Human Skeletal Muscle Mrna Expression In Response To Treadmill-based Endurance Training And Post-exercise Protein Supplementation

Abstract

Nutrient availability is known to influence the exercise response. However, there is a paucity of information regarding the role of post-exercise protein ingestion in modulating intra-muscular adaptation to treadmill-based endurance exercise training. PURPOSE: To examine the influence of post-exercise protein ingestion on mRNA gene expression in response to six-weeks treadmill running. METHODS: In a randomized parallel group design, 15 individuals (VO2max 55 ± 6 ml·kg-1·min-1) completed six weeks of treadmill running (4 sessions per week), progressively increasing in both duration (30-60 min) and intensity (70-75 % VO2max). Participants were randomly assigned to a group receiving a supplement containing carbohydrate (CHO; 1.6 g sucrose·kg-1; n= 7) or carbohydrate-protein (CHO-P; 0.8 g sucrose·kg-1 and 0.8 g whey protein hydrolysate·kg-1; n=8) ingested immediately post-exercise and then 1 h later. To determine mRNA expression of several mitochondrial, mitogenic signaling, protein synthesis and lipid/carbohydrate metabolism genes, muscle biopsy samples were collected at baseline and follow-up, with 48 h of lifestyle standardization to exclude any acute effects on transcriptional changes. RESULTS: An up-regulation in mammalian target of rapamycin (mTOR) gene expression was shown in CHO-P (+46%; p= 0.025) relative to CHO (+4%) following the intervention. Mitochondrial transcription factor A (TFAM) up-regulation was shown in CHO-P group (26%) when compared with CHO (13%), albeit this did not reach statistical significance (p=0.07). No changes in the expression of other mitochondrial, lipid/carbohydrate metabolism, mitogenic signaling genes were observed between groups (p>0.05). CONCLUSION: post-exercise protein supplementation up-regulates the expression of mTOR in skeletal muscle over six-weeks of treadmill-based endurance exercise training, indicating that post-exercise protein supplementation may have a potential role in accentuating skeletal muscle adaptations to endurance exercise training. Funder: Health Sciences Research Center, Lifestyle & Health Research Center (LHRC), Princess Nourah bint Abdulrahman University.