Insulin facilitation of muscle protein synthesis following resistance exercise in hindlimb-suspended rats is independent of a rapamycin-sensitive pathway

2004 ◽  
Vol 287 (6) ◽  
pp. E1070-E1075 ◽  
Author(s):  
James D. Fluckey ◽  
Esther E. Dupont-Versteegden ◽  
Micheal Knox ◽  
Dana Gaddy ◽  
Per A. Tesch ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Muscle Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Mammalian Target Of Rapamycin ◽  
Exercise Bout ◽  
Hindlimb Suspension ◽  
Sprague Dawley

Hindlimb suspension (HS) results in rapid losses of muscle mass, which may in part be explained by attenuated rates of protein synthesis. Mammalian target of rapamycin (mTOR) regulates protein synthesis and has been implicated as a potential mediator of the muscle mass decrement with HS. This study examined the effect of resistance exercise, a muscle hypertrophy stimulant, on rates of protein synthesis after 4 days of HS in mature male Sprague-Dawley rats. Flywheel resistance exercise (2 sets × 25 repetitions) was conducted on days 2 and 4 of HS (HSRE). Sixteen hours after the last exercise bout, soleus muscles were assessed for in vitro rates of protein synthesis, with and without insulin (signaling agonist) and/or rapamycin (mTOR inhibitor). Results demonstrated that soleus mass was reduced ( P < 0.05) with HS, but this loss of mass was not observed ( P > 0.05) with HSRE. Muscle protein synthesis was diminished ( P < 0.05) with HS, with or without insulin. HSRE also had reduced rates of synthesis without insulin; however, insulin administration yielded higher ( P < 0.05) rates in HSRE compared with HS or control. Rapamycin diminished protein synthesis in all groups ( P < 0.05), but insulin rescued synthesis rates in HS and HSRE to levels similar to insulin alone for each group, suggesting that alternate signaling pathways develop to increase protein synthesis with HS. These results demonstrate that the capacity for an augmented anabolic response to resistance exercise is maintained after 4 days of HS and is independent of a rapamycin-sensitive pathway.

scholarly journals Relationship between exercise volume and muscle protein synthesis in a rat model of resistance exercise

2017 ◽  
Vol 123 (4) ◽  
pp. 710-716 ◽  
Author(s):  
Riki Ogasawara ◽  
Yuki Arihara ◽  
Junya Takegaki ◽  
Koichi Nakazato ◽  
Naokata Ishii
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Mammalian Target Of Rapamycin ◽  
High Volume ◽  
Threshold Effect ◽  
Sprague Dawley ◽  
Downstream Target ◽  
The Relationship

Resistance exercise (RE) volume is recognized as an important factor that stimulates muscle protein synthesis (MPS) and is considered, at least in part, to be involved in the mammalian target of rapamycin complex 1 (mTORC1)-associated signaling. However, the effects of relatively high-volume RE on mTORC1 and MPS remain unclear. In the present study, we used an animal model of RE to investigate the relationship between RE volume and MPS. Male Sprague-Dawley rats were subjected to RE, and muscle samples were obtained 6 h after performing 1, 3, 5, 10, or 20 sets of RE. Although 1 set of RE did not increase MPS [measured by the surface sensing of translation (SUnSET) method], multiple sets (3, 5, 10, and 20 sets) significantly increased MPS. However, the increase in MPS reached a plateau after 3 or 5 sets of RE, and no further increase in MPS was observed with additional RE sets. In contrast to the MPS response, we observed that p70S6K phosphorylation at Thr389, a marker of mTORC1 activity, and Ser240/244 phosphorylation of rpS6, a downstream target of p70S6K, gradually increased with higher RE volume. The above results suggest that the relationship between RE volume and MPS was not linear. Thus the increase in MPS with increasing RE volume saturates before p70S6K phosphorylation, suggesting a threshold effect for the relationship between p70S6K activation and MPS. NEW & NOTEWORTHY The aim of this study was to investigate the relationship between resistance exercise (RE) volume and muscle protein synthesis. We found that the relationship between RE volume and p70S6K phosphorylation was almost linear, but the increase in muscle protein synthesis began to plateau after approximately five sets of RE.

