scholarly journals Damaging eccentric exercise attenuates disuse induced declines in daily myofibrillar protein synthesis and transiently prevents muscle atrophy in healthy men.

2021 ◽  
Author(s):  
Tom S. O. Jameson ◽  
Sean P Kilroe ◽  
Jonathan Fulford ◽  
Doaa Reda Abdelrahman ◽  
Andrew John Murton ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Eccentric Exercise ◽  
Vastus Lateralis ◽  
Quadriceps Muscle ◽  
Quadriceps Strength ◽  
Myofibrillar Protein ◽  
Muscle Volume ◽  
Vastus Lateralis Muscle ◽  
Deuterated Water ◽  
Myofibrillar Protein Synthesis

Introduction: Short-term disuse leads to muscle loss driven by lowered daily myofibrillar protein synthesis (MyoPS). However, disuse commonly results from muscle damage, and its influence on muscle deconditioning during disuse is unknown. Methods: 21 males (20±1 y, BMI=24±1 kg·m-2 (±SEM)) underwent 7 days of unilateral leg immobilization immediately preceded by 300 bilateral, maximal, muscle-damaging eccentric quadriceps contractions (DAM; n=10) or no exercise (CON; n=11). Participants ingested deuterated water and underwent temporal bilateral thigh MRI scans and vastus lateralis muscle biopsies of immobilized (IMM) and non-immobilized (N-IMM) legs. Results: N-IMM quadriceps muscle volume remained unchanged throughout in both groups. IMM quadriceps muscle volume declined after 2 days by 1.7±0.5% in CON (P=0.031; and by 1.3±0.6% when corrected to N-IMM; P=0.06) but did not change in DAM, and declined equivalently in CON (by 6.4±1.1% [5.0±1.6% when corrected to N-IMM]) and DAM (by 2.6±1.8% [4.0±1.9% when corrected to N-IMM]) after 7 days. Immobilization began to decrease MyoPS compared with N-IMM in both groups after 2 days (P=0.109), albeit with higher MyoPS rates in DAM compared with CON (P=0.035). Frank suppression of MyoPS was observed between days 2-7 in CON (IMM=1.04±0.12, N-IMM=1.86±0.10%·d-1; P=0.002) but not DAM (IMM=1.49±0.29, N-IMM=1.90±0.30%·d-1; P>0.05). Declines in MyoPS and quadriceps volume after 7 days correlated positively in CON (R2=0.403; P=0.035) but negatively in DAM (R2=0.483; P=0.037). Quadriceps strength declined following immobilization in both groups, but to a greater extent in DAM. Conclusion: Prior muscle damaging eccentric exercise increases MyoPS and prevents loss of quadriceps muscle volume after 2 (but not 7) days of disuse.

scholarly journals Dietary protein intake does not modulate daily myofibrillar protein synthesis rates or loss of muscle mass and function during short-term immobilization in young men: a randomized controlled trial

2020 ◽  
Author(s):  
Sean Paul Kilroe ◽  
Jonathan Fulford ◽  
Sarah Jackman ◽  
Andrew Holwerda ◽  
Annemie Gijsen ◽  
...  
Keyword(s):  
Muscle Mass ◽  
Dietary Protein ◽  
Protein Intake ◽  
Quadriceps Muscle ◽  
Myofibrillar Protein ◽  
Muscle Volume ◽  
Dietary Protein Intake ◽  
Short Term ◽  
Muscle Disuse ◽  
Myofibrillar Protein Synthesis

