Exogenous Ketosis during Early Acclimatization at High Altitude: Ventilatory, Cardiovascular and Muscular Responses to Maximal Exercise

Healthy active adults were randomized to intermittent exogenous ketosis with ketone monoester (n = 16) or placebo (n = 17) and performed incremental cycling tests to exhaustion, first at sea level (295 m) and then at 3375 m after about 69 hours of acclimatization. Preexercise blood ketone concentrations were about 2.1 mM in the ketone group versus about 0.3 mM in placebo. Both groups showed comparable altitude-induced reductions in peak power output and in blood and muscle oxygenation, and the increases in ventilation and cardiac output at altitude did not differ by group.