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Animal-derived dietary protein ingestion and physical activity stimulate myofibrillar protein synthesis rates in older adults. We determined whether a non-animal-derived diet can support daily myofibrillar protein synthesis rates to the same extent as an omnivorous diet. Nineteen healthy older adults (aged 66 (sem 1) years; BMI 24 (sem 1) kg/m2; twelve males, seven females) participated in a randomised, parallel-group, controlled trial during which they consumed a 3-d isoenergetic high-protein (1·8 g/kg body mass per d) diet, where the protein was provided from predominantly (71 %) animal (OMNI; n 9; six males, three females) or exclusively vegan (VEG; n 10; six males, four females; mycoprotein providing 57 % of daily protein intake) sources. During the dietary control period, participants conducted a daily bout of unilateral resistance-type leg extension exercise. Before the dietary control period, participants ingested 400 ml of deuterated water, with 50-ml doses consumed daily thereafter. Saliva samples were collected throughout to determine body water 2H enrichments, and muscle samples were collected from rested and exercised muscle to determine daily myofibrillar protein synthesis rates. Deuterated water dosing resulted in body water 2H enrichments of approximately 0·78 (sem 0·03) %. Daily myofibrillar protein synthesis rates were 13 (sem 8) (P = 0·169) and 12 (sem 4) % (P = 0·016) greater in the exercised compared with rested leg (1·59 (sem 0·12) v. 1·77 (sem 0·12) and 1·76 (sem 0·14) v. 1·93 (sem 0·12) %/d) in OMNI and VEG groups, respectively. Daily myofibrillar protein synthesis rates did not differ between OMNI and VEG in either rested or exercised muscle (P > 0·05). Over the course of a 3-d intervention, omnivorous- or vegan-derived dietary protein sources can support equivalent rested and exercised daily myofibrillar protein synthesis rates in healthy older adults consuming a high-protein diet.

We aimed to determine the effect of consuming pure isolated micellar casein or pure whey protein isolate on rates of myofibrillar protein synthesis (MPS) at rest and after resistance exercise in elderly men. Healthy elderly men (72 (sem 1) years; BMI 26·4 (sem 0·7) kg/m2) were divided into two groups (n 7 each) who received a primed, constant infusion of l-[ring-13C6]phenylalanine to measure MPS at rest and during 4 h of exercise recovery. Participants performed unilateral leg resistance exercise followed by the consumption of isonitrogenous quantities (20 g) of casein or whey. Blood essential amino acids and leucine concentration peaked 60 min post-drink and were greater in amplitude after whey protein ingestion (both, P < 0·05). MPS in the rested leg was 65 % higher (P = 0·002) after ingestion of whey (0·040 (sem 0·003) %/h) when compared with micellar casein (0·024 (sem 0·002) %/h). Similarly, resistance exercise-stimulated rates of MPS were greater (P < 0·001) after whey ingestion (0·059 (sem 0·005) %/h) v. micellar casein (0·035 (sem 0·002) %/h). We conclude that ingestion of isolated whey protein supports greater rates of MPS than micellar casein both at rest and after resistance exercise in healthy elderly men. This result is probably related to a greater hyperaminoacidaemia or leucinaemia with whey ingestion.

The currently accepted amount of protein required to achieve maximal stimulation of myofibrillar protein synthesis (MPS) following resistance exercise is 20–25 g. However, the influence of lean body mass (LBM) on the response of MPS to protein ingestion is unclear. Our aim was to assess the influence of LBM, both total and the amount activated during exercise, on the maximal response of MPS to ingestion of 20 or 40 g of whey protein following a bout of whole‐body resistance exercise. Resistance‐trained males were assigned to a group with lower LBM (≤65 kg; LLBM n = 15) or higher LBM (≥70 kg; HLBM n = 15) and participated in two trials in random order. MPS was measured with the infusion of 13C6‐phenylalanine tracer and collection of muscle biopsies following ingestion of either 20 or 40 g protein during recovery from a single bout of whole‐body resistance exercise. A similar response of MPS during exercise recovery was observed between LBM groups following protein ingestion (20 g – LLBM: 0.048 ± 0.018%·h−1; HLBM: 0.051 ± 0.014%·h−1; 40 g – LLBM: 0.059 ± 0.021%·h−1; HLBM: 0.059 ± 0.012%·h−1). Overall (groups combined), MPS was stimulated to a greater extent following ingestion of 40 g (0.059 ± 0.020%·h−1) compared with 20 g (0.049 ± 0.020%·h−1; P = 0.005) of protein. Our data indicate that ingestion of 40 g whey protein following whole‐body resistance exercise stimulates a greater MPS response than 20 g in young resistance‐trained men. However, with the current doses, the total amount of LBM does not seem to influence the response. We aimed to determine the influence of lean body mass on the response of muscle protein synthesis to protein ingestion following resistance exercise. The response of muscle protein synthesis following whole body resistance exercise is greater with ingestion of 40 g versus 20 g of whey protein in young, resistance‐trained men.

