20.500.12556/RUL-182856 Critical power and critical oxygenation examining transferability between normoxia and hypoxia We sought to investigate if critical oxygenation (COx) is a robust marker of exercise intensity, and if it remains stable in normoxia and hypoxia with simultaneous changes in critical power (CP) and heart rate (HR). Thirty-three highly trained endurance athletes (11 females) underwent two 3-min CP cycling tests in normoxia (87 m ASL, F$_i$O$_2$=20.8%) and normobaric hypoxia (3200 m ASL, F$_i$O$_2$=14.2%). Repeated measures ANOVA with partial eta (ηp2) and omega squared (ω$^2$) effect sizes was employed to compare systemic (SpO$_2$) and muscle oxygen saturation (SmO$_2$) at rest and COx, HR, and CP during exercise between normoxia and hypoxia with biological sex as an independent variable. Bayesian T-tests were conducted as the confirmatory analysis. Significant differences between normoxia and hypoxia for SpO$_2$ and SmO$_2$ were observed at rest in both sexes. During exercise, COx in the triceps brachii, CP and various HR indices exhibited significant differences (p<0.001), whereas differences were not significant in the vastus lateralis (p=0.355). The Bayesian analysis supported these findings. The decrease in COx in the triceps brachii in hypoxia was larger in females than in males (30 vs. 21% drop respectively, p=0.019). However, no environment sex interaction was found for CP, HR, and COx in vastus lateralis. COx in locomotor muscles remains stable across the tested ambient oxygen concentrations, whereas CP and HR exhibit significant differences between normoxia and hypoxia. Accordingly, COx may be useful in optimizing training load and cycling performance under different oxygen availability conditions. sport NIRS altitude hypoxia critical power testing muscle oxygenation cycling šport nadmorska višina hipoksija kritična moč testiranje mišična oksigenacija kolesarstvo true false true Angleški jezik Slovenski jezik Članek v reviji 2026-05-26 08:57:15 2026-05-26 08:57:16 2026-05-27 04:39:58 0000-00-00 00:00:00 2025 0 0 Str. 3299-3310 iss. 11 Vol. 125 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 796.61:616.12-008.44 1439-6327 10.1007/s00421-025-05825-y 238809859 s00421-025-05825-y.pdf s00421-025-05825-y.pdf 1 92CDC3AA010A8381448DCE833992248B de36ab8323bc9d75a7873628eaff05c59fb2bdb86abfbc45633e3c55556750ff 4ed924b9-58d1-11f1-b0ab-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=234461 https://link.springer.com/article/10.1007/s00421-025-05825-y 0 cd6f9561-58cf-11f1-b0ab-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=234460 Fakulteta za šport 0 0 0