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In the world of cycling and other endurance sports, athletes are always looking for ways to improve their performance. In recent years, carbon monoxide (CO) inhalers have emerged as a controversial tool in this area. Their use promises an increase in physical capacity, but raises important questions about their efficacy, safety and ethics.
Here we explore everything you need to know about this topic, based on scientific evidence and expert opinion.
What are carbon monoxide inhalers?
Carbon monoxide inhalers are devices designed to deliver small doses of carbon monoxide gas into the body. CO is a colourless, toxic gas that, in controlled concentrations, can have specific physiological effects. Although this substance is mainly known for its hazards in polluted environments, its application in microdoses has been studied in medical and sporting contexts.
In sport, the main purpose of these inhalers is to increase the efficiency of oxygen delivery to muscles by manipulating haemoglobin. However, its mechanism of action is still debated within the scientific community.
For what purpose is it used?
The rationale behind the use of carbon monoxide in sport lies in its interaction with haemoglobin. When inhaled in small amounts, CO binds to haemoglobin, forming carboxyhaemoglobin. This process displaces oxygen in red blood cells, but can also trigger an adaptive response in the body. Some studies suggest that this adaptation may improve the body’s ability to carry oxygen under conditions of physical exertion.
According to a study published in Frontiers in Physiology in 2021, controlled exposure to CO can stimulate the production of erythropoietin (EPO), a hormone that increases red blood cell production. This could benefit endurance athletes by improving their aerobic capacity. However, evidence is still limited, and effects vary according to dose and duration of exposure.
These are the potential benefits for sports performance
Proponents of carbon monoxide inhalers highlight several potential benefits. These include improved muscle oxygenation, greater endurance in long-duration events and faster recovery after intense exertion.
A 2019 study by the University of Colorado found that some athletes reported an improvement in their perception of exertion and a marginal increase in their performance in cycling time trials. However, these benefits were not similar and depended on individual factors such as previous training level and CO tolerance.
Associated risks and side effects
Despite the supposed advantages, the use of carbon monoxide in sport is far from safe. Associated risks include dizziness, nausea, loss of consciousness and, in extreme cases, brain damage or even death from poisoning.
In addition, the formation of carboxyhaemoglobin reduces the body’s ability to carry oxygen, which can lead to hypoxia in vital tissues. According to Dr Michael Joyner, an expert in exercise physiology at the Mayo Clinic, ‘the margin between a “safe” dose and a toxic dose of carbon monoxide is extremely small, making the practice inherently risky’.
The scientific community is divided on the use of carbon monoxide inhalers. While some researchers see interesting potential, many others warn of the dangers and lack of conclusive evidence.
An analysis published in ‘Sports Medicine’ in 2022 concluded that, while CO microdosing may offer benefits in controlled settings, the risks outweigh any potential improvements in performance. Furthermore, long-term studies on the effects of CO in athletes are virtually non-existent, making it difficult to assess its safety over time.
What is the legislation and ethical use in sport?
The use of carbon monoxide in sport raises serious ethical and legal issues. The World Anti-Doping Agency (WADA) does not currently include CO on its list of banned substances, but this could change if its ability to significantly enhance performance is demonstrated.
From an ethical point of view, many experts argue that its use contradicts the principles of fair play and puts the health of athletes at risk. In sports such as cycling, where anti-doping policies are strict, the introduction of this practice could open the door to a new type of controversy.
These are the potential benefits for sports performance
Proponents of carbon monoxide inhalers highlight several potential benefits. These include improved muscle oxygenation, greater endurance in long-duration events and faster recovery after intense exertion.
A 2019 study by the University of Colorado found that some athletes reported an improvement in their perception of exertion and a marginal increase in their performance in cycling time trials. However, these benefits were not similar and depended on individual factors such as previous training level and CO tolerance.
Associated risks and side effects
Despite the supposed advantages, the use of carbon monoxide in sport is far from safe. Associated risks include dizziness, nausea, loss of consciousness and, in extreme cases, brain damage or even death from poisoning.
In addition, the formation of carboxyhaemoglobin reduces the body’s ability to carry oxygen, which can lead to hypoxia in vital tissues. According to Dr Michael Joyner, an expert in exercise physiology at the Mayo Clinic, ‘the margin between a “safe” dose and a toxic dose of carbon monoxide is extremely small, making the practice inherently risky’.
The scientific community is divided on the use of carbon monoxide inhalers. While some researchers see interesting potential, many others warn of the dangers and lack of conclusive evidence.
An analysis published in ‘Sports Medicine’ in 2022 concluded that, while CO microdosing may offer benefits in controlled settings, the risks outweigh any potential improvements in performance. Furthermore, long-term studies on the effects of CO in athletes are virtually non-existent, making it difficult to assess its safety over time.
What is the legislation and ethical use in sport?
The use of carbon monoxide in sport raises serious ethical and legal issues. The World Anti-Doping Agency (WADA) does not currently include CO on its list of banned substances, but this could change if its ability to significantly enhance performance is demonstrated.
From an ethical point of view, many experts argue that its use contradicts the principles of fair play and puts the health of athletes at risk. In sports such as cycling, where anti-doping policies are strict, the introduction of this practice could open the door to a new type of controversy.
