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

• Autores: David S. Rowlands, Trent Stellingwerff, Andre R. Nelson, Stuart M. Phillips, James Faulkner, Nicholas A. Burd, Daniel R. Moore, Jim A. Clarke
• Localización: Medicine & Science in Sports & exercise: Official Journal of the American College of Sports Medicine, ISSN 0195-9131, Vol. 47, Nº. 3, 2015, págs. 547-555
• Idioma: inglés
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• Dialnet Métricas: 1 Cita
• Resumen

  • AB Protein-leucine ingestion after strenuous endurance exercise accentuates muscle protein synthesis and improves recovery of muscle performance. Purpose: The objective of this study is to determine whether a low-dose protein-leucine blend ingested after endurance exercise enhances skeletal muscle myofibrillar protein fractional synthetic rate (FSR). Method: In a crossover design, 12 trained men completed 100 min of high-intensity cycling, then ingested either 70/15/180/30 g of protein/leucine/carbohydrate/fat (15LEU), 23/5/180/30 g of 5LEU, or 0/0/274/30 g of CON beverages in randomized order in four 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) versus 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 versus 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. Conclusions: Ingesting 23 g of protein with 5 g of 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.