Skeletal Muscle myomiR Are Differentially Expressed by Endurance Exercise Mode and Combined Essential Amino Acid and Carbohydrate Supplementation

Skeletal muscle microRNAs (myomiR) expression is modulated by exercise, however, the influence of endurance exercise mode, combined with essential amino acid and carbohydrate (EAA+CHO) supplementation are not well defined. This study determined the effects of weighted versus non-weighted endurance exercise, with or without EAA+CHO ingestion on myomiR expression and their association with muscle protein synthesis (MPS). Twenty five adults performed 90 min of metabolically-matched (2.2 VO2 L·m-1) load carriage (LC; performed on a treadmill wearing a vest equal to 30% of individual body mass) or cycle ergometry (CE) exercise, during which EAA+CHO (10 g EAA and 46 g CHO) or non-nutritive control (CON) drinks were consumed. Expression of myomiR (RT-qPCR) were determined at rest (PRE), immediately post-exercise (POST), and 3 h into recovery (REC). Muscle protein synthesis (2H5-phenylalanine) was measured during exercise and recovery. Relative to PRE, POST, and REC expression of miR-1-3p, miR-206, miR-208a-5, and miR-499 was lower (P < 0.05) for LC compared to CE, regardless of dietary treatment. Independent of exercise mode, miR-1-3p and miR-208a-5p expression were lower (P < 0.05) after ingesting EAA+CHO compared to CON. Expression of miR-206 was highest for CE-CON than any other treatment (exercise-by-drink, P < 0.05). Common targets of differing myomiR were identified as markers within mTORC1 signaling, and miR-206 and miR-499 were inversely associated with MPS rates immediately post-exercise. These findings suggest the alterations in myomiR expression between exercise mode and EAA+CHO intake may in part be due to differing MPS modulation immediately post-exercise.