The Union Cycliste Internationale (UCU) has announced it will propose a ban on the use of carbon monoxide (CO) by riders at its next Management Committee meeting in January.
The UCI wants to officially ban the use of carbon monoxide on medical grounds but confirmed that it could be used by qualified medical personnel within the strict context of assessing total haemoglobin mass. The gas is not currently on WADA's list of banned substances.
The use of carbon monoxide in professional cycling hit the headlines during the 2024 Tour de France when Escape Collective revealed that UAE Team Emirates, Visma-Lease a Bike, and Israel-Premier Tech had used carbon monoxide rebreather techniques to test rider blood values at the start and end of altitude training camps.
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Tadej Pogačar and Jonas Vingegaard admitted they were aware of and had at least used the rebreathing equipment. Frequent inhalation is different to rebreathing, with the former potentially increasing aerobic capacity as a possible replacement for or supplement to altitude training.
It is unclear how the UCI will enforce any ban. Detection of carbon monoxide abuse would require an approved testing method, under WADA regulations. Cases may only come to light if evidence of carbon monoxide abuse emerges via police and media investigations or from whistleblowers.
WADA told Reuters that carbon monoxide abuse could fall under "Artificially enhancing the uptake, transport or delivery of oxygen" in its list of prohibited substances and methods.
"It is generally acknowledged that it can be dangerous for health so it would not be recommended.
Escape Collective confirmed that there was "no hard evidence that any WorldTeams are currently using CO inhalation for performance gains." However, the potential for it to be abused has prompted the UCI to act.
The UCI informed teams on the current knowledge of the effects on performance of repeated carbon monoxide (CO) inhalation at the recent UCI WorldTour Congress. The UCI called on WADA to "take a position" on the use of carbon monoxide for performance gains and UCI president David Lappartient reiterated that position at last week's WADA Executive Committee meeting in Saudi Arabia.
"Exposure to carbon monoxide has been discussed by WADA’s prohibited list expert advisory group on several occasions," WADA told Reuters.
"There is no general consensus on whether CO can have a performance-enhancing effect and no sufficiently robust data currently supports that proposition."
This week, UAE Team Emirates confirmed that they no longer use the carbon monoxide rebreathing technique to measure athlete performance.
Performance coordinator Jeroen Swart told a small group of media, including Cyclingnews, that UAE Team Emirates have "finished the process" with the technique. He said that it was "an exercise that we co-ordinated over 18 months" to assess rider's improvements during altitude training camps.
A UCI decision will be made by the Management Committee meeting at their next meeting which will take place in Arras, France, on 31 January and 1 February 2025, during the Cyclocross World Championships.
"Carbon monoxide is a toxic, odorless gas that is often a cause of household accidents. Inhaled in low doses and under strict safety conditions, the gas is used in medicine as a tracer to measure the pulmonary diffusion of oxygen or of the total haemoglobin mass," the UCI said.
"However, when inhaled repeatedly in non-medical conditions, it can cause side effects such as headaches, fatigue, nausea, vomiting, chest pain, breathing difficulties, and even loss of consciousness.
"The UCI considers that these health side effects, and the complete lack of knowledge about the long-term effects of repeated inhalation of carbon monoxide, justify a ban on the use of this gas due to medical reasons. Its use in a medical setting, by qualified medical personnel, and within the strict context of assessing total haemoglobin mass, would, however, remain authorised."
