W' reconstitution rate at different intensities above critical torque: The role of muscle size and maximal strength

2021 ◽  
Author(s):  
Leonardo Henrique Perinotto Abdalla ◽  
Ryan Michael Broxterman ◽  
Thomas Jackson Barstow ◽  
Camila Coelho Greco ◽  
Benedito Sérgio Denadai
Keyword(s):  
Muscle Size ◽  
Maximal Strength

scholarly journals Expression Levels of Long Non-Coding RNAs Change in Models of Altered Muscle Activity and Muscle Mass

2020 ◽  
Vol 21 (5) ◽  
pp. 1628 ◽  
Author(s):  
Keisuke Hitachi ◽  
Masashi Nakatani ◽  
Shiori Funasaki ◽  
Ikumi Hijikata ◽  
Mizuki Maekawa ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Mass ◽  
Muscle Atrophy ◽  
Skeletal Muscle Mass ◽  
Muscle Size ◽  
Skeletal Muscle Atrophy ◽  
Myostatin Gene ◽  
Expression Levels ◽  
Non Coding Rnas

Skeletal muscle is a highly plastic organ that is necessary for homeostasis and health of the human body. The size of skeletal muscle changes in response to intrinsic and extrinsic stimuli. Although protein-coding RNAs including myostatin, NF-κβ, and insulin-like growth factor-1 (IGF-1), have pivotal roles in determining the skeletal muscle mass, the role of long non-coding RNAs (lncRNAs) in the regulation of skeletal muscle mass remains to be elucidated. Here, we performed expression profiling of nine skeletal muscle differentiation-related lncRNAs (DRR, DUM1, linc-MD1, linc-YY1, LncMyod, Neat1, Myoparr, Malat1, and SRA) and three genomic imprinting-related lncRNAs (Gtl2, H19, and IG-DMR) in mouse skeletal muscle. The expression levels of these lncRNAs were examined by quantitative RT-PCR in six skeletal muscle atrophy models (denervation, casting, tail suspension, dexamethasone-administration, cancer cachexia, and fasting) and two skeletal muscle hypertrophy models (mechanical overload and deficiency of the myostatin gene). Cluster analyses of these lncRNA expression levels were successfully used to categorize the muscle atrophy models into two sub-groups. In addition, the expression of Gtl2, IG-DMR, and DUM1 was altered along with changes in the skeletal muscle size. The overview of the expression levels of lncRNAs in multiple muscle atrophy and hypertrophy models provides a novel insight into the role of lncRNAs in determining the skeletal muscle mass.

The role of maximal strength and load on initial power production

2000 ◽  
Vol 32 (10) ◽  
pp. 1763-1769 ◽  
Author(s):  
JOHN B. CRONIN ◽  
PETER J. McNAIR ◽  
ROBERT N. MARSHALL
Keyword(s):  
Power Production ◽  
Maximal Strength ◽  
Initial Power

scholarly journals Resistance Training in Hypoxia as a New Therapeutic Modality for Sarcopenia—A Narrative Review

Life ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 106
Author(s):  
Won-Sang Jung ◽  
Sung-Woo Kim ◽  
Jeong-Weon Kim ◽  
Hun-Young Park
Keyword(s):  
Resistance Training ◽  
Resistance Exercise ◽  
Intracellular Signaling ◽  
Exercise Intervention ◽  
Muscle Size ◽  
Therapeutic Modality ◽  
Bodily Function ◽  
Muscular Function ◽  
Low Altitude

