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Sex-Dependent Effects of Quadriceps Fat Content on Single Muscle Fiber Size in Older Adults

Evidence suggests that ectopic fat deposition interferes with skeletal muscle structure and function, but few studies have examined underlying morphological and contractile properties at the single fiber level. Healthy older (65-75 y) men (n=9) and women (n=9) underwent dynamometry for assessment of...

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Autores principales: Straight, Chad, Gordon, Joseph, Foster, Aurora, Remillard, Nicholas, Damon, Bruce, Chipkin, Stuart, Kent, Jane, Miller, Mark
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Oxford University Press 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7741817/
http://dx.doi.org/10.1093/geroni/igaa057.419
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author Straight, Chad
Gordon, Joseph
Foster, Aurora
Remillard, Nicholas
Damon, Bruce
Chipkin, Stuart
Kent, Jane
Miller, Mark
author_facet Straight, Chad
Gordon, Joseph
Foster, Aurora
Remillard, Nicholas
Damon, Bruce
Chipkin, Stuart
Kent, Jane
Miller, Mark
author_sort Straight, Chad
collection PubMed
description Evidence suggests that ectopic fat deposition interferes with skeletal muscle structure and function, but few studies have examined underlying morphological and contractile properties at the single fiber level. Healthy older (65-75 y) men (n=9) and women (n=9) underwent dynamometry for assessment of knee extensor maximal torque, water-fat magnetic resonance imaging to quantify quadriceps muscle cross-sectional area (CSA) and fat fraction (FF), and vastus lateralis biopsies to determine morphology and function of type I and II muscle fibers. Despite similar body mass indices (24.4±1.3 vs. 24.6±0.5 kg∙m2, p=0.93) and daily moderate-to-vigorous physical activity (46±7 vs. 41±9 min∙d-1, p=0.67), women had greater FF (9.0±0.3 [range: 7.6-10.6] vs. 7.9±0.4 [6.0-9.7] %, p=0.04) than men, indicating increased adipose tissue deposition in skeletal muscle. Women also had smaller quadriceps CSA (39.8±1.8 vs. 57.9±1.3 cm2, p=0.01), specific torque (1.5±0.1 vs. 1.9±0.1 Nm∙cm-2, p=0.01) and type II fiber CSA (3,943±312 [2,350-5,140] vs. 5,352±384 [3,560-6,590] µm2, p=0.01) than men. Type I CSA did not differ by sex (4,918±228 [3,740-5,600] vs. 5,630±440 [3,640-7,670] µm2, p=0.19). In older women, FF was inversely associated with single fiber CSA in type I (r= -0.81, p=0.02) and II (r= -0.76, p=0.03) fibers, and tended to be associated with slower myosin-actin cross-bridge kinetics (longer myosin attachment time) in type I fibers (r=0.65, p=0.08). These relationships were not observed in men. Overall, healthy older women have greater intramuscular fat than men, which may contribute to sex-specific effects on knee extensor specific torque through differences in muscle fiber size and cross-bridge kinetics.
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spelling pubmed-77418172020-12-21 Sex-Dependent Effects of Quadriceps Fat Content on Single Muscle Fiber Size in Older Adults Straight, Chad Gordon, Joseph Foster, Aurora Remillard, Nicholas Damon, Bruce Chipkin, Stuart Kent, Jane Miller, Mark Innov Aging Abstracts Evidence suggests that ectopic fat deposition interferes with skeletal muscle structure and function, but few studies have examined underlying morphological and contractile properties at the single fiber level. Healthy older (65-75 y) men (n=9) and women (n=9) underwent dynamometry for assessment of knee extensor maximal torque, water-fat magnetic resonance imaging to quantify quadriceps muscle cross-sectional area (CSA) and fat fraction (FF), and vastus lateralis biopsies to determine morphology and function of type I and II muscle fibers. Despite similar body mass indices (24.4±1.3 vs. 24.6±0.5 kg∙m2, p=0.93) and daily moderate-to-vigorous physical activity (46±7 vs. 41±9 min∙d-1, p=0.67), women had greater FF (9.0±0.3 [range: 7.6-10.6] vs. 7.9±0.4 [6.0-9.7] %, p=0.04) than men, indicating increased adipose tissue deposition in skeletal muscle. Women also had smaller quadriceps CSA (39.8±1.8 vs. 57.9±1.3 cm2, p=0.01), specific torque (1.5±0.1 vs. 1.9±0.1 Nm∙cm-2, p=0.01) and type II fiber CSA (3,943±312 [2,350-5,140] vs. 5,352±384 [3,560-6,590] µm2, p=0.01) than men. Type I CSA did not differ by sex (4,918±228 [3,740-5,600] vs. 5,630±440 [3,640-7,670] µm2, p=0.19). In older women, FF was inversely associated with single fiber CSA in type I (r= -0.81, p=0.02) and II (r= -0.76, p=0.03) fibers, and tended to be associated with slower myosin-actin cross-bridge kinetics (longer myosin attachment time) in type I fibers (r=0.65, p=0.08). These relationships were not observed in men. Overall, healthy older women have greater intramuscular fat than men, which may contribute to sex-specific effects on knee extensor specific torque through differences in muscle fiber size and cross-bridge kinetics. Oxford University Press 2020-12-16 /pmc/articles/PMC7741817/ http://dx.doi.org/10.1093/geroni/igaa057.419 Text en © The Author(s) 2020. Published by Oxford University Press on behalf of The Gerontological Society of America. http://creativecommons.org/licenses/by/4.0/ This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.
spellingShingle Abstracts
Straight, Chad
Gordon, Joseph
Foster, Aurora
Remillard, Nicholas
Damon, Bruce
Chipkin, Stuart
Kent, Jane
Miller, Mark
Sex-Dependent Effects of Quadriceps Fat Content on Single Muscle Fiber Size in Older Adults
title Sex-Dependent Effects of Quadriceps Fat Content on Single Muscle Fiber Size in Older Adults
title_full Sex-Dependent Effects of Quadriceps Fat Content on Single Muscle Fiber Size in Older Adults
title_fullStr Sex-Dependent Effects of Quadriceps Fat Content on Single Muscle Fiber Size in Older Adults
title_full_unstemmed Sex-Dependent Effects of Quadriceps Fat Content on Single Muscle Fiber Size in Older Adults
title_short Sex-Dependent Effects of Quadriceps Fat Content on Single Muscle Fiber Size in Older Adults
title_sort sex-dependent effects of quadriceps fat content on single muscle fiber size in older adults
topic Abstracts
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7741817/
http://dx.doi.org/10.1093/geroni/igaa057.419
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