-
1.
Effect of acute and short-term dietary fat ingestion on postprandial skeletal muscle protein synthesis rates in middle-aged, overweight, and obese men.
Tsintzas, K, Jones, R, Pabla, P, Mallinson, J, Barrett, DA, Kim, DH, Cooper, S, Davies, A, Taylor, T, Chee, C, et al
American journal of physiology. Endocrinology and metabolism. 2020;(3):E417-E429
Abstract
Muscle anabolic resistance to dietary protein is associated with obesity and insulin resistance. However, the contribution of excess consumption of fat to anabolic resistance is not well studied. The aim of these studies was to test the hypothesis that acute and short-term dietary fat overload will impair the skeletal muscle protein synthetic response to dietary protein ingestion. Eight overweight/obese men [46.4 ± 1.4 yr, body mass index (BMI) 32.3 ± 5.4 kg/m2] participated in the acute feeding study, which consisted of two randomized crossover trials. On each occasion, subjects ingested an oral meal (with and without fat emulsion), 4 h before the coingestion of milk protein, intrinsically labeled with [1-13C]phenylalanine, and dextrose. Nine overweight/obese men (44.0 ± 1.7 yr, BMI 30.1 ± 1.1 kg/m2) participated in the chronic study, which consisted of a baseline, 1-wk isocaloric diet, followed by a 2-wk high-fat diet (+25% energy excess). Acutely, incorporation of dietary amino acids into the skeletal muscle was twofold higher (P < 0.05) in the lipid trial compared with control. There was no effect of prior lipid ingestion on indices of insulin sensitivity (muscle glucose uptake, pyruvate dehydrogenase complex activity, and Akt phosphorylation) in response to the protein/dextrose drink. Fat overfeeding had no effect on muscle protein synthesis or glucose disposal in response to whey protein ingestion, despite increased muscle diacylglycerol C16:0 (P = 0.06) and ceramide C16:0 (P < 0.01) levels. Neither acute nor short-term dietary fat overload has a detrimental effect on the skeletal muscle protein synthetic response to dietary protein ingestion in overweight/obese men, suggesting that dietary-induced accumulation of intramuscular lipids per se is not associated with anabolic resistance.
-
2.
Effects of protein intake prior to carbohydrate-restricted endurance exercise: a randomized crossover trial.
Larsen, MS, Holm, L, Svart, MV, Hjelholt, AJ, Bengtsen, MB, Dollerup, OL, Dalgaard, LB, Vendelbo, MH, van Hall, G, Møller, N, et al
Journal of the International Society of Sports Nutrition. 2020;(1):7
Abstract
BACKGROUND Deliberately training with reduced carbohydrate availability, a paradigm coined training low, has shown to promote adaptations associated with improved aerobic capacity. In this context researchers have proposed that protein may be ingested prior to training as a means to enhance the protein balance during exercise without spoiling the effect of the low carbohydrate availability. Accordingly, this is being practiced by world class athletes. However, the effect of protein intake on muscle protein metabolism during training low has not been studied. This study aimed to examine if protein intake prior to exercise with reduced carbohydrate stores benefits muscle protein metabolism in exercising and non-exercising muscles. METHODS Nine well-trained subjects completed two trials in random order both of which included a high-intensity interval ergometer bike ride (day 1), a morning (day 2) steady state ride (90 min at 65% VO2peak, 90ss), and a 4-h recovery period. An experimental beverage was consumed before 90ss and contained either 0.5 g whey protein hydrolysate [WPH]/ kg lean body mass or flavored water [PLA]. A stable isotope infusion (L-[ring-13C6]-phenylalanine) combined with arterial-venous blood sampling, and plasma flow rate measurements were used to determine forearm protein turnover. Myofibrillar protein synthesis was determined from stable isotope incorporation into the vastus lateralis. RESULTS Forearm protein net balance was not different from zero during 90ss exercise (nmol/100 ml/min, PLA: 0.5 ± 2.6; WPH: 1.8, ± 3.3) but negative during the 4 h recovery (nmol/100 ml/min, PLA: - 9.7 ± 4.6; WPH: - 8.7 ± 6.5); no interaction (P = 0.5) or main effect of beverage (P = 0.11) was observed. Vastus lateralis myofibrillar protein synthesis rates were increased during 90ss exercise (+ 0.02 ± 0.02%/h) and recovery (+ 0.02 ± 0.02%/h); no interaction (P = 0.3) or main effect of beverage (P = 0.3) was observed. CONCLUSION We conclude that protein ingestion prior to endurance exercise in the energy- and carbohydrate-restricted state does not increase myofibrillar protein synthesis or improve net protein balance in the exercising and non-exercising muscles, respectively, during and in the hours after exercise compared to ingestion of a non-caloric control. TRIAL REGISTRATION clinicaltrials.gov, NCT01320449. Registered 10 May 2017 - Retrospectively registered, https://clinicaltrials.gov/ct2/show/NCT03147001.
