In a small post-hoc subgroup of 5 young men who did not develop severe acute mountain sickness, ketone ester intake appears effective to attenuate high-intensity endurance performance decline during subacute hypoxic exposure accompanied by repeated exercise until exhaustion.
Ketone ester (KE) intake did not change peak power output (PPO) during the first or second maximal incremental cycling tests in hypoxia.
KE intake increased peak power output by 36 W during the combined maximal-submaximal test (EXCOMBO) after 26.5 h of hypoxia.
KE intake increased resting blood oxygenation before all three exercise tests.
KE intake increased skeletal muscle oxygenation only before EXCOMBO.
KE intake did not affect sleep or cognitive function in the non-AMS subgroup.
The analysis was a post-hoc subgroup analysis of a larger project, restricted to participants without severe AMS, to isolate KE effects from AMS influences.
This study looked at whether drinking a ketone ester supplement could help people exercise better at simulated high altitude (about 4000-4500 m) over a 29-hour stay. It was a re-analysis of a subset of five young, healthy men from a larger study who did not develop severe altitude sickness, since altitude sickness can itself affect performance, sleep, and thinking. Ketone ester did not change peak cycling power during the first two maximal tests, done early (1.5 hours) and after about a day (25 hours) in low oxygen. However, in a later combined test after 26.5 hours, following repeated exercise to exhaustion, peak power was 36 W higher with ketones. Blood oxygen levels were higher with ketones before all three tests, while muscle oxygenation was higher only before the last test. Sleep and thinking performance were not changed. This research suggests ketone esters might help reduce the decline in high-intensity endurance performance during prolonged altitude exposure with repeated hard exercise. But the sample was very small (5 men), the analysis was post-hoc, and results may not apply to women, older people, or those who get altitude sickness, so larger studies are needed.
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Upload Your LabsStalmans M, Tominec D, Lauriks W, Robberechts R, Ramaekers M, Debevec T, et al.. (2026). Ketone monoester intake attenuates exercise performance decline in normobaric hypoxia: A post-hoc subgroup analysis of 5 young male adults without acute mountain sickness.. Physiological reports. https://doi.org/10.14814/phy2.71136