scholarly journals Does habitual dietary intake influence myofiber hypertrophy in response to resistance training? A cluster analysis

2009 ◽  
Vol 34 (4) ◽  
pp. 632-639 ◽  
Author(s):  
Anna E. Thalacker-Mercer ◽  
John K. Petrella ◽  
Marcas M. Bamman
Keyword(s):  
Cluster Analysis ◽  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Vastus Lateralis ◽  
Muscle Growth ◽  
Daily Intake ◽  
Dietary Recommendations ◽  
Extrinsic Factors ◽  
Cross Sectional

Although resistance exercise training (RT) is a common intervention to stimulate muscle protein synthesis and increase skeletal muscle mass, the optimal daily protein and total energy intakes sufficient to support RT-mediated muscle growth are as yet unclear. Further, the efficacy of RT varies widely among adults of all ages and whether this is attributable to interindividual differences in nutrition is not known. To determine if self-selected daily intake of macronutrients and specific components of dietary protein and fat are predictive of the magnitude of RT-mediated muscle growth, detailed 4-day dietary records were analyzed on 60 subjects previously clustered (K-means cluster analysis) as non-, modest, and extreme responders (non, n = 16; mod, n = 29; xtr, n = 15), based on the magnitudes of change in vastus lateralis myofiber cross-sectional area following a 16-week, 3-day-per-week, high-intensity RT. Despite the marked contrast between 60% myofiber hypertrophy in xtr and zero growth in non, we found no differences among response clusters in daily intakes of energy (mean ± SEM: non 102 ± 8; mod 111 ± 6; xtr 109 ± 5 kJ·kg–1·day–1), protein (non 0.97 ± 0.08; mod 1.07 ± 0.07; xtr 1.05 ± 0.06 g·kg–1·day–1), carbohydrate (non 3.02 ± 0.24; mod 3.18 ± 0.20; xtr 3.14 ± 0.17 g·kg–1·day–1), and fat (non 0.95 ± 0.09; mod 1.05 ± 0.08; xtr 1.03 ± 0.08 g·kg–1·day–1), which generally met or exceeded dietary recommendations. There were no cluster differences in intakes of branched chain amino acids known to stimulate muscle protein synthesis. Using the novel K-means clustering approach, we conclude from this preliminary study that protein and energy intakes were sufficient to facilitate modest and extreme muscle growth during RT and intrinsic or extrinsic factors other than nutrient ingestion apparently impaired the anabolic response in nonresponders.

Protein synthesis and the expression of growth-related genes are altered by running in human vastus lateralis and soleus muscles

2009 ◽  
Vol 296 (3) ◽  
pp. R708-R714 ◽  
Author(s):  
Matthew P. Harber ◽  
Justin D. Crane ◽  
Jared M. Dickinson ◽  
Bozena Jemiolo ◽  
Ulrika Raue ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Metabolic Response ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Vastus Lateralis ◽  
Muscle Growth ◽  
Ring Finger ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Before And After

