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Abstract: Purpose: Ingestion of whey protein increases myofibrillar but not muscle connective protein synthesis rates. Recently, we defined a whey and collagen protein blend (5:1-ratio) to optimize post-prandial plasma amino acid availability. Here, we assessed the ability of this blend to increase myofibrillar and muscle connective protein synthesis rates at rest and during early recovery from exercise.Methods: In a randomized, double-blind, parallel design, 28 men (age: 25 ± 5 y; BMI: 23.6 ± 2.3 kg/m2) were randomly allocated to ingest either 30 g of protein (25 g whey/5 g collagen; BLEND, n = 14) or a non-caloric placebo (PLA, n = 14) following a single session of unilateral leg resistance-type exercise. Participants received primed continuous L-[ring-13C6]-phenylalanine infusions with blood and muscle biopsy samples collection for 5 hours post-prandially to assess myofibrillar and muscle connective protein synthesis rates.Results: Protein ingestion strongly increased plasma amino acid concentrations, including plasma leucine and glycine concentrations (P < 0.001), with no changes following placebo ingestion (P > 0.05). Post-prandial myofibrillar and muscle connective protein synthesis rates were higher in the exercised compared to the rested leg (P < 0.001). In addition, myofibrillar protein synthesis rates were higher in BLEND compared to PLA in both the rested (0.038 ± 0.008 and 0.031 ± 0.006%·h-1, respectively; P < 0.05) and exercised (0.052 ± 0.011 and 0.039 ± 0.009%·h-1, respectively; P < 0.01) leg. Muscle connective protein synthesis rates were higher in BLEND compared to PLA in the rested (0.062 ± 0.013 and 0.051 ± 0.010%·h-1, respectively; P < 0.05), but not the exercised (0.090 ± 0.021 and 0.079 ± 0.016%·h-1, respectively; P = 0.11) leg.Conclusions: Ingestion of a whey (25 g) plus collagen (5 g) protein blend increases both myofibrillar and muscle connective protein synthesis rates at rest and further increases myofibrillar but not muscle connective protein synthesis rates during recovery from exercise in recreationally active, young men., Competing Interests: Conflict of Interest and Funding Source: This study was funded by a public-private cooperation between Maastricht University, The Netherlands, GELITA AG, Germany, and TKI Health~Holland, The Netherlands. L. J. C. vL. and his laboratory has received research grants, consulting fees, speaking honoraria, or a combination of these for research on the impact of exercise and nutrition on muscle metabolism, which include research funding from companies that produce collagen such as GELITA AG and PB Leiner. A full overview on research funding is provided at https://www.maastrichtuniversity.nl/l.vanloon. U. B. is an employee of GELITA AG. K. Baar has received has also received grants, consulting fees, speaking honoraria, and donations from nutritional companies such as PepsiCo, Bergstrom Nutrition, Ynsect, and GelTor to study the effect of dietary collagen on endogenous collagen synthesis. T. S. was supported by a research grant from GELITA AG to perform studies on collagen protein ingestion and post-exercise recovery. T. A., J. K., W. J. H. H., F. K. H., A. M. H., J. M. S., J. M. X. vK. and J. P. G. G. report no conflicts of interest related to this work. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The results of the present study do not constitute endorsement by the American College of Sports Medicine., (Copyright © 2024 by the American College of Sports Medicine.)

Whey protein ingestion during recovery from exercise increases myofibrillar but not muscle connective protein synthesis rates. It has been speculated that whey protein does not provide sufficient glycine to maximize postexercise muscle connective protein synthesis rates. In the present study, we assessed the impact of coingesting different amounts of collagen with whey protein as a nutritional strategy to increase plasma glycine availability during recovery from exercise. In a randomized, double-blind, crossover design, 14 recreationally active men (age: 26 ± 5 years; body mass index: 23.8 ± 2.1 kg·m-2) ingested in total 30 g protein, provided as whey protein with 0 g (WHEY), 5 g (WC05); 10 g (WC10), and 15 g (WC15) of collagen protein immediately after a single bout of resistance exercise. Blood samples were collected frequently over 6 hr of postexercise recovery to assess postprandial plasma amino acid kinetics and availability. Protein ingestion strongly increased plasma amino acid concentrations (p < .001) with no differences in plasma total amino acid availability between treatments (p > .05). The postprandial rise in plasma leucine and essential amino acid availability was greater in WHEY compared with the WC10 and WC15 treatments (p < .05). Plasma glycine and nonessential amino acid concentrations declined following whey protein ingestion but increased following collagen coingestion (p < .05). Postprandial plasma glycine availability averaged -8.9 ± 5.8, 9.2 ± 3.7, 23.1 ± 6.5, and 39.8 ± 11.0 mmol·360 min/L in WHEY, WC05, WC10, and WC15, respectively (incremental area under curve values, p < .05). Coingestion of a small amount of collagen (5 g) with whey protein (25 g) is sufficient to prevent the decline in plasma glycine availability during recovery from lower body resistance-type exercise in recreationally active men.

