IMPEDANCE MEASUREMENTS ARE RELATED TO DIETOR EXERCISE-INDUCED CHANGES IN SKELETAL MUSCLE MASS

AbstractPhosphatidylinositol 3-kinase (PI3K) plays an important role in protein metabolism and cell growth. We here show that mice (M-PDK1KO mice) with skeletal muscle–specific deficiency of 3′-phosphoinositide–dependent kinase 1 (PDK1), a key component of PI3K signaling pathway, manifest a reduced skeletal muscle mass under the static condition as well as impairment of mechanical load–induced muscle hypertrophy. Whereas mechanical load-induced changes in gene expression were not affected, the phosphorylation of ribosomal protein S6 kinase (S6K) and S6 induced by mechanical load was attenuated in skeletal muscle of M-PDK1KO mice, suggesting that PDK1 regulates muscle hypertrophy not through changes in gene expression but through stimulation of kinase cascades such as the S6K-S6 axis, which plays a key role in protein synthesis. Administration of the β2-adrenergic receptor (AR) agonist clenbuterol activated the S6K-S6 axis in skeletal muscle and induced muscle hypertrophy in mice. These effects of clenbuterol were attenuated in M-PDK1KO mice, and mechanical load–induced activation of the S6K-S6 axis and muscle hypertrophy were inhibited in mice with skeletal muscle–specific deficiency of β2-AR. Our results suggest that PDK1 regulates skeletal muscle mass under the static condition and that it contributes to mechanical load–induced muscle hypertrophy, at least in part by mediating signaling from β2-AR.

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RESISTANCE TRAINING-INDUCED CHANGES IN TOTAL BODY SKELETAL MUSCLE MASS AND DISTRIBUTION

Medicine & Science in Sports & Exercise ◽

10.1097/00005768-200305001-01639 ◽

2003 ◽

Vol 35 (Supplement 1) ◽

pp. S294

Author(s):

K Kojima ◽

T Abe ◽

C F. Kearns ◽

T Aoba ◽

T Matsumoto

Keyword(s):

Skeletal Muscle ◽

Resistance Training ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

Total Body ◽

Induced Changes

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Effects of higher habitual protein intake on resistance-training-induced changes in body composition and muscular strength in untrained older women: A clinical trial study

Nutrition and Health ◽

10.1177/0260106019838365 ◽

2019 ◽

Vol 25 (2) ◽

pp. 103-112 ◽

Cited By ~ 1

Author(s):

Hellen CG Nabuco ◽

Crisieli M Tomeleri ◽

Paulo Sugihara Junior ◽

Rodrigo R Fernandes ◽

Edilaine F Cavalcante ◽

...

Keyword(s):

Skeletal Muscle ◽

Body Composition ◽

Older Women ◽

Muscle Mass ◽

Protein Intake ◽

Muscular Strength ◽

Skeletal Muscle Mass ◽

High Protein ◽

High Protein Intake ◽

Induced Changes

Background: Aging is accompanied by progressive and accentuated decline in muscular strength and skeletal muscle mass, affecting health and functional autonomy. Both resistance training (RT) and diet are strategies that may contribute to improvement in the health of the elderly. Aim: The purpose of this study was to evaluate the effects of higher habitual protein intake on RT-induced changes in body composition and strength in untrained postmenopausal women. Methods: Seventy older women were submitted to an RT program. Body composition, muscular strength, and dietary intake (24 h dietary recall) were performed pre- and post-intervention. To verify different intervention effects according to protein intake of the participants, the sample was separated into tertiles according to protein intake: low, moderate, and high protein intake. Results: A time vs. group interaction ( p < 0.05) was observed, with high protein intake presenting greater increases compared with low protein intake, for skeletal muscle mass (5.3% vs. 1.3%), lower limb lean soft tissue (4.9% vs. 1.4%), upper lean soft tissue (4.9% vs. 1.2%), preacher curl (24% vs. 15.2%), and total strength (16.4% vs. 11.7%). A time vs. group interaction ( p < 0.05) was observed, with high protein intake presenting greater increases compared with moderate protein intake, for skeletal muscle mass (5.3% vs. 3.2%). In all groups, a main effect of time ( p < 0.05) was observed for knee extension and chest press. Conclusions: We conclude that intake of >1.0 g/kg/day of protein promotes gains in skeletal muscle mass and muscular strength after RT in untrained older women.

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Recent advances in understanding resistance exercise training-induced skeletal muscle hypertrophy in humans

F1000Research ◽

10.12688/f1000research.21588.1 ◽

2020 ◽

Vol 9 ◽

pp. 141 ◽

Cited By ~ 3

Author(s):

Sophie Joanisse ◽

Changhyun Lim ◽

James McKendry ◽

Jonathan C. Mcleod ◽

Tanner Stokes ◽

...

Keyword(s):

Skeletal Muscle ◽

Resistance Exercise ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

Muscle Hypertrophy ◽

Resistance Exercise Training ◽

Skeletal Muscle Hypertrophy ◽

Recent Advances ◽

Development And Utilization ◽

Exercise Induced

Skeletal muscle plays a pivotal role in the maintenance of physical and metabolic health and, critically, mobility. Accordingly, strategies focused on increasing the quality and quantity of skeletal muscle are relevant, and resistance exercise is foundational to the process of functional hypertrophy. Much of our current understanding of skeletal muscle hypertrophy can be attributed to the development and utilization of stable isotopically labeled tracers. We know that resistance exercise and sufficient protein intake act synergistically and provide the most effective stimuli to enhance skeletal muscle mass; however, the molecular intricacies that underpin the tremendous response variability to resistance exercise-induced hypertrophy are complex. The purpose of this review is to discuss recent studies with the aim of shedding light on key regulatory mechanisms that dictate hypertrophic gains in skeletal muscle mass. We also aim to provide a brief up-to-date summary of the recent advances in our understanding of skeletal muscle hypertrophy in response to resistance training in humans.

