Bigger weights may not beget bigger muscles: evidence from acute muscle protein synthetic responses after resistance exercise

2012 ◽  
Vol 37 (3) ◽  
pp. 551-554 ◽  
Author(s):  
Nicholas A. Burd ◽  
Cameron J. Mitchell ◽  
Tyler A. Churchward-Venne ◽  
Stuart M. Phillips
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Muscle Growth ◽  
Exercise Recovery ◽  
Maximal Strength ◽  
Volitional Fatigue ◽  
Exercise Induced ◽  
Induced Changes

It is often recommended that heavier training intensities (∼70%–80% of maximal strength) be lifted to maximize muscle growth. However, we have reported that intensities as low as 30% of maximum strength, when lifted to volitional fatigue, are equally effective at stimulating muscle protein synthesis rates during resistance exercise recovery. This paper discusses the idea that high-intensity contractions are not the exclusive driver of resistance exercise-induced changes in muscle protein synthesis rates.

Short-Term Training: When Do Repeated Bouts of Resistance Exercise Become Training?

2000 ◽  
Vol 25 (3) ◽  
pp. 185-193 ◽  
Author(s):  
Stuart M. Phillips
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Muscle Fibre ◽  
Time Course ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Cross Sectional ◽  
Volume Percentage ◽  
Muscle Balance ◽  
Induced Changes

Chronic resistance training induces increases in muscle fibre cross-sectional area (CSA), otherwise known as hypertrophy. This is due to an increased volume percentage of myofibrillar proteins within a given fibre. The exact time-course for muscle fibre hypertrophy is not well-documented but appears to require at least 6-7 weeks of regular resistive training at reasonably high intensity before increases in fibre CSA are deemed significant. Proposed training-induced changes in neural drive are hypothesized to increase strength due to increased synchrony of motor unit firing, reduced antagonist muscle activity and/or a reduction in any bilateral strength deficit. Nonetheless, increases in muscle protein synthesis were observed following an isolated bout of resistance exercise. In addition, muscle balance was positive, following resistance exercise when amino acids were infused/ingested. This showed that protein accretion occurred during the postexercise period. The implications of this hypothesis for training-induced increases in strength are discussed. Key words: hypertrophy, muscle protein synthesis, muscle protein breakdown, myofibrillar protein, strength.

Resistance Exercise–induced Regulation of Muscle Protein Synthesis to Intraset Rest

2020 ◽  
Vol 52 (5) ◽  
pp. 1022-1030
Author(s):  
AMADEO F. SALVADOR ◽  
ANDREW T. ASKOW ◽  
COLLEEN F. MCKENNA ◽  
HSIN-YU FANG ◽  
SARAH K. BURKE ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Exercise Induced

scholarly journals Resistance exercise load does not determine training-mediated hypertrophic gains in young men

2012 ◽  
Vol 113 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Cameron J. Mitchell ◽  
Tyler A. Churchward-Venne ◽  
Daniel W. D. West ◽  
Nicholas A. Burd ◽  
Leigh Breen ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Acute Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Vastus Lateralis ◽  
Muscle Volume ◽  
Maximal Strength ◽  
Heavy Load ◽  
Exercise Load

We have reported that the acute postexercise increases in muscle protein synthesis rates, with differing nutritional support, are predictive of longer-term training-induced muscle hypertrophy. Here, we aimed to test whether the same was true with acute exercise-mediated changes in muscle protein synthesis. Eighteen men (21 ± 1 yr, 22.6 ± 2.1 kg/m2; means ± SE) had their legs randomly assigned to two of three training conditions that differed in contraction intensity [% of maximal strength (1 repetition maximum)] or contraction volume (1 or 3 sets of repetitions): 30%-3, 80%-1, and 80%-3. Subjects trained each leg with their assigned regime for a period of 10 wk, 3 times/wk. We made pre- and posttraining measures of strength, muscle volume by magnetic resonance (MR) scans, as well as pre- and posttraining biopsies of the vastus lateralis, and a single postexercise (1 h) biopsy following the first bout of exercise, to measure signaling proteins. Training-induced increases in MR-measured muscle volume were significant ( P < 0.01), with no difference between groups: 30%-3 = 6.8 ± 1.8%, 80%-1 = 3.2 ± 0.8%, and 80%-3= 7.2 ± 1.9%, P = 0.18. Isotonic maximal strength gains were not different between 80%-1 and 80%-3, but were greater than 30%-3 ( P = 0.04), whereas training-induced isometric strength gains were significant but not different between conditions ( P = 0.92). Biopsies taken 1 h following the initial resistance exercise bout showed increased phosphorylation ( P < 0.05) of p70S6K only in the 80%-1 and 80%-3 conditions. There was no correlation between phosphorylation of any signaling protein and hypertrophy. In accordance with our previous acute measurements of muscle protein synthetic rates a lower load lifted to failure resulted in similar hypertrophy as a heavy load lifted to failure.

scholarly journals Expression of growth-related genes in young and older human skeletal muscle following an acute stimulation of protein synthesis

