The risks of carbon monoxide inhalation
CO is commonly used in sports medicine to measure total haemoglobin (Hb) mass and blood volume, aiding in the evaluation of endurance training and altitude exposure. While this technique has been widely practised, repeated CO inhalation carries significant health risks, including headaches, lethargy, nausea, dizziness, and confusion. More severe consequences may include heart rhythm disturbances, seizures, paralysis, and loss of consciousness.
Recognising these dangers, the UCI has prohibited the possession of commercially available CO re-breathing systems outside of medical facilities. This ban applies to all licensed riders, teams, and affiliated entities under UCI regulations. The inhalation of CO will remain permitted within a medical facility under professional supervision, but with strict limitations: only a single CO inhalation will be allowed per session, with a mandatory two-week interval before a second measurement can be taken.
For professional riders in UCI WorldTeams, UCI Women’s WorldTeams, and UCI ProTeams, any CO inhalation must be documented in their medical records as per the UCI Medical Rules.
UCI’s request to WADA
Although this ban is independent of the World Anti-Doping Code, the UCI has formally requested the World Anti-Doping Agency (WADA) to review the repeated use of CO both in and out of competition. If WADA classifies CO inhalation as a doping practice, further sanctions may be introduced.
A strong message for athlete welfare
UCI President David Lappartient reaffirmed the organisation’s commitment to athlete safety, stating, “The UCI takes a bold and necessary stance by banning the repeated use of carbon monoxide inhalation on medical grounds. Our priority is to protect the health and safety of our athletes, and today’s decision is another significant step in this direction.”
The next UCI Management Committee meeting, scheduled for June 2025 in Arzon, France, may provide further updates on this regulation and its potential impact on professional cycling.