l-Carnitine Supplementation in Older Women. A Pilot Study on Aging Skeletal Muscle Mass and Function

Proctor, David N., and Michael J. Joyner. Skeletal muscle mass and the reduction ofV˙o 2 max in trained older subjects. J. Appl. Physiol.82(5): 1411–1415, 1997.—The role of skeletal muscle mass in the age-associated decline in maximal O2 uptake (V˙o 2 max) is poorly defined because of confounding changes in muscle oxidative capacity and in body fat and the difficulty of quantifying active muscle mass during exercise. We attempted to clarify these issues by examining the relationship between several indexes of muscle mass, as estimated by using dual-energy X-ray absorptiometry and treadmillV˙o 2 max in 32 chronically endurance-trained subjects from four groups ( n = 8/group): young men (20–30 yr), older men (56–72 yr), young women (19–31 yr), and older women (51–72 yr).V˙o 2 max per kilogram body mass was 26 and 22% lower in the older men (45.9 vs. 62.0 ml ⋅ kg−1 ⋅ min−1) and older women (40.0 vs. 51.5 ml ⋅ kg−1 ⋅ min−1). These age differences were reduced to 14 and 13%, respectively, whenV˙o 2 max was expressed per kilogram of appendicular muscle. When appropriately adjusted for age and gender differences in appendicular muscle mass by analysis of covariance, whole bodyV˙o 2 max was 0.50 ± 0.09 l/min less ( P < 0.001) in the older subjects. This effect was similar in both genders. These findings suggest that the reducedV˙o 2 max seen in highly trained older men and women relative to their younger counterparts is due, in part, to a reduced aerobic capacity per kilogram of active muscle independent of age-associated changes in body composition, i.e., replacement of muscle tissue by fat. Because skeletal muscle adaptations to endurance training can be well maintained in older subjects, the reduced aerobic capacity per kilogram of muscle likely results from age-associated reductions in maximal O2 delivery (cardiac output and/or muscle blood flow).

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Sex Differences in the Associations between L-Arginine Pathway Metabolites, Skeletal Muscle Mass and Function, and their Responses to Resistance Exercise, in Old Age

The journal of nutrition health & aging ◽

10.1007/s12603-017-0964-6 ◽

2017 ◽

Vol 22 (4) ◽

pp. 534-540 ◽

Cited By ~ 5

Author(s):

M. da Boit ◽

S. Tommasi ◽

D. Elliot ◽

A. Zinellu ◽

S. Sotgia ◽

...

Keyword(s):

Skeletal Muscle ◽

Sex Differences ◽

Resistance Exercise ◽

Old Age ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

And Function

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Skeletal muscle index and its association with mobility among community‐dwelling older women

Baltic Journal of Health and Physical Activity ◽

10.29359/bjhpa.13.1.05 ◽

2021 ◽

Vol 13 (1) ◽

pp. 37-44

Author(s):

ZBIGNIEW M. OSSOWSKI

Keyword(s):

Skeletal Muscle ◽

Older People ◽

Older Women ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

Lower Extremities ◽

Community Dwelling ◽

Functional Mobility ◽

Skeletal Muscle Index ◽

Chair Stand

Background: The loss of muscle function and reduced mobility levels are the main reasons for the limitations of independence and disability in older people. The main aim of this study was to determine the relationship between the skeletal muscle index and mobility in older women. Material and methods: ‪The study involved 166 older women. Skeletal muscle mass and other body components were determined by bioimpedance using an InBody 720 device. Functional mobility was evaluated with the timed up-and-go test. 30-second chair stand was also used to measure the level of functional strength in lower extremities. Results: ‪The skeletal muscle index was positively correlated with functional mobility (r=-0.22; p=0.00) and 30-second chair stand (r=-0.47; p=0.00). However, the strength of lower extremities was a significantly better parameter in predicting mobility in older women than the skeletal muscle index and skeletal muscle mass. Conclusions: The functional strength of lower extremity muscles and the skeletal muscle index can have a positive effect on functional mobility in older people. The results may be helpful in clinical practice when diagnosing mobility limitations and in the process of programming physical activity of older women aimed at the prevention of sarcopenia.