ABSTRACT Background Short-term (<1 wk) muscle disuse lowers daily myofibrillar protein synthesis (MyoPS) rates resulting in muscle mass loss. The understanding of how daily dietary protein intake influences such muscle deconditioning requires further investigation. Objectives To assess the influence of graded dietary protein intakes on daily MyoPS rates and the loss of muscle mass during 3 d of disuse. Methods Thirty-three healthy young men (aged 22 ± 1 y; BMI = 23 ± 1 kg/m2) initially consumed the same standardized diet for 5 d, providing 1.6 g protein/kg body mass/d. Thereafter, participants underwent a 3-d period of unilateral leg immobilization during which they were randomly assigned to 1 of 3 eucaloric diets containing relatively high, low, or no protein (HIGH: 1.6, LOW: 0.5, NO: 0.15 g protein/kg/d; n = 11 per group). One day prior to immobilization participants ingested 400 mL deuterated water (D2O) with 50-mL doses consumed daily thereafter. Prior to and immediately after immobilization upper leg bilateral MRI scans and vastus lateralis muscle biopsies were performed to measure quadriceps muscle volume and daily MyoPS rates, respectively. Results Quadriceps muscle volume of the control legs remained unchanged throughout the experiment (P > 0.05). Immobilization led to 2.3 ± 0.4%, 2.7 ± 0.2%, and 2.0 ± 0.4% decreases in quadriceps muscle volume (P < 0.05) of the immobilized leg in the HIGH, LOW, and NO groups (P < 0.05), respectively, with no significant differences between groups (P > 0.05). D2O ingestion resulted in comparable plasma free [2H]-alanine enrichments during immobilization (∼2.5 mole percentage excess) across groups (P > 0.05). Daily MyoPS rates during immobilization were 30 ± 2% (HIGH), 26 ± 3% (LOW), and 27 ± 2% (NO) lower in the immobilized compared with the control leg, with no significant differences between groups (P > 0.05). Conclusions Three days of muscle disuse induces considerable declines in muscle mass and daily MyoPS rates. However, daily protein intake does not modulate any of these muscle deconditioning responses. Clinical trial registry number: NCT03797781

scholarly journals Short-term muscle disuse induces a rapid and sustained decline in daily myofibrillar protein synthesis rates

2020 ◽  
Vol 318 (2) ◽  
pp. E117-E130 ◽  
Author(s):  
Sean P. Kilroe ◽  
Jonathan Fulford ◽  
Andrew M. Holwerda ◽  
Sarah R. Jackman ◽  
Benjamin P. Lee ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Young Men ◽  
Myofibrillar Protein ◽  
Deuterated Water ◽  
Short Term ◽  
Muscle Disuse ◽  
Before And After ◽  
Mri Scans ◽  
The Impact ◽  
Myofibrillar Protein Synthesis

Short-term muscle disuse has been reported to lower both postabsorptive and postprandial myofibrillar protein synthesis rates. This study assessed the impact of disuse on daily myofibrillar protein synthesis rates following short-term (2 and 7 days) muscle disuse under free living conditions. Thirteen healthy young men (age: 20 ± 1 yr; BMI: 23 ± 1 kg/m−2) underwent 7 days of unilateral leg immobilization via a knee brace, with the nonimmobilized leg acting as a control. Four days before immobilization participants ingested 400 mL of 70% deuterated water, with 50-mL doses consumed daily thereafter. Upper leg bilateral MRI scans and muscle biopsies were collected before and after 2 and 7 days of immobilization to determine quadriceps volume and daily myofibrillar protein synthesis rates. Immobilization reduced quadriceps volume in the immobilized leg by 1.7 ± 0.3 and 6.7 ± 0.6% after 2 and 7 days, respectively, with no changes in the control leg. Over the 1-wk immobilization period, myofibrillar protein synthesis rates were 36 ± 4% lower in the immobilized (0.81 ± 0.04%/day) compared with the control (1.26 ± 0.04%/day) leg ( P < 0.001). Myofibrillar protein synthesis rates in the control leg did not change over time ( P = 0.775), but in the immobilized leg they were numerically lower during the 0- to 2-day period (16 ± 6%, 1.11 ± 0.09%/day, P = 0.153) and were significantly lower during the 2- to 7-day period (44 ± 5%, 0.70 ± 0.06%/day, P < 0.001) when compared with the control leg. We conclude that 1 wk of muscle disuse induces a rapid and sustained decline in daily myofibrillar protein synthesis rates in healthy young men.

