No Benefit of Ingestion of a Ketone Monoester Supplement on 10-km Running Performance

Med Sci Sports Exerc. 2019 Dec;51(12):2506-2515. doi: 10.1249/MSS.0000000000002065.


Purpose: Preexercise ingestion of exogenous ketones alters the metabolic response to exercise, but effects on exercise performance have been equivocal.

Methods: On two occasions in a double-blind, randomized crossover design, eight endurance-trained runners performed 1 h of submaximal exercise at approximately 65% V˙O2max immediately followed by a 10-km self-paced time trial (TT) on a motorized treadmill. An 8% carbohydrate-electrolyte solution was consumed before and during exercise, either alone (CHO + PLA), or with 573 mg·kg of a ketone monoester supplement (CHO + KME). Expired air, HR, and RPE were monitored during submaximal exercise. Serial venous blood samples were assayed for plasma glucose, lactate, and β-hydroxybutyrate concentrations.

Results: CHO + KME produced plasma β-hydroxybutyrate concentrations of approximately 1.0 to 1.3 mM during exercise (P < 0.001), but plasma glucose and lactate concentrations were similar during exercise in both trials. V˙O2, running economy, respiratory exchange ratio, HR, and RPE were also similar between trials. Performance in the 10-km TT was not different (P = 0.483) between CHO + KME (mean, 2402 s; 95% confidence interval, 2204-2600 s) and CHO + PLA (mean, 2422 s; 95% confidence interval, 2217-2628 s). Cognitive performance, measured by reaction time and a multitasking test, did not differ between trials.

Conclusions: Compared with carbohydrate alone, coingestion of KME by endurance-trained athletes elevated plasma β-hydroxybutyrate concentrations, but did not improve 10-km running TT or cognitive performance.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • 3-Hydroxybutyric Acid / blood
  • Adult
  • Beverages
  • Blood Glucose / metabolism
  • Cross-Over Studies
  • Dietary Carbohydrates / administration & dosage
  • Dietary Carbohydrates / adverse effects
  • Dietary Supplements* / adverse effects
  • Double-Blind Method
  • Electrolytes / administration & dosage
  • Electrolytes / adverse effects
  • Exercise Test
  • Female
  • Humans
  • Ketones / administration & dosage*
  • Ketones / adverse effects
  • Lactic Acid / blood
  • Male
  • Physical Endurance / physiology*
  • Running / physiology*


  • Blood Glucose
  • Dietary Carbohydrates
  • Electrolytes
  • Ketones
  • Lactic Acid
  • 3-Hydroxybutyric Acid