The Effects of 31-Day Exogenous Ketone Consumption on Running Performance, Cognitive Function, Metabolism, Body...

Exogenous ketone supplementation acutely elevates circulating beta-hydroxybutyrate (R-BHB), but the impact of chronic repeated dosing on exercise performance, cognition, mood, and cardiometabolic health remains unclear.

To evaluate the effects of 31 days of thrice-daily ketone monoester (KME) supplementation (90 g/day; high-dose) on exercise performance, executive function, mood, metabolism, body composition, blood pressure, and tolerability in recreational runners.

In a single-blind, randomized-controlled trial, 18 runners consumed either (R)-3-hydroxybutyl (R)-3-hydroxybutyrate (KME; 30 g/dose; n = 9) or an isocaloric, flavor-matched placebo (PLA; 30 g/dose; n = 9) three times daily for 31 days. Outcomes included 5-km time trial (5KTT) performance, cognitive function, mood, body composition, blood pressure, and tolerability. Metabolism and substrate oxidation (rest and graded exercise) were performed after 31-d supplementation was completed to assess metabolic responses following 31 days of repeated exogenous ketone exposure.

31-day KME did not alter 5KTT performance, but improved cognitive function, as evidenced by faster Stroop Incongruent (p = 0.015) and Switching task responses (p = 0.038). Mood and quality of life scores were unchanged. Metabolically, the KME reliably elevated post-ingestion R-BHB (∼3.0 mM; p < 0.001) and lowered glycemia by 15% (p < 0.001). After the 31-day KME supplementation stopped, KME-treatment preserved mean absolute VO₂ during graded exercise testing (p = 0.029), without accompanying improvements in running performance.

High-dose KME administration for 31-days did not alter running performance, but increased cognitive function and oxygen uptake during maximal graded exercise even after ketone administration stopped, indicating that selected physiological measures differed between groups when assessed after the supplementation period.