There is a shift in thinking about dietary protein requirements from daily requirements to individual meal requirements. Per meal, stimulation of muscle protein synthesis has a saturable dose relationship with the quantity of dietary protein consumed. Protein intake above the saturable dose does not further contribute to the synthetic response; the “excess” amino acids are predominantly oxidized. Given that daily dietary protein intake is finite, finding protein distribution patterns that both reduce amino acid oxidation and maximize their contribution towards protein synthesis (in theory improving net balance) could be “optimal” and is of practical scientific interest to promote beneficial changes in skeletal muscle-related outcomes. This article reviews both observational and randomized controlled trial research on the protein distribution concept. The current evidence on the efficacy of consuming an “optimal” protein distribution to favorably influence skeletal muscle-related changes is limited and inconsistent. The effect of protein distribution cannot be sufficiently disentangled from the effect of protein quantity. Consuming a more balanced protein distribution may be a practical way for adults with marginal or inadequate protein intakes (<0.80 g·kg−1·d−1) to achieve a moderately higher total protein intake. However, for adults already consuming 0.8–1.3 g·kg−1·d−1, the preponderance of evidence supports that consuming at least one meal that contains sufficient protein quantity to maximally stimulate muscle protein synthesis, independent of daily distribution, is helpful to promote skeletal muscle health.

The culture in many team sports involves consumption of large amounts of alcohol after training/competition. The effect of such a practice on recovery processes underlying protein turnover in human skeletal muscle are unknown. We determined the effect of alcohol intake on rates of myofibrillar protein synthesis (MPS) following strenuous exercise with carbohydrate (CHO) or protein ingestion. In a randomized cross-over design, 8 physically active males completed three experimental trials comprising resistance exercise (8×5 reps leg extension, 80% 1 repetition maximum) followed by continuous (30 min, 63% peak power output (PPO)) and high intensity interval (10×30 s, 110% PPO) cycling. Immediately, and 4 h post-exercise, subjects consumed either 500 mL of whey protein (25 g; PRO), alcohol (1.5 g·kg body mass⁻¹), 12±2 standard drinks) co-ingested with protein (ALC-PRO), or an energy-matched quantity of carbohydrate also with alcohol (25 g maltodextrin; ALC-CHO). Subjects also consumed a CHO meal (1.5 g CHO·kg body mass⁻¹) 2 h post-exercise. Muscle biopsies were taken at rest, 2 and 8 h post-exercise. Blood alcohol concentration was elevated above baseline with ALC-CHO and ALC-PRO throughout recovery (P<0.05). Phosphorylation of mTOR(Ser2448) 2 h after exercise was higher with PRO compared to ALC-PRO and ALC-CHO (P<0.05), while p70S6K phosphorylation was higher 2 h post-exercise with ALC-PRO and PRO compared to ALC-CHO (P<0.05). Rates of MPS increased above rest for all conditions (∼29-109%, P<0.05). However, compared to PRO, there was a hierarchical reduction in MPS with ALC-PRO (24%, P<0.05) and with ALC-CHO (37%, P<0.05). We provide novel data demonstrating that alcohol consumption reduces rates of MPS following a bout of concurrent exercise, even when co-ingested with protein. We conclude that alcohol ingestion suppresses the anabolic response in skeletal muscle and may therefore impair recovery and adaptation to training and/or subsequent performance.

Fish oil (FO) supplementation potentiates muscle protein synthesis (MPS) in response to a hyperaminoacidemic–hyperinsulinemic infusion. Whether FO supplementation potentiates MPS in response to protein ingestion or when protein ingestion is combined with resistance exercise (RE) remains unknown. In a randomized, parallel group design, 20 healthy males were randomized to receive 5 g/day of either FO or coconut oil control (CO) for 8 weeks. After supplementation, participants performed a bout of unilateral RE followed by ingestion of 30 g of whey protein. Skeletal muscle biopsies were obtained before and after supplementation for assessment of muscle lipid composition and relevant protein kinase activities. Infusion of l‐[ring‐13C6] phenylalanine was used to measure basal myofibrillar MPS at rest (REST), in a nonexercised leg following protein ingestion (FED) and following RE and protein ingestion (FEDEX). MPS was significantly elevated above REST during FEDEX in both the FO and CO groups, but there was no effect of supplementation. There was a significant increase in MPS in both groups above REST during FED but no effect of supplementation. Supplementation significantly decreased panPKB activity at REST in the FO group but not the CO group. There was a significant increase from REST at post‐RE for PKB and AMPKα2 activity in the CO group but not in the FO group. In FEDEX, there was a significant increase in p70S6K1 activity from REST at 3 h in the CO group only. These data highlight that 8 weeks of FO supplementation alters kinase signaling activity in response to RE plus protein ingestion without influencing MPS. Fish oil supplementation has been shown to potentiate rates of muscle protein synthesis (MPS) in response to a hyperaminocidemic–hyperinsulinemic infusion in both young and older adults. Here, we show that 8 weeks of fish oil supplementation does not significantly alter MPS following the oral ingestion of whey protein or when whey protein ingestion is preceded by a bout of unilateral resistance exercise in young healthy men.