We measured the impact of blood flow restriction on muscle protein synthesis rates, muscle mass and strength during 2 weeks of strict bed rest. Twelve healthy, male adults (age: 24 ± 3 years, body mass index: 23.7 ± 3.1 kg/m 2 ) were subjected to 14 days of strict bed rest with unilateral blood flow restriction performed three times daily in three 5 min cycles (200 mmHg). Participants consumed deuterium oxide and we collected blood and saliva samples throughout 2 weeks of bed rest. Before and immediately after bed rest, lean body mass (dual-energy X-ray absorptiometry scan) and thigh muscle volume (magnetic resonance imaging scan) were assessed in both the blood flow restricted (BFR) and control (CON) leg. Muscle biopsies were collected and unilateral muscle strength (one-repetition maximum; 1RM) was assessed for both legs before and after the bed rest period. Bed rest resulted in 1.8 ± 1.0 kg lean body mass loss (P < 0.001). Thigh muscle volume declined from 7.1 ± 1.1 to 6.7 ± 1.0 L in CON and from 7.0 ± 1.1 to 6.7 ± 1.0 L in BFR (P < 0.001), with no differences between treatments (P = 0.497). In addition, 1RM leg extension strength decreased from 60.2 ± 10.6 to 54.8 ± 10.9 kg in CON and from 59.2 ± 12.1 to 52.9 ± 12.0 kg in BFR (P = 0.014), with no differences between treatments (P = 0.594). Muscle protein synthesis rates during bed rest did not differ between the BFR and CON leg (1.11 ± 0.12 vs. 1.08 ± 0.13%/day, respectively; P = 0.302). Two weeks of bed rest substantially reduces skeletal muscle mass and strength. Blood flow restriction during bed rest does not modulate daily muscle protein synthesis rates and does not preserve muscle mass or strength. KEY POINTS: Bed rest, often necessary for recovery from illness or injury, leads to the loss of muscle mass and strength. It has been postulated that blood flow restriction may attenuate the loss of muscle mass and strength during bed rest. We investigated the effect of blood flow restriction on muscle protein synthesis rates, muscle mass and strength during 2 weeks of strict bed rest. Blood flow restriction applied during bed rest does not modulate daily muscle protein synthesis rates and does not preserve muscle mass or strength. Blood flow restriction is not effective in preventing muscle atrophy during a prolonged period of bed rest., (© 2024 The Authors. The Journal of Physiology published by John Wiley & Sons Ltd on behalf of The Physiological Society.)

Introduction: Plant-derived proteins have received considerable attention as an alternative to animal-based proteins and are now frequently used in both plant-based diets and sports nutrition products. However, little information is available on the anabolic properties of potato-derived protein. This study compares muscle protein synthesis rates after the ingestion of 30 g potato protein versus 30 g milk protein at rest and during recovery from a single bout of resistance exercise in healthy, young males., Methods: In a randomized, double-blind, parallel-group design, 24 healthy young males (24 ± 4 yr) received primed continuous l -[ ring - 13 C 6 ]-phenylalanine infusions while ingesting 30 g potato-derived protein or 30 g milk protein after a single bout of unilateral resistance exercise. Blood and muscle biopsies were collected for 5 h after protein ingestion to assess postprandial plasma amino acid profiles and mixed muscle protein synthesis rates at rest and during recovery from exercise., Results: Ingestion of both potato and milk protein increased mixed muscle protein synthesis rates when compared with basal postabsorptive values (from 0.020% ± 0.011% to 0.053% ± 0.017%·h -1 and from 0.021% ± 0.014% to 0.050% ± 0.012%·h -1 , respectively; P < 0.001), with no differences between treatments ( P = 0.54). In the exercised leg, mixed muscle protein synthesis rates increased to 0.069% ± 0.019% and 0.064% ± 0.015%·h -1 after ingesting potato and milk protein, respectively ( P < 0.001), with no differences between treatments ( P = 0.52). The muscle protein synthetic response was greater in the exercised compared with the resting leg ( P < 0.05)., Conclusions: Ingestion of 30 g potato protein concentrate increases muscle protein synthesis rates at rest and during recovery from exercise in healthy, young males. Muscle protein synthesis rates after the ingestion of 30 g potato protein do not differ from rates observed after ingesting an equivalent amount of milk protein., (Copyright © 2022 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American College of Sports Medicine.)