Recent evidence suggests aerobic exercise may help preserve soleus muscle mass during unloading. The purpose of this investigation was to examine the muscle-specific metabolic response to running as it relates to muscle growth. Mixed-muscle protein synthesis [fractional synthetic rate (FSR)] and gene expression (GE) were examined in the vastus lateralis (VL) and soleus (SOL) muscles from eight men (26 ± 2 yr; V̇o2max 63 ± 2 ml·kg−1·min−1) before and after a 45-min level-grade treadmill run at 77 ± 1% intensity. Muscle glycogen utilization was similar between muscles. Resting FSR was similar between the VL (0.080 ± 0.007 %/h) and SOL (0.086 ± 0.008 %/h) and was higher ( P < 0.05) 24 h postexercise compared with rest for both muscles. The absolute change in FSR was not different between muscles (0.030 ± 0.007 vs. 0.037 ± 0.012 %/h for VL and SOL). At baseline, myostatin GE was approximately twofold higher ( P < 0.05) in SOL compared with VL, while no other muscle-specific differences in GE were present. After running, myostatin GE was suppressed ( P < 0.05) in both muscles at 4 h and was higher ( P < 0.05) than baseline at 24 h for VL only. Muscle regulatory factor 4 mRNA was elevated ( P < 0.05) at 4 h in both SOL and VL; MyoD and peroxisome-proliferator-activated receptor-gamma coactivator-1α (PGC-1α) were higher ( P < 0.05) at 4 h, and forkhead box [FOXO]3A was higher at 24 h in SOL only, while muscle-RING-finger protein-1 (MuRF-1) was higher ( P < 0.05) at 4 h in VL only. Myogenin and atrogin-1 GE were unaltered. The similar increases between muscles in FSR support running as part of the exercise countermeasure to preserve soleus mass during unloading. The subtle differences in GE suggest a potential mechanism for muscle-specific adaptations to chronic run training.

scholarly journals Proteasome- and Calpain-Mediated Proteolysis, but Not Autophagy, Is Required for Leucine-Induced Protein Synthesis in C2C12 Myotubes

Physiologia ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 22-33
Author(s):  
Shelby C. Osburn ◽  
Christopher G. Vann ◽  
David D. Church ◽  
Arny A. Ferrando ◽  
Michael D. Roberts
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Muscle Growth ◽  
Proteasome Inhibition ◽  
Coupled Processes ◽  
C2c12 Myotubes ◽  
Calpain Inhibitor ◽  
Tightly Coupled

Muscle protein synthesis and proteolysis are tightly coupled processes. Given that muscle growth is promoted by increases in net protein balance, it stands to reason that bolstering protein synthesis through amino acids while reducing or inhibiting proteolysis could be a synergistic strategy in enhancing anabolism. However, there is contradictory evidence suggesting that the proper functioning of proteolytic systems in muscle is required for homeostasis. To add clarity to this issue, we sought to determine if inhibiting different proteolytic systems in C2C12 myotubes in conjunction with acute and chronic leucine treatments affected markers of anabolism. In Experiment 1, myotubes underwent 1-h, 6-h, and 24-h treatments with serum and leucine-free DMEM containing the following compounds (n = 6 wells per treatment): (i) DMSO vehicle (CTL), (ii) 2 mM leucine + vehicle (Leu-only), (iii) 2 mM leucine + 40 μM MG132 (20S proteasome inhibitor) (Leu + MG132), (iv) 2 mM leucine + 50 μM calpeptin (calpain inhibitor) (Leu + CALP), and (v) 2 mM leucine + 1 μM 3-methyladenine (autophagy inhibitor) (Leu + 3MA). Protein synthesis levels significantly increased (p < 0.05) in the Leu-only and Leu + 3MA 6-h treatments compared to CTL, and levels were significantly lower in Leu + MG132 and Leu + CALP versus Leu-only and CTL. With 24-h treatments, total protein yield was significantly lower in Leu + MG132 cells versus other treatments. Additionally, the intracellular essential amino acid (EAA) pool was significantly greater in 24-h Leu + MG132 treatments versus other treatments. In a follow-up experiment, myotubes were treated for 48 h with CTL, Leu-only, and Leu + MG132 for morphological assessments. Results indicated Leu + MG132 yielded significantly smaller myotubes compared to CTL and Leu-only. Our data are limited in scope due to the utilization of select proteolysis inhibitors. However, this is the first evidence to suggest proteasome and calpain inhibition with MG132 and CALP, respectively, abrogate leucine-induced protein synthesis in myotubes. Additionally, longer-term Leu + MG132 treatments translated to an atrophy phenotype. Whether or not proteasome inhibition in vivo reduces leucine- or EAA-induced anabolism remains to be determined.

scholarly journals Activation of mTORC1 signaling and protein synthesis in human muscle following blood flow restriction exercise is inhibited by rapamycin

