Low carbohydrate availability promotes a distinct circulating microRNA profile 24 h following aerobic exercise

Low carbohydrate availability during recovery from aerobic exercise alters skeletal muscle microRNA (miRNA) profiles, which may mechanistically regulate exercise recovery. However, its impact on circulating miRNA (c-miRNA) profiles remains unclear. This study aimed to determine the effects of low versus adequate carbohydrate availability on c-miRNA profiles during recovery from aerobic exercise. Nine males (22 ± 4 yr, 1.81 ± 0.09 m, 83.9 ± 11.9 kg, 25.7 ± 2.3 kg/m², means ± SD) completed this randomized, crossover study comprising two glycogen depletion trials, followed by 24 h of isocaloric refeeding to induce low (LOW; 1.5 g/kg carbohydrate, 3.0 g/kg fat) or adequate (AD; 6.0 g/kg carbohydrate, 1.0 g/kg fat) carbohydrate availability. Total c-miRNA was extracted from serum 24 h following glycogen depletion exercise. Data were log-transformed and analyzed as fold change relative to AD. Bioinformatics was conducted on significant c-miRNA and associated pathways (miRTarBase/KEGG). Follow-up transfection of miR-375-3p mimic or inhibitor into C2C12 cells assessed metabolic, inflammatory, and catabolic pathways at the gene and protein levels. Of the 84 miRNAs assessed, miR-335-5p (-0.49 ± 0.60; <i>P</i> = 0.04) and miR-375-3p (-1.57 ± 1.25; <i>P</i> = 0.01) were significantly lower, and miR-214-3p (1.76 ± 1.85; <i>P</i> = 0.02) was significantly higher in AD versus LOW. In vitro experiments indicated that miR-375-3p regulates catabolic pathways at the gene and protein level. Low carbohydrate availability alters c-miRNA profiles, particularly miR-375-3p, which targets proteostasis and metabolism 24 h into recovery from aerobic exercise. These findings identify unique c-miRNA targets as potential biomarkers for the mechanistic effects of low carbohydrate availability on exercise recovery.<b>NEW & NOTEWORTHY</b> Low carbohydrate consumption (LOW) 24 h in recovery from aerobic exercise elicits a distinct circulating miRNA profile compared with adequate carbohydrate consumption (AD). MicroRNA 375-3p was the most significantly different between the LOW and AD treatments. Follow-up in vitro experiments suggest that AD carbohydrate availability blunts catabolic signaling during postexercise recovery.