Ketone monoester intake attenuates exercise performance decline in normobaric hypoxia: A post‐hoc subgroup analysis of 5 young male adults without acute mountain sickness

Abstract

In hypoxia, endurance performance, sleep, and cognitive function are impaired. Ketone ester (KE) intake can elevate blood, brain, and skeletal muscle oxygenation, making it an interesting strategy to attenuate hypoxia‐induced impairments. Given that acute mountain sickness (AMS) influences these parameters, we evaluated the effects of KE intake in non‐AMS developing individuals. In a larger project, 14 young, healthy, male participants performed a 29‐h protocol at a simulated altitude of 4000–4500 m, involving regular KE or placebo intake. Five participants completed both sessions without developing severe AMS. They completed two maximal incremental cycling tests after 1.5 and 25 h (EX _MAX1 and EX _MAX2 , resp.) and a combined maximal‐submaximal test after 26.5 h (EX _COMBO ), while resting blood, brain, and skeletal muscle oxygenation and cognitive function were regularly (5‐6x) evaluated, and sleep was analyzed. KE did not alter peak power output (PPO) during EX _MAX1 or EX _MAX2 , but increased PPO by 36 W during EX _COMBO . KE increased blood oxygenation before EX _MAX1 , EX _MAX2 , and EX _COMBO and increased muscle oxygenation only before EX _COMBO . Sleep and cognitive function were not affected by KE intake. In a non‐AMS developing subgroup, KE appears effective to attenuate high‐intensity endurance performance decline during subacute hypoxic exposure accompanied by repeated exercise until exhaustion.