20.500.12556/RUL-183685 The effects of 2 days of intermittent exogenous ketosis at high altitude on baroreflex sensitivity and ventilation under hypoxic and hypercapnic conditions High-altitude (HA) exposure induces an integrated physiological response to mitigate hypoxemia. Exogenous ketosis at simulated HA was previously shown to accentuate sympathetic activation and attenuate pulse oxygen saturation (Sp$_{O2}$) decreases through hyperventilation. The aim of this study was to extend these findings by investigating the effects of intermittent exogenous ketosis (IEK) across 2 days at terrestrial HA (3,375 m) on baroreflex sensitivity, heart rate variability, and hypoxic/hypercapnic ventilatory responses. Thirty-four healthy active adults completed neutral, hypoxic, and hypercapnic (0.03 FI$_{CO2}$) exposures, each comprising 6 min of seated rest, once at sea level (SL) and once after 2 days at HA. Across the 2 days, participants intermittently ingested either ketone monoester supplements (IEK) or placebo (PLA). During each exposure, blood pressure, ventilation, Sp$_{O2}$, and end-tidal CO$_2$ pressure (PET$_{CO2}$) were continuously recorded, and arterialized capillary blood gas content was measured in the final 30 s. Baroreflex sensitivity and time-domain metrics of heart rate variability were reduced at HA (P = 0.006–0.043) but unaffected by group (P = 0.288–0.525). However, ventilation at HA under all three conditions was significantly higher in IEK compared with PLA (all P < 0.001). In hypoxia, this induced a higher Sp$_{O2}$ (P = 0.038) and capillary O$_2$ pressure (P = 0.003). In hypercapnia, this induced a lower PET$_{CO2}$ and capillary CO$_2$ tension (both P < 0.001). These results extend previous findings, suggesting that IEK enhances ventilation at terrestrial HA after 2 days of exposure, with this effect being independent from baroreflex sensitivity or heart rate variability changes. automatic control blood pressure hypobaric hypoxia ketone bodies sympathetic nervous system high altitude anoksija krvni tlak avtomatski nadzor ketoza ketonska telesa hipobarična hipoksija simpatično živčevje visoka nadmorska višina true false true Angleški jezik Slovenski jezik Članek v reviji 2026-06-17 10:10:17 2026-06-17 10:10:24 2026-06-18 04:34:02 0000-00-00 00:00:00 2025 0 0 Str. R350-R362 iss. 2 Vol. 329 2025 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 612 1522-1490 10.1152/ajpregu.00125.2025 243716867 narang-et-al-2025-the-effects-of-2-days-of-intermittent-exogenous-ketosis-at-high-altitude-on-baroreflex-sensitivity.pdf narang-et-al-2025-the-effects-of-2-days-of-intermittent-exogenous-ketosis-at-high-altitude-on-baroreflex-sensitivity.pdf 1 27D5A2FB0962FFBD365467BDB6C25E7B d9f298e176f57315bcd9514d851708da8a8b44698d9acb0c91451f26bf711f83 7c3fbd52-6a2a-11f1-9b0d-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=235831 https://journals.physiology.org/doi/abs/10.1152/ajpregu.00125.2025 1 eeab5c05-6a23-11f1-9b0d-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=235825 Fakulteta za šport 0 0 0