Myofibrillar protein synthesis in young and old human subjects after three months of resistance training

1995 ◽  
Vol 268 (3) ◽  
pp. E422-E427 ◽  
Author(s):  
S. Welle ◽  
C. Thornton ◽  
M. Statt
Keyword(s):  
Protein Synthesis ◽  
Muscle Protein ◽  
Myofibrillar Protein ◽  
Whole Body ◽  
Synthesis Rate ◽  
Vastus Lateralis Muscle ◽  
Body Protein ◽  
Men And Women ◽  
Older Subjects ◽  
Myofibrillar Protein Synthesis

Muscle protein synthesis is slower in healthy older men and women than in young adults, but whether this results from relative disuse rather than aging is unclear. The present study was done to examine rates of myofibrillar protein synthesis before and after a 3-mo progressive resistance exercise program in young and old men and women. Protein synthesis was determined by incorporation of the tracer L-[1-13C]leucine into myofibrillar proteins obtained from the vastus lateralis muscle by needle biopsy. Before exercise, mean fractional myofibrillar synthesis was 33% slower (P < 0.01) in nine older subjects (62-72 yr old, 5 men and 4 women) than in 9 young subjects (22-31 yr old, 5 men and 4 women). Initial strength, as determined by three-repetition-maximum tests, was significantly less in the older group. Strength and training weights increased similarly in young and old groups, when expressed in relation to baseline values. Posttraining myofibrillar synthesis was determined on the day after the final training session. There was not a significant change in fractional myofibrillar synthesis in either the young or the old group after training, and the rate in the older group remained 27% slower (P < 0.05). Whole body protein turnover increased approximately 10% only in the younger group, and 24-h urinary 3-methylhistidine excretion (an index of myofibrillar proteolysis) was not significantly affected by training. These data suggest that the slower myofibrillar synthesis rate in older subjects cannot be explained by disuse.

scholarly journals Myofibrillar protein synthesis and muscle hypertrophy individualized responses to systematically changing resistance training variables in trained young men

2019 ◽  
Vol 127 (3) ◽  
pp. 806-815 ◽  
Author(s):  
Felipe Damas ◽  
Vitor Angleri ◽  
Stuart M. Phillips ◽  
Oliver C. Witard ◽  
Carlos Ugrinowitsch ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Training ◽  
Muscle Hypertrophy ◽  
Vastus Lateralis ◽  
Young Men ◽  
Myofibrillar Protein ◽  
Training Volume ◽  
Hypertrophic Response ◽  
Specific Protocol ◽  
Myofibrillar Protein Synthesis

The manipulation of resistance training (RT) variables is used among athletes, recreational exercisers, and compromised populations (e.g., elderly) attempting to potentiate muscle hypertrophy. However, it is unknown whether an individual’s inherent predisposition dictates the RT-induced muscle hypertrophic response. Resistance-trained young [26 (3) y] men ( n = 20) performed 8 wk unilateral RT (2 times/wk), with 1 leg randomly assigned to a standard progressive RT [control (CON)] and the contralateral leg to a variable RT (VAR; modulating exercise load, volume, contraction type, and interset rest interval). The VAR leg completed all 4 RT variations every 2 wk. Bilateral vastus lateralis cross-sectional area (CSA) was measured, pre- and post-RT and acute integrated myofibrillar protein synthesis (MyoPS) rates were assessed at rest and over 48 h following the final RT session. Muscle CSA increase was similar between CON and VAR ( P > 0.05), despite higher total training volume (TTV) in VAR ( P < 0.05). The 0–48-h integrated MyoPS increase postexercise was slightly greater for VAR than CON ( P < 0.05). All participants were considered “responders” to RT, although none benefited to a greater extent from a specific protocol. Between-subjects variability (MyoPS, 3.30%; CSA, 37.8%) was 40-fold greater than the intrasubject (between legs) variability (MyoPS, 0.08%; CSA, 0.9%). The higher TTV and greater MyoPS response in VAR did not translate to a greater muscle hypertrophic response. Manipulating common RT variables elicited similar muscle hypertrophy than a standard progressive RT program in trained young men. Intrinsic individual factors are key determinants of the MyoPS and change in muscle CSA compared with extrinsic manipulation of common RT variables. NEW & NOTEWORTHY Systematically manipulating resistance training (RT) variables during RT augments the stimulation of myofibrillar protein synthesis (MyoPS) and training volume but fails to potentiate muscle hypertrophy compared with a standard progressive RT. Any modest further MyoPS increase and higher training volumes do not reflect in a greater hypertrophic response. Between-subject variability was 40-fold greater than the variability promoted by extrinsic manipulation of RT variables, indicating that individual intrinsic factors are stronger determinants of the hypertrophic response.

