Cycling's UCI ban repeated carbon monoxide rebreathing

Jonas Vingegaard and Tadej Pogacar's teams had both used the carbon monoxide rebreathing technique

Cycling's world governing body the UCI has voted for a ban on the use of repeated carbon monoxide rebreathing equipment, after it was established last year some teams were using it to measure haemoglobin levels in their riders' blood before and after altitude training.

There had been questions around whether it can be used to enhance performance if used repetitively - or if it is simply too dangerous to inhale a deadly gas as a scientific measurement.

There had been growing confusion in the sport about what a ban will really mean, given the UCI was expected to allow it in a "medical setting".

But the announcement on 1 February defines the test as allowable only in a "medical facility" by a "medical professional", undertaken twice within two weeks of each other, for comparison.

What is carbon monoxide rebreathing?

Carbon monoxide rebreathing is a process that has been around for a long time in endurance sports - it involves an athlete inhaling a small amount of carbon monoxide, a deadly gas given off during the process of burning any material, because it gives a reading of how much haemoglobin is present in the blood.

This is usually done at the beginning and end of altitude training.

Haemoglobin is a protein found in the red bloods cells that carry oxygen around the body. If there is more haemoglobin in the blood, more oxygen can be carried to the muscles, giving an athlete more resistance to lactic acid burn - helping them go faster for longer.

The device is a machine that is connected to an external supply of oxygen and carbon monoxide, and the athlete uses an integrated rebreathing circuit.

Cycling and blood will never have an easy association, thanks to Lance Armstrong's infamous use of transfusions - which produce more red blood cells - to cheat his way to Tour de France victories around 20 years ago.

Who is doing it?

The current rebreathing issue would perhaps not be so prevalent if some of the riders and teams involved weren't the biggest in the sport, with three-time Tour de France winner Tadej Pogacar and his UAE Team Emirates-XRG squad being one, along with his closest rival Jonas Vingegaard of Visma Lease A Bike.

Stories of its use emerged at last year's Tour, a season in which the winning margins of some of the sport's best riders were vastly increased.

Can it enhance performance?

The maker of the device being used by teams admits enhancing performance could be possible, albeit easily detectable.

"When you inhale carbon monoxide you reduce [the] oxygen content of blood, so all of a sudden the body [behaves] as if you are at high altitude," says Carsten Lundby co-founder of rebreathing equipment manufacturer Detalo Health.

"If you inhale it once, it's like being exposed to high altitude for a couple of hours – this will do nothing to your performance.

"If you inhale carbon monoxide four or five times a day over the ratio of a month, you will get more haemoglobin, but this would be a misuse of our device - this is not what it was intended for," adds Lundby, who is also professor at the University of Lillehammer in Norway.

"And due to real-time surveillance of each machine, we can easily identify whether our devices would be misused."

The UCI was necessarily looking to snuff out cheating with a ban. It says it was seeking the ruling on grounds of safety, adding "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".

What the teams think

One team who have bought a device and employ Lundby himself to use it are Chris Froome's Israel-Premier Tech.

"Israel-Premier Tech's sole use is for testing purposes to measure the impact of altitude training," they say.

And Visma Lease a Bike said it was "nothing new, a method used for decades to measure the effects of altitude training".

They added: "It's a completely normal practice in multiple sports, conducted with experienced scientists and their equipment. In this way, it is neither harmful to health nor performance-enhancing."

The carbon monoxide rebreathing machine in question

What does Wada think?

So, if you can enhance performance, can it be traced? In theory, any change on blood values would be identified by an athlete's biological passport.

But the World Anti-Doping Agency (Wada) is not taking any chances and is looking into it, telling BBC Sport there is uncertainty if misusing the process would register on the biological passport because of a lack of research.

"Exposure to carbon monoxide (CO) has been discussed by Wada on several occasions," a representative said. "There is no general consensus on whether CO can have a performance-enhancing effect and no sufficiently robust data currently supports that.

"But Wada is currently investigating the effects of frequently and repeatedly using this CO rebreathing method vis-a-vis artificially enhancing the uptake, transport or delivery of oxygen.

"In any event, it is generally acknowledged that it can be dangerous for health so it would not be recommended."

What might happen next?

Many feel the issue has been stirred up by the cycling media and the UCI is simply taking an approach to demonstrate proactivity.

The ban comes into force on 10 February, following the decision by the UCI's executive body at a meeting in France.

It is uncertain when Wada will know if any further action needs to be taken but teams say they are prepared to work with the UCI on whatever decision is made.