20.500.12556/RUL-182511 Muscle oxygen saturation plateau definition and verification in different oxygen availability conditions in locomotor and non-locomotor muscles Novel wearable near-infrared spectroscopy devices allow for a better understanding of muscle oxygenation kinetics during exercise. A muscle oxygen saturation (SmO$_2$) plateau is often applied in the scientific literature, but clear criteria for its definition remain unestablished to date. The aim of this study was to develop criteria allowing for definition of SmO$_2$ plateaus. Multiple variables associated with physiological plateaus during exercise were assessed to develop a framework for an SmO$_2$ plateau. Subsequently, the existence of an SmO$_2$ plateau during 3 min all-out cycling trials (critical oxygenation plateau) was tested in different conditions of oxygen availability (i.e., normoxia and hypoxia) in vastus lateralis and triceps brachii among 30 endurance athletes. Plateau determination methods based on a threshold of change of ±5 arbitrary units (a.u.) of SmO$_2$ and expert visual assessment showed almost perfect agreement. However, a threshold of 10 a.u. yielded high SmO$_2$ variability associated with a large number of possibly false-positive detections. Conversely, relative changes (thresholds of 5% and 10%) did not align with other methods, corresponding to low absolute changes, limiting their applicability. The inter-rater agreement between individual visual assessments exhibited a higher reliability among expert versus non-expert raters. The determination of an SmO$_2$ plateau depends on the applied methodology. Overall, a critical oxygenation plateau was observed in the vastus lateralis in both normoxia and hypoxia in >90% of cases. The results of this study allow recommendation either for the use of a threshold of change corresponding to 5 a.u. of SmO$_2$ or expert visual assessment, using 30 s segments. sport critical oxygenation critical power elite athlete exercise hypoxia near-infrared spestroscopy šport kritična oksigenacija kritična moč vrhunski športnik vadba hipoksija bližnja infrardeča spektroskopija true false true Angleški jezik Slovenski jezik Članek v reviji 2026-05-14 10:50:29 2026-05-14 10:50:30 2026-05-16 04:15:11 0000-00-00 00:00:00 2026 0 0 Str. 464-473 iss. 2 Vol. 111 2026 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 796:616.12-008.44 1469-445X 10.1113/EP092862 247424259 Experimental_Physiology_-_2025_-_Kowalski_-_Muscle_oxygen_saturation_plateau__Definition_and_verification_in_different.pdf Experimental_Physiology_-_2025_-_Kowalski_-_Muscle_oxygen_saturation_plateau__Definition_and_verification_in_different.pdf 1 4E449BF44AC011DF5E795924F3FBB2DE c105b716a60af24695bca14c1e20a159d5de57dc12a34818dcc030829847ceca 98ba887a-4f72-11f1-b0ab-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=233848 https://physoc.onlinelibrary.wiley.com/doi/10.1113/EP092862 1 a8353a1c-4f71-11f1-b0ab-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=233846 Fakulteta za šport 0 0 0