Post-exercise Muscle Protein Synthesis Research Articles

Protein dose requirements to maximize skeletal muscle protein synthesis after repeated bouts of resistance exercise in young trained women.

Studies examining the effect of protein (PRO) feeding on post resistance exercise (RE) muscle protein synthesis (MPS) have primarily been performed in men, and little evidence is available regarding the quantity of PRO required to maximally stimulate MPS in trained women following repeated bouts of RE. We therefore quantified acute (4 h and 8 h) and extended (24 h) effects of two bouts of resistance exercise, alongside protein-feeding, in women, and the PRO requirement to maximize MPS. Twenty-four RE trained women (26.6 ± 0.7 years, mean ± SEM) performed two bouts of whole-body RE (3 × 8 repetitions/maneuver at 75% 1-repetition maximum) 4 h apart, with post-exercise ingestion of 15 g, 30 g, or 60 g whey PRO (n = 8/group). Saliva, venous blood, and a vastus lateralis muscle biopsy were taken at 0 h, 4 h, 8 h, and 24 h post-exercise. Plasma leucine and branched chain amino acids were quantified using gas chromatography mass spectrometry (GC-MS) after ingestion of D2 O. Fifteen grams PRO did not alter plasma leucine concentration or myofibrillar synthetic rate (MyoFSR). Thirty and sixty grams PRO increased plasma leucine concentration above baseline (105.5 ± 5.3 μM; 120.2 ± 7.4 μM, respectively) at 4 h (151.5 ± 8.2 μM, p < 0.01; 224.8 ± 16.0 μM, p < 0.001, respectively) and 8 h (176.0 ± 7.3 μM, p < 0.001; 281.7 ± 21.6 μM, p < 0.001, respectively). Ingestion of 30 g PRO increased MyoFSR above baseline (0.068 ± 0.005%/h) from 0 to 4 h (0.140 ± 0.021%/h, p < 0.05), 0 to 8 h (0.121 ± 0.012%/h, p < 0.001), and 0 to 24 h (0.099 ± 0.011%/h, p < 0.01). Ingestion of 60 g PRO increased MyoFSR above baseline (0.063 ± 0.003%/h) from 0 to 4 h (0.109 ± 0.011%/h, p < 0.01), 0 to 8 h (0.093 ± 0.008%/h, p < 0.01), and 0 to 24 h (0.086 ± 0.006%/h, p < 0.01). Post-exercise ingestion of 30 g or 60 g PRO, but not 15 g, acutely increased MyoFSR following two consecutive bouts of RE and extended the anabolic window over 24 h. There was no difference between the 30 g and 60 g responses.

OR06-01-23 Essential Amino Acid-Enriched Whey Protein Rescues Post-Exercise Muscle Protein Synthesis During Energy Deficit

OR06-01-23 Essential Amino Acid-Enriched Whey Protein Rescues Post-Exercise Muscle Protein Synthesis During Energy Deficit

Raw Eggs To Support Postexercise Recovery in Healthy Young Men: Did Rocky Get It Right or Wrong?

Egg protein is ingested during recovery from exercise to facilitate the postexercise increase in muscle protein synthesis rates and, as such, to support the skeletal muscle adaptive response to exercise training. The impact of cooking egg protein on postexercise muscle protein synthesis is unknown. We sought to compare the impact of ingesting unboiled (raw) compared with boiled eggs during postexercise recovery on postprandial myofibrillar protein synthesis rates. In a parallel design, 45 healthy, resistance-trained young men (age: 24 y; 95% CI: 23, 25 y) were randomly assigned to ingest 5 raw eggs (∼30 g protein), 5 boiled eggs (∼30 g protein), or a control breakfast (∼5 g protein) during recovery from a single session of whole-body resistance-type exercise. Primed continuous l-[ring-13C6]-phenylalanine infusions were applied, with frequent blood sampling. Muscle biopsies were collected immediately after cessation of resistance exercise and at 2 and 5 h into the postexercise recovery period. Primary (myofibrillar protein synthesis rates) and secondary (plasma amino acid concentrations) outcomes were analyzed using repeated-measures (time × group) ANOVA. Ingestion of eggs significantly increased plasma essential amino acid (EAA) concentrations, with 20% higher peak concentrations following ingestion of boiled compared with raw eggs (time × group: P < 0.001). Myofibrillar protein synthesis rates were significantly increased during the postexercise period when compared with basal, postabsorptive values in all groups (2-4-fold increase: P < 0.001). Postprandial myofibrillar protein synthesis rates were 20% higher after ingesting raw eggs [0.067%/h; 95% CI: 0.056, 0.077%/h; effect size (Cohen d): 0.63], and 18% higher after ingesting boiled eggs (0.065%/h; 95% CI: 0.058, 0.073%/h; effect size: 0.69) when compared with the control breakfast (0.056%/h; 95% CI: 0.048, 0.063%/h), with no significant differences between groups (time × group: P = 0.077). The ingestion of raw, as opposed to boiled, eggs attenuates the postprandial rise in circulating EAA concentrations. However, postexercise muscle protein synthesis rates do not differ after ingestion of 5 raw compared with 5 boiled eggs in healthy young men. This trial was registered at the Nederlands Trial Register as NL6506 (www.trialregister.nl).

