The International Cycling Union (UCI) has issued a statement urging riders to cease inhaling carbon monoxide (CO) in an effort to combat the growing concerns over its use in the sport. This message, delivered on Tuesday, comes after increasing awareness of the substance's performance-enhancing effects, which have raised alarms within the cycling community.

At a meeting held in Nice, UCI officials addressed this topic alongside other significant matters, including the High Temperature Protocol and the sport’s evolving role in addressing climate change. Among the key points discussed was the use of CO in cycling, a method that has drawn attention for its potential misuse in enhancing endurance and optimizing altitude training.

The UCI’s statement specifically requests that riders refrain from repeatedly inhaling carbon monoxide, emphasizing that its use should be limited to controlled medical environments and only for rare, single inhalations. The organization made it clear that carbon monoxide should never be used routinely as a performance aid. In fact, it was highlighted that while a single inhalation could potentially be medically acceptable in certain cases, the practice should not be repeated on a regular basis.

"Seminar participants were also brought up to date on the current knowledge of the effects on performance of repeated carbon monoxide (CO) inhalation," the UCI's statement reads. "The UCI clearly asks teams and riders not to use repeated CO inhalation. Only the medical use of a single inhalation of CO in a controlled medical environment could be acceptable." The UCI also called on the World Anti-Doping Agency (WADA) to take an official position on this issue, considering its implications for fairness in the sport.

However, there is a safer and more sustainable alternative to the dangers of carbon monoxide inhalation: rebreathing your own carbon dioxide (CO2) at targeted intervals, which can be done with a specialized facemask. This method, which mimics the effects of altitude training by reducing oxygen levels and triggering adaptations in the body, is considered safer and avoids the potential risks associated with inhaling toxic substances like CO. We previously posted on this, stressing that rebreathing CO2 is a far safer practice for those seeking to optimize performance, without putting their health at risk.

Carbon monoxide has become a topic of increasing concern, especially following revelations that several teams used the substance during the recent Tour de France. It was reported that the riders may have used CO to enhance the effects of altitude training and potentially boost their blood oxygen levels. However, the UCI has stressed that repeated use of CO can be dangerous and should be approached with caution.

In addition to discussing carbon monoxide, the meeting in Nice covered other pressing issues facing the sport. One such topic was financial fairness, with the UCI planning to examine this issue further between 2026 and 2028. Technical fraud, safety improvements, and the SafeR initiative were also among the discussions, with the UCI promising to deliver new proposals in early 2025 to address ongoing safety concerns in cycling.