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Plasma Nucleotide Dynamics during Exercise and Recovery in Highly Trained Athletes and Recreationally Active Individuals

BioMed Research International ◽

10.1155/2018/4081802 ◽

2018 ◽

Vol 2018 ◽

pp. 1-11 ◽

Cited By ~ 3

Author(s):

Ewa A. Zarębska ◽

Krzysztof Kusy ◽

Ewa M. Słomińska ◽

Łukasz Kruszyna ◽

Jacek Zieliński

Keyword(s):

Skeletal Muscle ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

Muscle Blood Flow ◽

Venous Blood ◽

Recovery Period ◽

Competitive Athletes ◽

Total Body ◽

Exercise Induced ◽

Age Range

Circulating plasma ATP is able to regulate local skeletal muscle blood flow and 02 delivery causing considerable vasodilatation during exercise. We hypothesized that sport specialization and specific long-term training stimuli have an impact on venous plasma [ATP] and other nucleotides concentration. Four athletic groups consisting of sprinters (n=11; age range 21–30 yr), endurance-trained athletes (n=16; age range 18–31 yr), futsal players (n=14; age range 18–30 yr), and recreationally active individuals (n=12; age range 22–33 yr) were studied. Venous blood samples were collected at rest, during an incremental treadmill test, and during recovery. Baseline [ATP] was 759±80 nmol·l−1 in competitive athletes and 680±73 nmol·l−1 in controls and increased during exercise by ~61% in competitive athletes and by ~31% in recreationally active participants. We demonstrated a rapid increase in plasma [ATP] at exercise intensities of 83–87% of VO2max in competitive athletes and 94% in controls. Concentrations reported after 30 minutes of recovery were distinct from those obtained preexercise in competitive athletes (P<0.001) but not in controls (P=0.61). We found a correlation between total-body skeletal muscle mass and resting and maximal plasma [ATP] in competitive athletes (r=0.81 and r=0.75, respectively). In conclusion, sport specialization is significantly related to plasma [ATP] at rest, during exercise, and during maximal effort. Intensified exercise-induced plasma [ATP] increases may contribute to more effective vessel dilatation during exercise in highly trained athletes than in recreational runners. The most rapid increase in ATP concentration was associated with the respiratory compensation point. No differences between groups of competitive athletes were observed during the recovery period suggesting a similar pattern of response after exercise. Total-body skeletal muscle mass is indirectly related to plasma [ATP] in highly trained athletes.

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Effect of a High Fat and High Protein Diet on Exercise-Induced Skeletal Muscle Hypertrophy in Rats

International Journal Of Nutrition ◽

10.14302/issn.2379-7835.ijn-19-3011 ◽

2019 ◽

Vol 4 (3) ◽

pp. 29-40

Author(s):

Takako Fujii ◽

Tomohiro Sonou ◽

Naoya Nakai ◽

Koji Okamura

Keyword(s):

Skeletal Muscle ◽

Body Weight ◽

Amino Acid ◽

Muscle Mass ◽

Acid Concentration ◽

Skeletal Muscle Mass ◽

Muscle Hypertrophy ◽

High Protein Diet ◽

High Fat ◽

Exercise Induced

The skeletal muscle mass varies by race. Dietary habits over generations are a factor that influences the skeletal muscle mass, as well as genetic factors. Therefore, we investigated the effects of diets with different macronutrient contents on exercise-induced muscle hypertrophy in rats. Male 4-week-old Sprague–Dawley rats were randomly divided into three groups: a normal-diet (N), high-protein diet (HP) and high-fat diet (HF) group. The food intake was manipulated to gain comparable body weight across the three groups. All rats were performed a climbing training exercise for 8 weeks. The final body weight and weight of the liver, kidneys and adipose tissues did not significantly differ among the groups. The flexor hullucis lingus was significantly higher in the HF group than in the HP group. The total lipid content in the muscle was significantly higher in the HF group than in the N group, while it did not differ significant between the HF and HP groups. There were no marked differences in the water or protein content in the muscle among the groups. The plasma amino acid concentration was significantly or tended to be lower in the HP group than in the HF or N group, except for the branched-chain amino acid concentration, which tended to be higher after ingesting the HP diet than other diets. These findings suggest that consuming an HP diet is not likely to facilitate exercise-induced muscle hypertrophy, partly due to the plasma amino acid imbalance induced by habitual HP diet consumption.

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Protein Intake and Exercise-Induced Skeletal Muscle Hypertrophy: An Update

Nutrients ◽

10.3390/nu12072023 ◽

2020 ◽

Vol 12 (7) ◽

pp. 2023

Author(s):

Louise Deldicque

Keyword(s):

Skeletal Muscle ◽

Muscle Mass ◽

Protein Intake ◽

Skeletal Muscle Mass ◽

Muscle Hypertrophy ◽

Sport Performance ◽

Skeletal Muscle Hypertrophy ◽

Exercise Induced ◽

Net Protein

Skeletal muscle mass is critical for sport performance and in many pathological conditions. The combination of protein intake and resistance exercise is the most efficient strategy to promote skeletal muscle hypertrophy and remodeling. However, to be really efficient, certain conditions need to be considered. The amount, type and source of proteins do all matter as well as the timing of ingestion and spreading over the whole day. Optimizing those conditions favor a positive net protein balance, which in the long term, may result in muscle mass accretion. Last but not least, it is also essential to take the nutritional status and the exercise training load into consideration when looking for maintenance or gain of skeletal muscle mass.

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