152 Comparison of an Antioxidant Source and Antioxidant Plus BCAA on Athletic Performance and Post Exercise Recovery of Horses

Abstract Antioxidant supplementation has been shown to decrease post exercise oxidative stress but can lead to decreased post-exercise muscle protein synthesis. The objective of this study was to compare the effects of the supplementation with a control feed with low antioxidant content (CONT) to a high antioxidant feed (AO), versus a high antioxidant and branched chain amino acid feed (BCAO) on post-exercise protein synthesis and oxidative stress. Our hypothesis is that supplementing AO with BCAO will reduce oxidative stress without hindering muscle protein synthesis. Eighteen mixed breed conditioned polo horses were assigned to one of the three treatments. All horses consumed CONT for 30 days and were then submitted to a lactate threshold test (LT). One hour after this and all LT, each group was assigned and given their treatments. LT were done at 15 and 30 days of supplementation. Blood was collected before, two and four hours after LT, and analyzed for oxidative stress based on glutathione peroxidase, superoxide dismutase and malondialdehyde concentrations by ELISA. Muscle biopsies were taken before and 4 hours after LT and analyzed for the expression of protein synthesis by RT-PCR. Results were analyzed in a mixed model by ANOVA and compared by LSM. A reduction of oxidative stress was found over time (P &amp;lt; 0.050) with no treatment effect (P &amp;gt;0.50). An upregulation of protein synthesis after exercise was found for muscle primers CD36, CPT1, DK4, MyF5, and Myogenin (P &amp;lt; 0.050). There was a treatment by time effect for MyoD (P = 0.027), where AO was upregulated the most after exercise compared to BCAO and CONT. DK4 had a treatment by time effect trend (P = 0.073), where AO and BCAO were upregulated and CONT was unchanged after exercise. This study demonstrated post exercise muscle synthesis with no advantage of AO plus BCAO compared to AO.

Does Exercise Intensity Influence Dietary Protein Requirements Of Male Endurance Athletes?

Adequate protein intake is important for endurance athletes to replenish exercise-induced amino acid (AA) oxidation and support post-exercise muscle and whole body protein synthesis. High-intensity endurance exercise is associated with increased carbohydrate oxidation during exercise and greater protein turnover (synthesis and breakdown) after exercise relative to lower intensity exercise. Muscle glycogen depletion can increase AA oxidation during exercise and increase daily protein requirements. PURPOSE: To determine the impact of exercise intensity during prolonged endurance exercise on estimates of dietary protein requirements in endurance athletes. METHODS: Eight males (26±3y, 76±16kg; 62±6 ml O2·kg-1· min-1; mean±SD) completed two trials in a randomized order with exercise (20-km run) performed at a low (LOW; 72±1% HRmax, 55±5% VO2peak) or high (HIGH; 88±1%HRmax, 75±7% VO2peak) intensity. After 2 days of exercise and dietary (1.4g·kg-1·d-1 protein) control, participants consumed 0.6g·kg-1 CHO before a 20-km treadmill run with continuous HR monitoring and periodic measurement of gas exchange (indirect calorimetry). During the 8h post-exercise recovery period, participants consumed 8.6g·kg-1·d-1 CHO and hourly meals providing 0.93g ·kg-1·d-1 protein as crystalline AA modeled after egg protein, which was enriched with [13C]phenylalanine as an indicator AA. Breath and urine were collected at isotopic and metabolic steady state to determine phenylalanine excretion (F13CO2), flux (Q; estimate of protein breakdown), and oxidation (OX; reciprocal of protein synthesis). RESULTS: Preliminary analysis (n=6) showed that respiratory exchange ratio during exercise was higher in HIGH vs. LOW (0.92±0.03 vs. 0.88±0.03, p<0.05), which corresponded to a 37% greater CHO oxidation rate in HIGH (3.12±0.76 vs. 1.96±0.52 g·min-1, p<0.01). Exercise duration was shorter in HIGH vs LOW (86±18 vs. 112±23 min, p<0.01). F13CO2 was not different between trials (HIGH: 0.94±0.25 vs. LOW: 0.89±0.14 umol·kg-1·h-1, p>0.05). Urinary analysis is ongoing to determine Q and OX. CONCLUSION: Preliminary findings suggest that prolonged, high-intensity endurance exercise increases CHO oxidation during exercise but has little impact on estimates of protein requirements of male endurance athletes.

