scholarly journals Exercise, Protein Metabolism, and Muscle Growth

2001 ◽  
Vol 11 (1) ◽  
pp. 109-132 ◽  
Author(s):  
Kevin D. Tipton ◽  
Robert R. Wolfe
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Muscle Hypertrophy ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Muscle Growth ◽  
Protein Breakdown ◽  
Muscle Protein Breakdown ◽  
Amino Acid Availability ◽  
Muscle Protein Metabolism

Exercise has a profound effect on muscle growth, which can occur only if muscle protein synthesis exceeds muscle protein breakdown; there must be a positive muscle protein balance. Resistance exercise improves muscle protein balance, but, in the absence of food intake, the balance remains negative (i.e., catabolic). The response of muscle protein metabolism to a resistance exercise bout lasts for 24-48 hours; thus, the interaction between protein metabolism and any meals consumed in this period will determine the impact of the diet on muscle hypertrophy. Amino acid availability is an important regulator of muscle protein metabolism. The interaction of postexercise metabolic processes and increased amino acid availability maximizes the stimulation of muscle protein synthesis and results in even greater muscle anabolism than when dietary amino acids are not present. Hormones, especially insulin and testosterone, have important roles as regulators of muscle protein synthesis and muscle hypertrophy. Following exercise, insulin has only a permissive role on muscle protein synthesis, but it appears to inhibit the increase in muscle protein breakdown. Ingestion of only small amounts of amino acids, combined with carbohydrates, can transiently increase muscle protein anabolism, but it has yet to be determined if these transient responses translate into an appreciable increase in muscle mass over a prolonged training period.

Muscle protein metabolism in female swimmers after a combination of resistance and endurance exercise

1996 ◽  
Vol 81 (5) ◽  
pp. 2034-2038 ◽  
Author(s):  
Kevin D. Tipton ◽  
Arny A. Ferrando ◽  
Bradley D. Williams ◽  
Robert R. Wolfe
Keyword(s):  
Protein Synthesis ◽  
Resistance Training ◽  
Endurance Exercise ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Whole Body ◽  
Protein Breakdown ◽  
Body Protein ◽  
Muscle Protein Metabolism

Tipton, Kevin D., Arny A. Ferrando, Bradley D. Williams, and Robert R. Wolfe. Muscle protein metabolism in female swimmers after a combination of resistance and endurance exercise. J. Appl. Physiol. 81(5): 2034–2038, 1996.—There is little known about the responses of muscle protein metabolism in women to exercise. Furthermore, the effect of adding resistance training to an endurance training regimen on net protein anabolism has not been established in either men or women. The purpose of this study was to quantify the acute effects of combined swimming and resistance training on protein metabolism in female swimmers by the direct measurement of muscle protein synthesis and whole body protein degradation. Seven collegiate female swimmers were each studied on four separate occasions with a primed constant infusion of ring-[13C6]phenylalanine (Phe) to measure the fractional synthetic rate (FSR) of the posterior deltoid and whole body protein breakdown. Measurements were made over a 5-h period at rest and after each of three randomly ordered workouts: 1) 4,600 m of intense interval swimming (SW); 2) a whole body resistance-training workout with no swimming on that day (RW); and 3) swimming and resistance training combined (SR). Whole body protein breakdown was similar for all treatments (0.75 ± 0.04, 0.69 ± 0.03, 0.69 ± 0.02, and 0.71 ± 0.04 μmol ⋅ min−1 ⋅ kg−1for rest, RW, SW, and SR, respectively). The FSR of the posterior deltoid was significantly greater ( P< 0.05) after SR (0.082 ± 0.015%/h) than at rest (0.045 ± 0.006%/h). There was no significant difference in the FSR after RW (0.048 ± 0.004%/h) or SW (0.064 ± 0.008%/h) from rest or from SR. These data indicate that the combination of swimming and resistance exercise stimulates net muscle protein synthesis above resting levels in female swimmers.