Hypoxic training is believed to be generally useful for improving exercise performance in various athletes. Nowadays, exercise intervention in hypoxia is recognized as a new therapeutic modality for health promotion and disease prevention or treatment based on the lower mortality and prevalence of people living in high-altitude environments than those living in low-altitude environments. Recently, resistance training in hypoxia (RTH), a new therapeutic modality combining hypoxia and resistance exercise, has been attempted to improve muscle hypertrophy and muscle function. RTH is known to induce greater muscle size, lean mass, increased muscle strength and endurance, bodily function, and angiogenesis of skeletal muscles than traditional resistance exercise. Therefore, we examined previous studies to understand the clinical and physiological aspects of sarcopenia and RTH for muscular function and hypertrophy. However, few investigations have examined the combined effects of hypoxic stress and resistance exercise, and as such, it is difficult to make recommendations for implementing universal RTH programs for sarcopenia based on current understanding. It should also be acknowledged that a number of mechanisms proposed to facilitate the augmented response to RTH remain poorly understood, particularly the role of metabolic, hormonal, and intracellular signaling pathways. Further RTH intervention studies considering various exercise parameters (e.g., load, recovery time between sets, hypoxic dose, and intervention period) are strongly recommended to reinforce knowledge about the adaptational processes and the effects of this type of resistance training for sarcopenia in older people.

scholarly journals An updated systematic review and meta-analysis on the compatibility of concurrent aerobic and strength training for skeletal muscle size and function

2021 ◽  
Author(s):  
Moritz Schumann ◽  
Joshua F Feuerbacher ◽  
Marvin Sünkeler ◽  
Nils Freitag ◽  
Bent Rønnestad ◽  
...  
Keyword(s):  
Systematic Review ◽  
Strength Training ◽  
Muscle Hypertrophy ◽  
Meta Analysis ◽  
Muscle Size ◽  
Concurrent Training ◽  
Strength Development ◽  
Maximal Strength ◽  
Explosive Strength ◽  
The Impact

ObjectiveThis systematic review assessed the compatibility of concurrent aerobic and strength training compared to sole strength training regarding adaptations in muscle function (maximal and explosive strength) and muscle mass. Subgroup analyses were conducted to examine the impact of training modality, exercise type, exercise order, training frequency, age, and training status.DesignA systematic literature search was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). PROSPERO: CRD42020203777Data sourcesPubMed/MEDLINE, ISI Web of Science, Embase, CINAHL, SPORTDiscus and Scopus were systematically searched (12th of August 2020, updated on the 15th of March 2021).Eligibility criteriaPopulation: Healthy adults of any sex and age; Intervention: Supervised, concurrent aerobic and strength training of at least 4 weeks; Comparison: Sole strength training with matched strength training volume; Outcome: maximal strength, explosive strength and muscle hypertrophy. ResultsA total of 43 studies were included. The estimated average standardised mean differences (SMD) based on the random-effects model were -0.06 (95% CI: -0.20, 0.09, p=0.446), -0.28 (95% CI: -0.48, - 0.08, p=0.007) and -0.01 (95% CI: -0.16, 0.18, p=0.919) for maximal strength, explosive strength and muscle hypertrophy, respectively. The attenuation in explosive strength was more pronounced when concurrent training was performed within the same session (p=0.043) compared with separating the sessions by at least 3 h (p>0.05). Summary/ConclusionConcurrent aerobic and strength training does not compromise muscle hypertrophy and maximal strength development. However, explosive strength gains may be attenuated, especially when aerobic and strength training are performed within the same session.

Effects of Resistive Training and Chromium Picolinate on Body Composition and Skeletal Muscle Size in Older Women

2002 ◽  
Vol 12 (2) ◽  
pp. 125-135 ◽  
Author(s):  
Wayne W. Campbell ◽  
Lyndon J.O. Joseph ◽  
Richard A. Anderson ◽  
Stephanie L. Davey ◽  
Jeremy Hinton ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Body Composition ◽  
Older Women ◽  
Muscle Size ◽  
Whole Body ◽  
Chromium Picolinate ◽  
High Dose ◽  
Type I ◽  
Maximal Strength ◽  
Resistive Training

