Exercise Mode Combined with Essential Amino Acid and Carbohydrate Supplementation Differentially Regulate Skeletal Muscle microRNA

Abstract

Skeletal muscle microRNAs (myomiR) have been implicated in modulating intracellular regulation of muscle protein synthesis by negative inhibition of the mTORC1 pathway. The acute effects of endurance exercise mode and recovery essential amino acid and carbohydrate (EAA+CHO) nutrition on myomiR expression are not well defined. PURPOSE: Determine the effects of endurance exercise mode, with or without EAA+CHO ingestion on myomiR expression. METHODS: Twenty five adults (mean ± SD; 22 ± 2 y, 82 ± 11 kg, VO2peak 4.0 ± 0.5 L[BULLET OPERATOR]min-1) performed 90 min of metabolically-matched (2.2 ± 0.1 VO2 L[BULLET OPERATOR]m-1) load carriage (LC; performed on a treadmill wearing a vest equal to 30% of individual body mass; load carried 24 ± 3 kg) or cycle ergometry (CE) exercise, during which EAA+CHO (10 g EAA and 46 g CHO) or non-nutritive control (CON) drinks were consumed. Expressions of myomiR were determined using RT-qPCR in muscle samples obtained at rest (PRE), immediately post-exercise (POST) and after 3-hr recovery (REC). RESULTS: Relative to PRE, POST and REC expressions of miR-1-3p, miR-206, miR-208a-5 and miR-499 were 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). CONCLUSIONS: These data show that myomiR expression is differentially regulated by endurance exercise mode and EAA+CHO nutrition. Weight bearing exercise downregulates myomiR expression, whereas myomiR expression appears to be upregulated after non-weight bearing exercise. Consuming EAA+CHO attenuated the increase in myomiR expression with non-weight bearing exercise, yet the suppression of myomiR expression with feeding was more pronounced when EAA+CHO were consumed during weight bearing exercise. These findings suggest that combining weight bearing exercise with protein and carbohydrate supplementation may facilitate muscle anabolic adaptations to exercise by lowering mTORC1 inhibition.