerobic capacity. For this reason, consumption immediately before or during training is counterproductive from a sports science perspective. Furthermore, the psychotropic effect impairs coordination and reaction time, which significantly increases the risk of accidents on a bicycle or during trail running in rough terrain.

In the recovery phase after endurance sports, other aspects come into focus for athletes. Consumers frequently report improved subjective recovery and faster muscle relaxation. However, scientific evidence of accelerated physiological regeneration through cannabinoids is scarce. While cannabidiol (CBD) is valued for its suspected anti-inflammatory properties, THC can affect the sleep cycle. Deep, undisturbed sleep is essential for muscle regeneration. Research suggests that chronic consumption can shorten the crucial REM sleep phases, which impairs long-term performance development.

• Increased heart rate leads to faster fatigue during aerobic exercise.
• Increased risk of falls and injuries due to impaired psychomotor coordination.
• Potential impairment of sleep quality due to shifts in sleep phases during THC consumption.
• CBD is used in the recovery phase due to its subjectively relaxing effects on the muscles.

Legal framework in Swiss sport and everyday life

For athletes in Switzerland, the statutory limit values are of central importance. Cannabis products with a total THC content of less than one percent are not considered narcotics under the Narcotics Act and are legally available. Nevertheless, active athletes must be cautious: in organized sport, THC is subject to the anti-doping regulations of Swiss Sport Integrity and the World Anti-Doping Agency (WADA). THC is prohibited in competition, while CBD is permitted in competition. However, due to contamination in over-the-counter CBD products, there is always a risk of an unintentional positive doping test, which is why the utmost caution is advised when selecting products.

Another critical aspect concerns road traffic in Switzerland. Anyone travelling by bicycle or car after consuming THC-containing cannabis risks harsh sanctions. A strict zero-tolerance policy applies, with a statutory limit of 1.5 micrograms of THC per litre of blood. Since THC and its metabolites accumulate in the body and are only broken down slowly, unfitness to drive can still be detected days after the last consumption. This also affects athletes who use cannabis exclusively for evening recovery and set off for a training session on public roads the following day.

• Statutory THC limit of less than one percent for legal purchase in Switzerland.
• Strict zero tolerance in road traffic with a limit of 1.5 micrograms of THC per litre of blood.
• THC is prohibited in competitive sport according to WADA guidelines; CBD is permitted under certain conditions.
• Risk of cross-contamination with THC in supposedly pure CBD products.

Methods of consumption and health risk minimisation

The method of consumption plays a decisive role for endurance athletes, as lung function forms the basis of aerobic performance. The classic smoking of cannabis, especially in combination with tobacco, releases tar, carbon monoxide and other combustion products. These harmful substances damage the airways, reduce lung volume and impair gas exchange in the alveoli. For ambitious athletes, smoking is therefore the most harmful form of consumption. Although vaporising using a vaporizer protects the lungs from combustion residues, the hot aerosols can still irritate the airways and lead to bronchial hyperreactivity.

As an alternative, some athletes choose oral forms of consumption such as oils or capsules. This completely eliminates the strain on the respiratory tract, but the pharmacokinetics change drastically. The onset of action is significantly delayed and its intensity is more difficult to predict, as it has to pass through the gastrointestinal tract. This increases the risk of overdose. In case of uncertainty or adverse effects, Tox Info Suisse offers medical advice around the clock on telephone number 145. Athletes should also be aware that medical cannabis has been prescribable by doctors without a BAG exceptional permit since August 2022, enabling controlled use.

• Smoking causes long-term damage to the airways and reduces the oxygen uptake capacity of the lungs.
• Vaporising avoids combustion pollutants, but can still irritate the bronchi.
• Oral ingestion protects the lungs, but carries risks due to a delayed onset of action and difficulty in dosing.
• Medical cannabis has been directly prescribable by doctors in Switzerland since August 2022.

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