Or just altitude camps. In the CO paper they were claiming that CO rebreathing had "similar impact" as altitude camps, which makes a lot of sense given both of

Or just altitude camps. In the CO paper they were claiming that CO rebreathing had "similar impact" as altitude camps, which makes a lot of sense given both of them are essentially attempts to deprive body of oxygen. Don't be surprised if cyclist suddenly all started spending their off season in Tibet or something.