PARIS — Double Tour de France champion Jonas Vingegaard has advocated for a prohibition on the contentious method of carbon monoxide rebreathing, a practice employed by some athletes to assess their performance levels.
In a recent interview with Le Monde, published on Saturday, the Visma-Lease a Bike cyclist stated his team utilizes the method responsibly, but expressed concern that others exploit it to enhance their performance artificially.
The scrutiny surrounding carbon monoxide began during the previous year’s Tour de France, when the cycling website Escape Collective revealed that various riders were inhaling the harmful gas to improve the efficacy of their altitude training. The carbon monoxide is used as a tracer to gauge the absorption of oxygen in the lungs or to assess the total hemoglobin mass, which is crucial for a cyclist’s success.
“My team employs carbon monoxide to evaluate blood volume and total hemoglobin mass,” Vingegaard explained. “We inhale it once prior to an altitude training session, then repeat the process at the end to determine the capacity for maximum oxygen uptake.”
However, he noted that certain athletes misuse this technique for doping purposes by inhaling low doses of carbon monoxide regularly, resulting in marked performance enhancements. “This is unjust and ought to be prohibited by the World Anti-Doping Agency,” he asserted.
In response, the UCI, cycling’s governing body, announced in December it would address the potential medical ban during a management committee meeting scheduled to take place in France from January 31 to February 1.
The UCI indicated that repeated inhalation of the gas in non-medical settings could lead to adverse health effects such as headaches, fatigue, nausea, vomiting, chest pain, respiratory issues, and even loss of consciousness.
During the interview, Vingegaard was also questioned about the remarkable achievements of his rival Tadej Pogacar, who triumphed in the Giro, Tour de France, and the road world championships in 2024—an impressive “triple crown” in cycling—along with securing victories in other renowned one-day races.
“I can understand the doubts regarding his performance, but he has set new benchmarks that we now have to aspire to,” Vingegaard commented. “He is currently the top cyclist in the world. Nevertheless, the margin between us isn’t excessively wide. I could potentially have competed against him during the Tour.”
Vingegaard finished second in last year’s Tour, trailing Pogacar by a margin exceeding six minutes. However, his preparation for the significant event was notably disrupted due to a crash which resulted in a broken collarbone, fractured ribs, and a collapsed lung.
“Had it not been for the truncated training schedule after my accident, I likely would have performed better in the Tour. That situation had a considerable physical and psychological effect on me,” he reflected. “To clinch the Grande Boucle, every detail is essential, and I remain satisfied with my second-place finish.”