scholarly journals The anabolic role of plant-based proteins in response to chronic resistance exercise

2021 ◽  
Vol 11 (3) ◽  
pp. 14-23
Author(s):  
Carina Sousa Santos ◽  
Eudes Souza Oliveira Júnior ◽  
Marcus James Lopes de Sá ◽  
Elizabethe Adriana Esteves
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Resistance Exercise ◽  
Muscle Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
The Elderly ◽  
Food Sources ◽  
Dietary Adequacy ◽  
The Face

Proper maintenance of skeletal muscle mass is essential to prevent sarcopenia and ensure health and quality of life as aging progress. The two determinants of muscle protein synthesis are the increased load on skeletal muscle through resistance exercise and protein intake. For an effective result of maintaining or increasing muscle mass, it is relevant to consider the quantitative and adequate intake of protein, and the dietary source of protein since the plant-based protein has differences in comparison to animals that limit its anabolic capacity. Given the increase in vegetarianism and the elderly population, which consumes fewer food sources of animal protein, the importance of understanding how protein of plant-based protein can sustain muscle protein synthesis in the long term when associated with resistance exercise is justified, as well as the possibilities of dietary adequacy in the face of this demand.

Resistance exercise and nutrition to counteract muscle wasting

2009 ◽  
Vol 34 (5) ◽  
pp. 817-828 ◽  
Author(s):  
Jonathan P. Little ◽  
Stuart M. Phillips
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Muscle Mass ◽  
Muscle Wasting ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Effective Means ◽  
Resistance Exercise Training ◽  
Highly Effective

Loss of muscle mass is an unfavourable consequence of aging and many chronic diseases. The debilitating effects of muscle loss include declines in physical function and quality of life and increases in morbidity and mortality. Loss of muscle mass is the result of a decrease in muscle protein synthesis, an increase in muscle protein degradation, or a combination of both. Much research on muscle wasting has tended to focus on preventing muscle protein breakdown, and less attention has been paid to providing adequate stimulation to increase muscle protein synthesis. In this review, we present evidence to suggest that interventions aimed at increasing muscle protein synthesis represent the most effective countermeasure for preventing, delaying, or reversing the loss of skeletal muscle mass experienced in various muscle wasting conditions. Based on results from acute and chronic studies in humans in a wide variety of wasting conditions, we propose that resistance exercise training combined with appropriately timed protein (likely leucine-rich) ingestion represents a highly effective means to promote muscle hypertrophy, and may represent a highly effective treatment strategy to counteract the muscle wasting tassociated with aging and chronic disease.

Gaining Weight: The Scientific Basis of Increasing Skeletal Muscle Mass

1999 ◽  
Vol 24 (4) ◽  
pp. 305-316 ◽  
Author(s):  
Michael E. Houston
Keyword(s):  
Protein Synthesis ◽  
Resistance Training ◽  
Resistance Exercise ◽  
Muscle Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Recovery Period ◽  
Scientific Basis ◽  
Whole Body ◽  
Anabolic Hormone

Most athletes today tend to have a larger muscle mass than their predecessors. Better training and nutrition practices are responsible for much of this difference, but whatever the mechanism, the balance between muscle protein synthesis and breakdown must be in favor of increased muscle protein. Applying new techniques for measuring whole body and muscle protein synthesis to resistance exercise has led to some interesting results. In the recovery period following resistance exercise, both muscle protein synthesis and breakdown are accelerated in the fasted state. Ingestion of carbohydrate or carbohydrate and protein during recovery further increases muscle protein synthesis, due in part to an improved anabolic hormone environment. In addition, the anabolic effect of a resistance training bout may last well beyond 48 hours. Using information obtained from research studies, better training and dietary practices can optimize the benefits from resistance training, Key words: protein synthesis, protein breakdown, anabolic hormones, nutrition, resistance training

scholarly journals Essential amino acid and carbohydrate ingestion before resistance exercise does not enhance postexercise muscle protein synthesis