No effect of menstrual cycle on myofibrillar and connective tissue protein synthesis in contracting skeletal muscle

2006 ◽  
Vol 290 (1) ◽  
pp. E163-E168 ◽  
Author(s):  
Benjamin F. Miller ◽  
Mette Hansen ◽  
Jens L. Olesen ◽  
Allan Flyvbjerg ◽  
Peter Schwarz ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Menstrual Cycle ◽  
Collagen Synthesis ◽  
Acute Exercise ◽  
Vastus Lateralis ◽  
Myofibrillar Protein ◽  
Cycle Phase ◽  
Acute Bout ◽  
Tissue Protein Synthesis ◽  
Myofibrillar Protein Synthesis

We tested the hypothesis that acute exercise would stimulate synthesis of myofibrillar protein and intramuscular collagen in women and that the phase of the menstrual cycle at which the exercise took place would influence the extent of the change. Fifteen young, healthy female subjects were studied in the follicular (FP, n = 8) or the luteal phase (LP, n = 7, n = 1 out of phase) 24 h after an acute bout of one-legged exercise (60 min of kicking at 67% Wmax), samples being taken from the vastus lateralis in both the exercised and resting legs. Rates of synthesis of myofibrillar and muscle collagen proteins were measured by incorporation of [13C]leucine. Myofibrillar protein synthesis (means ± SD; rest FP: 0.053 ± 0.009%/h, LP: 0.055 ± 0.013%/h) was increased at 24-h postexercise (FP: 0.131 ± 0.018%/h, P < 0.05, LP: 0.134 ± 0.018%/h, P < 0.05) with no differences between phases. Similarly, muscle collagen synthesis (rest FP: 0.024 ± 0.017%/h, LP: 0.021 ± 0.006%/h) was elevated at 24-h postexercise (FP: 0.073 ± 0.016%/h, P < 0.05, LP: 0.072 ± 0.015%/h, P < 0.05), but the responses did not differ between menstrual phases. Therefore, there is no effect of menstrual cycle phase, at rest or in response to an acute bout of exercise, on myofibrillar protein synthesis and muscle collagen synthesis in women.

Sex-based comparisons of myofibrillar protein synthesis after resistance exercise in the fed state

2012 ◽  
Vol 112 (11) ◽  
pp. 1805-1813 ◽  
Author(s):  
Daniel W. D. West ◽  
Nicholas A. Burd ◽  
Tyler A. Churchward-Venne ◽  
Donny M. Camera ◽  
Cameron J. Mitchell ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Vastus Lateralis ◽  
Recovery Period ◽  
Myofibrillar Protein ◽  
Men And Women ◽  
Fed State ◽  
Protein Ingestion ◽  
Exercise Induced ◽  
Myofibrillar Protein Synthesis