Skeletal Muscle Regulatory Markers Responses Following Whole And Egg White Ingestion In Resistance Trained Men

Protein ingestion is recommended to maximize muscular adaptations post resistance training (RT). Eggs are a rich food source commonly consumed post-workout to meet protein requirements. Although removing egg yolk is often promoted for the improvement of body composition (BC), whole-egg (WE) consumption has been shown to cause a greater stimulation of post-exercise muscle protein synthesis than egg-white (EW). However, changes in BC and skeletal muscle regulatory markers to chronic RT coupled with WE or EW consumption have not been evaluated. PURPOSE: To compare the effects of WE vs. EW ingestion after 12 wks of RT on BC and skeletal muscle regulatory markers in RT men. METHODS: Thirty RT men [age (24 ± 2 yrs), were randomized to either a WE (n=15) or EW (n=15) consumption group for 12 wks. The WE group ingested three WE while the EW group ingested six EW immediately post-workout and at the same time on non-training days. RT consisted of 10 exercises/session, 3x wk. Three sets of 3-14 reps (load was progressed) were performed for each exercise. Body weight, fat mass (FM), skeletal muscle mass (SMM) as well as serum follistatin (FOL), myostatin (MYO) and basic fibroblast growth factor (FGF-2) levels were measured at baseline and after 12 wks. RESULTS: Significant main effects of time were observed for body weight, SMM, FOL and FGF-2 which significantly (P < 0.05) increased, and for FM and MYO which significantly (P < 0.05) decreased. However, no significant group × time interactions were noted for any markers. Although non-significant, the WE group had ~1 Kg of extra FM loss than EW group. CONCLUSIONS: There are no differences in the changes achieved in BC and skeletal muscle regulatory factors after 12 wks of RT between WE and EW consumption. Although BC did not differ between groups, the ~1 Kg of extra FM loss seen after WE consumption may be an advantage for fitness enthusiasts with aesthetic goals.

Hot-water Immersion Does Not Increase Post-exercise Muscle Protein Synthesis Rates

Protein ingestion and heating are strategies employed by athletes to improve post-exercise recovery and, as such, to facilitate muscle reconditioning following exercise. However, whether post-exercise heating affects post-prandial protein handling and subsequent muscle protein synthesis rates during recovery from exercise has not been assessed. PURPOSE: To assess the impact of post-exercise heating on post-prandial myofibrillar protein synthesis rates during recovery from a single bout of resistance-type exercise in healthy, young males. METHODS: Twelve healthy, male adults (age: 23±1 y) performed a single bout of resistance-type exercise followed by 20 min water immersion of both legs. One leg was immersed in hot water (46°C: HWI) while the other leg was immersed in thermoneutral water (30°C: CON). After water immersion, a beverage was ingested containing 20 g intrinsically L-[1-13C]-phenylalanine and L-[1-13C]-leucine labelled milk protein with 45 g of carbohydrates. In addition, primed continuous L-[ring-2H5]-phenylalanine and L-[1-13C]-leucine infusions were applied, with frequent collection of blood and muscle samples to assess myofibrillar protein synthesis rates in vivo over a 5 h recovery period. RESULTS: Muscle temperature immediately after water immersion was higher in the HWI compared to the CON leg (37.5±0.1 vs 35.2±0.2 °C; P<0.001). Incorporation of dietary protein-derived L-[1-13C]-phenylalanine into myofibrillar protein did not differ significantly between the HWI and CON leg during the 5 h recovery period (0.025±0.003 vs 0.024±0.002 MPE; P=0.953). Post-exercise myofibrillar protein synthesis rates did not differ between the HWI and the CON leg based upon L-[1-13C]-leucine (0.050±0.005 vs 0.049±0.002%·h-1, respectively; P=0.815) as well as L-[ring-2H5]-phenylalanine (0.048±0.002 vs 0.047±0.003%·h-1, respectively; P=0.877). CONCLUSIONS: Hot-water immersion during recovery from resistance-type exercise does not increase the post-prandial rise in myofibrillar protein synthesis rates. In addition, post-exercise heating does not increase the capacity of the muscle to use dietary protein derived amino acids for de novo muscle protein accretion during subsequent recovery.

