Skip Navigation LinksHome > Published Ahead-of-Print > Protein-Leucine Fed Dose Effects on Muscle Protein Synthesis...
Medicine & Science in Sports & Exercise:
doi: 10.1249/MSS.0000000000000447
Original Investigation: PDF Only

Protein-Leucine Fed Dose Effects on Muscle Protein Synthesis After Endurance Exercise.

Rowlands, David S.; Nelson, Andre R.; Phillips, Stuart M.; Faulkner, James A.; Clarke, Jim; Burd, Nicholas A.; Moore, Daniel; Stellingwerff, Trent

Published Ahead-of-Print
Collapse Box

Abstract

Protein-leucine ingestion following strenuous endurance exercise accentuates muscle protein synthesis and improves recovery of muscle performance.

Purpose: To determine if a low-dose protein-leucine blend ingested following endurance exercise enhances skeletal muscle myofibrillar protein fractional synthetic rate (FSR).

Method: In a crossover design, twelve trained men completed 100 min of high-intensity cycling, then ingested either 70/15/180/30g protein/leucine/carbohydrate/fat (15LEU), 23/5/180/30g (5LEU) or 0/0/274/30g (CON) beverages in randomised order in 4 servings during the first 90 min of a 240-min recovery period. Muscle biopsies were collected at 30 and 240-min into recovery with FSR determined by L-[ring-13C6]phenylalanine incorporation and mTORC1-pathway phosphorylation by Western blot.Results

The 33% (90%CL +/-12%) increase in FSR with 5LEU (mean, SD, 0.080, 0.014%[middle dot]h-1) vs. CON (0.060, 0.012%[middle dot]h-1) represented near-maximal FSR stimulation. Tripling protein-leucine dose (15LEU, 0.090, 0.11%[middle dot]h-1) negligibly increased FSR (13% +/-12% vs. 5LEU). Despite similar FSR, mTORC1Ser2448 phosphorylation only increased with 15LEU at 30-min, whereas p70S6KThr389, rpS6Ser240/244, and 4E-BP1[gamma]Ser112 phosphorylation increased with protein-leucine quantity at one or both time points. Plasma leucine and essential amino-acid concentrations decreased during recovery in CON but increased with protein-leucine dose. Serum insulin was increased in 15LEU vs CON (60% +/-20%), but was unaffected relative to 5LEU. Regression analysis revealed p70S6K-rpS6 phosphorylation moderately predicted FSR, but the associations with plasma leucine and essential amino acids were small.

Conclusion: Ingesting 23 g of protein with 5 g added leucine achieved near-maximal FSR after endurance exercise, an effect unlikely attributable to mTORC1-S6K-rpS6 signaling, insulin, or amino acids. Translating the effects of protein-leucine quantity on protein synthesis to optimizing adaptation and performance requires further research.

(C) 2014 American College of Sports Medicine

Login

Article Tools

Share

Search for Similar Articles
You may search for similar articles that contain these same keywords or you may modify the keyword list to augment your search.

Connect With Us