We made sex-based comparisons of rates of myofibrillar protein synthesis (MPS) and anabolic signaling after a single bout of high-intensity resistance exercise. Eight men (20 ± 10 yr, BMI = 24.3 ± 2.4) and eight women (22 ± 1.8 yr, BMI = 23.0 ± 1.9) underwent primed constant infusions of l-[ ring-13C6]phenylalanine on consecutive days with serial muscle biopsies. Biopsies were taken from the vastus lateralis at rest and 1, 3, 5, 24, 26, and 28 h after exercise. Twenty-five grams of whey protein was ingested immediately and 26 h after exercise. We also measured exercise-induced serum testosterone because it is purported to contribute to increases in myofibrillar protein synthesis (MPS) postexercise and its absence has been hypothesized to attenuate adaptative responses to resistance exercise in women. The exercise-induced area under the testosterone curve was 45-fold greater in men than women in the early (1 h) recovery period following exercise ( P < 0.001). MPS was elevated similarly in men and women (2.3- and 2.7-fold, respectively) 1–5 h postexercise and after protein ingestion following 24 h recovery. Phosphorylation of mTORSer2448 was elevated to a greater extent in men than women acutely after exercise ( P = 0.003), whereas increased phosphorylation of p70S6K1Thr389 was not different between sexes. Androgen receptor content was greater in men (main effect for sex, P = 0.049). Atrogin-1 mRNA abundance was decreased after 5 h recovery in both men and women ( P < 0.001), and MuRF-1 expression was elevated in men after protein ingestion following 24 h recovery ( P = 0.003). These results demonstrate minor sex-based differences in signaling responses and no difference in the MPS response to resistance exercise in the fed state. Interestingly, our data demonstrate that exercise-induced increases in MPS are dissociated from postexercise testosteronemia and that stimulation of MPS occurs effectively with low systemic testosterone concentrations in women.

scholarly journals A mycoprotein-based high-protein vegan diet supports equivalent daily myofibrillar protein synthesis rates compared with an isonitrogenous omnivorous diet in older adults: a randomised controlled trial

2020 ◽  
pp. 1-11
Author(s):  
Alistair J. Monteyne ◽  
Mandy V. Dunlop ◽  
David J. Machin ◽  
Mariana O. C. Coelho ◽  
George F. Pavis ◽  
...  
Keyword(s):  
Older Adults ◽  
Protein Synthesis ◽  
Controlled Trial ◽  
Control Period ◽  
Myofibrillar Protein ◽  
High Protein ◽  
Dietary Control ◽  
Deuterated Water ◽  
Healthy Older Adults ◽  
Myofibrillar Protein Synthesis

Abstract Animal-derived dietary protein ingestion and physical activity stimulate myofibrillar protein synthesis rates in older adults. We determined whether a non-animal-derived diet can support daily myofibrillar protein synthesis rates to the same extent as an omnivorous diet. Nineteen healthy older adults (aged 66 (sem 1) years; BMI 24 (sem 1) kg/m2; twelve males, seven females) participated in a randomised, parallel-group, controlled trial during which they consumed a 3-d isoenergetic high-protein (1·8 g/kg body mass per d) diet, where the protein was provided from predominantly (71 %) animal (OMNI; n 9; six males, three females) or exclusively vegan (VEG; n 10; six males, four females; mycoprotein providing 57 % of daily protein intake) sources. During the dietary control period, participants conducted a daily bout of unilateral resistance-type leg extension exercise. Before the dietary control period, participants ingested 400 ml of deuterated water, with 50-ml doses consumed daily thereafter. Saliva samples were collected throughout to determine body water 2H enrichments, and muscle samples were collected from rested and exercised muscle to determine daily myofibrillar protein synthesis rates. Deuterated water dosing resulted in body water 2H enrichments of approximately 0·78 (sem 0·03) %. Daily myofibrillar protein synthesis rates were 13 (sem 8) (P = 0·169) and 12 (sem 4) % (P = 0·016) greater in the exercised compared with rested leg (1·59 (sem 0·12) v. 1·77 (sem 0·12) and 1·76 (sem 0·14) v. 1·93 (sem 0·12) %/d) in OMNI and VEG groups, respectively. Daily myofibrillar protein synthesis rates did not differ between OMNI and VEG in either rested or exercised muscle (P > 0·05). Over the course of a 3-d intervention, omnivorous- or vegan-derived dietary protein sources can support equivalent rested and exercised daily myofibrillar protein synthesis rates in healthy older adults consuming a high-protein diet.

scholarly journals Differential Stimulation of Post-Exercise Myofibrillar Protein Synthesis in Humans Following Isonitrogenous, Isocaloric Pre-Exercise Feeding

