Acute Nutritional Ketosis During Early Recovery from Exercise Does Not Affect Skeletal Muscle Transcriptomic Response
Purpose: Recent research suggests that Ketone monoester (KME) supplementation may enhance skeletal muscle adaptation to exercise, possibly modulated be an increased secretion of erythropoietin (EPO) and increased muscle glycogen resynthesis, but the precise molecular pathways driving the response remain uncertain. Therefore, we aimed at characterising the modulation of skeletal muscle by KME through a genome-wide characterisation of the transcriptome early post-exercise. Methods: Following a randomized, double-blind, crossover design, recreationally active men [n= 9; age: 26 ± 5 (means ± SD); height: 1.80 ± 0.07 m; body mass: 80 ± 9 kg; V?O2max: 47 ± 4 mL·kg-1·min-1]) completed two experimental trials where they ingested either 1.25 g/kg of KME (>96% (R)-3-hydroxybutyl (R)-3-hydroxybutyrate) or a taste-matched placebo (PLA) drink around exercise (90-min cycling  at 60% of VO2max) in standardised conditions. . Venous blood samples were taken throughout baseline, exercise and recovery, and skeletal muscle biopsies were taken at baseline and 3-h post exercise. Results: KME intake elevated serum ßHB concentrations post-exercise to 3.3 ± 0.5 mM and remained elevated levels during recovery (range: ~4.0–4.7 mM). Remarkably, there was no marked upregulation or downregulation of differentially expressed genes at 3-h post-exercise with KME supplementation compared to PLA. Although, baseline serum EPO levels were higher in PLA (12.8 ± 3.9 IU/L) compared to KME (10.1 ± 5.7 IU/L) and remained slightly higher in PLA throughout recovery, there was not significant difference between conditions. Pre- and post- exercise muscle glycogen concentrate were similar between conditions (KME PRE: 501 ± 118 mmol/kg, KME POST, 284 ± 117 mmol/kg, PLA PRE: 492 ± 102 mmol/kg, PLA POST: 282 ± 184 mmol/kg). Conclusions: Our findings indicate that despite a sustained post-exercise increase in serum ßHB concentrations, KME supplementation did not induce transcriptional changes in skeletal muscle. Additionally, in contrast to previous studies, KME did not affect glycogen concentrations or serum EPO levels during the first 3-hours post-exercise. Overall design: Our aims were to perform an exploratory assessment of post-exercise skeletal muscle transcriptome response, to replicate findings on the effect of KME on EPO, and skeletal muscle glycogen during recovery from exercise. We hypothesized that KME would have a marked modulatory effect on skeletal muscle transcriptome and enhance EPO concentrations along with increased muscle glycogen resynthesis. This randomized, double-blind, placebo-controlled, crossover design study involved two experimental sessions involving two experimental visits, separated by 7-14 days. Each experimental sessions compromised a 90 min cycling session at 60% V?O2max. Subjects received either 1.25 g·kg-1 (range: ~85 – 110 g) of KME [>96% (R)-3-hydroxybutyl (R)-3-hydroxybutyrate] or a volume and taste-matched placebo (PLA) drink. Both drinks were spread in four dosages (0.5 g·kg-1, 0.25 g·kg-1, 0.25 g·kg-1, 0.25 g·kg-1) to be ingested i) at min 45 of exercise ii) immediately after exercise completion iii) 1-h post-exercise iv) 2-h post exercise. On trial days, participants arrived at the laboratory on the morning (0730 to 0830 h) and venous blood samples were drawn at i) ~30 min pre-exercise ii) immediately after exercise completion iii) 60-min post-exercise iv) 120-min post exercise v) 180-min post exercise. Skeletal muscle biopsies were obtained from the vastus lateralis of the quadriceps ~60-min pre-exercise and 180-min post-exercise. Subjects received a standardized breakfast containing 1 g·kg-1 carbohydrate, 0.1 g·kg-1 protein, 0.03 g·kg-1 fat exactly 30 min pre-exercise. After exercise completion, participants consumed at 30-min post-exercise a recovery drink containing 1 g·kg-1 carbohydrate, 0.4 g·kg-1 protein. During exercise finger-prick blood samples were collected to measure lactate concentrations (Biosen C-Line, EKF Diagnostics, Cardiff, UK), respiratory gas exchange (VyntusTM CPX metabolic cart, Vyaire, Mettawa, Illinois, USA), heart rate monitor (H10 Polar, Polar Electro Oy, Kempele, Finland), and rating of perceived exertion (RPE, 6-20 scale, ((Borg, 1982)) were also recorded on the last 3-min of every 15-min.