{"id":69255,"date":"2024-09-13T16:00:00","date_gmt":"2024-09-13T14:00:00","guid":{"rendered":"http:\/\/bba736ef-a74e-4bf7-b030-747d1937ba3a"},"modified":"2024-09-13T16:25:25","modified_gmt":"2024-09-13T14:25:25","slug":"the-history-of-carbon-monoxide-rebreathing-and-whether-it-should-be-banned-according-to-the-united-states-anti-doping-agencys-director-of-science","status":"publish","type":"rss_feed","link":"https:\/\/c01.purpledshub.com\/cyclingplus\/rss_feed\/the-history-of-carbon-monoxide-rebreathing-and-whether-it-should-be-banned-according-to-the-united-states-anti-doping-agencys-director-of-science\/","title":{"rendered":"The history of carbon monoxide rebreathing \u2013 and whether it should be banned \u2013 according to the United States Anti-Doping Agency\u2019s director of science"},"content":{"rendered":"

Laura Lewis explains what carbon monoxide rebreathing is and whether the method should be outlawed <\/p>

By Laura Lewis\n <\/p>

Published: Friday, 13 September 2024 at 14:00 PM<\/p>

\n\n

Carbon monoxide rebreathing hit the headlines at the 2024 Tour de France as a method used, according to an initial report by Escape Collective<\/a>, by UAE Team Emirates, Visma-Lease a Bike and Israel-Premier Tech.<\/em><\/p>

A statement released by Tadej Poga\u010dar\u2019s UAE Team Emirates later clarified the method has been used to test haemoglobin levels and, in turn, the impact of altitude training. Crucially, the practice is not banned by the World Anti-Doping Agency (WADA).<\/em><\/p>

\u201cCarbon monoxide rebreathing is a method to assess total haemoglobin mass and has been used in altitude training and research for over 20 years. It is a well-established, safe, professional method that is backed by a very large amount of research,\u201d read the statement.<\/em><\/p>

\u201cWe measure the haemoglobin mass at the start of an altitude training camp and at the end of the camp. In this way we minimise our athlete\u2019s exposure to carbon monoxide and not the other way around. Any links to our team using this type of technology for unethical purposes are being made without any merit and without any facts or evidence to support them.\u201d<\/em><\/p>

In this guest column, originally published in Cycling Plus magazine, the United States Anti-Doping Agency\u2019s (USADA) director of science, Laura Lewis<\/a>, explains what carbon monoxide rebreathing is, its relatively long history in sport from a scientific standpoint, and whether the method should be banned.<\/em><\/p>

UAE Team Emirates, Visma-Lease a Bike and Israel-Premier Tech have reportedly used carbon monoxide rebreathing as a way to measure the impact of altitude training. – Getty Images<\/span><\/figcaption><\/figure>

Carbon monoxide has a much higher affinity than oxygen to bind to haemoglobin, meaning that if you breathe it in, you have less oxygen attached to haemoglobin, so you enter a hypoxic state, as you would at altitude.\u00a0<\/p>

Picture the situation as a bus and the seats as haemoglobin. The larger customers are the carbon monoxide and take up all the seats, leaving little room for the thinner oxygen customers.\u00a0<\/p>

It does eventually unbind (it has a half-life of around 12 hours), but in very high doses all the seats are used up, so there\u2019s no room for oxygen and the result is death.<\/p>

But that\u2019s at high doses. We\u2019ve been using it in science for years to measure the total amount of haemoglobin someone has. You ask athletes to inhale a bolus [single large dose] of carbon monoxide \u2013 75 to 125ml of gas, or around 1.25ml per kg of body weight.<\/p>

The \u2018bong\u2019 test\u00a0<\/h2>
\"Rush
‘Normal’ levels of carbon monoxide can be around 0.5 per cent as a result of exhausts and pollution. – Justin Tallis \/ AFP via Getty Images<\/span><\/figcaption><\/figure>

In what cyclists used to affectionately call the \u2018bong\u2019 test, you have this glass-like spirometer, which looks a little like a flute with a big bag at the end. You\u2019re rebreathing through this closed circuit for two minutes. That\u2019s how long it takes for the carbon monoxide to mix into your system.\u00a0<\/p>

There\u2019s also an automated machine that some of the teams have been talking about that\u2019s come out of Norway, but I\u2019ve never used it. The one we\u2019ve used is really portable. It usually raises the carbon monoxide levels in your blood to around 5 per cent. <\/p>

You\u2019d normally have levels of around 0.5 per cent just from exhausts and pollution, while a smoker\u2019s is always about 3 per cent. For a normal adult, those levels would be at 2 per cent by the next morning and back to normal within a day; quicker if you\u2019re exercising in that time.<\/p>

A long history<\/h2>
\"Aerial
The USADA’s Laura Lewis has used carbon monoxide rebreathing to measure haemoglobin levels at the top of the Stelvio Pass. – Getty Images<\/span><\/figcaption><\/figure>

I did the test every stage during the 2010 Tour Down Under and showed that the haemoglobin levels of Cycling Australia\u2019s national team remained stable. <\/p>

I\u2019ve used this test at altitude around the world to see how riders are reacting to the rarefied air, to find out if the training is working, as you want the haemoglobin levels to rise during an altitude camp thanks to their bodies making higher levels of natural EPO [erythropoietin].\u00a0<\/p>

I used it at the top of the Stelvio, then analysed the results at the Mapei lab, which has its headquarters in Milan. It\u2019s a legitimate way to measure haemoglobin response to altitude.<\/p>

We also use it to see how riders are reacting to training and if they need iron supplementation, for example. You can also measure haemoglobin mass really accurately with the Evans Blue Dye test, but that requires injecting a person with a tracer, so isn\u2019t used.<\/p>