Holy smokes: UCI bans carbon monoxide rebreathing

On Saturday, the UCI introduced a new regulation banning the repeated inhalation of carbon monoxide (CO) in cycling. The decision was made during the UCI Management Committee meeting in Arras, France, on Jan. 31 and Feb. 1, held in conjunction with the ‘cross worlds in Liévin, France. The ban will officially take effect on Feb. 10. (So get your CO in now, while you can, I guess.)

Carbon monoxide is commonly used in sports medicine to measure total haemoglobin mass and blood volume, particularly in assessing the effects of endurance training and altitude exposure. However, the repeated inhalation of CO poses serious health risks, including headaches, lethargy, nausea, dizziness, and confusion. More severe cases can lead to heart rhythm disturbances, seizures, paralysis, and even loss of consciousness.

The CO controversy

In November, the UCI urged the World Anti-Doping Agency (WADA) to address the use of carbon monoxide inhalation, follwing reports that the practice was widespread among top teams at the Tour de France.

A carbon monoxide rebreather is used in sports to simulate the effects of altitude training by briefly exposing athletes to controlled amounts of carbon monoxide. The UCI has also urged teams and riders to avoid the “repeated use” of the method, citing its performance-enhancing potential and the inhalation of a toxic gas as reasons for concern.

Pogi and Vingegaard

Several riders have been tied to the use–including Tour de France winners Jonas Vingegaard and Tadej Pogačar.

“We only used it at Visma-Lease a Bike to test whether our altitude training camps were effective or not,” Vingegaard said. “If the technique is being misused to improve performance, I understand the decision to ban it.”

When asked about health risks, Vingegaard appeared to downplay them. “Inhaling carbon monoxide is equivalent to smoking one cigarette. Many people smoke multiple cigarettes a day,” he said. “I’m not afraid of one cigarette. Not that I’ve ever smoked a cigarette myself. But beyond that, I prefer not to take a position on this issue.”

To mitigate these dangers, the new UCI regulation prohibits the possession of commercially available CO re-breathing systems connected to oxygen and CO cylinders outside of medical facilities. This rule applies to all UCI licence-holders, teams, and affiliated bodies, as well as anyone in possession of such equipment on behalf of riders or teams.

How riders can use CO still

Despite the ban, CO inhalation will still be permitted within a medical facility under the supervision of a qualified medical professional. In such cases, strict guidelines will be enforced: only one CO inhalation to measure total Hb mass will be allowed, with a mandatory two-week gap before a second inhalation is permitted. For riders competing in UCI WorldTeams, UCI Women’s WorldTeams, and UCI ProTeams, any CO inhalation for Hb mass measurement must be documented in their medical records, in accordance with UCI Medical Rules (Articles 13.3.020 to 13.3.026).

Pogačar and his UAE Team Emirates squad have previously confirmed they had used CO rebreathers before but had already decided to stop even before the UCI made the announcement.

“To clear things up, carbon monoxide rebreathing is a technique that’s been used for 20 years and validated by athletes worldwide to measure haemoglobin mass during altitude training,”  Jeroen Swart, performance coordinator for UAE Team Emirates, said.

In late January, a statement was apparently mistranslated by the French paper Le Monde, according to Visma-Lease a Bike. The French outlet quoted an athlete as saying they inhale it once before altitude camp and again after to measure maximum oxygen capacity. However, the piece also quoted them as saying, “But teams divert its usage by inhaling frequent microdoses of carbon monoxide, which significantly enhances the performance of some riders. Vingegaard said, “It is not fair and WADA should ban it.'”

Although this regulation is independent of the World Anti-Doping Code and the UCI Anti-Doping Regulations, the UCI has formally requested the World Anti-Doping Agency (WADA) to take an official stance on the repeated use of CO in and out of competition.

This decisive move reflects the UCI’s commitment to safeguarding rider health while maintaining the integrity of professional cycling, the statement concluded.