2009 ◽  
Vol 106 (5) ◽  
pp. 1730-1739 ◽  
Author(s):  
Satoshi Fujita ◽  
Hans C. Dreyer ◽  
Micah J. Drummond ◽  
Erin L. Glynn ◽  
Elena Volpi ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Resistance Exercise ◽  
Essential Amino Acid ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Exercise Bout ◽  
Control Group ◽  
Carbohydrate Ingestion ◽  
Postexercise Recovery

Ingestion of an essential amino acid-carbohydrate (EAA + CHO) solution following resistance exercise enhances muscle protein synthesis during postexercise recovery. It is unclear whether EAA + CHO ingestion before resistance exercise can improve direct measures of postexercise muscle protein synthesis (fractional synthetic rate; FSR). We hypothesized that EAA + CHO ingestion before a bout of resistance exercise would prevent the exercise-induced decrease in muscle FSR and would result in an enhanced rate of muscle FSR during postexercise recovery. We studied 22 young healthy subjects before, during, and for 2 h following a bout of high-intensity leg resistance exercise. The fasting control group ( n = 11) did not ingest nutrients, and the EAA + CHO group ( n = 11) ingested a solution of EAA + CHO 1 h before beginning the exercise bout. Stable isotopic methods were used in combination with muscle biopsies to determine FSR. Immunoblotting procedures were utilized to assess cell signaling proteins associated with the regulation of FSR. We found that muscle FSR increased in the EAA + CHO group immediately following EAA + CHO ingestion ( P < 0.05), returned to basal values during exercise, and remained unchanged at 1 h postexercise. Muscle FSR decreased in the fasting group during exercise and increased at 1 h postexercise ( P < 0.05). However, the 2 h postexercise FSR increased by ∼50% in both groups with no differences between groups ( P > 0.05). Eukaryotic elongation factor 2 phosphorylation was reduced in both groups at 2 h postexercise (EAA + CHO: 39 ± 7%; fasting: 47 ± 9%; P < 0.05). We conclude that EAA + CHO ingestion before resistance exercise does not enhance postexercise FSR compared with exercise without nutrients.

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.

Resistance exercise, muscle loading/unloading and the control of muscle mass

2006 ◽  
Vol 42 ◽  
pp. 61-74 ◽  
Author(s):  
Keith Baar ◽  
Gustavo Nader ◽  
Sue Bodine
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Muscle Mass ◽  
Translation Initiation ◽  
Muscle Protein ◽  
Mammalian Target Of Rapamycin ◽  
Complete Breakdown ◽  
Muscle Loading ◽  
The Difference ◽  
Exercise Muscle

Muscle mass is determined by the difference between the rate of protein synthesis and degradation. If synthesis is greater than degradation, muscle mass will increase (hypertrophy) and when the reverse is true muscle mass will decrease (atrophy). Following resistance exercise/increased loading there is a transient increase in protein synthesis within muscle. This change in protein synthesis correlates with an increase in the activity of protein kinase B/Akt and mTOR (mammalian target of rapamycin). mTOR increases protein synthesis by increasing translation initiation and by inducing ribosomal biogenesis. By contrast, unloading or inactivity results in a decrease in protein synthesis and a significant increase in muscle protein breakdown. The decrease in synthesis is due in part to the inactivation of mTOR and therefore a decrease in translation initiation, but also to a decrease in the rate of translation elongation. The increase in degradation is the result of a co-ordinated response of the calpains, lysosomal proteases and the ATP-dependent ubiquitin-proteosome. Caspase 3 and the calpains act upstream of the ubiquitin–proteosome system to assist in the complete breakdown of the myofibrillar proteins. Two muscle specific E3 ubiquitin ligases, MuRF1 and MAFbx/atrogen-1, have been identified as key regulators of muscle atrophy. In this chapter, these pathways and how the balance between anabolism and catabolism is affected by loading and unloading will be discussed.

scholarly journals A comparison of 2H2O and phenylalanine flooding dose to investigate muscle protein synthesis with acute exercise in rats

