Protein supplementation augments the adaptive response of skeletal muscle to resistance-type exercise training: A meta-analysis

Departments of Human Movement Sciences and Human Biology, NUTRIM School for Nutrition, Toxicology and Metabolism, Maastricht University Medical Centre+, Maastricht, Netherlands, and the Division of Human Nutrition, Wageningen University, Wageningen, Netherlands.
American Journal of Clinical Nutrition (Impact Factor: 6.77). 11/2012; 96(6). DOI: 10.3945/ajcn.112.037556
Source: PubMed


BACKGROUND: Protein ingestion after a single bout of resistance-type exercise stimulates net muscle protein accretion during acute postexercise recovery. Consequently, it is generally accepted that protein supplementation is required to maximize the adaptive response of the skeletal muscle to prolonged resistance-type exercise training. However, there is much discrepancy in the literature regarding the proposed benefits of protein supplementation during prolonged resistance-type exercise training in younger and older populations. OBJECTIVE: The objective of the study was to define the efficacy of protein supplementation to augment the adaptive response of the skeletal muscle to prolonged resistance-type exercise training in younger and older populations. DESIGN: A systematic review of interventional evidence was performed through the use of a random-effects meta-analysis model. Data from the outcome variables fat-free mass (FFM), fat mass, type I and II muscle fiber cross-sectional area, and 1 repetition maximum (1-RM) leg press strength were collected from randomized controlled trials (RCTs) investigating the effect of dietary protein supplementation during prolonged (>6 wk) resistance-type exercise training. RESULTS: Data were included from 22 RCTs that included 680 subjects. Protein supplementation showed a positive effect for FFM (weighted mean difference: 0.69 kg; 95% CI: 0.47, 0.91 kg; P < 0.00001) and 1-RM leg press strength (weighted mean difference: 13.5 kg; 95% CI: 6.4, 20.7 kg; P < 0.005) compared with a placebo after prolonged resistance-type exercise training in younger and older subjects. CONCLUSION: Protein supplementation increases muscle mass and strength gains during prolonged resistance-type exercise training in both younger and older subjects.