Epinephrine depletion exacerbates the fasting-induced protein breakdown in fast-twitch skeletal muscles

2013 ◽  
Vol 305 (12) ◽  
pp. E1483-E1494 ◽  
Author(s):  
Flávia A. Graça ◽  
Dawit A. P. Gonçalves ◽  
Wilian A. Silveira ◽  
Eduardo C. Lira ◽  
Valéria Ernestânia Chaves ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Skeletal Muscles ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Physiological Role ◽  
Protein Breakdown ◽  
Muscle Protein Metabolism ◽  
Fast Twitch ◽  
Fasted Rats

The physiological role of epinephrine in the regulation of skeletal muscle protein metabolism under fasting is unknown. We examined the effects of plasma epinephrine depletion, induced by adrenodemedullation (ADMX), on muscle protein metabolism in fed and 2-day-fasted rats. In fed rats, ADMX for 10 days reduced muscle mass, the cross-sectional area of extensor digitorum longus (EDL) muscle fibers, and the phosphorylation levels of Akt. In addition, ADMX led to a compensatory increase in muscle sympathetic activity, as estimated by the rate of norepinephrine turnover; this increase was accompanied by high rates of muscle protein synthesis. In fasted rats, ADMX exacerbated fasting-induced proteolysis in EDL but did not affect the low rates of protein synthesis. Accordingly, ADMX activated lysosomal proteolysis and further increased the activity of the ubiquitin (Ub)-proteasome system (UPS). Moreover, expression of the atrophy-related Ub ligases atrogin-1 and MuRF1 and the autophagy-related genes LC3b and GABARAPl1 were upregulated in EDL muscles from ADMX-fasted rats compared with sham-fasted rats, and ADMX reduced cAMP levels and increased fasting-induced Akt dephosphorylation. Unlike that observed for EDL muscles, soleus muscle proteolysis and Akt phosphorylation levels were not affected by ADMX. In isolated EDL, epinephrine reduced the basal UPS activity and suppressed overall proteolysis and atrogin-1 and MuRF1 induction following fasting. These data suggest that epinephrine released from the adrenal medulla inhibits fasting-induced protein breakdown in fast-twitch skeletal muscles, and these antiproteolytic effects on the UPS and lysosomal system are apparently mediated through a cAMP-Akt-dependent pathway, which suppresses ubiquitination and autophagy.

scholarly journals Short-term insulin and nutritional energy provision do not stimulate muscle protein synthesis if blood amino acid availability decreases

2005 ◽  
Vol 289 (6) ◽  
pp. E999-E1006 ◽  
Author(s):  
Jill A. Bell ◽  
Satoshi Fujita ◽  
Elena Volpi ◽  
Jerson G. Cadenas ◽  
Blake B. Rasmussen
Keyword(s):  
Protein Synthesis ◽  
Amino Acid ◽  
Insulin Infusion ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Protein Breakdown ◽  
Short Term ◽  
Muscle Protein Breakdown ◽  
Amino Acid Availability ◽  
Leg Muscle

Muscle protein synthesis requires energy and amino acids to proceed and can be stimulated by insulin under certain circumstances. We hypothesized that short-term provision of insulin and nutritional energy would stimulate muscle protein synthesis in healthy subjects only if amino acid availability did not decrease. Using stable isotope techniques, we compared the effects on muscle phenylalanine kinetics across the leg of an amino acid-lowering, high-energy (HE, n = 6, 162 ± 20 kcal/h) hyperglycemic hyperlipidemic hyperinsulinemic clamp with systemic insulin infusion to a low-energy (LE, n = 6, 35 ± 3 kcal/h, P < 0.05 vs. HE) euglycemic hyperinsulinemic clamp with local insulin infusion in the femoral artery. Basal blood phenylalanine concentrations and phenylalanine net balance, muscle protein breakdown, and synthesis (nmol·min−1·100 g leg muscle−1) were not different between groups. During insulin infusion, femoral insulinemia increased to a similar extent between groups and blood phenylalanine concentration decreased 27 ± 3% in the HE group but only 9 ± 2% in the LE group ( P < 0.01 HE vs. LE). Phenylalanine net balance increased in both groups, but the change was greater ( P < 0.05) in the LE group. Muscle protein breakdown decreased in the HE group (58 ± 12 to 35 ± 7 nmol·min−1·100 g leg muscle−1) and did not change in the LE group. Muscle protein synthesis was unchanged in the HE group (39 ± 6 to 30 ± 7 nmol·min−1·100 g leg muscle−1) and increased ( P < 0.05) in the LE group (41 ± 9 to 114 ± 26 nmol·min−1·100 g leg muscle−1). We conclude that amino acid availability is an important factor in the regulation of muscle protein synthesis in response to insulin, as decreased blood amino acid concentrations override the positive effect of insulin on muscle protein synthesis even if excess energy is provided.

scholarly journals Glucocorticoid effects on insulin- and IGF-I-regulated muscle protein metabolism during aging