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Lipoprotein subfractions in patients with sarcopenia and their relevance to skeletal muscle mass and function

Experimental Gerontology ◽

10.1016/j.exger.2021.111668 ◽

2021 ◽

pp. 111668

Author(s):

Hui Gong ◽

Yang Liu ◽

Xing Lyu ◽

Lini Dong ◽

Xiangyu Zhang

Keyword(s):

Skeletal Muscle ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

Lipoprotein Subfractions ◽

And Function

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NEUROMUSCULAR CHANGES WITH AGING AND SARCOPENIA

Journal of Frailty & Aging ◽

10.14283/jfa.2018.35 ◽

2018 ◽

pp. 1-3

Author(s):

B.C. Clark

Keyword(s):

Skeletal Muscle ◽

Muscle Mass ◽

Muscle Function ◽

Skeletal Muscle Mass ◽

The Past ◽

Conceptual Definition ◽

Age Related ◽

Per Se ◽

Definition Of ◽

And Function

Sarcopenia was originally conceptualized as the age-related loss of skeletal muscle mass. Over the ensuing decades, the conceptual definition of sarcopenia has changed to represent a condition in older adults that is characterized by declining muscle mass and function, with “function” most commonly conceived as muscle weakness and/or impaired physical performance (e.g., slow gait speed). Findings over the past 15-years, however, have demonstrated that changes in grip and leg extensor strength are not primarily due to muscle atrophy per se, and that to a large extent, are reflective of declines in the integrity of the nervous system. This article briefly summarizes findings relating to the complex neuromuscular mechanisms that contribute to reductions in muscle function associated with advancing age, and the implications of these findings on the development of effective therapies.

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Sarcopenia in women with hip fracture: A comparison of hormonal biomarkers and their relationship to skeletal muscle mass and function

Osteoporosis and Sarcopenia ◽

10.1016/j.afos.2020.06.001 ◽

2020 ◽

Vol 6 (3) ◽

pp. 139-145

Author(s):

Ming Li Yee ◽

Raphael Hau ◽

Alison Taylor ◽

Mark Guerra ◽

Peter Guerra ◽

...

Keyword(s):

Skeletal Muscle ◽

Hip Fracture ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

And Function

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Skeletal Muscle Mass Regulation in Critical Illness

10.1093/med/9780199653461.003.0035 ◽

2014 ◽

Author(s):

Zudin Puthucheary ◽

Hugh Montgomery ◽

Nicholas Hart ◽

Stephen Harridge

Keyword(s):

Skeletal Muscle ◽

Critical Illness ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

Bed Rest ◽

Protein Homeostasis ◽

Highly Sensitive ◽

And Function ◽

Inadequate Nutrition

Muscle is a dynamic, plastic, and malleable tissue that is highly sensitive to mechanical and metabolic signals. Muscle mass is regulated by protein homeostasis, with protein being continually turned over, reflecting a balance between synthesis and breakdown. This chapter discusses the effect of critical illness on skeletal muscle mass, protein homeostasis, and the intracellular signalling driving anabolism and catabolism. The focus will be on the unique challenges to which the skeletal muscle are exposed, such as inflammation, sepsis, sedation, and inadequate nutrition, which, in combination with the disuse signals of immobilization and bed rest, engender dramatic changes in muscle structure and function. The mechanisms regulating muscle loss during critical illness are being unravelled, but many questions remain unanswered. Detailed understanding of these mechanisms will help drive strategies to minimize or prevent intensive care-acquired muscle weakness and the long-term consequences experienced by ICU survivors.

