What is carbon monoxide inhalation, the controversial but legal practice people at the Tour de France can't stop talking about?

UAE Team Emirates, Visma-Lease a Bike and Israel-Premier Tech have confirmed that their riders occasionally inhale carbon monoxide for the purpose of optimising altitude training

Tadej Pogacar and Jonas Vingegaard
(Image credit: Getty Images)

In the past week, the Tour de France has been abuzz with talk around carbon monoxide (CO) inhalation, with both Tadej Pogačar and Jonas Vingegaard confirming their previous use of the controversial but legal practice.

An Escape Collective investigation towards the end of the Tour’s second week introduced the concept of CO inhalation to the wider public, detailing how athletes across various sports are turning to the technique to optimise their altitude training and potentially improve their body’s blood levels. 

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