2014 ◽  
Vol 306 (10) ◽  
pp. E1198-E1204 ◽  
Author(s):  
David M. Gundermann ◽  
Dillon K. Walker ◽  
Paul T. Reidy ◽  
Michael S. Borack ◽  
Jared M. Dickinson ◽  
...  
Keyword(s):  
Blood Flow ◽  
Protein Synthesis ◽  
Time Course ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Vastus Lateralis ◽  
Human Muscle ◽  
Leg Extension ◽  
Or Groups ◽  
Mtorc1 Signaling

Restriction of blood flow to a contracting muscle during low-intensity resistance exercise (BFR exercise) stimulates mTORC1 signaling and protein synthesis in human muscle within 3 h postexercise. However, there is a lack of mechanistic data to provide a direct link between mTORC1 activation and protein synthesis in human skeletal muscle following BFR exercise. Therefore, the primary purpose of this study was to determine whether mTORC1 signaling is necessary for stimulating muscle protein synthesis after BFR exercise. A secondary aim was to describe the 24-h time course response in muscle protein synthesis and breakdown following BFR exercise. Sixteen healthy young men were randomized to one of two groups. Both the control (CON) and rapamycin (RAP) groups completed BFR exercise; however, RAP was administered 16 mg of the mTOR inhibitor rapamycin 1 h prior to BFR exercise. BFR exercise consisted of four sets of leg extension exercise at 20% of 1 RM. Muscle biopsies were collected from the vastus lateralis before exercise and at 3, 6, and 24 h after BFR exercise. Mixed-muscle protein fractional synthetic rate increased by 42% at 3 h postexercise and 69% at 24 h postexercise in CON, whereas this increase was inhibited in the RAP group. Phosphorylation of mTOR (Ser2448) and S6K1 (Thr389) was also increased in CON but inhibited in RAP. Mixed-muscle protein breakdown was not significantly different across time or groups. We conclude that activation of mTORC1 signaling and protein synthesis in human muscle following BFR exercise is inhibited in the presence of rapamycin.

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.

scholarly journals Nutritional and endocrinological manipulation of lean deposition in forage-fed steers

1991 ◽  
Vol 66 (2) ◽  
pp. 171-185 ◽  
Author(s):  
J. M. Dawson ◽  
P. J. Buttery ◽  
M. J. Lammiman ◽  
J. B. Soar ◽  
C. P. Essex ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Degradation ◽  
Lipid Composition ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Vastus Lateralis ◽  
Live Weight ◽  
Dry Matter Content ◽  
Semitendinosus Muscle ◽  
Intramuscular Lipid

The effect of supplementing grass silage with fishmeal on growth, muscle composition and the rate of muscle protein synthesis was investigated in young Friesian steers with and without oestradiol implants. The effect of the β-adrenergic agonist cimaterol was simultaneously investigated in animals fed on silage alone. Treatments lasted for 9 or 10 weeks. Fishmeal supplementation significantly increased animal growth rates (P < 0.001) and the weights of three dissected muscles (P < 0.001) compared with the silage-fed controls. These effects were further enhanced in animals also implanted with oestradiol. Muscle weights expressed as a proportion of body-weight were increased by fishmeal, suggesting that protein deposition had been enhanced. No further increase in the proportional muscle weights was obtained with oestradiol. Muscle dry matter content tended to be increased in both implanted and non-implanted animals receiving fishmeal compared with controls, but the proportions of protein, fat and ash were relatively constant. The intramuscular lipid composition was slightly altered by fishmeal. Muscle protein fractional synthetic rates (FSR), measured by continuous infusion of [3H]tyrosine, were increased by fishmeal in all three muscles of both implanted and non-implanted animals. There were no differences, however, due to oestradiol, over non-implanted fishmeal animals. This suggests that oestradiol may increase muscle accretion by reducing protein degradation rate. Cimaterol significantly increased longissimus dorsi (P < 0.05) and vastus lateralis (P < 0.01) muscle weights but had no effect on semitendinosus muscle weight or live-weight gain. The proportion of protein was increased (P <0.001) and the fat content reduced (P < 0.05) in all three muscles but intramuscular lipid composition was not markedly affected. Whilst methylhistidine: creatinine excretion was reduced by cimaterol, FSR were increased in the I. dorsi and v. lateralis muscles suggesting β-agonists have effects on both protein synthesis and protein degradation.