2009 ◽  
Vol 297 (1) ◽  
pp. E252-E259 ◽  
Author(s):  
Heath G. Gasier ◽  
Steven E. Riechman ◽  
Michael P. Wiggs ◽  
Stephen F. Previs ◽  
James D. Fluckey
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
High Intensity ◽  
Acute Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Primary Objective ◽  
Sprague Dawley ◽  
Sprague Dawley Rats ◽  
Single Bout

The primary objective of this investigation was to determine whether 2H2O and phenylalanine (Phe) flooding dose methods yield comparable fractional rates of protein synthesis (FSR) in skeletal muscle following a single bout of high-intensity resistance exercise (RE). Sprague-Dawley rats were assigned by body mass to either 4-h control (CON 4 h; n = 6), 4-h resistance exercise (RE 4 h; n = 6), 24-h control (CON 24 h; n = 6), or 24-h resistance exercise (RE 24 h; n = 6). The RE groups were operantly conditioned to engage in a single bout of high-intensity, “squat-like” RE. All rats were given an intraperitoneal injection of 99.9% 2H2O and provided 4.0% 2H2O drinking water for either 24 ( n = 12) or 4 h ( n = 12) prior to receiving a flooding dose of l-[2,3,4,5,6-3H]Phe 16 h post-RE. Neither method detected an effect of RE on FSR in the mixed gastrocnemius, plantaris, or soleus muscle. Aside from the qualitative similarities between methods, the 4-h 2H2O FSR measurements, when expressed in percent per hour, were quantitatively greater than the 24-h 2H2O and Phe flooding in all muscles ( P < 0.001), and the 24-h 2H2O was greater than the Phe flooding dose in the mixed gastrocnemius and plantaris ( P < 0.05). In contrast, the actual percentage of newly synthesized protein was significantly higher in the 24- vs. 4-h 2H2O and Phe flooding dose groups ( P < 0.001). These results suggest that the methodologies provide “qualitatively” similar results when a perturbation such as RE is studied. However, due to potential quantitative differences between methods, the experimental question should determine what approach should be used.

Myofibrillar disruption following acute concentric and eccentric resistance exercise in strength-trained men

2000 ◽  
Vol 78 (8) ◽  
pp. 656-661 ◽  
Author(s):  
Martin J Gibala ◽  
Stephen A Interisano ◽  
Mark A Tarnopolsky ◽  
Brian D Roy ◽  
Jay R MacDonald ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Resistance Exercise ◽  
Biceps Brachii ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Exercise Bout ◽  
Post Exercise ◽  
Acute Bout ◽  
Baseline Values ◽  
Eccentric Actions

We have previously quantified the extent of myofibrillar disruption which occurs following an acute bout of resistance exercise in untrained men, however the response of well-trained subjects is not known. We therefore recruited six strength-trained men, who ceased training for 5 days and then performed 8 sets of 8 uni-lateral repetitions, using a load equivalent to 80% of their concentric (Con) 1-repetition maximum. One arm performed only Con actions by lifting the weight and the other arm performed only eccentric actions (Ecc) by lowering it. Needle biopsy samples were obtained from biceps brachii of each arm ~21 h following exercise, and at baseline (i.e., after 5 days without training), and subsequently analyzed using electron microscopy to quantify myofibrillar disruption. A greater (P [Formula: see text] 0.05) proportion of disrupted fibres was found in the Ecc arm (45 ± 11%) compared with baseline values (4 ± 2%), whereas fibre disruption in the Con arm (27 ± 4%) was not different (P > 0.05) from baseline values. The proportion of disrupted fibres and the magnitude of disruption (quantified by sarcomere counting) was considerably less severe than previously observed in untrained subjects after an identical exercise bout. Mixed muscle protein synthesis, assessed from ~21-29 h post-exercise, was not different between the Con- and Ecc-exercised arms. We conclude that the Ecc phase of resistance exercise is most disruptive to skeletal muscle and that training attenuates the severity of this effect. Moreover, it appears that fibre disruption induced by habitual weightlifting exercise is essentially repaired after 5 days of inactivity in trained men.Key words: muscle damage, muscle injury, protein synthesis, hypertrophy, leucine.

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