1998 ◽  
Vol 156 (1) ◽  
pp. 83-89 ◽  
Author(s):  
D Dardevet ◽  
C Sornet ◽  
I Savary ◽  
E Debras ◽  
P Patureau-Mirand ◽  
...  
Keyword(s):  
Protein Synthesis ◽  
Muscle Atrophy ◽  
Protein Metabolism ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Recovery Period ◽  
Adult Rats ◽  
Igf I ◽  
Muscle Protein Metabolism ◽  
Old Rats

This study was performed to assess the effect of glucocorticoids (dexamethasone) on insulin- and IGF-I-regulated muscle protein metabolism in adult and old rats. Muscle atrophy occurred more rapidly in old rats, and recovery of muscle mass was impaired when compared with adults. Muscle wasting resulted mainly from increased protein breakdown in adult rat but from depressed protein synthesis in the aged animal. Glucocorticoid treatment significantly decreased the stimulatory effect of insulin and IGF-I on muscle protein synthesis in adult rats by 25.9 and 58.1% respectively. In old rats, this effect was even greater, being 49.3 and 100% respectively. With regard to muscle proteolysis, glucocorticoids blunted the anti-proteolytic action of insulin and IGF-I in both age groups. During the recovery period, adult rats reversed the glucocorticoid-induced resistance of muscle protein metabolism within 3 days, at which time old rats still exhibited the decrease in insulin-regulated proteolysis. In conclusion, the higher sensitivity of old rat muscle to glucocorticoids may in part result from the greater modification of the effects of insulin and IGF-I on muscle protein metabolism. These responses to glucocorticoids in old rats may be associated with the emergence of muscle atrophy with advancing age.

Effect of exercise and recovery on muscle protein synthesis in human subjects

1990 ◽  
Vol 259 (4) ◽  
pp. E470-E476 ◽  
Author(s):  
F. Carraro ◽  
C. A. Stuart ◽  
W. H. Hartl ◽  
J. Rosenblatt ◽  
R. R. Wolfe
Keyword(s):  
Protein Synthesis ◽  
Aerobic Exercise ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Nitrogen Excretion ◽  
Control Group ◽  
Protein Breakdown ◽  
Muscle Protein Breakdown ◽  
Synthetic Rate ◽  
Fractional Synthetic Rate

Previous studies using indirect means to assess the response of protein metabolism to exercise have led to conflicting conclusions. Therefore, in this study we have measured the rate of muscle protein synthesis in normal volunteers at rest, at the end of 4 h of aerobic exercise (40% maximal O2 consumption), and after 4 h of recovery by determining directly the rate of incorporation of 1,2-[13C]leucine into muscle. The rate of muscle protein breakdown was assessed by 3-methylhistidine (3-MH) excretion, and total urinary nitrogen excretion was also measured. There was an insignificant increase in 3-MH excretion in exercise of 37% and a significant increase (P less than 0.05) of 85% during 4 h of recovery from exercise (0.079 +/- 0.008 vs. 0.147 +/- 0.0338 mumol.kg-1.min-1 for rest and recovery from exercise, respectively). Nonetheless, there was no effect of exercise on total nitrogen excretion. Muscle fractional synthetic rate was not different in the exercise vs. the control group at the end of exercise (0.0417 +/- 0.004 vs. 0.0477 +/- 0.010%/h for exercise vs. control), but there was a significant increase in fractional synthetic rate in the exercise group during the recovery period (0.0821 +/- 0.006 vs. 0.0654 +/- 0.012%/h for exercise vs. control, P less than 0.05). Thus we conclude that although aerobic exercise may stimulate muscle protein breakdown, this does not result in a significant depletion of muscle mass because muscle protein synthesis is stimulated in recovery.

Muscle Protein Metabolism in the Elderly: Influence of Exercise and Nutrition

2001 ◽  
Vol 26 (6) ◽  
pp. 588-606 ◽  
Author(s):  
Kevin D. Tipton
Keyword(s):  
Protein Synthesis ◽  
Muscle Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Effective Means ◽  
The Elderly ◽  
Protein Breakdown ◽  
Small Magnitude ◽  
Muscle Protein Breakdown ◽  
Metabolic Basis