Resistance exercise acutely increases MHC and mixed muscle protein synthesis rates in 78–84 and 23–32 yr olds

2000 ◽  
Vol 278 (4) ◽  
pp. E620-E626 ◽  
Author(s):  
Debbie L. Hasten ◽  
Jina Pak-Loduca ◽  
Kathleen A. Obert ◽  
Kevin E. Yarasheski
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Vastus Lateralis ◽  
Weight Lifting ◽  
Synthesis Rate ◽  
Vastus Lateralis Muscle ◽  
Short Term ◽  
Mixed Protein

We determined whether short-term weight-lifting exercise increases the synthesis rate of the major contractile proteins, myosin heavy chain (MHC), actin, and mixed muscle proteins in nonfrail elders and younger women and men. Fractional synthesis rates of mixed, MHC, and actin proteins were determined in seven healthy sedentary 23- to 32-yr-old and seven healthy 78- to 84-yr-old participants in paired studies done before and at the end of a 2-wk weight-lifting program. The in vivo rate of incorporation of 1-[13C]leucine into vastus lateralis MHC, actin, and mixed proteins was determined using a 14-h constant intravenous infusion of 1-[13C]leucine. Before exercise, the mixed and MHC fractional synthetic rates were lower in the older than in the younger participants ( P ≤ 0.04). Baseline actin protein synthesis rates were similar in the two groups ( P = not significant). Over a 2-wk period, participants completed ten 1- to 1.5-h weight-lifting exercise sessions: 2–3 sets per day of 9 exercises, 8–12 repetitions per set, at 60–90% of maximum voluntary muscle strength. At the end of exercise, MHC and mixed protein synthetic rates increased in the younger (88 and 121%) and older participants (105 and 182%; P < 0.001 vs. baseline). These findings indicate that MHC and mixed protein synthesis rates are reduced more than actin in advanced age. Similar to that of 23–32 yr olds, the vastus lateralis muscle in 78–84 yr olds retains the capacity to increase MHC and mixed protein synthesis rates in response to short-term resistance exercise.

scholarly journals Circadian regulation of muscle growth independent of locomotor activity

2020 ◽  
Vol 117 (49) ◽  
pp. 31208-31218
Author(s):  
Jeffrey J. Kelu ◽  
Tapan G. Pipalia ◽  
Simon M. Hughes
Keyword(s):  
Physical Activity ◽  
Protein Synthesis ◽  
Circadian Clock ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Muscle Growth ◽  
Diurnal Variations ◽  
Dominant Negative ◽  
Messenger Rnas ◽  
Free Running

Muscle tissue shows diurnal variations in function, physiology, and metabolism. Whether such variations are dependent on the circadian clock per se or are secondary to circadian differences in physical activity and feeding pattern is unclear. By measuring muscle growth over 12-h periods in live prefeeding larval zebrafish, we show that muscle grows more during day than night. Expression of dominant negative CLOCK (ΔCLK), which inhibits molecular clock function, ablates circadian differences and reduces muscle growth. Inhibition of muscle contraction reduces growth in both day and night, but does not ablate the day/night difference. The circadian clock and physical activity are both required to promote higher muscle protein synthesis during the day compared to night, whereas markers of protein degradation,murfmessenger RNAs, are higher at night. Proteasomal inhibitors increase muscle growth at night, irrespective of physical activity, but have no effect during the day. Although physical activity enhances TORC1 activity, and the TORC1 inhibitor rapamycin inhibits clock-driven daytime growth, no effect on muscle growth at night was detected. Importantly, day/night differences in 1) muscle growth, 2) protein synthesis, and 3)murfexpression all persist in entrained larvae under free-running constant conditions, indicating circadian drive. Removal of circadian input by exposure to either permanent darkness or light leads to suboptimal muscle growth. We conclude that diurnal variations in muscle growth and metabolism are a circadian property that is independent of, but augmented by, physical activity, at least during development.

