Habitual high-protein diet does not influence muscle protein synthesis in response to acute resistance exercise in rats

Ferrando, Arny A., Kevin D. Tipton, Marcas M. Bamman, and Robert R. Wolfe. Resistance exercise maintains skeletal muscle protein synthesis during bed rest. J. Appl. Physiol. 82(3): 807–810, 1997.—Spaceflight results in a loss of lean body mass and muscular strength. A ground-based model for microgravity, bed rest, results in a loss of lean body mass due to a decrease in muscle protein synthesis (MPS). Resistance training is suggested as a proposed countermeasure for spaceflight-induced atrophy because it is known to increase both MPS and skeletal muscle strength. We therefore hypothesized that scheduled resistance training throughout bed rest would ameliorate the decrease in MPS. Two groups of healthy volunteers were studied during 14 days of simulated microgravity. One group adhered to strict bed rest (BR; n = 5), whereas a second group engaged in leg resistance exercise every other day throughout bed rest (BREx; n = 6). MPS was determined directly by the incorporation of infusedl-[ ring-13C6]phenylalanine into vastus lateralis protein. After 14 days of bed rest, MPS in the BREx group did not change and was significantly greater than in the BR group. Thus moderate-resistance exercise can counteract the decrease in MPS during bed rest.

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Exercise May Promote Skeletal Muscle Hypertrophy via Enhancing Leucine-Sensing: Preliminary Evidence

Frontiers in Physiology ◽

10.3389/fphys.2021.741038 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yan Zhao ◽

Jason Cholewa ◽

Huayu Shang ◽

Yueqin Yang ◽

Xiaomin Ding ◽

...

Keyword(s):

Protein Synthesis ◽

Resistance Exercise ◽

Aerobic Exercise ◽

Protein Concentration ◽

Muscle Hypertrophy ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Muscle Fibers ◽

Mtor Signaling ◽

Treadmill Running

Several studies have indicated a positive effect of exercise (especially resistance exercise) on the mTOR signaling that control muscle protein synthesis and muscle remodeling. However, the relationship between exercise, mTOR activation and leucine-sensing requires further clarification. Two month old Sprague-Dawley rats were subjected to aerobic exercise (treadmill running at 20 m/min, 6° incline for 60 min) and resistance exercise (incremental ladder climbing) for 4 weeks. The gastrocnemius muscles were removed for determination of muscle fibers diameter, cross-sectional area (CSA), protein concentration and proteins involved in muscle leucine-sensing and protein synthesis. The results show that 4 weeks of resistance exercise increased the diameter and CSA of gastrocnemius muscle fibers, protein concentration, the phosphorylation of mTOR (Ser2448), 4E-BP1(Thr37/46), p70S6K (Thr389), and the expression of LeuRS, while aerobic exercise just led to a significant increase in protein concentration and the phosphorylation of 4E-BP1(Thr37/46). Moreover, no difference was found for Sestrin2 expression between groups. The current study shows resistance exercise, but not aerobic exercise, may increase muscle protein synthesis and protein deposition, and induces muscle hypertrophy through LeuRS/mTOR signaling pathway. However, further studies are still warranted to clarify the exact effects of vary intensities and durations of aerobic exercise training.

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The effect of light load resistance exercise and whey protein supplementation on muscle protein synthesis and amino‐acid transporters in elderly (702.7)

The FASEB Journal ◽

10.1096/fasebj.28.1_supplement.702.7 ◽

2014 ◽

Vol 28 (S1) ◽

Author(s):

Jakob Agergaard ◽

Jacob Bülow ◽

Jacob Kildevang Jensen ◽

Søren Reitelseder ◽

Peter Schjerling ◽

...

Keyword(s):

Protein Synthesis ◽

Amino Acid ◽

Resistance Exercise ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Load Resistance ◽

Protein Supplementation ◽

Amino Acid Transporters ◽

Light Load ◽

Effect Of Light

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RESISTANCE EXERCISE PREVENTS THE DECREASE OF MUSCLE PROTEIN SYNTHESIS DURING PROLONGED BED REST 776

Medicine & Science in Sports & Exercise ◽

10.1097/00005768-199605001-00774 ◽

1996 ◽

Vol 28 (Supplement) ◽

pp. 130

Author(s):

A. A. Ferrando ◽

K. D. Tipton ◽

M. M. Bamman ◽

R. R. Wolfe

Keyword(s):

Protein Synthesis ◽

Resistance Exercise ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Bed Rest

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Rapamycin‐insensitive mechanistic target of rapamycin regulates basal and resistance exercise‐induced muscle protein synthesis

The FASEB Journal ◽

10.1096/fj.201701422r ◽

2018 ◽

Vol 32 (11) ◽

pp. 5824-5834 ◽

Cited By ~ 20

Author(s):

Riki Ogasawara ◽

Takeshi Suginohara

Keyword(s):

Protein Synthesis ◽

Resistance Exercise ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Target Of Rapamycin ◽

Mechanistic Target Of Rapamycin ◽

Exercise Induced

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A Clinically Relevant Decrease in Contractile Force Differentially Regulates Control of Glucocorticoid Receptor Translocation in Mouse Skeletal Muscle

Journal of Applied Physiology ◽

10.1152/japplphysiol.01064.2020 ◽

2021 ◽

Author(s):

Kirsten R. Dunlap ◽

Jennifer L. Steiner ◽

Michael L. Rossetti ◽

Scot R. Kimball ◽

Bradley S. Gordon

Keyword(s):

Protein Synthesis ◽

Glucocorticoid Receptor ◽

Resistance Exercise ◽

Muscle Atrophy ◽

Nuclear Translocation ◽

Muscle Protein ◽

Muscle Protein Synthesis ◽

Contractile Force ◽

Force Generation ◽

Protein Balance

Muscle atrophy decreases physical function and overall health. Increased glucocorticoid production and/or use of prescription glucocorticoids can significantly induce muscle atrophy by activating the glucocorticoid receptor thereby transcribing genes that shift protein balance in favor of net protein degradation. While mechanical overload can blunt glucocorticoid-induced atrophy in young muscle, those affected by glucocorticoids generally have impaired force generation. It is unknown whether contractile force alters the ability of resistance exercise to mitigate glucocorticoid receptor translocation and induce a desirable shift in protein balance when glucocorticoids are elevated. In the present study, mice were subjected to a single bout of unilateral, electrically induced muscle contractions by stimulating the sciatic nerve at 100 Hz or 50 Hz frequencies to elicit high force or moderate force contractions of the tibialis anterior, respectively. Dexamethasone was used to activate the glucocorticoid receptor. Dexamethasone increased glucocorticoid signaling, including nuclear translocation of the receptor, but this was mitigated only by high force contractions. The ability of high force contractions to mitigate glucocorticoid receptor translocation coincided with a contraction-mediated increase in muscle protein synthesis, which did not occur in the dexamethasone treated mice subjected to moderate force contractions. Though moderate force contractions failed to increase protein synthesis following dexamethasone treatment, both high and moderate force contractions blunted the glucocorticoid-mediated increase in LC3 II:I marker of autophagy. Thus, these data show that force generation is important for the ability of resistance exercise to mitigate glucocorticoid receptor translocation and promote a desirable shift in protein balance when glucocorticoids are elevated.

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