Dose-response effects of dietary protein on muscle protein synthesis during recovery from endurance exercise in young men: a double-blind randomized trial. Issue 2 (2nd May 2020)

• Record Type: Journal Article
• Authors: Churchward-Venne, Tyler A; Pinckaers, Philippe J M; Smeets, Joey S J; Betz, Milan W; Senden, Joan M; Goessens, Joy P B; Gijsen, Annemie P; Rollo, Ian; Verdijk, Lex B; van Loon, Luc J C
• Is Part Of: American journal of clinical nutrition. Volume 112:Issue 2(2020)
• Page Start: 303
• Page End: 317
• Publication Date: 2020-05-02
• Subjects: myofibrillar protein synthesis -- mitochondrial protein synthesis -- skeletal muscle -- dose-response -- dietary protein -- carbohydrate -- endurance exercise -- young men; Diet therapy -- Periodicals; Nutrition -- Periodicals; Dietetics -- Periodicals; 613.205
• DOI: 10.1093/ajcn/nqaa073
• Languages: English
• ISSNs: 0002-9165

Abstract

ABSTRACT: Background: Protein ingestion increases skeletal muscle protein synthesis rates during recovery from endurance exercise. Objectives: We aimed to determine the effect of graded doses of dietary protein co-ingested with carbohydrate on whole-body protein metabolism, and skeletal muscle myofibrillar (MyoPS) and mitochondrial (MitoPS) protein synthesis rates during recovery from endurance exercise. Methods: In a randomized, double-blind, parallel-group design, 48 healthy, young, endurance-trained men (mean ± SEM age: 27 ± 1 y) received a primed continuous infusion of l -[ring- 2 H5 ]-phenylalanine, l -[ring-3, 5- 2 H2 ]-tyrosine, and l -[1- 13 C]-leucine and ingested 45 g carbohydrate with either 0 (0 g PRO), 15 (15 g PRO), 30 (30 g PRO), or 45 (45 g PRO) g intrinsically l -[1- 13 C]-phenylalanine and l -[1- 13 C]-leucine labeled milk protein after endurance exercise. Blood and muscle biopsy samples were collected over 360 min of postexercise recovery to assess whole-body protein metabolism and both MyoPS and MitoPS rates. Results: Protein intake resulted in ∼70%–74% of the ingested protein-derived phenylalanine appearing in the circulation. Whole-body net protein balance increased dose-dependently after ingestion of 0, 15, 30, or 45 g protein (mean ± SEM: −0.31± 0.16, 5.08 ± 0.21, 10.04 ± 0.30, and 13.49 ± 0.55 μmol phenylalanine · kg −1 · h −1, respectively; P < 0.001). 30 g PRO stimulated a ∼46% increase in MyoPS rates (%/h) compared with 0 g PRO and was sufficient to maximize MyoPS rates after endurance exercise. MitoPS rates were not increased after protein ingestion; however, incorporation of dietary protein–derived l -[1- 13 C]-phenylalanine into de novo mitochondrial protein increased dose-dependently after ingestion of 15, 30, and 45 g protein at 360 min postexercise (0.018 ± 0.002, 0.034 ± 0.002, and 0.046 ± 0.003 mole percentage excess, respectively; P < 0.001). Conclusions: Protein ingested after endurance exercise is efficiently digested and absorbed into the circulation. Whole-body net protein balance and dietary protein–derived amino acid incorporation into mitochondrial protein respond to increasing protein intake in a dose-dependent manner. Ingestion of 30 g protein is sufficient to maximize MyoPS rates during recovery from a single bout of endurance exercise. This trial was registered at trialregister.nl as NTR5111.