Signal transduction pathways that regulate muscle growth

2008 ◽  
Vol 44 ◽  
pp. 99-108 ◽  
Author(s):  
Henning Wackerhage ◽  
Aivaras Ratkevicius
Keyword(s):  
Signal Transduction ◽  
Protein Synthesis ◽  
Growth Factor ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Muscle Growth ◽  
Mammalian Target Of Rapamycin ◽  
High Growth ◽  
Signal Transduction Pathways ◽  
Cellular Functions

Progressive high-resistance exercise with 8–12 repetitions per set to near failure for beginners and 1–12 repetitions for athletes will increase muscle protein synthesis for up to 72 h; approx. 20 g of protein, especially when ingested directly after exercise, will promote high growth by elevating protein synthesis above breakdown. Muscle growth is regulated by signal transduction pathways that sense and compute local and systemic signals and regulate various cellular functions. The main signalling mechanisms are the phosphorylation of serine, threonine and tyrosine residues by kinases and their dephosphorylation by phosphatases. Muscle growth is stimulated by the mTOR (mammalian target of rapamycin) system, which senses (i) IGF-1 (insulin-like growth factor 1)/MGF (mechano-growth factor)/insulin and/or (ii) mechanical signals, (iii) amino acids and (iv) the energetic state of the muscle, and regulates protein synthesis accordingly. The action of the mTOR system is opposed by myostatin-Smad signalling which inhibits muscle growth via gene transcription.

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.

Effect of an Amino Acid, Protein, and Carbohydrate Mixture on Net Muscle Protein Balance after Resistance Exercise

2004 ◽  
Vol 14 (3) ◽  
pp. 255-271 ◽  
Author(s):  
Elisabet Børsheim ◽  
Asle Aarsland ◽  
Robert R. Wolfe
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Whey Protein ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Vastus Lateralis ◽  
Area Under The Curve ◽  
Constant Infusion ◽  
Delayed Response ◽  
Protein Balance

This study tests the hypotheses that (a) a mixture of whey protein, amino acids (AA), and carbohydrates (CHO) stimulates net muscle protein synthesis to a greater extent than isoenergetic CHO alone after resistance exercise; and (b) that the stimulatory effect of a protein, AA, and CHO mixture will last beyond the 1 st hour after intake. Eight subjects participated in 2 trials. In one (PAAC), they ingested 77.4 g CHO, 17.5 g whey protein, and 4.9 g AA 1 hr after resistance exercise. In the other (CON), 100 g CHO was ingested instead. They received a primed constant infusion of L-[2H5]-phenylalanine, and samples from femoral artery and vein, and biopsies from vastus lateralis were obtained. The area under the curve for net uptake of phenylalanine into muscle above pre-drink value was 128 ±42 mg • leg-1 (PAAC) versus 32 ± 10 mg - leg-1 (CON) for the 3 hr after the drink (p = .04). The net protein balance response to the mixture consisted of two components, one rapid immediate response, and a smaller delayed response about 90 min after drink, whereas in CON only a small delayed response was seen. We conclude that after resistance exercise, a mixture of whey protein, AA, and CHO stimulated muscle protein synthesis to a greater extent than isoenergetic CHO alone. Further, compared to previously reported findings, the addition of protein to an AA + CHO mixture seems to extend the anabolic effect.

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