Effects of Salmon Ingestion on Post-Exercise Muscle Protein Synthesis: Exploration of Whole Protein Foods Versus Isolated Nutrients

Abstract Objectives Healthy eating patterns consist of eating whole foods as opposed to single nutrients. The maintenance of skeletal muscle mass is of particular interest to overall health. As such, there is a need to underpin the role of eating nutrients within their natural whole-food matrix versus isolated nutrients on the regulation of postprandial muscle protein synthesis rates. This study assessed the effects of eating salmon, a potential food within a healthy Mediterranean style eating pattern, on the stimulation of post-exercise muscle protein synthesis rates versus eating these same nutrients in isolation in healthy young adults. Methods In a crossover design, 10 recreationally active adults (24 ± 4 y; 5 M, 5 F) performed an acute bout of resistance exercise followed by the ingestion of salmon (SAL) (20.5 g protein and 7.5 g fat) or its matched constituents in the form of crystalline amino acids and fish oil (ISO). Blood and muscle biopsies were collected at rest and after exercise at 2 and 5 h during primed continuous infusions of L-[ring-2H5]phenylalanine for the measurement of myofibrillar protein synthesis and plasma amino acid profiles. Data were analyzed by using a 2-factor (time × condition) repeated-measures ANOVA with Tukey's post hoc test. Results Plasma essential amino acid concentrations increased to a similar extent in both SAL and ISO during the postprandial period (P &amp;gt; 0.05). Likewise, postprandial plasma leucine concentrations did not differ between nutrient condition (P &amp;gt; 0.05). The post-exercise myofibrillar protein synthetic responses were similarly stimulated in both nutrition conditions early (0–2 h; 0.079 ± 0.039%/h (SAL) compared to 0.071 ± 0.078%/h (ISO); P = 0.64) and returned to baseline later (2–5 h; 0.046 ± 0.020%/h (SAL) compared to 0.038 ± 0.025%/h (ISO); P = 0.90). Similarly, there were no differences in the stimulation of myofibrillar protein synthesis rates between SAL and ISO during the entire 0–5 h recovery period (0.058 ± 0.024%/h compared to 0.045 ± 0.027%/h, respectively; P = 0.66). Conclusions We show that the ingestion of salmon or its isolated nutrients increases plasma amino acid concentrations and enhances the stimulation of post-exercise muscle protein synthesis rates with no differences in the temporal or cumulative responses in healthy young adults. Funding Sources USDA National Institute of Food and Agriculture Hatch project.

Effects of whey protein hydrolysate ingestion on post-exercise muscle protein synthesis compared with intact whey protein in rats

BackgroundIt is well known that ingestion of protein sources can stimulate muscle protein synthesis (MPS). The intake of whey protein is highly effective especially for accelerating MPS. Whey protein hydrolysate (WPH) can raise postprandial plasma concentration of amino acids, which impact stimulation of MPS more rapidly and highly than intact whey protein. However, it is unclear which is more effective for stimulating MPS, WPH or intact whey protein. The aim of the present study was to compare the effects of the WPH and whey protein on MPS in rats after exercise.MethodsRats were first subjected to a 2 h. swimming protocol. After this, in experiment 1, we evaluated time-dependent changes in the fractional synthetic rate (FSR) of the triceps muscle in Male Sprague-Dawley rats after ingestion of intact whey protein (30, 60, 90 or 120 min after ingestion). Then in experiment 2, at the time point that the results of Experiment 1 revealed postprandial FSR was highest (60 min after ingestion), we measured the FSR after ingestion of the WPH or whey protein at two different doses (0.5 or 2.0 g protein/kg body weight), or with deionized water (control), again after exercise. Plasma components and mammalian target of rapamycin (mTOR) signaling were also measured.ResultsIn experiment 1, postprandial FSR was highest 60 min after whey protein was administered. In experiment 2, the FSR 60 min after ingestion of the WPH was higher than that of whey protein (significant treatment main effect). Moreover, at a lower dose, only the WPH ingestion caused greater MPS and phosphorylated 4E-binding protein 1 (4E-BP1) levels compared with the control group.ConclusionThese results indicate that ingestion of the WPH was associated with greater post-exercise MPS compared with intact whey protein, especially at lower doses.

