Ketone monoester supplementation during a live high – train low training camp does not yield an additional adaptive response

Recent evidence indicates that oral ketone monoester (KE) intake acutely increases blood [EPO] following exercise in normoxia and improves endurance performance following an exercise training program. Therefore, we investigated whether post-exercise and pre-sleep KE supplementation may improve performance and hematological adaptations to an altitude training program. Eighteen recreational cyclists (9 male, 9 female) performed a five-week, live-high, train-low (LHTL) program, involving progressive normobaric hypoxia (2000-3000m) and 4–7 training sessions per week, followed by a one-week tapering period under normoxic conditions. Throughout the six-week period, subjects received either 25g KE (n=9) or an isocaloric placebo (CON; n=9) both post-exercise and pre-sleep for a total daily dose of 50g. Experimental measurements were performed before (PRE) and after (POST) LHTL, and after the subsequent taper (POST + 7), and included a 30-minute time trial (TT30), maximal oxygen uptake rate (VO 2 max) test, determination of gross mechanical efficiency, repeated sprint performance, measurements of hemoglobin mass, blood draws and muscle biopsies. In both groups, mean power output during TT30 improved by 9% (p<0.001) alongside increases in VO 2 max (+8%, p=0.001) and absolute hemoglobin mass (+8.77%, p<0.001) from PRE to POST + 7. KE ingestion did not further improve any of these responses. In contrast, repeated sprint performance increased in CON, but not in KE. Skeletal muscle capillarization, as well as vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1 alpha (HIF-1α) protein content in skeletal muscle, were neither impacted by the training program nor by KE. These data provide no clear evidence that KE ingestion offers additional benefits during a LHTL training program in recreationally active cyclists.