Dose-response effects of dietary protein on muscle protein synthesis during recovery from endurance exercise in young men: a double-blind randomized trial

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-2H5]-phenylalanine, l-[ring-3,5-2H2]-tyrosine, and l-[1-13C]-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-[1-13C]-phenylalanine and l-[1-13C]-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-[1-13C]-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.

Supplement with whey protein hydrolysate in contrast to carbohydrate supports mitochondrial adaptations in trained runners

“…However, the 4-h time course may be too short to detect the rise in mitochondrial MPS, which is supported by data from Di Donato et al showing a rise in mitochondrial MPS 24-28h following intense endurance exercise, but not 0.5-4.5h post exercise (13). Intriguingly, Churchward-Venne et al brings new life to the debate with their recent study, investigating how different doses of dietary PRO co-ingested with CHO in uence synthesis of myo brillar and mitochondrial MPS (11). In line with previous studies, they report no difference in mitochondrial MPS in response to none or an increasing dose of protein.…”

“…In line with previous studies, they report no difference in mitochondrial MPS in response to none or an increasing dose of protein. However, by labeling the protein ingested with a L-[1-13 C]-phenylalanine, the research group demonstrated that incorporation of dietary protein-derived L-[1-13 C]-phenylalanine into de novo synthesis of mitochondrial protein increased dosedependently after ingestion of 15, 30 and 45 g of PRO at 360 min post exercise (11). In support of a positive interaction between consuming protein post exercise and mitochondrial adaptations, Hill et al demonstrated that a 2-week dietary intervention of co-ingestion with CHO-PRO compared to CHO, resulted in signi cantly greater increases in PGC-1α 6h after endurance exercise (14).…”

“…The impact of adding PRO to a CHO drink on fraction-speci c muscle protein synthesis following endurance exercise have been investigated in a number of studies (9)(10)(11)(12). A greater increase in mTOR ser2448 phosphorylation and myo brillar MPS have been observed when consuming PRO-CHO compared to CHO only following 90-120 min of cycling (9)(10)(11) and sprint intervals (12). These ndings suggest that intake of dietary PRO in the recovery phase of endurance training is important to support muscle adaptations.…”

“…Nevertheless, the in uence of PRO supplementation on mitochondrial MPS is less clear. Today, three studies have found no signi cant effect of PRO supplementation on mitochondrial MPS following endurance exercise (9,11,12). However, it has been speculated that the lack of increase in mitochondrial MPS may be attributed to the relatively short time course (4-6 hours) investigated (9,12).…”

“…Intriguingly, Churchward-Venne et al reported a dose-dependent increase in dietary protein-derived L-[1-13 C]-phenylalanine incorporation into mitochondrial protein (11), but not other measured amino acids, suggesting that speci c amino acids from ingested PRO contribute to mitochondrial biogenesis following endurance exercise (11). In support, PGC1-α mRNA, a biomarker of mitochondrial biogenesis has been shown to be increased by PRO supplementation at 6h after a 60 min endurance bout (14).…”