Nutrients ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1657 ◽  
Author(s):  
Robert W. Davies ◽  
Joseph J. Bass ◽  
Brian P. Carson ◽  
Catherine Norton ◽  
Marta Kozior ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Whey Protein ◽  
Deuterium Oxide ◽  
Vastus Lateralis ◽  
Isotope Ratio Mass Spectrometry ◽  
Negative Control ◽  
Myofibrillar Protein ◽  
Double Blind ◽  
Post Exercise ◽  
Myofibrillar Protein Synthesis

The aim of this study was to test the effects of two disparate isonitrogenous, isocaloric pre-exercise feeds on deuterium-oxide (D2O) derived measures of myofibrillar protein synthesis (myoPS) in humans. Methods: In a double-blind parallel group design, 22 resistance-trained men aged 18 to 35 years ingested a meal (6 kcal·kg−1, 0.8 g·kg−1 carbohydrate, 0.2 g·kg−1 fat) with 0.33 g·kg−1 nonessential amino acids blend (NEAA) or whey protein (WHEY), prior to resistance exercise (70% 1RM back-squats, 10 reps per set to failure, 25% duty cycle). Biopsies of M. vastus lateralis were obtained pre-ingestion (PRE) and +3 h post-exercise (POST). The myofibrillar fractional synthetic rate (myoFSR) was calculated via deuterium labelling of myofibrillar-bound alanine, measured by gas chromatography–pyrolysis–isotope ratio mass spectrometry (GC-Pyr-IRMS). Data are a mean percentage change (95% CI). Results: There was no discernable change in myoFSR following NEAA (10(−5, 25) %, p = 0.235), whereas an increase in myoFSR was observed after WHEY (28 (13, 43) %, p = 0.003). Conclusions: Measured by a D2O tracer technique, a disparate myoPS response was observed between NEAA and WHEY. Pre-exercise ingestion of whey protein increased post-exercise myoPS, whereas a NEAA blend did not, supporting the use of NEAA as a viable isonitrogenous negative control.

scholarly journals The Effect of Whey Protein Supplementation on Myofibrillar Protein Synthesis and Performance Recovery in Resistance-Trained Men

Nutrients ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 845
Author(s):  
Robert W. Davies ◽  
Joseph J. Bass ◽  
Brian P. Carson ◽  
Catherine Norton ◽  
Marta Kozior ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Whey Protein ◽  
Deuterium Oxide ◽  
Vastus Lateralis ◽  
Isotope Ratio Mass Spectrometry ◽  
Myofibrillar Protein ◽  
Protein Supplementation ◽  
Muscle Recovery ◽  
Double Blind ◽  
Myofibrillar Protein Synthesis

Background: The aim of this study was to investigate the effect of whey protein supplementation on myofibrillar protein synthesis (myoPS) and muscle recovery over a 7-d period of intensified resistance training (RT). Methods: In a double-blind randomised parallel group design, 16 resistance-trained men aged 18 to 35 years completed a 7-d RT protocol, consisting of three lower-body RT sessions on non-consecutive days. Participants consumed a controlled diet (146 kJ·kg−1·d−1, 1.7 g·kg−1·d−1 protein) with either a whey protein supplement or an isonitrogenous control (0.33 g·kg−1·d−1 protein). To measure myoPS, 400 ml of deuterium oxide (D2O) (70 atom %) was ingested the day prior to starting the study and m. vastus lateralis biopsies were taken before and after RT-intervention. Myofibrillar fractional synthetic rate (myoFSR) was calculated via deuterium labelling of myofibrillar-bound alanine, measured by gas chromatography-pyrolysis-isotope ratio mass spectrometry (GC-Pyr-IRMS). Muscle recovery parameters (i.e., countermovement jump height, isometric-squat force, muscle soreness and serum creatine kinase) were assessed daily. Results: MyoFSR PRE was 1.6 (0.2) %∙d−1 (mean (SD)). Whey protein supplementation had no effect on myoFSR (p = 0.771) or any recovery parameter (p = 0.390–0.989). Conclusions: Over an intense 7-d RT protocol, 0.33 g·kg−1·d−1 of supplemental whey protein does not enhance day-to-day measures of myoPS or postexercise recovery in resistance-trained men.

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