UCI confirms imminent ban on carbon monoxide rebreathing "outside a medical facility", citing health reasons

The UCI has confirmed that a ban on the "repeated inhalation" of carbon monoxide "outside a medical facility" will take effect from 10 February 2025, claiming that the controversial method of measuring an athlete's haemoglobin can cause chronic health problems if used frequently. Cycling's governing body proposed its plans for the ban in December last year, and the new regulation means that teams and riders will be forbidden from being in the possession of commercially available carbon monoxide rebreathing devices connected to oxygen and carbon monoxide cylinders. 

> What is carbon monoxide rebreathing?

To recap (if you don't want to read a whole feature on it in the link above, but feel free to knock yourself out) carbon monoxide rebreathing has been around for decades, and is considered an accurate way of measuring an athlete's haemoglobin levels (the protein that is responsible for moving the oxygen in red blood cells around the body). This can prove beneficial to cyclists on an altitude training camp, for example, to see if the training has resulted in an improved level of haemoglobin. 

There are theories that the inhalation itself can provide small performance benefits, but the teams and riders who use the machines claim it is simply for measuring performance, not enhancing it. Top riders such as Tadej Pogačar and Jonas Vingegaard have openly admitted to using carbon monoxide rebreathers, with Pogačar saying it was a “pretty simple test”, but one that he'd never actually completed. 

(Detalo Health)

The UCI's reason for the ban outside of "a medical facility" doesn't mention performance enhancement, only citing the protection of riders and providing a list of potential health problems its repeated inhalation could cause. 

"... its repeated inhalation can result in acute and chronic health problems, for example headaches, lethargy, nausea, dizziness, and confusion. Such symptoms can worsen at any time and develop into problems with heart rhythm, seizures, paralysis, and loss of consciousness", says the statement. 

The 'outside a medical facility' part, as we understand it, means that nothing much should change for top teams like UAE Team Emirates and Visma-Lease a Bike, because they claim their tests carried out at training camps are performed under a strict medical setting by experienced professionals. There will have to be adjustments if any riders were inhaling more than once a fortnight, though.

The new rules state: "The inhalation of CO will remain authorised within a medical facility and under the responsibility of a medical professional experienced in the manipulation of this gas for medical reasons and in line with the following restrictions: only one CO inhalation to measure total Hb mass will be permitted. A second CO inhalation will only be authorised two weeks after the initial Hb measurement.

"For riders in UCI WorldTeams, UCI Women’s WorldTeams and UCI ProTeams, any CO inhalation for the purpose of determining total Hb mass must be recorded in the medical file established for each athlete, in compliance with Articles 13.3.020 to 13.3.026 of the UCI Medical Rules." 

The UCI says that its ban is independent of the World Anti-Doping Code and the UCI Anti-doping Regulations; however, the governing body has urged the World Anti-Doping Agency (WADA) to "take position on the repeated use of CO in and out of competition."

As this "ban" doesn't completely forbid the use of carbon monoxide rebreathing, the performance enhancement claims are unlikely to go away any time soon. In November, the veteran Romain Bardet suggested that the growing use of carbon monoxide in the peloton could explain the dramatic jump in form of certain riders in the past two years. "There will always be the desire to seek competitive advantages”, he said. 

Days later, two-time Tour de France winner Jonas Vingegaard denied any knowledge of the method being used for performance enhancement, and said he would stop using it if it was banned.