Protein timing has no effect on lean mass, strength and functional capacity gains induced by resistance exercise in postmenopausal women: A randomized clinical trial

Short-term studies have shown that protein intake immediately post-exercise increases muscle protein synthesis. However, the effect of protein timing (comparing protein intake post-exercise vs. several hours after exercise) on lean mass and strength gains in long-term studies is still not fully elucidated. Thus, the aim of our study was to evaluate the effect of protein timing on lean mass, strength and functional capacity gains induced by resistance exercise in postmenopausal women. Thirty-four postmenopausal women (60.9±6.7 years) participated in this double-blind, parallel-group, randomized clinical trial. All individuals performed the same resistance training protocol in the morning, 3 times a week, at 70% of 1-maximum repetition (1-RM), over 8 weeks. Participants were randomly assigned to protein-carbohydrate group (PC) (n=17), that ingested 30g of whey protein immediately after exercise and 30g of maltodextrin in the afternoon; and to carbohydrate-protein group (CP) (n=17), that ingested 30g of maltodextrin immediately after exercise and 30g of whey protein in the afternoon. Lean mass was assessed using dual-energy X-ray absorptiometry, handgrip strength by a dynamometer, and strength was evaluated by 1-RM of bench press and leg extension. One mile walk test was performed to assess the functional capacity. Both the PC group (37.3 [35.0-39.7] to 38.1 [35.9-40.5] kg) and the CP group (38.2 [36.0-40.5] to 38.8 [36.5-41.3] kg) increased the total lean mass (p<0.001). An increase was also observed in both groups for 1-RM bench press, 1-RM leg extension and handgrip strength (p<0.001). In addition, the time of 1-mile walk test decreased in both groups (p=0.019). No differences were noted for group and time interaction for these variables (p>0.05). Protein timing has no effect on lean mass, strength and functional capacity gains induced by resistance exercise in postmenopausal women. This trial was registered at ClinicalTrials.gov as NCT03372876.

Achieving Optimal Post-Exercise Muscle Protein Remodeling in Physically Active Adults through Whole Food Consumption.

Dietary protein ingestion is critical to maintaining the quality and quantity of skeletal muscle mass throughout adult life. The performance of acute exercise enhances muscle protein remodeling by stimulating protein synthesis rates for several hours after each bout, which can be optimized by consuming protein during the post-exercise recovery period. To date, the majority of the evidence regarding protein intake to optimize post-exercise muscle protein synthesis rates is limited to isolated protein sources. However, it is more common to ingest whole food sources of protein within a normal eating pattern. Emerging evidence demonstrates a promising role for the ingestion of whole foods as an effective nutritional strategy to support muscle protein remodeling and recovery after exercise. This review aims to evaluate the efficacy of the ingestion of nutrient-rich and protein-dense whole foods to support post-exercise muscle protein remodeling and recovery with pertinence towards physically active people.

Consumption of whole eggs promotes greater stimulation of postexercise muscle protein synthesis than consumption of isonitrogenous amounts of egg whites in young men

Background: Protein in the diet is commonly ingested from whole foods that contain various macro- and micronutrients. However, the effect of consuming protein within its natural whole-food matrix on postprandial protein metabolism remains understudied in humans.Objective: We aimed to compare the whole-body and muscle protein metabolic responses after the consumption of whole eggs with egg whites during exercise recovery in young men.Design: In crossover trials, 10 resistance-trained men [aged 21 ± 1 y; 88 ± 3 kg; body fat: 16% ± 1% (means ± SEMs)] received primed continuous l-[ring-2H5]phenylalanine and l-[1-13C]leucine infusions and performed a single bout of resistance exercise. After exercise, participants consumed intrinsically l-[5,5,5-2H3]leucine-labeled whole eggs (18 g protein, 17 g fat) or egg whites (18 g protein, 0 g fat). Repeated blood and muscle biopsy samples were collected to assess whole-body leucine kinetics, intramuscular signaling, and myofibrillar protein synthesis.Results: Plasma appearance rates of protein-derived leucine were more rapid after the consumption of egg whites than after whole eggs (P = 0.01). Total plasma availability of leucine over the 300-min postprandial period was similar (P= 0.75) between the ingestion of whole eggs (68% ± 1%) and egg whites (66% ± 2%), with no difference in whole-body net leucine balance (P = 0.27). Both whole-egg and egg white conditions increased the phosphorylation of mammalian target of rapamycin complex 1, ribosomal protein S6 kinase 1, and eukaryotic translation initiation factor 4E-binding protein 1 during postexercise recovery (all P < 0.05). However, whole-egg ingestion increased the postexercise myofibrillar protein synthetic response to a greater extent than did the ingestion of egg whites (P= 0.04).Conclusions: We show that the ingestion of whole eggs immediately after resistance exercise resulted in greater stimulation of myofibrillar protein synthesis than did the ingestion of egg whites, despite being matched for protein content in young men. Our data indicate that the ingestion of nutrient- and protein-dense foods differentially stimulates muscle anabolism compared with protein-dense foods. This trial was registered at clinicaltrials.gov as NCT03117127.