Background Protein intake is essential to maximally stimulate muscle protein synthesis, and the amino acid leucine seems to possess a superior effect on muscle protein synthesis compared to other amino acids. Native whey has higher leucine content and thus a potentially greater anabolic effect on muscle than regular whey (WPC-80). This study compared the acute anabolic effects of ingesting 2 × 20 g of native whey protein, WPC-80 or milk protein after a resistance exercise session. Methods A total of 24 young resistance trained men and women took part in this double blind, randomized, partial crossover, controlled study. Participants received either WPC-80 and native whey ( n  = 10), in a crossover design, or milk ( n  = 12). Supplements were ingested immediately (20 g) and two hours after (20 g) a bout of heavy-load lower body resistance exercise. Blood samples and muscle biopsies were collected to measure plasma concentrations of amino acids by gas-chromatography mass spectrometry, muscle phosphorylation of p70S6K, 4E–BP1 and eEF-2 by immunoblotting, and mixed muscle protein synthesis by use of [ 2 H 5 ]phenylalanine-infusion, gas-chromatography mass spectrometry and isotope-ratio mass spectrometry. Being the main comparison, differences between native whey and WPC-80 were analysed by a one-way ANOVA and comparisons between the whey supplements and milk were analysed by a two-way ANOVA. Results Native whey increased blood leucine concentrations more than WPC-80 and milk ( P  < 0.05). Native whey ingestion induced a greater phosphorylation of p70S6K than milk 180 min after exercise ( P  = 0.03). Muscle protein synthesis rates increased 1–3 h hours after exercise with WPC-80 (0.119%), and 1–5 h after exercise with native whey (0.112%). Muscle protein synthesis rates were higher 1–5 h after exercise with native whey than with milk (0.112% vs. 0.064, P  = 0.023). Conclusions Despite higher-magnitude increases in blood leucine concentrations with native whey, it was not superior to WPC-80 concerning effect on muscle protein synthesis and phosphorylation of p70S6K during a 5-h post-exercise period. Native whey increased phosphorylation of p70S6K and muscle protein synthesis rates to a greater extent than milk during the 5-h post exercise period. Trial registration This study was retrospectively registered at clinicaltrials.gov as NCT02968888 .

Essential (EAA) and branched chain (BCAA) amino acid ingestion support whole-body anabolism after resistance exercise and can attenuate markers of postexercise myofibrillar protein breakdown (i.e. urinary 3-methylhistidine; 3MH). Leucine is often considered a primary anabolic EAA through its ability to activate the mechanistic target of rapamycin complex 1 (mTORC1) and stimulate muscle protein synthesis. The dipeptide leucine (dileucine) has been shown to more effectively stimulate myofibrillar protein synthesis than leucine in young males at rest. Therefore, we aimed to determine the effect of a dileucine-containing essential amino acid formula (DIEAA; 2 g dileucine, 1 g leucine, 9.15 g total EAA) on the anabolic and catabolic responses following resistance exercise in young recreationally active adults when compared with ingesting branched chain amino acids (BCAA; 3 g leucine, 1.5 g isoleucine, 1.5 g valine) or isonitrogenous (to DIEAA) collagen hydrolysate (COL). In a randomized, double-blind, crossover design, 12 healthy adults (8 M, 4F, aged 24 ± 3 y) performed a 60 min bout of whole-body resistance exercise, after which they ingested DIEAA, BCAA, or COL protein beverages containing 100 mg L-[1- C]leucine (#NCT05754125). Total exogenous leucine retention (as an estimate of whole-body anabolism) was assessed over the 6 h postprandial period by determining total leucine oxidation from CO enrichment (isotope ratio mass spectrometry) in repeated breath samples. A urinary 3MH:creatinine ratio (3MH:Cr) over 6 h was used as an estimate of skeletal muscle myofibrillar protein breakdown. To further assess the anabolic potential of nutrients, C2C12 myotubes were treated with a subset (  = 7) of human serum-conditioned media for 4 h to measure downstream mTORC1 substrate phosphorylation, protein synthesis (puromycin and L- -[D ]phenylalanine incorporation) and breakdown (ubiquitinated protein), and myotube hypertrophy. Total exogenous leucine retention were similar (  = 0.68) between DIEAA (215.72 ± 42.45 μmol·kg ) and BCAA conditions (219.15 ± 45.26 μmol·kg ), with both DIEAA and BCAA being greater (  < 0.0001) than COL (37.25 ± 8.16 μmol·kg ). There were no differences (  = 0.58) in 3MH:Cr between supplement conditions. There was no effect of condition on puromycin incorporation into nascent peptides (  = 0.31), total protein ubiquitination as an estimate of protein breakdown (  = 0.59), phosphorylation of downstream mTORC1 substrates -RPS6 (  = 0.39) or -4E-BP1 (  = 0.50), and myotube diameter (  = 0.55). Stable isotope-derived rates of mixed muscle protein synthesis (MPS) demonstrated a trend toward a main effect (  = 0.086) with pairwise comparisons revealing a large effect of DIEAA compared to COL (dz = 1.47), a medium effect of DIEAA compared to BCAA (dz = 0.81), and a trivial effect of BCAA comapred to COL (dz = 0.002). Dileucine-supplemented EAA and BCAA support greater whole-body anabolism compared with COL after resistance exercise independent of attenuation in urinary estimates of myofibrillar protein breakdown. Exploratory experiments reveal a potential anabolic effect of DIEAA in stimulating MPS. Collectively, these findings suggest that consuming dileucine with sufficient EAA and BCAA increases exogenous leucine retention to support whole-body anabolism during postexercise recovery in individuals performing resistance training.