Background: Protein ingestion increases muscle protein synthesis rates. The food matrix in which protein is provided can strongly modulate the postprandial muscle protein synthetic response. So far, the muscle protein synthetic response to the ingestion of whole foods remains largely unexplored., Objectives: To compare the impact of ingesting 30 g protein provided as milk protein or cheese on postprandial plasma amino acid concentrations and muscle protein synthesis rates at rest and during recovery from exercise in vivo in young males., Methods: In this randomized, parallel-group intervention trial, 20 healthy males aged 18-35 y ingested 30 g protein provided as cheese or milk protein concentrate following a single-legged resistance-type exercise session consisting of 12 sets of leg press and leg extension exercises. Primed, continuous intravenous L-[ring-13C6]-phenylalanine infusions were combined with the collection of blood and muscle tissue samples to assess postabsorptive and 4-h postprandial muscle protein synthesis rates at rest and during recovery from exercise. Data were analyzed using repeated measures Time × Group (× Leg) ANOVA., Results: Plasma total amino acid concentrations increased after protein ingestion (Time: P < 0.001), with 38% higher peak concentrations following milk protein than cheese ingestion (Time × Group: P < 0.001). Muscle protein synthesis rates increased following both cheese and milk protein ingestion from 0.037 ± 0.014 to 0.055 ± 0.018%·h-1 and 0.034 ± 0.008 to 0.056 ± 0.010%·h-1 at rest and even more following exercise from 0.031 ± 0.010 to 0.067 ± 0.013%·h-1 and 0.030 ± 0.008 to 0.063 ± 0.010%·h-1, respectively (Time: all P < 0.05; Time × Leg: P = 0.002), with no differences between cheese and milk protein ingestion (Time × Group: both P > 0.05)., Conclusion: Cheese ingestion increases muscle protein synthesis rates both at rest and during recovery from exercise. The postprandial muscle protein synthetic response to the ingestion of cheese or milk protein does not differ when 30 g protein is ingested at rest or during recovery from exercise in healthy, young males., (© The Author(s) 2022. Published by Oxford University Press on behalf of the American Society for Nutrition.)

Background: Protein ingestion increases muscle protein synthesis rates. The food matrix in which protein is provided can strongly modulate the postprandial muscle protein synthetic response. So far, the muscle protein synthetic response to the ingestion of whole foods remains largely unexplored., Objectives: To compare the impact of ingesting 30 g protein provided as milk protein or cheese on postprandial plasma amino acid concentrations and muscle protein synthesis rates at rest and during recovery from exercise in vivo in young males., Methods: In this randomized, parallel-group intervention trial, 20 healthy males aged 18-35 y ingested 30 g protein provided as cheese or milk protein concentrate following a single-legged resistance-type exercise session consisting of 12 sets of leg press and leg extension exercises. Primed, continuous intravenous L-[ring- 13 C 6 ]-phenylalanine infusions were combined with the collection of blood and muscle tissue samples to assess postabsorptive and 4-h postprandial muscle protein synthesis rates at rest and during recovery from exercise. Data were analyzed using repeated measures Time × Group (× Leg) ANOVA., Results: Plasma total amino acid concentrations increased after protein ingestion (Time: P < 0.001), with 38% higher peak concentrations following milk protein than cheese ingestion (Time × Group: P < 0.001). Muscle protein synthesis rates increased following both cheese and milk protein ingestion from 0.037 ± 0.014 to 0.055 ± 0.018%·h -1 and 0.034 ± 0.008 to 0.056 ± 0.010%·h -1 at rest and even more following exercise from 0.031 ± 0.010 to 0.067 ± 0.013%·h -1 and 0.030 ± 0.008 to 0.063 ± 0.010%·h -1 , respectively (Time: all P < 0.05; Time × Leg: P = 0.002), with no differences between cheese and milk protein ingestion (Time × Group: both P > 0.05)., Conclusion: Cheese ingestion increases muscle protein synthesis rates both at rest and during recovery from exercise. The postprandial muscle protein synthetic response to the ingestion of cheese or milk protein does not differ when 30 g protein is ingested at rest or during recovery from exercise in healthy, young males., (Copyright © 2022 American Society for Nutrition.)