Muscle Protein Turnover and the Molecular Regulation of Muscle Mass during Hypoxia.

: Effects of environmental hypoxia on fat-free mass are well studied. Negative energy balance, increased nitrogen excretion, and fat-free mass loss are commonly observed in lowlanders sojourning at high altitude. Reductions in fat-free mass can be minimized if energy consumption matches energy expenditure. However, in nonresearch settings, achieving energy balance during high-altitude sojourns is unlikely, and myofibrillar protein mass is usually lost, but the mechanisms accounting for the loss of muscle mass are not clear. At sea level, negative energy balance reduces basal and blunts postprandial muscle protein synthesis, with no relevant change in muscle protein breakdown. Downregulations in muscle protein synthesis and loss of fat-free mass during energy deficit at sea level are largely overcome by consuming at least twice the recommended dietary allowance for protein. Hypoxia may increase or not affect resting muscle protein synthesis, blunt postexercise muscle protein synthesis, and markedly increase proteolysis independent of energy status. Hypoxia-induced mTORC1 dysregulation and an upregulation in calpain- and ubiquitin proteasome-mediated proteolysis may drive catabolism in lowlanders sojourning at high altitude. However, the combined effects of energy deficit, exercise, and dietary protein manipulations on the regulation of muscle protein turnover have never been studied at high altitude. This article reviews the available literature related to the effects of high altitude on fat-free mass, highlighting contemporary studies that assessed the influence of altitude exposure (or hypoxia) on muscle protein turnover and intramuscular regulation of muscle mass. Knowledge gaps are addressed, and studies to identify effective and feasible countermeasures to hypoxia-induced muscle loss are discussed.

Intake of a Ketone Ester Drink during Recovery from Exercise Promotes mTORC1 Signaling but Not Glycogen Resynthesis in Human Muscle.

Purpose: Ketone bodies are energy substrates produced by the liver during prolonged fasting or low-carbohydrate diet. The ingestion of a ketone ester (KE) rapidly increases blood ketone levels independent of nutritional status. KE has recently been shown to improve exercise performance, but whether it can also promote post-exercise muscle protein or glycogen synthesis is unknown.Methods: Eight healthy trained males participated in a randomized double-blind placebo-controlled crossover study. In each session, subjects undertook a bout of intense one-leg glycogen-depleting exercise followed by a 5-h recovery period during which they ingested a protein/carbohydrate mixture. Additionally, subjects ingested a ketone ester (KE) or an isocaloric placebo (PL).Results: KE intake did not affect muscle glycogen resynthesis, but more rapidly lowered post-exercise AMPK phosphorylation and resulted in higher mTORC1 activation, as evidenced by the higher phosphorylation of its main downstream targets S6K1 and 4E-BP1. As enhanced mTORC1 activation following KE suggests higher protein synthesis rates, we used myogenic C2C12 cells to further confirm that ketone bodies increase both leucine-mediated mTORC1 activation and protein synthesis in muscle cells.Conclusion: Our results indicate that adding KE to a standard post-exercise recovery beverage enhances the post-exercise activation of mTORC1 but does not affect muscle glycogen resynthesis in young healthy volunteers. In vitro, we confirmed that ketone bodies potentiate the increase in mTORC1 activation and protein synthesis in leucine-stimulated myotubes. Whether, chronic oral KE intake during recovery from exercise can facilitate training-induced muscular adaptation and remodeling need to be further investigated.

Greater Stimulation of Postexercise Muscle Protein Synthesis after Consumption of Whole Eggs versus Egg Whites in Healthy Young Men