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    • "dvantage to the supplemented group regardless of when the protein was consumed . This may be the case and we acknowledge that 1 . 3 g / kg / d does not fall within even our recommendations for a protein intake that appears to be optimal for hypertrophy ( Phillips , 2014a ) . Nonetheless , it is interesting to note that in a meta - analysis done by Cermak et al . ( 2012 ) only 3 of the 16 studies she analyzed showed statistically significant gains in lean mass with protein supplementation in young persons . While there were a further 4 – 5 studies that approached statistical significance , the fact that only 3 ( 19% ) of the studies [ one of which was in women in a hypoenergetic state ( Josse et al . ,"
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    ABSTRACT: Skeletal muscle mass is regulated by a balance between muscle protein synthesis (MPS) and muscle protein breakdown (MPB). In healthy humans, MPS is more sensitive (varying 4-5 times more than MPB) to changes in protein feeding and loading rendering it the primary locus determining gains in muscle mass. Performing resistance exercise (RE) followed by the consumption of protein results in an augmentation of MPS and, over time, can lead to muscle hypertrophy. The magnitude of the RE-induced increase in MPS is dictated by a variety of factors including: the dose of protein, source of protein, and possibly the distribution and timing of post-exercise protein ingestion. In addition, RE variables such as frequency of sessions, time under tension, volume, and training status play roles in regulating MPS. This review provides a brief overview of our current understanding of how RE and protein ingestion can influence gains in skeletal muscle mass in young, healthy individuals. It is the goal of this review to provide nutritional recommendations for optimal skeletal muscle adaptation. Specifically, we will focus on how the manipulation of protein intake during the recovery period following RE augments the adaptive response.
    Frontiers in Physiology 09/2015; 6:245. DOI:10.3389/fphys.2015.00245 · 3.53 Impact Factor
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    • "Early deep breathing exercises after CABG surgery contribute to a better preservation of pulmonary function [33]. Nutritional support, such as protein supplementation, in combination with resistance-type exercises significantly augments type 1 and type 2 muscle fibre cross-sectional area (CSA), at least in peripheral muscles [34]. The impact of such intervention on respiratory muscles and respiratory function should be studied as well. "
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    ABSTRACT: Unlabelled: Pulmonary function is significantly reduced in the acute phase after coronary artery bypass graft (CABG) surgery. Because pulmonary function partly depends on respiratory muscle strength, we studied whether reductions in pulmonary function are related to postoperative alterations in circulatory factors that affect muscle protein synthesis. Methods: Slow vital capacity (SVC) was assessed in 22 subjects before and 9 ± 3 days after CABG surgery. Blood testosterone, cortisol, insulin-like growth factor-1 (IGF-1), growth hormone, sex-hormone binding globulin (SHBG), glucose, insulin, c-peptide, c-reactive protein (CRP) content, and free androgen index, cortisol/testosterone ratio, HOMA-IR index were assessed before surgery and during the first three days after surgery. Intubation, surgery time and cumulative chest tube drainage were measured. Correlations between changes in SVC and blood parameters after surgery or subject characteristics were studied. This was a prospective observational study. Results: After CABG surgery SVC decreased by 37 ± 18% (P < 0.01). Free androgen index, blood SHBG, testosterone and IGF-1 content decreased, while HOMA-IR index, cortisol/testosterone ratio, blood growth hormone, insulin and CRP content increased (P < 0.0025) in the first three days after surgery. Decrease in SVC was independently (P < 0.05) related to higher preoperative SVC (SC β = 0.66), and greater increase in blood cortisol (SC β = 0.54) and CRP (SC β = 0.37) content after surgery. Conclusions: Larger reductions in pulmonary function after CABG surgery are present in patients experiencing greater postoperative increases in blood CRP and cortisol levels. Decrements in pulmonary function after CABG surgery are, at least in part, thus related to alterations in circulatory factors that affect muscle protein synthesis.
    International Journal of Clinical and Experimental Medicine 09/2015; 8(7-7):10938-46. · 1.28 Impact Factor
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    • "Participants were instructed to maintain their normal eating habits and to consume no supplements (other than the whey protein given in the study) throughout the study. As ingestion of protein enhances the anabolic effect of resistance exercise, stimulating MPS (Witard et al. 2014) and increasing muscle mass (Cermak et al. 2012), and ~20 g of whey protein has been reported to be effective in maximizing MPS response after resistance exercise (Witard et al. 2014), each subject ingested 25 g of isolated whey protein immediately after each RT bout to maximally stimulate the rate of MPS. Participants were instructed to refrain from other physical activities 72 h before T1 and throughout the entire experimental protocol. "
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    ABSTRACT: It has been proposed that skeletal muscle shows signs of resistance training (RT)-induced muscle hypertrophy much earlier (i.e., ~3-4 weeks of RT) than previously thought. We determined if early increases in whole muscle cross-sectional area (CSA) during a period of RT were concomitant with edematous muscle swelling and thus not completely attributable to hypertrophy. We analyzed vastus lateralis muscle ultrasound CSA images and their respective echo intensities (CSA-USecho) at the beginning (T1), in the 3rd week of RT (T2) and at the end (T3) of a 10-week RT period in ten untrained young men. Functional parameters [training volume (TV = load × reps × sets) and maximal voluntary contraction (MVC)] and muscle damage markers (myoglobin and interleukin-6) were also assessed. Muscle CSA increased significantly at T2 (~2.7 %) and T3 (~10.4 %) versus T1. Similarly, CSA-USecho increased at T2 (~17.2 %) and T3 (~13.7 %). However, when CSA-USecho was normalized to the increase in muscle CSA, only T2 showed a significantly higher USecho versus T1. Additionally, TV increased at T2 and T3 versus T1, but MVC increased only at T3. Myoglobin and Interleukin-6 were elevated at T2 versus T1, and myoglobin was also higher at T2 versus T3. We propose that early RT-induced increases in muscle CSA in untrained young individuals are not purely hypertrophy, since there is concomitant edema-induced muscle swelling, probably due to muscle damage, which may account for a large proportion of the increase. Therefore, muscle CSA increases (particularly early in an RT program) should not be labeled as hypertrophy without some concomitant measure of muscle edema/damage.
    Arbeitsphysiologie 08/2015; DOI:10.1007/s00421-015-3243-4 · 2.19 Impact Factor
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Lisette C P G M de Groot