World cycling governing body is expected to ban the use of carbon monoxide rebreather devices
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| Photo: Detalo Health |
Since the story first emerged after last year's Tour de France that top teams use carbon monoxide (CO) to test athlete's fitness, the rumour mill hasn't stopped.
Remember Tadej Pogačar won the Tour de France by over six minutes - an impressive margin over his nearest rival, Jonas Vingegaard. The way he trounced his rivals in the mountains around the Côte d'Azur in the closing stages of the race he looked like he was certainly rocket fuel.
When asked about using CO after stage 16 of the Tour, in Nimes, he brushed off the question and didn't know what the reporter was talking about. He later clarified his answer, saying he'd thought he was being asked about inhaling exhaust fumes, and explained that the rebreather was a simple test he uses to see how well he responds to altitude training.
Visma-Lease a Bike, the team of second-placed rider Jonas Vingegaard, himself a two-time Tour de France winner, also confirmed that they include CO rebreather, as have Israel-Premier Tech, the team of Chris Froome and Derek Gee. All teams maintain that their use of the rebreather is for testing purposes only and not specifically to enhance performance.
Such is the talk about its use that Union Cycliste Internationale (UCI), cycling's world governing body are due to make a decision on its use, and will call on the World Antidoping Agency (WADA) to ban the use of carbon monoxide rebreather devices.
But what is the deal with carbon monoxide? Is there really an issue with its use, or is this just a bit of hot air?
Well, to start with, CO can kill you. The red blood cells in your body contain haemoglobin, a protein that binds to oxygen (O2) as you breathe in, and carries it around the body. CO molecules have a similar structure to O2 molecules, and haemoglobin combines with CO over 200 times more easily than with O2, so is difficult (though still possible) for the link to be broken to allow in O2.
In everyday life we breath in tiny amounts of the colourless and odourless CO gas from things like motor vehicle exhaust fumes, cigarettes, and barbecues. These amounts can be displaced from the body over a few hours as you breathe in more O2 and CO breaks down naturally.
But low amounts, for example from an old or faulty gas fire over time can still cause symptoms. You may begin to feel sick, have headaches feel weak. and get dizzy. Continuous exposure to CO will leave you out of breath. In the absence of urgent medical attention this leads to asphyxiation (oxygen starvation), resulting in multiple organ failure and death.
Remember, most people who sadly die in house fires succumb to CO poisoning from smoke inhalation rather than burns. As CO is a slightly lighter gas than O2 the advice is to crouch down to the ground where the air is cleaner, if you are caught in the smoke from a fire.
So why would an athlete tamper with a potentially lethal substance? I've no more an idea than anyone else! I guess it's for the reason why folks inject synthetic erythropoietin (EPO), a blood-boosting hormone in which the difference between benefiting or severely harming a person is very small.
The use of CO as a way to measure haemoglobin in the blood using a rebreather (O2 and CO circuit) was first published around 20 years ago. It is generally used while training at altitude - at the start of the training camp and at the end of the stay, to see how well their body responded to training. So why the fuss now?
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| Photo: Detalo Health |
Well, when CO is inhaled, the slightly reduced supply of oxygen leads the body to react by producing more red blood cells to compensate - which is what happens when at altitude.
So in a way the rebreather method could be expanded, not just as a device for measuring haemoglobin levels at the start and end of an altitude training camp, but it could also help promote the production of more haemoglobin. (Though manufacturers of rebreather devices don't endorse this type of use.)
And, given cycling's history, I guess the doping rumour mill turns ever faster when a rider is more than head and shoulders above all the other competitors, as we saw in this masterclass of Pogi Power at last year's Tour de France.
Results from a recently study published in the Journal of Applied Physiology (T. Urianstad, et al. 2024) suggest that the regular inhalation of a small quantity of CO when at altitude could lead to an increase in a person's VO2 max (a measure of aerobic capacity), and power out put at lactate threshold (the moment when high intensity effort leads to lactic acid build up in muscles) compared with when training at sea level.
In the study published last year, 31 elite male cycle racers were divided into three groups and their training data were collected over three weeks: two groups lived and trained at 2,100m altitude, with one of these groups receiving CO twice a day, while the third group lived and trained at sea level.
At the end of the the three weeks the athletes who trained at altitude and inhaled CO had a higher VO2 max and 1-minute power output at lactate threshold than those who stayed at sea level. Between the two groups at altitude, the athletes who received CO had an increased amount of haemoglobin in their blood, but there wasn't a statistically significant difference in athletic performances between the athletes.
These results are similar to those from other previously published studies with CO. So at the moment, the jury is out as to whether actual performance improves, given that the increased haemoglobin doesn't translate to real-world performance advantages. But then again, there could still be a case for using CO based on the haemoglobin results.
However, this could be seen as a legalised way of blood doping, and because of the way an athlete's haemoglobin can be increased, it can also mask classic illegal blood doping with EPO.
A word also needs to be mentioned too about the long-term effects of regular inhalation of CO. The long-term consequences of CO inhalation have not yet been established. There is a theory that CO could have anti-inflammatory effects and protect against certain health conditions, but at present none of the medical regulatory authorities have approved the use of CO for medical purposes, especially as continued regular use could lead to health complications in the future.
The opinion of some clinicians in the sports medicine community is that CO rebreathers shouldn't be used at all.
From an ethical standpoint there is a danger that amateur athletes may try to copy their professional counterparts, without medical supervision or support, leading to catastrophic consequences.
The professional cycling anti-doping campaign group, Movement for a Credible Cycling (MPCC) have spoken out against the use of CO rebreathers. Board member of MPCC, and general manager of Equipe Groupama-FDJ, the outspoken Marc Madiot, has said he would never have any of his team riders use the device, even if all the other World Tour teams were using it. Speaking in a recent interview with Le Monde newspaper he said, “I'm sorry, but you don't make cyclists breathe gas. It's nonsense. No and no, that's it!”
We await the statement from the UCI later this week.
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