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Clinical impact of sarcopenia assessment in patients with hepatocellular carcinoma undergoing treatments

Journal of Gastroenterology ◽

10.1007/s00535-020-01711-w ◽

2020 ◽

Vol 55 (10) ◽

pp. 927-943 ◽

Cited By ~ 2

Author(s):

Giovanni Marasco ◽

Matteo Serenari ◽

Matteo Renzulli ◽

Luigina Vanessa Alemanni ◽

Benedetta Rossini ◽

...

Keyword(s):

Hepatocellular Carcinoma ◽

Skeletal Muscle ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

Appropriate Treatment ◽

Risk Of Mortality ◽

Short And Long Term ◽

Poor Outcomes ◽

And Function

Abstract Changes in body composition are associated with poor outcomes in cancer patients including hepatocellular carcinoma (HCC). Sarcopenia, defined as the loss of skeletal muscle mass, quality and function, has been associated with a higher rate of complications and recurrences in patients with cirrhosis and HCC. The assessment of patient general status before HCC treatment, including the presence of sarcopenia, is a key-point for achieving therapy tolerability and to avoid short- and long-term complications leading to poor patients’ survival. Thus, we aimed to review the current literature evaluating the role of sarcopenia assessment related to HCC treatments and to critically provide the clinicians with the most recent and valuable evidence. As a result, sarcopenia can be predictive of poor outcomes in patients undergoing liver resection, transplantation and systemic therapies, offering the chance to clinicians to improve the muscular status of these patients, especially those with high-grade sarcopenia at high risk of mortality. Further studies are needed to clarify the predictive value of sarcopenia in other HCC treatment settings and to evaluate its role as an additional staging tool for identifying the most appropriate treatment. Besides, interventional studies aiming at increasing the skeletal muscle mass for reducing complications and increasing the survival in patients with HCC are needed.

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The gut microbiota influences skeletal muscle mass and function in mice

Science Translational Medicine ◽

10.1126/scitranslmed.aan5662 ◽

2019 ◽

Vol 11 (502) ◽

pp. eaan5662 ◽

Cited By ~ 37

Author(s):

Shawon Lahiri ◽

Hyejin Kim ◽

Isabel Garcia-Perez ◽

Musarrat Maisha Reza ◽

Katherine A. Martin ◽

...

Keyword(s):

Skeletal Muscle ◽

Neuromuscular Junction ◽

Gut Microbiota ◽

Muscle Mass ◽

Skeletal Muscle Mass ◽

Neuromuscular Junctions ◽

Short Chain Fatty Acids ◽

Germ Free ◽

Mouse Skeletal Muscle ◽

And Function

The functional interactions between the gut microbiota and the host are important for host physiology, homeostasis, and sustained health. We compared the skeletal muscle of germ-free mice that lacked a gut microbiota to the skeletal muscle of pathogen-free mice that had a gut microbiota. Compared to pathogen-free mouse skeletal muscle, germ-free mouse skeletal muscle showed atrophy, decreased expression of insulin-like growth factor 1, and reduced transcription of genes associated with skeletal muscle growth and mitochondrial function. Nuclear magnetic resonance spectrometry analysis of skeletal muscle, liver, and serum from germ-free mice revealed multiple changes in the amounts of amino acids, including glycine and alanine, compared to pathogen-free mice. Germ-free mice also showed reduced serum choline, the precursor of acetylcholine, the key neurotransmitter that signals between muscle and nerve at neuromuscular junctions. Reduced expression of genes encoding Rapsyn and Lrp4, two proteins important for neuromuscular junction assembly and function, was also observed in skeletal muscle from germ-free mice compared to pathogen-free mice. Transplanting the gut microbiota from pathogen-free mice into germ-free mice resulted in an increase in skeletal muscle mass, a reduction in muscle atrophy markers, improved oxidative metabolic capacity of the muscle, and elevated expression of the neuromuscular junction assembly genes Rapsyn and Lrp4. Treating germ-free mice with short-chain fatty acids (microbial metabolites) partly reversed skeletal muscle impairments. Our results suggest a role for the gut microbiota in regulating skeletal muscle mass and function in mice.

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