Background: Insects have recently been identified as a more sustainable protein-dense food source and may represent a viable alternative to conventional animal-derived proteins., Objectives: We aimed to compare the impacts of ingesting lesser mealworm- and milk-derived protein on protein digestion and amino acid absorption kinetics, postprandial skeletal muscle protein synthesis rates, and the incorporation of dietary protein-derived amino acids into de novo muscle protein at rest and during recovery from exercise in vivo in humans., Methods: In this double-blind randomized controlled trial, 24 healthy, young men ingested 30 g specifically produced, intrinsically l-[1-13C]-phenylalanine and l-[1-13C]-leucine labeled lesser mealworm- or milk-derived protein after a unilateral bout of resistance-type exercise. Primed continuous l-[ring-2H5]-phenylalanine, l-[ring-3,5-2H2]-tyrosine, and l-[1-13C]-leucine infusions were applied, with frequent collection of blood and muscle tissue samples., Results: A total of 73% ± 7% and 77% ± 7% of the lesser mealworm and milk protein-derived phenylalanine was released into the circulation during the 5 h postprandial period, respectively, with no significant differences between groups (P < 0.05). Muscle protein synthesis rates increased after both lesser mealworm and milk protein concentrate ingestion from 0.025 ± 0.008%/h to 0.045 ± 0.017%/h and 0.028 ± 0.010%/h to 0.056 ± 0.012%/h at rest and from 0.025 ± 0.012%/h to 0.059 ± 0.015%/h and 0.026 ± 0.009%/h to 0.073 ± 0.020%/h after exercise, respectively (all P < 0.05), with no differences between groups (both P > 0.05). Incorporation of mealworm and milk protein-derived l-[1-13C]-phenylalanine into de novo muscle protein was greater after exercise than at rest (P < 0.05), with no differences between groups (P > 0.05)., Conclusions: Ingestion of a meal-like amount of lesser mealworm-derived protein is followed by rapid protein digestion and amino acid absorption and increases muscle protein synthesis rates both at rest and during recovery from exercise. The postprandial protein handling of lesser mealworm does not differ from ingesting an equivalent amount of milk protein concentrate in vivo in humans.This trial was registered at www.trialregister.nl as NL6897., (© The Author(s) 2021. Published by Oxford University Press on behalf of the American Society for Nutrition.)

Background: Protein ingestion increases muscle protein synthesis rates. However, limited data are currently available on the effects of branched-chain amino acid (BCAA) and branched-chain ketoacid (BCKA) ingestion on postprandial muscle protein synthesis rates., Objective: The aim of this study was to compare the impact of ingesting 6 g BCAA, 6 g BCKA, and 30 g milk protein (MILK) on the postprandial rise in circulating amino acid concentrations and subsequent myofibrillar protein synthesis rates in older males., Methods: In a parallel design, 45 older males (age: 71 ± 1 y; BMI: 25.4 ± 0.8 kg/m2) were randomly assigned to ingest a drink containing 6 g BCAA, 6 g BCKA, or 30 g MILK. Basal and postprandial myofibrillar protein synthesis rates were assessed by primed continuous l-[ring-13C6]phenylalanine infusions with the collection of blood samples and muscle biopsies., Results: Plasma BCAA concentrations increased following test drink ingestion in all groups, with greater increases in the BCAA and MILK groups compared with the BCKA group (P < 0.05). Plasma BCKA concentrations increased following test drink ingestion in all groups, with greater increases in the BCKA group compared with the BCAA and MILK groups (P < 0.05). Ingestion of MILK, BCAA, and BCKA significantly increased early myofibrillar protein synthesis rates (0-2 h) above basal rates (from 0.020 ± 0.002%/h to 0.042 ± 0.004%/h, 0.022 ± 0.002%/h to 0.044 ± 0.004%/h, and 0.023 ± 0.003%/h to 0.044 ± 0.004%/h, respectively; P < 0.001), with no differences between groups (P > 0.05). Myofibrillar protein synthesis rates during the late postprandial phase (2-5 h) remained elevated in the MILK group (0.039 ± 0.004%/h; P < 0.001), but returned to baseline values following BCAA and BCKA ingestion (0.024 ± 0.005%/h and 0.024 ± 0.005%/h, respectively; P > 0.05)., Conclusions: Ingestion of 6 g BCAA, 6 g BCKA, and 30 g MILK increases myofibrillar protein synthesis rates during the early postprandial phase (0-2 h) in vivo in healthy older males. The postprandial increase following the ingestion of 6 g BCAA and BCKA is short-lived, with higher myofibrillar protein synthesis rates only being maintained following the ingestion of an equivalent amount of intact milk protein. This trial was registered at Nederlands Trial Register (www.trialregister.nl) as NTR6047., (Copyright © American Society for Nutrition 2019.)