This study assessed the effect of resistive training (RT), with or without high-dose chromium picolinate (Cr-pic) supplementation, on body composition and skeletal muscle size of older women. Seventeen sedentary women, age range 54-71 years. BMI 28.8±2.4 kg/m2. were randomly assigned (double-blind) to groups (Cr-pic. n = 9; Placebo, n = 8) that consumed either 924 μg Cr/d as Cr-pic or a low-Cr placebo (<0.2 μg Cr/d) during a 12-week RT program (2 day/ week, 3 sets · exercise−1 · d1,80% of 1 repetition maximum). Urinary chromium excretion was 60-fold higher in the Cr-pic group, compared to the Placebo group (p < .001), during the intervention. Resistive training increased maximal strength of the muscle groups trained by 8 to 34% (p < .001), and these responses were not influenced by Cr-pic supplementation. Percent body fat and fat-free mass were unchanged with RT in these weight-stable women, independent of Cr-pic supplementation. Type I and type II muscle fiber areas of the m. vastus lateralis were not changed over time and were not influenced by Cr-pic supplementation. These data demonstrate that high-dose Cr-pic supplementation did not increase maximal strength above that of resistive training alone in older women. Further, these data show that, under these experimental conditions, whole body composition and skeletal muscle size were not significantly changed due to resistive training and were not influenced by supplemental chromium picolinate.

Calcineurin differentially regulates maintenance and growth of phenotypically distinct muscles

2002 ◽  
Vol 282 (5) ◽  
pp. C984-C992 ◽  
Author(s):  
Patrick O. Mitchell ◽  
Stephen T. Mills ◽  
Grace K. Pavlath
Keyword(s):  
Skeletal Muscle ◽  
Cyclosporin A ◽  
Human Health ◽  
Muscle Growth ◽  
Growth Conditions ◽  
Muscle Size ◽  
Molecular Pathways ◽  
Adult Skeletal Muscle ◽  
Growth Differential

Adequate muscle mass is critical for human health. The molecular pathways regulating maintenance and growth of adult skeletal muscle are little understood. Calcineurin (CN) is implicated as a key signaling molecule in hypertrophy. Whether CN is involved in all forms of muscle growth or in different muscles is unknown. Here, we examine the role of CN in regulating maintenance of muscle size and growth of atrophied muscle in the soleus (slow) and plantaris (fast). The CN inhibitor cyclosporin A (CsA) differentially affects muscle growth and maintenance depending on muscle phenotype. The plantaris is more severely affected by CsA than the soleus in both growth conditions. One-week vs. 2-wk CsA treatment suggests that both CN-dependent and CN-independent growth occur in the atrophied soleus, whereas plantaris growth appears to be totally CN dependent. Our results suggest that CN regulates multiple types of muscle growth, depending both on muscle phenotype and stage of myofiber growth. Differential expression of components of the CN pathway occurs and may contribute to the differences between muscles.

scholarly journals Role of Phosphoinositide 3-OH Kinase p110β in Skeletal Myogenesis

2015 ◽  
Vol 35 (7) ◽  
pp. 1182-1196 ◽  
Author(s):  
Ronald W. Matheny ◽  
Melissa A. Riddle-Kottke ◽  
Luis A. Leandry ◽  
Christine M. Lynch ◽  
Mary N. Abdalla ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
C2c12 Cells ◽  
Muscle Size ◽  
Whole Body ◽  
Myoblast Differentiation ◽  
Delayed Differentiation ◽  
Conditional Deletion ◽  
Glucose Tolerant ◽  
Old Mice