-
3.
Muscle Protein Synthesis and Whole-Body Protein Turnover Responses to Ingesting Essential Amino Acids, Intact Protein, and Protein-Containing Mixed Meals with Considerations for Energy Deficit.
Gwin, JA, Church, DD, Wolfe, RR, Ferrando, AA, Pasiakos, SM
Nutrients. 2020;(8)
Abstract
Protein intake recommendations to optimally stimulate muscle protein synthesis (MPS) are derived from dose-response studies examining the stimulatory effects of isolated intact proteins (e.g., whey, egg) on MPS in healthy individuals during energy balance. Those recommendations may not be adequate during periods of physiological stress, specifically the catabolic stress induced by energy deficit. Providing supplemental intact protein (20-25 g whey protein, 0.25-0.3 g protein/kg per meal) during strenuous military operations that elicit severe energy deficit does not stimulate MPS-associated anabolic signaling or attenuate lean mass loss. This occurs likely because a greater proportion of the dietary amino acids consumed are targeted for energy-yielding pathways, whole-body protein synthesis, and other whole-body essential amino acid (EAA)-requiring processes than the proportion targeted for MPS. Protein feeding formats that provide sufficient energy to offset whole-body energy and protein-requiring demands during energy deficit and leverage EAA content, digestion, and absorption kinetics may optimize MPS under these conditions. Understanding the effects of protein feeding format-driven alterations in EAA availability and subsequent changes in MPS and whole-body protein turnover is required to design feeding strategies that mitigate the catabolic effects of energy deficit. In this manuscript, we review the effects, advantages, disadvantages, and knowledge gaps pertaining to supplemental free-form EAA, intact protein, and protein-containing mixed meal ingestion on MPS. We discuss the fundamental role of whole-body protein balance and highlight the importance of comprehensively assessing whole-body and muscle protein kinetics when evaluating the anabolic potential of varying protein feeding formats during energy deficit.
-
4.
Lactalbumin, Not Collagen, Augments Muscle Protein Synthesis with Aerobic Exercise.
Oikawa, SY, Macinnis, MJ, Tripp, TR, McGlory, C, Baker, SK, Phillips, SM
Medicine and science in sports and exercise. 2020;(6):1394-1403
Abstract
INTRODUCTION Protein ingestion and the ensuing hyperaminoacidemia stimulates skeletal muscle protein synthesis in the postexercise period. This response facilitates muscle remodeling, which is important during intensified training. The aim of this study was to determine whether supplementation with α-lactalbumin (LA), with high leucine and tryptophan contents, would improve responses to short periods of intensified aerobic training compared with supplementation with an isonitrogenous quantity of collagen peptides (CP). METHODS Endurance-trained participants (5 male, 6 female, 24 ± 4 yr, V˙O2 = 53.2 ± 9.1 mL·kg·min, peak power output = 320 ± 48 W; means ± SD) consumed a controlled diet (1.0 g·kg·d protein) and refrained from habitual training for 11 d while taking part in this double-blind randomized, crossover trial. The two intervention phases, which consisted of brief intensified training (4 × 4-min cycling intervals at 70% of peak power output on 3 consecutive days) combined with the ingestion of LA or CP supplements after exercise (20 g) and before sleep (40 g), were separated by 4 d of washout without protein supplementation (i.e., the control phase). In response to each phase, myofibrillar (MyoPS), sarcoplasmic protein synthesis (SarcPS) rates (via H2O ingestion) and parameters of sleep quality were measured. RESULTS LA ingestion increased plasma leucine (P < 0.001) and tryptophan concentrations (P < 0.001) relative to CP. Intensified training increased MyoPS and SarcPS above the washout phase in LA- and CP-supplemented phases (P < 0.01), with increases being 13% ± 5% and 5% ± 7% greater with LA than CP for MyoPS (P < 0.01) and SarcPS, respectively (P < 0.01). CONCLUSIONS Despite an isonitrogenous diet, protein synthesis was enhanced to a greater extent when trained participants consumed LA compared with CP during intensified aerobic training, suggesting that protein quality is an important consideration for endurance-trained athletes aiming to augment adaption to exercise training.
-
5.
Intramuscular Mechanisms Mediating Adaptation to Low-Carbohydrate, High-Fat Diets during Exercise Training.