2009 ◽  
Vol 106 (4) ◽  
pp. 1403-1411 ◽  
Author(s):  
Micah J. Drummond ◽  
Mitsunori Miyazaki ◽  
Hans C. Dreyer ◽  
Bart Pennings ◽  
Shaheen Dhanani ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Resistance Exercise ◽  
Human Skeletal Muscle ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Muscle Growth ◽  
Age Groups ◽  
Essential Amino Acids ◽  
Exercise Muscle

Muscle growth is associated with an activation of the mTOR signaling pathway and satellite cell regulators. The purpose of this study was to determine whether 17 selected genes associated with mTOR/muscle protein synthesis and the satellite cells/myogenic program are differentially expressed in young and older human skeletal muscle at rest and in response to a potent anabolic stimulus [resistance exercise + essential amino acid ingestion (RE+EAA)]. Twelve male subjects (6 young, 6 old) completed a bout of heavy resistance exercise. Muscle biopsies were obtained before and at 3 and 6 h post RE+EAA. Subjects ingested leucine-enriched essential amino acids at 1 h postexercise. mRNA expression was determined using qRT-PCR. At rest, hVps34 mRNA was elevated in the older subjects ( P < 0.05) while there was a tendency for levels of myoD, myogenin, and TSC2 mRNA to be higher than young. The anabolic stimulus (RE+EAA) altered mRNAs associated with mTOR regulation. Notably, REDD2 decreased in both age groups ( P < 0.05) but the expression of Rheb mRNA increased only in the young. Finally, cMyc mRNA was elevated ( P < 0.05) in both young and old at 6 h post RE+EAA. Furthermore, RE+EAA also increased expression of several mRNAs associated with satellite function in the young ( P < 0.05), while expression of these mRNAs did not change in the old. We conclude that several anabolic genes in muscle are more responsive in young men post RE+EAA. Our data provide new insights into the regulation of genes important for transcription and translation in young and old human skeletal muscle post RE+EAA.

scholarly journals Resistance exercise-induced increases in putative anabolic hormones do not enhance muscle protein synthesis or intracellular signalling in young men

2009 ◽  
Vol 587 (21) ◽  
pp. 5239-5247 ◽  
Author(s):  
Daniel W. D. West ◽  
Gregory W. Kujbida ◽  
Daniel R. Moore ◽  
Philip Atherton ◽  
Nicholas A. Burd ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Young Men ◽  
Intracellular Signalling ◽  
Anabolic Hormones ◽  
Exercise Induced

Insulin-facilitated increase of muscle protein synthesis after resistance exercise involves a MAP kinase pathway

2006 ◽  
Vol 290 (6) ◽  
pp. E1205-E1211 ◽  
Author(s):  
James D. Fluckey ◽  
Micheal Knox ◽  
Latasha Smith ◽  
Esther E. Dupont-Versteegden ◽  
Dana Gaddy ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Signaling Pathways ◽  
Kinase Inhibitor ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Muscle Growth ◽  
Primary Component ◽  
Sprague Dawley ◽  
Sprague Dawley Rats

Recent studies have implicated the mTOR-signaling pathway as a primary component for muscle growth in mammals. The purpose of this investigation was to examine signaling pathways for muscle protein synthesis after resistance exercise. Sprague-Dawley rats (male, 6 mo old) were assigned to either resistance exercise or control groups. Resistance exercise was accomplished in operantly conditioned animals using a specially designed flywheel apparatus. Rats performed two sessions of resistance exercise, separated by 48 h, each consisting of 2 sets of 25 repetitions. Sixteen hours after the second session, animals were killed, and soleus muscles were examined for rates of protein synthesis with and without insulin and/or rapamycin (mTOR inhibitor) and/or PD-098059 (PD; MEK kinase inhibitor). Results of this study demonstrated that rates of synthesis were higher ( P < 0.05) with insulin after exercise compared with without insulin, or to control muscles, regardless of insulin. Rapamycin lowered ( P < 0.05) rates of synthesis in controls, with or without insulin, and after exercise without insulin. However, insulin was able to overcome the inhibition of rapamycin after exercise ( P < 0.05). PD had no effect on protein synthesis in control rats, but the addition of PD to exercised muscle resulted in lower ( P < 0.05) rates of synthesis, and this inhibition was not rescued by insulin. Western blot analyses demonstrated that the inhibitors used in the present study were selective and effective for preventing activation of specific signaling proteins. Together, these results suggest that the insulin-facilitated increase of muscle protein synthesis after resistance exercise requires multiple signaling pathways.

scholarly journals The response of muscle protein synthesis following whole-body resistance exercise is greater following 40 g than 20 g of ingested whey protein

2016 ◽  
Vol 4 (15) ◽  
pp. e12893 ◽  
Author(s):  
Lindsay S. Macnaughton ◽  
Sophie L. Wardle ◽  
Oliver C. Witard ◽  
Chris McGlory ◽  
D. Lee Hamilton ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Whey Protein ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Whole Body ◽  
Body Resistance
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