Purpose The aim of this study was to compare activation of cellular signaling pathways regulating protein synthesis and glucose uptake in skeletal muscle between resistance and endurance exercise. Moreover, the effect of resistance exercise volume was examined. Methods Three groups of male volunteers (26 ± 3 years) were examined: 5 × 10 repetition maximum (RM) resistance exercise (RE) with leg press device (5 × 10 RE; n  = 8), 10 × 10 RE ( n  = 11), and endurance exercise (strenuous 50-min walking with extra load on a treadmill; EE; n  = 8). Muscle biopsies were obtained from m.vastus lateralis 30 min pre- and post-exercise. Results Downstream markers of mTORC1, p-p70S6K Thr421/Ser424 and p-rpS6 Ser240/244 , increased more after 10 × 10 RE than after 5 × 10 RE ( p  < 0.05) and EE ( p  < 0.01–0.001). Exercise-induced changes in p-IRS-I Ser636/639 that inhibit IRS-I signaling via negative feedback from hyperactivated mTORC1 signaling were greater ( p  < 0.05) after 10 × 10 RE compared with 5 × 10 RE and EE. The changes in energy sensor p-AMPKα Thr172 were greater after 10 × 10 RE and EE ( p  < 0.05–0.01) than after 5 × 10 RE. A major regulator of glucose uptake in muscle, p-AS160 Thr642 , increased more after 10 × 10 RE than after 5 × 10 RE ( p  < 0.01) and EE ( p  < 0.05). Conclusion 10 × 10 RE induced greater activation of important signaling proteins regulating glucose uptake (p-AS160) and protein synthesis (p-p70S6K, p-rpS6) than 5 × 10 RE and EE. The present findings further suggest that, especially after 10 × 10 RE, IRS-I signaling is downregulated and that AS160 is activated through AMPK signaling pathway.

Greater force produced with eccentric (ECC) compared to concentric (CONC) contractions, may comprise a stronger driver of muscle growth, which may be further augmented by protein supplementation. We investigated the effect of differentiated contraction mode with either whey protein hydrolysate and carbohydrate (WPH + CHO) or isocaloric carbohydrate (CHO) supplementation on regulation of anabolic signalling, muscle protein synthesis (MPS) and muscle hypertrophy. Twenty-four human participants performed unilateral isolated maximal ECC versus CONC contractions during exercise habituation, single-bout exercise and 12 weeks of training combined with WPH + CHO or CHO supplements. In the exercise-habituated state, p-mTOR, p-p70S6K, p-rpS6 increased by approximately 42, 206 and 213 %, respectively, at 1 h post-exercise, with resistance exercise per se; whereas, the phosphorylation was exclusively maintained with ECC at 3 and 5 h post-exercise. This acute anabolic signalling response did not differ between the isocaloric supplement types, neither did protein fractional synthesis rate differ between interventions. Twelve weeks of ECC as well as CONC resistance training augmented hypertrophy with WPH + CHO group compared to the CHO group (7.3 ± 1.0 versus 3.4 ± 0.8 %), independently of exercise contraction type. Training did not produce major changes in basal levels of Akt-mTOR pathway components. In conclusion, maximal ECC contraction mode may constitute a superior driver of acute anabolic signalling that may not be mirrored in the muscle protein synthesis rate. Furthermore, with prolonged high-volume resistance training, contraction mode seems less influential on the magnitude of muscle hypertrophy, whereas protein and carbohydrate supplementation augments muscle hypertrophy as compared to isocaloric carbohydrate supplementation .