Howard, EE, Margolis, LM
Nutrients. 2020;(9)
Abstract
Interest in low-carbohydrate, high-fat (LCHF) diets has increased over recent decades given the theorized benefit of associated intramuscular adaptations and shifts in fuel utilization on endurance exercise performance. Consuming a LCHF diet during exercise training increases the availability of fat (i.e., intramuscular triglyceride stores; plasma free fatty acids) and decreases muscle glycogen stores. These changes in substrate availability increase reliance on fat oxidation for energy production while simultaneously decreasing reliance on carbohydrate oxidation for fuel during submaximal exercise. LCHF diet-mediated changes in substrate oxidation remain even after endogenous or exogenous carbohydrate availability is increased, suggesting that the adaptive response driving changes in fat and carbohydrate oxidation lies within the muscle and persists even when the macronutrient content of the diet is altered. This narrative review explores the intramuscular adaptations underlying increases in fat oxidation and decreases in carbohydrate oxidation with LCHF feeding. The possible effects of LCHF diets on protein metabolism and post-exercise muscle remodeling are also considered.
-
6.
Leucine-Enriched Essential Amino Acids Improve Recovery from Post-Exercise Muscle Damage Independent of Increases in Integrated Myofibrillar Protein Synthesis in Young Men.
Waskiw-Ford, M, Hannaian, S, Duncan, J, Kato, H, Abou Sawan, S, Locke, M, Kumbhare, D, Moore, D
Nutrients. 2020;(4)
Abstract
BACKGROUND Leucine-enriched essential amino acids (LEAAs) acutely enhance post-exercise myofibrillar protein synthesis (MyoPS), which has been suggested to be important for muscle repair and recovery. However, the ability of LEAAs to concurrently enhance MyoPS and muscle damage recovery in free-living humans has not been studied. METHODS In a randomized, double-blind, placebo-controlled, parallel-group design, twenty recreationally active males consuming a controlled diet (1.2 g/kg/d of protein) were supplemented thrice daily with 4 g of LEAAs (containing 1.6 g leucine) or isocaloric placebo for four days following an acute bout of lower-body resistance exercise (RE). MyoPS at rest and integrated over 96 h of recovery was measured by D2O. Isometric and isokinetic torque, muscle soreness, Z-band streaming, muscle heat shock protein (HSP) 25 and 72, plasma creatine kinase (CK), and plasma interleukin-6 (IL-6) were measured over 96 h post-RE to assess various direct and indirect markers of muscle damage. RESULTS Integrated MyoPS increased ~72% over 96 h after RE (p < 0.05), with no differences between groups (p = 0.98). Isometric, isokinetic, and total peak torque decreased ~21% by 48 h after RE (p < 0.05), whereas total peak torque was ~10% greater overall during recovery in LEAAs compared to placebo (p < 0.05). There were moderate to large effects for peak torque in favour of LEAAs. Muscle soreness increased during recovery with no statistical differences between groups but small to moderate effects in favour of LEAAs that correlated with changes in peak torque. Plasma CK, plasma IL-6, and muscle HSP25 increased after RE (p < 0.05) but were not significantly different between groups (p ≥ 0.13). Consistent with a trend toward attenuated Z-band streaming in LEAAs (p = 0.07), muscle HSP72 expression was lower (p < 0.05) during recovery in LEAAs compared with placebo. There were no correlations between MyoPS and any measures of muscle damage (p ≥ 0.37). CONCLUSION Collectively, our data suggest that LEAAs moderately attenuated muscle damage without concomitant increases in integrated MyoPS in the days following an acute bout of resistance exercise in free-living recreationally active men.
-
7.
Casein Ingestion Does Not Increase Muscle Connective Tissue Protein Synthesis Rates.
Trommelen, J, Holwerda, AM, Senden, JM, Goessens, JPB, VAN Kranenburg, J, Gijsen, AP, Verdijk, LB, VAN Loon, LJC
Medicine and science in sports and exercise. 2020;(9):1983-1991
-
-
Free full text
-
Abstract
PURPOSE This study aimed to assess the effect of dietary protein ingestion on intramuscular connective tissue protein synthesis rates during overnight recovery from a single bout of resistance exercise. METHODS Thirty-six healthy, young males were randomly assigned to one of three treatments. One group ingested 30 g intrinsically L-[1-C]-phenylalanine-labeled casein protein before sleep (PRO, n = 12). The other two groups performed a bout of resistance exercise in the evening and ingested either placebo (EX, n = 12) or 30 g intrinsically L-[1-C]-phenylalanine-labeled casein protein before sleep (EX + PRO, n = 12). Continuous intravenous infusions of L-[ring-H5]-phenylalanine and L-[1-C]-leucine were applied, and blood and muscle tissue samples were collected to assess connective tissue protein synthesis rates and dietary protein-derived amino acid incorporation in the connective tissue protein fraction. RESULTS Resistance exercise resulted in higher connective tissue protein synthesis rates when compared with rest (0.086 ± 0.017%·h [EX] and 0.080 ± 0.019%·h [EX + PRO] vs 0.059 ± 0.016%·h [PRO]; P < 0.05). Postexercise casein protein ingestion did not result in higher connective tissue protein synthesis rates when compared with postexercise placebo ingestion (P = 1.00). Dietary protein-derived amino acids were incorporated into the connective tissue protein fraction at rest, and to a greater extent during recovery from exercise (P = 0.002). CONCLUSION Resistance exercise increases intramuscular connective tissue protein synthesis rates during overnight sleep, with no further effect of postexercise protein ingestion. However, dietary protein-derived amino acids are being used as precursors to support de novo connective tissue protein synthesis.
