Professional road cycling has made huge leaps in curbing cheating since Lance Armstrong’s 7-year dominance of the Tour de France. But rabid cycling fans and insider pundits still harbor fears that cheating is still producing winning performances at the highest levels. The complete trust of the top riders and teams has been hard to come by. Any hint of foul play generates extreme scrutiny.

From barbituates, steroids, pain killers, EPO, blood transfusions, and motor doping, big-money cycling has exercised extreme measures to obtain the most marginal of competitive advantages. So when chatter surfaces about a new, high-tech, novel way to squeeze out a gain, it isn’t much of a surprise.

Last year, word spread that road cycling’s winningest riders and teams could inhale poisonous gas in the name of performance. This shocked even the most scrupulous fans.

But today, the Union Cycliste Internationale (UCI) officially banned the potentially deadly practice of repeated carbon monoxide inhalation from all competitive cycling under its jurisdiction.

The official press release summarizes the ban as follows: “The new regulation forbids the possession, outside a medical facility, of commercially available CO re-breathing systems connected to oxygen and CO cylinders. This ban applies to all license-holders, teams, and/or bodies subject to the UCI Regulations and to anyone else who might possess such equipment on behalf of riders or teams.”

The new ruling goes into effect on February 10.

Carbon Monoxide Cheating: Why Cyclists Do It

Carbon monoxide (CO) gas can be an invisible, silent killer. This is why we have CO detectors in RVs and homes. CO has a stronger affinity to the oxygen-carrying component in red blood cells (hemoglobin, or Hb) than oxygen itself.

When inhaled, CO displaces oxygen and eventually causes “suffocation” from the inside. We need detectors because the gas has no taste, color, or odor.

Ironically, CO’s strong affinity for Hb can potentially also enhance aerobic performance. Anything that reduces the blood’s oxygen level over time will stimulate a compensatory response to reestablish this capacity. This is why athletes go to altitude.

The lower partial pressure of oxygen at higher elevations results in fewer oxygen molecules bound to red blood cells. This also means the blood transfers less oxygen to working muscles.

As the athlete continues to live and work at altitude, the body produces more blood volume, hemoglobin, and other factors to compensate. Theoretically, this boosted oxygen-carrying ability provides a greater advantage at lower altitudes.

Repeatedly inhaling CO has the same oxygen-lowering effect as high altitude but with a different mechanism. Instead of less air pressure driving less oxygen into the blood and tissues, CO competes with the oxygen for binding sites on the Hb of red blood cells. Less oxygen bound to Hb ultimately means less oxygen for working muscles.

Studies strongly suggest that it triggers the same compensatory adaptations. But, unlike altitude training, CO inhalation can be extremely harmful.

How Are Cyclists Doing It?

‘Rebreathing’ Test

The practice of CO “doping” actually stems from a diagnostic test teams used to determine training efficacy. Specifically, CO “rebreathing” helped determine blood volume and Hb mass, which helped teams quantify physiological gains made during altitude training camps.

It worked like this: Athletes determine a baseline measurement for CO blood levels using blood and breathing tests. Then, the athlete inhales a small amount of CO diluted with oxygen for 2 minutes through an enclosed circuit. The CO binds to Hb in the red blood cells to form carboxyhemoglobin.

After these 2 minutes, teams measured the amount of carboxyhemoglobin in the breath and blood and compared it to the baseline levels to calculate Hb mass. This Hb mass is an indicator of the effectiveness of altitude training or any other method used to increase the oxygen-carrying capacity of blood.

CO rebreathing machines specific to this type of testing automate this procedure. However, athletes can achieve the same results through a manual process using a closed-circuit carbon monoxide rebreather system.

Although these machines and testing procedures have been in use for a long time and do not inherently imply cheating, the possibility of abuse (and negative health consequences) exists. This triggered the spate of speculation and group ride chatter.

When the media connected top teams and contenders of this year’s Tour de France to CO rebreathing tests, the chatter amplified.

Cheating by Inhaling Carbon Monoxide

The jump from legal and logical testing to outright cheating is not black and white. The same physiological response to CO and machinery applies. The devil (and potential death) is in the details and in the wording.

Carbon monoxide rebreathing is testing. Instead of the 2 minutes of breathing the CO and oxygen mixture to determine Hb mass, cheating, as determined by the UCI, involves repeatedly inhaling CO to stimulate the artificial response of producing more Hb and other blood factors to improve performance.

Athletes can combine repeated inhalation of CO with altitude training. This is termed “super altitude.”

What Happens Next?

I’ve been around cycling a long time. Only time will tell how this news plays out at the sport’s elite level.

As the UCI press release states, it isn’t poking athletes for blood to determine cheating. It’s taking the much lower-tech approach of prohibiting the possession of commercial CO rebreathing machines.

If I’m optimistic, the road racing industry still stings from the Armstrong Era and all the associated fallout, and they will thereby voluntarily abide by the ruling.

But my inner retro-grouch and experience with this type of workaround prohibition of a potentially performance-enhancing method say otherwise. During my tenure as a trainer in professional sports, the governing body involved prohibited having IV equipment outside of a medical facility. This is the exact wording the UCI uses for CO rebreathing equipment.

Like professional road racing, the money involved was huge. So, what did athletes do to avoid breaking the rules? They arranged for fast transport between racing events on the same day to the nearest ER. Then, they got performance-enhancing, extraneous fluid replacement under “doctor’s orders.” This strategy proved hugely beneficial when events were closely spaced during the hottest races.

Again, this was only possible for the racers and teams with the largest budgets. The same applies here. Not every team can afford a CO rebreathing machine or the professionals to run them. This opens the door for lower-funded athletes and teams to try “back alley” methods to gain equal footing.

I saw this often. It was scary. But winners don’t like to lose, and common sense can take a back seat to “best efforts.”

Let’s all hope that professional cyclists and teams abide by the rules and respect the potential for harm. Cycling doesn’t need a “super altitude era.”