Although the causes of sarcopenia are multi-factorial, at least some, such as poor nutrition and inactivity, may be preventable. Changes in muscle mass must be a result of net muscle protein breakdown over that particular time period. Stable isotope methodology has been used to examine the metabolic basis of muscle loss. Net muscle protein breakdown may occur due to a decrease in the basal level of muscle protein synthesis. However, changes of this type would likely be of small magnitude and undetectable by current methodology. Hormonal mediators may also be important, especially in association with forced inactivity. Net muscle protein breakdown may be also attributed to alterations in the periods of net muscle protein synthesis and breakdown each day. Reduced activity, combined with ineffectual nutrient intake, could lead to decreased net muscle protein balance. Chronic resistance exercise training clearly is an effective means of increasing muscle mass and strength in elderly individuals. Although sometimes limited, acute metabolic studies provide valuable information for maintenance of muscle mass with age. Key words: sarcopenia, inactivity, strength training, muscle protein synthesis, muscle hypertrophy

Exercise training and protein metabolism: influences of contraction, protein intake, and sex-based differences

2009 ◽  
Vol 106 (5) ◽  
pp. 1692-1701 ◽  
Author(s):  
Nicholas A. Burd ◽  
Jason E. Tang ◽  
Daniel R. Moore ◽  
Stuart M. Phillips
Keyword(s):  
Signaling Pathways ◽  
Protein Turnover ◽  
Muscle Hypertrophy ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Protein Breakdown ◽  
Muscle Protein Turnover ◽  
Muscle Protein Breakdown ◽  
Response To Exercise ◽  
Net Protein

Muscle contraction during exercise, whether resistive or endurance in nature, has profound affects on muscle protein turnover that can persist for up to 72 h. It is well established that feeding during the postexercise period is required to bring about a positive net protein balance (muscle protein synthesis − muscle protein breakdown). There is mounting evidence that the timing of ingestion and the protein source during recovery independently regulate the protein synthetic response and influence the extent of muscle hypertrophy. Minor differences in muscle protein turnover appear to exist in young men and women; however, with aging there may be more substantial sex-based differences in response to both feeding and resistance exercise. The recognition of anabolic signaling pathways and molecules are also enhancing our understanding of the regulation of protein turnover following exercise perturbations. In this review we summarize the current understanding of muscle protein turnover in response to exercise and feeding and highlight potential sex-based dimorphisms. Furthermore, we examine the underlying anabolic signaling pathways and molecules that regulate these processes.

Age and aerobic exercise training effects on whole body and muscle protein metabolism

2004 ◽  
Vol 286 (1) ◽  
pp. E92-E101 ◽  
Author(s):  
Kevin R. Short ◽  
Janet L. Vittone ◽  
Maureen L. Bigelow ◽  
David N. Proctor ◽  
K. Sreekumaran Nair
Keyword(s):  
Protein Synthesis ◽  
Exercise Training ◽  
Protein Metabolism ◽  
Protein Turnover ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Fat Free Mass ◽  
Whole Body ◽  
Men And Women ◽  
Muscle Protein Metabolism

Aging in humans is associated with loss of lean body mass, but the causes are incompletely defined. Lean tissue mass and function depend on continuous rebuilding of proteins. We tested the hypotheses that whole body and mixed muscle protein metabolism declines with age in men and women and that aerobic exercise training would partly reverse this decline. Seventy-eight healthy, previously untrained men and women aged 19-87 yr were studied before and after 4 mo of bicycle training (up to 45 min at 80% peak heart rate, 3-4 days/wk) or control (flexibility) activity. At the whole body level, protein breakdown (measured as [13C]leucine and [15N]phenylalanine flux), Leu oxidation, and protein synthesis (nonoxidative Leu disposal) declined with age at a rate of 4-5% per decade ( P < 0.001). Fat-free mass was closely correlated with protein turnover and declined 3% per decade ( P < 0.001), but even after covariate adjustment for fat-free mass, the decline in protein turnover with age remained significant. There were no differences between men and women after adjustment for fat-free mass. Mixed muscle protein synthesis also declined with age 3.5% per decade ( P < 0.05). Exercise training improved aerobic capacity 9% overall ( P < 0.01), and mixed muscle protein synthesis increased 22% ( P < 0.05), with no effect of age on the training response for either variable. Fat-free mass, whole body protein turnover, and resting metabolic rate were unchanged by training. We conclude that rates of whole body and muscle protein metabolism decline with age in men and women, thus indicating that there is a progressive decline in the body's remodeling processes with aging. This study also demonstrates that aerobic exercise can enhance muscle protein synthesis irrespective of age.

scholarly journals Combined in vivo muscle mass, muscle protein synthesis and muscle protein breakdown measurement: a ‘Combined Oral Stable Isotope Assessment of Muscle (COSIAM)’ approach