-
8.
Muscle protein turnover and low-protein diets in patients with chronic kidney disease.
Garibotto, G, Picciotto, D, Saio, M, Esposito, P, Verzola, D
Nephrology, dialysis, transplantation : official publication of the European Dialysis and Transplant Association - European Renal Association. 2020;(5):741-751
Abstract
Adaptation to a low-protein diet (LPD) involves a reduction in the rate of amino acid (AA) flux and oxidation, leading to more efficient use of dietary AA and reduced ureagenesis. Of note, the concept of 'adaptation' to low-protein intakes has been separated from the concept of 'accommodation', the latter term implying a decrease in protein synthesis, with development of wasting, when dietary protein intake becomes inadequate, i.e. beyond the limits of the adaptive mechanisms. Acidosis, insulin resistance and inflammation are recognized mechanisms that can increase protein degradation and can impair the ability to activate an adaptive response when an LPD is prescribed in a chronic kidney disease (CKD) patient. Current evidence shows that, in the short term, clinically stable patients with CKD Stages 3-5 can efficiently adapt their muscle protein turnover to an LPD containing 0.55-0.6 g protein/kg or a supplemented very-low-protein diet (VLPD) by decreasing muscle protein degradation and increasing the efficiency of muscle protein turnover. Recent long-term randomized clinical trials on supplemented VLPDs in patients with CKD have shown a very good safety profile, suggesting that observations shown by short-term studies on muscle protein turnover can be extrapolated to the long-term period.
-
9.
Resistance Exercise-induced Regulation of Muscle Protein Synthesis to Intraset Rest.
Salvador, AF, Askow, AT, McKenna, CF, Fang, HY, Burke, SK, Li, Z, Ulanov, AV, Paluska, SA, Petruzzello, SJ, Boppart, MD, et al
Medicine and science in sports and exercise. 2020;(5):1022-1030
Abstract
UNLABELLED During a traditional set configuration of resistance exercise (TRD), characterized by a continuous completion of repetitions, a decrease in power output tends to occur throughout a set of repetitions. Inclusion of intraset rest, otherwise known as a cluster set configuration (CLU), counteracts this power decline. However, the effect of a CLU configuration on postexercise myofibrillar protein synthesis rates (MPS) and anabolic signaling has not been investigated. PURPOSE We aimed to determine if any mechanistic differences exist between TRD and CLU signaling events associated with muscle anabolism. METHODS In randomized crossover trials, eight resistance-trained participants (23 ± 1 yr, 81 ± 4.7 kg, body fat: 18% ± 1.9%; 1 repetition maximum [1RM], 150 ± 9.1 kg) performed an acute bout of CLU (4 sets × (2 × 5) repetitions, 30-s intraset rest, 90-s interset rest) and TRD (4 sets × 10 repetitions, 120-s interset rest) barbell back squats at approximately 70% 1RM with total volume load equated during primed continuous L-[ring-C6]phenylalanine infusions. Blood and muscle biopsy samples were collected at rest and after exercise at 0, 2, and 5 h. RESULTS There was no difference in postexercise MPS between the CLU and TRD condition (P > 0.05) and no changes in phosphorylation of mTORC1 downstream targets (p70S6K and 4EBP1). Total and phosphorylated yes-associated protein on Ser127 transiently increased (P < 0.01) immediately after exercise (t = 0) in CLU (~2.1-fold) and TRD condition (~2.2-fold). CONCLUSIONS Our results show that CLU is a viable anabolic option by preserving power output with similar MPS stimulation when compared with the TRD condition in trained young adults.
-
10.
Protein Distribution and Muscle-Related Outcomes: Does the Evidence Support the Concept?
Hudson, JL, Iii, REB, Campbell, WW
Nutrients. 2020;(5)
Abstract
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.