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
    • "Therefore, augmentation , or at the very least, maintenance of skeletal muscle mass across the lifespan is critical to offset the progression of disability and disease, thereby closing the ever-expanding gap between healthy life expectancy and average life expectancy in developed nations (Murray et al. 2013). To date, the most effective means of increasing skeletal muscle mass, strength, or offsetting sarcopenia and dynapenia in ageing and disease, remains resistancetype exercise combined with consumption of adequate proteinbased nutrition (Cermak et al. 2012; Constantin et al. 2013; Tieland et al. 2012). The robust stimulation of MPS in healthy young individuals in response to these combined anabolic stimuli is well defined, and results in muscle hypertrophy (Mitchell et al. 2012; Tipton et al. 1999). "
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    ABSTRACT: Skeletal muscle mass plays a vital role in locomotion, whole-body metabolic health, and is a positive predictor of longevity. It is well established the mammalian target of rapamycin (mTOR) is a central regulator of skeletal muscle protein turnover. The pursuit to find novel nutrient compounds or functional food sources that possess the ability to activate mTOR and promote skeletal muscle protein accretion has been on going. Over the last decade, a key role has been proposed for the phospholipid phosphatidic acid (PA) in mTOR activation. Mechanical load-induced (i.e., resistance exercise) intramuscular PA can directly bind to and activate mTOR. In addition, PA provided exogenously in cell culture heightens mTOR activity, albeit indirectly. Thus, endogenously generated PA and exogenous provision of PA appear to act through distinct mechanisms that converge on mTOR and, potentially, may amplify muscle protein synthesis. In support of this notion, limited evidence from humans suggests that resistance exercise training combined with oral supplemental PA enhances strength gains and muscle hypertrophy. However, the precise mechanisms underpinning the augmented muscle remodelling response with supplemental PA remain elusive. In this review, we will critically examine available evidence from cell cultures and animal and human experimental models to provide an overview of the mechanisms through which endogenous and exogenous PA may act to promote muscle anabolism, and discuss the potential for PA as a therapeutic tool to maintain or restore skeletal muscle mass in the context of ageing and disease.
    Applied Physiology Nutrition and Metabolism 09/2015; 40(12). DOI:10.1139/apnm-2015-0350 · 2.34 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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