TY - JOUR AU - Rodger, Shem AU - Plews, Daniel AU - Laursen, Paul AU - Driller, Matthew PY - 2017/06/30 Y2 - 2024/03/29 TI - The effects of an oral β-hydroxybutyrate supplement on exercise metabolism and cycling performance JF - Journal of Science and Cycling JA - J Sci Cycling VL - 6 IS - 1 SE - DO - UR - https://jsc-journal.com/index.php/JSC/article/view/304 SP - 26-31 AB - <p>The purpose of the present study was to examine the effects of an oral β-hydroxybutyrate<strong> </strong>(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, VO<sub>2peak</sub>; 68.0 ± 6.7 ml.min<sup>-1</sup>kg<sup>-1</sup>) 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 &gt; 0.05) and was associated with a <em>trivial</em> effect<em> </em>(ES ±90%CI = 0.19 ±0.37). Ingestion of the BHB supplement was associated with a <em>large</em> increase in blood BHB concentrations when compared to PLA for the 4PT (ES = 1.75 ±0.50, p &lt; 0.01). The increased BHB concentration was accompanied by a <em>moderate</em> increase in the respiratory exchange ratio (RER) during the submaximal exercise phase (ES = 0.54 ±0.45, p = &gt;0.05) and a <em>moderate</em> increase during the 4PT (ES = 0.78 ±0.57, p = 0.03). Submaximal VO<sub>2 </sub>did not differ between trials, however, VO<sub>2</sub> was higher during the 4PT phase in the BHB trial (ES = 0.28 ±0.32; <em>small</em>). In conclusion, BHB supplementation altered blood BHB concentrations, RER and VO<sub>2</sub> values during steady state sub-maximal exercise, but did not improve 4-minute cycling performance.</p><p> </p> ER -