Autologous blood doping detection is done indirectly via CO rebreathing technique to measure the nonphysiologic increases in Hb mass. The principle of CO rebreathing method used currently requires an O 2 -CO gas mixture inhalation for about 10-15mins.  By measuring the difference in carboxyhemoglobin concentration (HbCO) before and after rebreathing, the volume of CO and the binding capacity of Hb for CO ( g-1), total Hb mass can be calculated.  This detection method is problematic for an athlete as it is not desirable to breathe in CO shortly before a competition, which may potentially affect their performances.
Nicole Sapstead, chief executive of UK Anti-Doping, described the findings as “disappointing and concerning statistics”, but she said many things had changed since 2011, including stiffer sanctions. “Testing methods continue to advance but testing is only one part of the anti-doping process,” she said. “There is now greater investment in educating elite and up and coming athletes about the dangers and consequences of taking banned substances, as well as a greater emphasis on intelligence and investigations as an alternative way of catching those who seek to break the rules.”