Carbon Monoxide Rebreathing in Endurance Sport: From Diagnostic Total Haemoglobin Mass Assessment to Prohibited Non-Diagnostic Use - A Critical Narrative Review of Performance Effects, Safety, and Anti-Doping Regulation
DOI:
https://doi.org/10.12775/QS.2026.74.75254Keywords
carbon monoxide, total haemoglobin mass, endurance performance, erythropoiesis, blood manipulation, anti-doping, narrative reviewAbstract
Background: Diagnostic carbon monoxide (CO) rebreathing measures total haemoglobin
mass (tHb-mass), whereas repeated non-diagnostic exposure has been proposed as an
erythropoietic intervention in endurance sport.
Aim: To critically evaluate diagnostic validity, performance effects, safety, anti-doping
detection, and current regulation.
Material and methods: A structured narrative review used a targeted PubMed update,
citation chaining, and official WADA/UCI documents. Thirty-three full-text-accessible
sources were selected purposively and synthesized thematically.
Results: Standardized CO rebreathing can provide reproducible tHb-mass estimates, but
procedures are not automatically interchangeable. Acute CO impairs oxygen-dependent
exercise. Repeated exposure increased tHb-mass in some small trials, yet effects on VO2max
and sport performance were inconsistent; the 2026 crossover trial reported haematological
expansion without performance improvement. Long-term safety is unquantified. WADA M1.4
prohibits non-diagnostic equipment-mediated CO delivery, while UCI rules impose additional
cycling-specific conditions.
Conclusions: Diagnostic measurement and performance-oriented exposure must be
separated. A tHb-mass increase is not proof of ergogenic benefit, safety evidence is
inadequate, and non-diagnostic equipment-mediated use is prohibited
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Copyright (c) 2026 Krzysztof Talarowski, Konrad Talarek, Wioleta Pluta, Piotr Tylec, Jakub Bryl, Roksana Milaniuk, Aleksandra Pacek, Szymon Daniszewski, Izabela Czerny, Arkadiusz Ściubak, Beata Surówka, Aleksandra Drzewiecka, Kinga Ostojska
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