ANALYSIS: Why are riders like Tadej Pogacar and Jonas Vingegaard using carbon monoxide?

Cycling, like any other professional sport, sees riders and teams constantly experimenting with different training methods, dietary plans, and supplements, all to find the extra 1%. But in a sport where the smallest of margins can make the difference between a grand tour victory, and dropping like a stone on the first climb, there is a constant flow of new products and methods that fall in a grey area between legal and illegal. Cycling’s past is one riddled with shady characters, and words such as EPO and blood doping are dark clouds that still linger over the sport.

In 2024, the new controversy is carbon monoxide. Back in July, the two main protagonists of the last five Tour de France, Tadej Pogacar and Jonas Vingegaard, both confirmed they had used it previously - although it's unclear how much and if it had any effects. At this stage, it is still legal, but whether this is simply a training revolution or another dark path for cycling (which could definitely do without any more dark paths), remains to be seen. Cycling fans naturally get suspicious of any performance-enhancing mechanism, especially those that they may not understand. So, we want to look at what the benefits are of carbon monoxide, and how teams are using it to create performance gains.

Should it be illegal in sport? This article may not answer that question, but it will hopefully help you to understand why it is becoming more popular in cycling, and why some riders and experts have their concerns.

Stay with us, its about to get scientific, but we’ll break it down and find out its relevance to cyclists shortly.

Carbon monoxide (CO) is a colourless, odourless gas produced by the incomplete combustion of carbon-containing materials. In the human body, CO is generated during the breakdown of heme by the enzyme heme oxygenase. At low concentrations, CO functions as a signalling molecule, influencing various physiological processes.

In the context of athletic performance, particularly in endurance sports like cycling, CO has gathered attention for its potential to enhance oxygen delivery and utilisation. When inhaled in controlled, low doses, CO binds to haemoglobin, forming carboxyhaemoglobin. This binding reduces the oxygen-carrying capacity of the blood, simulating hypoxic conditions similar to those experienced at high altitudes. The body responds by increasing the production of erythropoietin (EPO), stimulating the generation of red blood cells and then elevating total haemoglobin mass. An increase in haemoglobin mass can improve oxygen transport to muscles, potentially enhancing endurance performance.

Ok, confused? Yep, we are too, so here’s a more concise explanation: By mimicking the effects of high-altitude training through controlled CO exposure, athletes may boost their red blood cell count, leading to better oxygen delivery during prolonged physical activity. Beyond cycling, other endurance sports have explored CO inhalation for performance benefits, particularly any where maximum aerobic capacity is a priority.

While controlled CO exposure may offer performance advantages, it carries significant health risks. CO has a high affinity for haemoglobin, binding more readily than oxygen and forming carboxyhaemoglobin. Elevated levels of carboxyhaemoglobin can reduce oxygen delivery to tissues, leading to symptoms such as headaches, dizziness, and, in severe cases, loss of consciousness or death. Chronic exposure, even at low levels, may result in cardiovascular and neurological complications. So, like other dark paths cycling has gone down in the past, carbon monoxide certainly has health risks to even the fittest athletes.

The margin between a potentially beneficial dose and a harmful one is narrow, making precise control essential. Unsupervised or improper use of CO inhalation poses serious health risks, which highlights the need for medical oversight and for riders and teams to strictly follow safety rules.

During the 2024 Tour de France, the use of carbon monoxide rebreathing techniques by top teams, including UAE Team Emirates and Team Visma Lease a Bike, sparked discomfort within the peloton. These teams employed CO rebreathing to measure haemoglobin mass, and whilst this is not illegal, it was viewed with a raised eyebrow by many within the media and cycling fans. Riders like Tadej Pogacar and Jonas Vingegaard defended the method, emphasising its role in assessing training efficiency rather than performance enhancement. This is different to other performance enhancing drugs of the past, as it is an assessor of current fitness levels, rather than a fitness boost.

In an interview with Eurosport, French cyclist Romain Bardet expressed awareness of CO inhalation practices, acknowledging the ‘arms race’ amongst teams to have the most advanced mechanisms to boost performance. He highlighted the ethical considerations and the need for clear regulations, noting that in a highly competitive environment, reliance on individual ethics is insufficient in the constant battle to keep things fair.

The use of substances or methods that enhance performance while remaining within legal boundaries is not unique to cycling. In sports like athletics and swimming, techniques such as hypoxic training (simulating high-altitude conditions) and the use of supplements like ketones have been tested and used to gain a competitive edge. These practices often spark debates about fairness, health implications, and the spirit of sport, highlighting the ongoing tension between innovation and regulation in athletic performance.

The introduction of carbon monoxide rebreathing as a performance-enhancing method has raised critical questions regarding the boundaries of what is deemed ethical in professional cycling. Governing bodies like the UCI and the World Anti-Doping Agency (WADA) face significant challenges when addressing innovative methods that fall within legal limits but hang on the edge of what might be considered fair competition. The debate often lies not in whether these practices are allowed under current regulations but in whether they align with the spirit of fair play that sports organisations aim to uphold.

Historically, sports authorities have had to adapt to new scientific discoveries rapidly, balancing the need to maintain a level playing field with the understanding that advancements in training and recovery are inevitable. Like Formula 1 cars are constantly getting faster as technology improves, cyclists also get faster as their training, diet, and resources become more advanced.

The case of carbon monoxide rebreathing places the UCI and WADA at a crossroads: should they wait for conclusive evidence of harm or unfair advantage before acting, or take a proactive stance to preserve the sport’s reputation from any more harm?

The impact of carbon monoxide rebreathing extends beyond the peloton and into the realm of public opinion and media scrutiny. Cycling, still damaged by past doping scandals, remains under intense observation. The mention of new, unconventional practices often triggers scepticism among fans, who fear that the sport is playing a dangerous game once more. This reaction is magnified by the media, which frequently positions such stories within the larger narrative of cycling's troubled history with performance enhancement.

The media portrayal of carbon monoxide usage can sway public opinion on the topic, framing it either as a clever, legal method of maximizing athletic output or as another potential scandal in the making. High-profile endorsements or criticisms from riders and teams play a crucial role in shaping these narratives. For instance, when Tadej Pogacar and Jonas Vingegaard admitted to using CO rebreathing, the conversation shifted to whether this represented forward-thinking training or an ethical grey zone that could lead to future bans.

Understanding public perception is key to predicting how long methods like CO rebreathing will remain part of competitive cycling. If widespread backlash grows, it may push governing bodies to re-evaluate and potentially ban the practice. As such, public and media reactions act as unofficial watchdogs of what practices are acceptable, influencing the direction of sports regulation and the evolution of training methodologies.