The majority of protein consumed in the diet is obtained from whole food sources that contain a mixture of macro‐ and micronutrients. Whereas the majority of research investigated the effect of isolated protein sources on protein metabolism, our aim was to assess the muscle anabolic potential of consuming a complete protein within its naturally occurring, nutrient dense food matrix during recovery from resistance exercise in young men. In crossover trials, 10 healthy resistance‐trained men (21±1 y; 88±3 kg; bodyfat: 16±1%) received primed continuous L‐[ring‐2H5]phenylalanine and L‐[1‐13C]leucine infusions. Repeated blood and muscle biopsies were collected before and after a single bout of resistance exercise (4 sets of 10 repetitions at 80% of 10‐RM for both leg press and leg extensions). Immediately after resistance exercise, participants ingested intrinsically L‐[5,5,5‐2H3]leucine labeled whole eggs (18 g protein, 17 g fat) or egg whites (18 g protein, 0 g fat) cooked in scrambled form. Exogenous leucine appearance rates increased (P&lt;0.001) after protein ingestion with peak values of 513±57 nmol leucine·kg−1·min−1 occurring at 75 min after egg white ingestion compared with 496±38 nmol leucine·kg−1·min−1 at 120 min after whole egg ingestion. The total amount of protein derived leucine that became available in circulation over the 300 min postprandial period was similar (P=0.53) between whole egg (75±2.3%) and egg white ingestion (77±1.7%). Whole egg ingestion supported greater post‐exercise myofibrillar protein synthesis rates when compared to egg white ingestion (0.034%/h and 0.024%/h respectively; P=0.02). We conclude that whole egg ingestion stimulates the muscle protein synthetic response more effectively than the consumption of isonitrogenous amounts of egg whites during recovery from resistance exercise in healthy young men. This effect is not attributed to divergent postprandial protein‐derived amino acid availability, suggesting that some intrinsic factor within whole eggs and/or the divergent macronutrient profile may have modified the anabolic potential of this complete protein.Support or Funding InformationVision 20/20 Grant, Division of Nutritional Sciences, University of Illinois, Urbana‐Champaign

The impact of postexercise essential amino acid ingestion on the ubiquitin proteasome and autophagosomal-lysosomal systems in skeletal muscle of older men.

Essential amino acid (EAA) ingestion enhances postexercise muscle protein synthesis, and, in particular, the anabolic response of older adults appears sensitive to the quantity of ingested leucine. The effect of leucine ingestion on muscle breakdown following resistance exercise (RE) is less understood. The purpose of this study was to identify the impact of postexercise leucine ingestion on the ubiquitin proteasome and autophagosomal-lysosomal systems following acute RE in older men. Subjects (72 ± 2 yr) performed RE and 1 h postexercise ingested 10 g of EAA containing a leucine quantity similar to quality protein (control, 1.8 g leucine, n = 7) or enriched in leucine (leucine, 3.5 g leucine, n = 8). Stable isotope infusion and muscle biopsies (vastus lateralis) obtained at rest and 2, 5, and 24 h postexercise were used to examine protein content (Western blot), mRNA expression (RT-quantitative PCR), and muscle protein fractional breakdown rate (FBR). Muscle-specific RING finger 1 mRNA increased in both groups at 2 and 5 h (P < 0.05). LC3 mRNA increased, and the LC3BII-to-LC3BI ratio decreased at all postexercise time points in control (P < 0.05). Conversely, LC3 mRNA only increased at 2 h, and the LC3BII-to-LC3BI ratio only decreased at 2 and 5 h in leucine (P < 0.05). Tumor necrosis factor receptor-associated factor-6 mRNA increased (P < 0.05) in control at 5 h. FBR was not statistically different between groups or from basal 24 h postexercise (P > 0.05). These data indicate that ingesting a larger quantity of leucine following RE may further reduce postexercise skeletal muscle autophagy in older men; however, it does not appear to influence the acute postexercise elevation in markers of the ubiquitin proteasome system or the breakdown of intact proteins.NEW & NOTEWORTHY The impact of postexercise leucine ingestion on processes of skeletal muscle breakdown in older adults is not well understood. Additional postexercise leucine ingestion appears to further reduce autophagy, but it does not interfere with the increase in ubiquitin proteasome system markers or the breakdown of intact proteins in skeletal muscle of older men. Postexercise leucine ingestion may promote a healthier protein pool and favorable muscle adaptations in older adults through greater accretion of myofibrillar proteins.

Co-ingestion of carbohydrate with leucine-enriched essential amino acids does not augment acute postexercise muscle protein synthesis in a strenuous exercise-induced hypoinsulinemic state.

