Protein Supplementation Does Not Affect Myogenic Adaptations to Resistance Training

Abstract

It has been proposed that protein supplementation during resistance exercise training enhances muscle hypertrophy. The degree of hypertrophy during training is controlled in part through activation of satellite cells and myonuclear accretion. Purpose To determine the efficacy of protein supplementation (and the type of protein) during traditional resistance training on myofiber cross-sectional-area, satellite cell content and myonuclear addition. Methods Healthy young men participated in supervised whole body progressive resistance training 3d/wk for 12 weeks. Participants were randomized to one of three groups ingesting a daily 22g macronutrient dose of soy-dairy protein blend (PB, N=22), whey protein isolate (WP, N=15) or an isocaloric maltodextrin placebo (MDP, N=17). Lean mass, vastus lateralis myofiber-type-specific cross-sectional-area, satellite cell content and myonuclear addition were assessed pre and post resistance training. Results PB and the pooled protein treatments (PB+WP=PRO) exhibited a greater whole body lean mass %change compared to MDP (p=0.057 for PB) and (P=0.050 for PRO), respectively. All treatments demonstrated similar leg muscle hypertrophy and vastus lateralis myofiber-type-specific cross-sectional-area (P<0.05). Increases in myosin heavy chain I and II myofiber satellite cell content and myonuclei content were also detected following exercise training (P<0.05). Conclusion Protein supplementation during resistance training has a modest effect on whole body lean mass as compared to exercise training without protein supplementation and there was no effect on any outcome between protein supplement types (Blend vs Whey). However, protein supplementation did not enhance resistance exercise-induced increases in myofiber hypertrophy, satellite cell content or myonuclear addition in young healthy men. We propose that as long as protein intake is adequate during muscle overload the adaptations in muscle growth and function will not be influenced by protein supplementation.

Effect of 8-week leucine supplementation and resistance exercise training on muscle hypertrophy and satellite cell activation in rats

“…This finding suggests that the long-term administration of leucine in the absence of resistance exercise training may not induce skeletal muscle hypertrophy. Previous studies claiming that leucine can induce hypertrophy by increasing the phosphorylation of proteins in protein synthesis signaling pathways, including the S6K1 and 4EBP1 signaling pathways, have mostly investigated the acute effects of leucine (Norton and Layman 2006;Dreyer et al 2008;Reidy et al 2017). In addition, Koopman et al (2008), and Pereira et al (2014) reported that leucine supplementation is effective during the early stages of protein synthesis, and induces skeletal muscle repair or regeneration, rather than hypertrophy.…”

“…; Reidy et al. ). Accordingly, the rats were anesthetized using inhalation anesthetics (isoflurane), and the extensor digitorum longus (EDL) muscle, about 98% of which contains type II fibers, was removed (Armstrong and Phelps ).…”

“…Once the 8-week-long leucine ingestion and climbing exercises were over, the rats were sacrificed after they had fasted for approximately 12 h, 48 h after the last exercise, and 24 h after the last leucine administration. Several previous studies have reported that an additional protein intake affects fast-twitch fibers, rather than slow-twitch fibers (Hartman et al 2007;Farup et al 2014;Reidy et al 2017). Accordingly, the rats were anesthetized using inhalation anesthetics (isoflurane), and the extensor digitorum longus (EDL) muscle, about 98% of which contains type II fibers, was removed (Armstrong and Phelps 1984).…”

Muscle fiber hypertrophy in response to 6 weeks of high-volume resistance training in trained young men is largely attributed to sarcoplasmic hypertrophy

“…<0.001), and DAVID indicated that the following functionally-annotated pathways were upregulated (FDR value <0.05): a) glycolysis (8 proteins), b) acetylation (23 proteins), c) gluconeogenesis (5 proteins) and d) cytoplasm (20 proteins). At W7, sarcoplasmic protein concentrations remained higher than PRE INTRODUCTION Weeks to months of resistance training increases skeletal muscle mean fiber crosssectional area (fCSA) [1][2][3][4][5][6][7][8][9][10]. Tracer studies have also demonstrated that a single bout of resistance exercise increases muscle protein synthesis (MPS) and myofibrillar protein synthesis (MyoPS) rates up to 72 hours post-exercise (reviewed in [11][12][13]).…”

<p>Whey protein supplementation and muscle mass: current perspectives</p>

“…Despite the available evidence supporting the benefits of protein supplementation, mainly from whey, to maximize muscle mass gain, there are still some controversial results 7,8 questioning the effectiveness of using protein for supporting muscle mass accretion in recreationally trained participants. It is likely that some uncontrolled factors, such as the type and quality of the protein source, the protocol of ingestion, including the dose per singular intake, timing of ingestion, eating patterns, including meal frequency and macronutrient distribution, the coingestion of other nutrients, and the energy content of the daily diet could have caused discrepancies between studies.…”