Phosphoinositide 3-OH kinase (PI3K) regulates a number of developmental and physiologic processes in skeletal muscle; however, the contributions of individual PI3K p110 catalytic subunits to these processes are not well-defined. To address this question, we investigated the role of the 110-kDa PI3K catalytic subunit β (p110β) in myogenesis and metabolism. In C2C12 cells, pharmacological inhibition of p110β delayed differentiation. We next generated mice with conditional deletion of p110β in skeletal muscle (p110β muscle knockout [p110β-mKO] mice). While young p110β-mKO mice possessed a lower quadriceps mass and exhibited less strength than control littermates, no differences in muscle mass or strength were observed between genotypes in old mice. However, old p110β-mKO mice were less glucose tolerant than old control mice. Overexpression of p110β accelerated differentiation in C2C12 cells and primary human myoblasts through an Akt-dependent mechanism, while expression of kinase-inactive p110β had the opposite effect. p110β overexpression was unable to promote myoblast differentiation under conditions of p110α inhibition, but expression of p110α was able to promote differentiation under conditions of p110β inhibition. These findings reveal a role for p110β during myogenesis and demonstrate that long-term reduction of skeletal muscle p110β impairs whole-body glucose tolerance without affecting skeletal muscle size or strength in old mice.

scholarly journals Regulation of the Growth of Multinucleated Muscle Cells by an Nfatc2-Dependent Pathway

2001 ◽  
Vol 153 (2) ◽  
pp. 329-338 ◽  
Author(s):  
Valerie Horsley ◽  
Bret B. Friday ◽  
Sarah Matteson ◽  
Kristy Miller Kegley ◽  
Jonathan Gephart ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Muscle Growth ◽  
Muscle Cells ◽  
Muscle Size ◽  
Growth Defect ◽  
Activated T Cells ◽  
Cross Sectional ◽  
Development And Differentiation ◽  
Muscle Cultures

The nuclear factor of activated T cells (NFAT) family of transcription factors regulates the development and differentiation of several tissue types. Here, we examine the role of NFATC2 in skeletal muscle by analyzing adult NFATC2−/− mice. These mice exhibit reduced muscle size due to a decrease in myofiber cross-sectional area, suggesting that growth is blunted. Muscle growth was examined during regeneration after injury, wherein NFATC2-null myofibers form normally but display impaired growth. The growth defect is intrinsic to muscle cells, since the lack of NFATC2 in primary muscle cultures results in reduced cell size and myonuclear number in myotubes. Retroviral-mediated expression of NFATC2 in the mutant cells rescues this cellular phenotype. Myonuclear number is similarly decreased in NFATC2−/− mice. Taken together, these results implicate a novel role for NFATC2 in skeletal muscle growth. We demonstrate that during growth of multinucleated muscle cells, myoblasts initially fuse to form myotubes with a limited number of nuclei and that subsequent nuclear addition and increases in myotube size are controlled by a molecular pathway regulated by NFATC2.

scholarly journals Dietary supplements containing prohibited substances: A review (Part 2)

2014 ◽  
Vol 26 (3) ◽  
pp. 87
Author(s):  
Pieter Van der Bijl
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Adverse Effects ◽  
Dietary Supplements ◽  
Muscle Size ◽  
Intentional Ingestion ◽  
Low Concentrations ◽  
Increased Strength

The role of prohormones, ‘classic’ and ‘designer’ steroids, clenbuterol, peptide hormones and newer molecules causing concern in dietary supplements is discussed. Apart from their potential adverse effects on athletes’ health, their non-achievement of increased strength and muscle size, trace quantities present in contaminated dietary supplements can lead to failed doping tests. The methodologies used for the identification and determination of prohibited substances in very low concentrations, mainly liquid chromatography and mass spectrometry, are also addressed. Of concern is the anticipation that the number of dietary supplements containing (not yet) prohibited designer steroids and other performance-enhancing newer chemical entities will increase. Athletes, coaches and sports doctors should therefore be provided with information regarding dietary supplements and be advised to minimise risks for non-intentional ingestion of forbidden substances by using safe products listed on databases, such as those obtainable in The Netherlands and Germany. 

Role of dactinomycin in the improved survival of children with Wilms' tumor

JAMA ◽  
1966 ◽  
Vol 195 (12) ◽  
pp. 1005-1009 ◽  
Author(s):  
D. J. Fernbach
Keyword(s):  
Wilms Tumor
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