Strenuous exercise following overnight fasting increases fat oxidation during exercise, which can modulate training adaptation. However, such exercise induces muscle protein catabolism by decreasing blood insulin concentrations and increasing amino acid oxidation during the exercise. Leucine-enriched essential amino acids (LEAAs) enhance muscle protein synthesis (MPS) at rest and after exercise. However, it remains to be clarified if the co-ingestion of carbohydrate with LEAAs induces an additional increase in MPS, particularly in a hypoinsulinemic state induced by strenuous exercise. Eight-week-old male Sprague–Dawley rats were made to perform strenuous jump exercise (height 35 cm, 200 jumps, 3-s intervals), after which they ingested distilled water and 1 g/kg LEAAs with or without 1 g/kg of glucose. The fractional synthesis rate was determined by measuring the incorporation of l-[ring-2H5]-phenylalanine into skeletal muscle protein. Immediately after the exercise, plasma insulin concentration was significantly lower than that at the basal level. Co-ingestion of glucose with LEAAs alleviated the reduction in plasma insulin concentration, while LEAA ingestion alone did not. LEAA administration with or without glucose led to a higher MPS compared with water administration (P < 0.05). However, the co-ingestion of glucose with LEAAs did not induce further increases in MPS compared with LEAA ingestion alone. Thus, the co-ingestion of glucose with LEAAs does not additionally increase MPS under a strenuous exercise–induced hypoinsulinemic state when glucose is co-ingested with a dose of LEAAs that maximally stimulates MPS.

No effect of anti-inflammatory medication on postprandial and postexercise muscle protein synthesis in elderly men with slightly elevated systemic inflammation

BackgroundBased on circulating C-reactive protein (CRP) levels, some individuals develop slightly increased inflammation as they age. In elderly inflamed rats, the muscle response to protein feeding is impaired, whereas it can be maintained by treatment with non-steroidal anti-inflammatory drugs (NSAIDs). It is unknown whether this applies to elderly humans with increased inflammation. Thus, the muscle response to whey protein bolus ingestion with and without acute resistance exercise was compared between healthy elderly individuals and elderly individuals with slightly increased inflammation±NSAID treatment. MethodsTwenty-four elderly men (>60years) were recruited. Of those, 14 displayed a slightly increased systemic inflammation (CRP>2mg/l) and were randomly assigned to NSAID (Ibuprofen 1800mg/day) or placebo treatment for 1week. The remaining 10 elderly individuals served as healthy controls (CRP<1mg/l). The muscle protein synthetic response was measured as the fractional synthetic rate (FSR) and p70S6K phosphorylation-to-total protein ratio. ResultsThe basal myofibrillar FSR and the myofibrillar FSR responses to whey protein bolus ingestion with and without acute resistance exercise were maintained in inflamed elderly compared to healthy controls (p>0.05) and so was p70S6K phosphorylation. Moreover, NSAID treatment did not significantly improve the myofibrillar and connective tissue FSR responses or reduce the plasma CRP level in inflamed, elderly individuals (p>0.05). ConclusionA slight increase in systemic inflammation does not affect the basal myofibrillar FSR or the myofibrillar FSR responses, which suggests that elderly individuals with slightly increased inflammation can benefit from protein ingestion and resistance exercise to stimulate muscle protein anabolism. Moreover, the NSAID treatment did not significantly affect the myofibrillar or connective tissue FSR responses to protein ingestion and acute resistance exercise.

What is the Optimal Amount of Protein to Support Post-Exercise Skeletal Muscle Reconditioning in the Older Adult?

Hyperaminoacidemia following protein ingestion enhances the anabolic effect of resistance-type exercise by increasing the stimulation of muscle protein synthesis and attenuating the exercise-mediated increase in muscle protein breakdown rates. Although factors such as the source of protein ingested and the timing of intake relative to exercise can impact post-exercise muscle protein synthesis rates, the amount of protein ingested after exercise appears to be the key nutritional factor dictating the magnitude of the muscle protein synthetic response during post-exercise recovery. In younger adults, muscle protein synthesis rates after resistance-type exercise respond in a dose-dependent manner to ingested protein and are maximally stimulated following ingestion of ~20g of protein. In contrast to younger adults, older adults are less sensitive to smaller doses of ingested protein (less than ~20g) after exercise, as evidenced by an attenuated increase in muscle protein synthesis rates during post-exercise recovery. However, older muscle appears to retain the capacity to display a robust stimulation of muscle protein synthesis in response to the ingestion of greater doses of protein (~40g), and such an amount may be required for older adults to achieve a robust stimulation of muscle protein synthesis during post-exercise recovery. The aim of this article is to discuss the current state of evidence regarding the dose-dependent relationship between dietary protein ingestion and changes in skeletal muscle protein synthesis during recovery from resistance-type exercise in older adults. We provide recommendations on the amount of protein that may be required to maximize skeletal muscle reconditioning in response to resistance-type exercise in older adults.

Refining dietary protein recommendations for the athlete

Refining dietary protein recommendations for the athlete