GeroScience ◽  
2021 ◽  
Author(s):  
Jessica Cegielski ◽  
Daniel J. Wilkinson ◽  
Matthew S. Brook ◽  
Catherine Boereboom ◽  
Bethan E. Phillips ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Protein Synthesis ◽  
Stable Isotope ◽  
Muscle Mass ◽  
Protein Turnover ◽  
Skeletal Muscle Mass ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Protein Breakdown ◽  
Muscle Protein Breakdown

AbstractOptimising approaches for measuring skeletal muscle mass and turnover that are widely applicable, minimally invasive and cost effective is crucial in furthering research into sarcopenia and cachexia. Traditional approaches for measurement of muscle protein turnover require infusion of expensive, sterile, isotopically labelled tracers which limits the applicability of these approaches in certain populations (e.g. clinical, frail elderly). To concurrently quantify skeletal muscle mass and muscle protein turnover i.e. muscle protein synthesis (MPS) and muscle protein breakdown (MPB), in elderly human volunteers using stable-isotope labelled tracers i.e. Methyl-[D3]-creatine (D3-Cr), deuterium oxide (D2O), and Methyl-[D3]-3-methylhistidine (D3-3MH), to measure muscle mass, MPS and MPB, respectively. We recruited 10 older males (71 ± 4 y, BMI: 25 ± 4 kg.m2, mean ± SD) into a 4-day study, with DXA and consumption of D2O and D3-Cr tracers on day 1. D3-3MH was consumed on day 3, 24 h prior to returning to the lab. From urine, saliva and blood samples, and a single muscle biopsy (vastus lateralis), we determined muscle mass, MPS and MPB. D3-Cr derived muscle mass was positively correlated to appendicular fat-free mass (AFFM) estimated by DXA (r = 0.69, P = 0.027). Rates of cumulative myofibrillar MPS over 3 days were 0.072%/h (95% CI, 0.064 to 0.081%/h). Whole-body MPB over 6 h was 0.052 (95% CI, 0.038 to 0.067). These rates were similar to previous literature. We demonstrate the potential for D3-Cr to be used alongside D2O and D3-3MH for concurrent measurement of muscle mass, MPS, and MPB using a minimally invasive design, applicable for clinical and frail populations.

Anabolic resistance: the effects of aging, sexual dimorphism, and immobilization on human muscle protein turnoverThis paper is one of a selection of papers published in this Special Issue, entitled 14th International Biochemistry of Exercise Conference – Muscles as Molecular and Metabolic Machines, and has undergone the Journal’s usual peer review process.

2009 ◽  
Vol 34 (3) ◽  
pp. 377-381 ◽  
Author(s):  
Michael J. Rennie
Keyword(s):  
Protein Synthesis ◽  
Protein Metabolism ◽  
Older Persons ◽  
Muscle Protein ◽  
Muscle Protein Synthesis ◽  
Response Relationship ◽  
Dose Response Relationship ◽  
Anabolic Resistance ◽  
Muscle Protein Metabolism ◽  
The Right

In healthy active older persons, there is no derangement of muscle protein metabolism. However, there is a major deficit in the ability of older muscles to regulate their maintenance during feeding and exercise. The dose–response relationship between myofibrillar protein synthesis and the availability of essential amino acids (EAA) is shifted down and to the right, and giving extra amino acids is unable to overcome this. There is no sex difference in basal or fed muscle protein metabolism in the young, but postmenopausal women have a greater anabolic resistance than older men. Anabolic resistance is also shown by the decreased phosphorylation in the PKB–mTOR–eIF4BP1 pathway in response to increased EAA. The muscle synthetic system is refractory to EAA provision, irrespective of the availability of insulin, insulin-like growth factor 1, and growth hormone. However, insulin is a major regulator of muscle protein breakdown, and there is a blunting of the ability of older muscle to decrease proteolysis in response to low concentrations of insulin, such as those observed after a light breakfast. Providing more EAA seems not to be useful, and modern N-balance data confirm that the dietary protein requirements of older persons are not increased. The sigmoidal dose–response relationship between muscle protein synthesis and resistance exercise intensity is shifted downward and to the right in older men. Decreased physical activity itself, even in young subjects, can produce anabolic resistance of muscle protein synthesis, which cannot be overcome by increasing amino acid availability. Exercise may retune the amino acid and (or) insulin sensitivity of muscle in older people.

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