Post-exercise ketone supplementation improves endurance performance and mitochondrial adaptations during an 8-week endurance training intervention

Abstract

Post-exercise ketone supplementation (PEKS) previously improved endurance performance and muscular adaptations during overload training. However, whether and how PEKS improves endurance performance during a periodised endurance training period remains unclear. Twenty-eight trained males completed 8 weeks of supervised cycling, receiving either 25 g of the ketone monoester (R)-hydroxybutyl (R)-hydroxybutyrate (KE, n = 14) or isocaloric placebo (CON, n = 14) post-exercise and before sleep. Outcomes included exercise performance and muscular/cardiac adaptations assessed at baseline (PRE), week 3 (MID) and 7 (POST), and following a taper week (POST+(1week)). The training intervention improved 30 min time trial performance (TT30min), absolute and relative V-O2peak, peak power output during the V(O2peak )test (PPO V-O2peak), citrate synthase (CS) activity, and peak cardiac output (all P < 0.05 PRE vs. POST). Notably, TT30min (CON: 291 +/- 27 W vs. KE: 302 +/- 28 W, P < 0.001, Hedges' g = 0.40) was 4% higher in KE compared to CON at POST. Although peak cardiac output was similar, relativeV(O2peak) increased more in KE (+12%) than CON (+6%, Delta P < 0.001), suggesting enhanced peripheral oxygen utilisation. Accordingly, CS activity was at POST 14% higher in KE (9.37 +/- 1.36 mol h(-1) kg protein(-1)) compared to CON (8.21 +/- 0.97 mol h(-1) kg protein(-1), P = 0.035, Hedges' g = 0.98) and OXPHOS complex II muscle protein content remained unaltered in CON while increasing by 25% in KE (P = 0.030 vs. PRE). In conclusion, these findings establish PEKS as a nutritional strategy to enhance endurance performance and mitochondrial adaptations during periodised endurance training.