Ingestion of exogenous ketones alters the metabolic response to exercise and may improve exercise performance, but has not been explored in variable intensity team sport activity, or for effects on cognitive function.
On two occasions in a double-blind, randomised crossover design, eleven male team sport athletes performed the Loughborough Intermittent Shuttle Test (Part A, 5x15 min intermittent running; Part B, shuttle run to exhaustion), with a cognitive test battery before and after. A 6.4% carbohydrate-electrolyte solution was consumed before and during exercise either alone (PLA), or with 750 mg⋅kg−1 of a ketone ester supplement (KE). Heart rate (HR), rating of perceived exertion (RPE), and 15 m sprint times were recorded throughout, and serial venous blood samples were assayed for plasma glucose, lactate and β-hydroxybutyrate (βHB).
KE resulted in plasma βHB concentrations of ~1.5 to 2.6 mM during exercise (P < 0.001). Plasma glucose and lactate concentrations were lower during KE compared to PLA (moderate-to-large effect sizes). HR, RPE and 15 m sprint times did not differ between trials. Run time to exhaustion was not different (P = 0.126, d = 0.45) between PLA [(mean (95% CI); 268, (199, 336) sec] and KE (229, (178, 280) sec]. Incorrect responses in a multi-tasking test increased from pre- to post-exercise in PLA [1.8 (−0.6, 4.1)] but not KE [0.0 (−1.8, 1.8)] (P = 0.017; d = 0.70).
Compared to carbohydrate alone, co-ingestion of a ketone ester by team sport athletes attenuated the rise in plasma lactate concentrations, but did not improve shuttle run time to exhaustion or 15 m sprint times during intermittent running. An attenuation of the decline in executive function after exhausting exercise suggests a cognitive benefit after KE ingestion.
1School of Health and Human Performance, and
2National Institute for Cellular Biotechnology, Dublin City University, Dublin, Ireland
CORRESPONDING AUTHOR Brendan Egan, PhD, School of Health and Human Performance, Dublin City University, Glasnevin, Dublin 9, Ireland. e: email@example.com. t: +353 1 7008803. f: +353 1 7008888
This work was funded in part by an Irish Research Council Enterprise Partnership Postgraduate Fellowship (EPSPG2016177). The ketone ester studied in this work was provided in-kind by KetoneAid, Inc. KetoneAid provided input into the dosing strategy employed but had no role in the implementation, interpretation or dissemination of this work. No conflict of interest, financial or otherwise, is declared by the authors. The authors declare that the results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation, and do not constitute endorsement by the American College of Sports Medicine.
Submitted for publication April 2018.
Accepted for publication June 2018.