The effects of an oral β-hydroxybutyrate supplement on exercise metabolism and cycling performance

Shem Rodger, Daniel Plews, Paul Laursen, Matthew Driller

Abstract


The purpose of the present study was to examine the effects of an oral β-hydroxybutyrate (BHB) supplement on cycling performance. Using a double-blind, placebo-controlled, crossover design, 12 highly-trained cyclists (mean ± SD: age; 35 ± 8 y, mass; 74.5 ± 7.6 kg, VO2peak; 68.0 ± 6.7 ml.min-1kg-1) were supplemented with two 30 ml servings of an oral BHB supplement or placebo formula (PLA) prior to and during exercise. Participants cycled at a submaximal intensity (80% of second ventilatory threshold) for 90-min, followed by a 4-min maximal cycling performance test (4PT). The difference in 4PT power output between trials was not statistically significant (p > 0.05) and was associated with a trivial effect (ES ±90%CI = 0.19 ±0.37). Ingestion of the BHB supplement was associated with a large increase in blood BHB concentrations when compared to PLA for the 4PT (ES = 1.75 ±0.50, p < 0.01). The increased BHB concentration was accompanied by a moderate increase in the respiratory exchange ratio (RER) during the submaximal exercise phase (ES = 0.54 ±0.45, p = >0.05) and a moderate increase during the 4PT (ES = 0.78 ±0.57, p = 0.03). Submaximal VO2 did not differ between trials, however, VO2 was higher during the 4PT phase in the BHB trial (ES = 0.28 ±0.32; small). In conclusion, BHB supplementation altered blood BHB concentrations, RER and VO2 values during steady state sub-maximal exercise, but did not improve 4-minute cycling performance.

 


Keywords


ketones; ketosis; fat metabolism; ergogenic aids

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