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Contractile properties are impaired in congenital myopathies

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@article{1a195acba20f48db94d022267f5aeeee,
title = "Contractile properties are impaired in congenital myopathies",
abstract = "The ratio between muscle strength and muscle cross-sectional area is called the specific force. Fatty replacement of muscles is seen in many myopathies, affecting the specific force, without necessarily affecting the ability of the remaining muscle fibers to contract. This ability is called the contractility and is the ratio between muscle strength and the lean muscle cross-sectional area, i.e. the contractile cross-sectional area. We hypothesized that contractility is disrupted in patients with congenital myopathy, because of defects in contractile proteins of the sarcomere. Peak torque across ankle and knee joints was measured by isokinetic dynamometry in 16 patients with congenital myopathy and 13 healthy controls. Five patients only participated partially in the dynamometer measurements due to severe muscle weakness. Dixon MRI technique was used to quantify muscle fat fractions and calculate cross-sectional area. Patients with congenital myopathy had lower cross-sectional area in all muscle groups (P<0.01), higher fat fraction (P<0.01) and less strength (P<0.005) in all studied muscle groups. Their fat content was more than doubled and peak torque lower than half that in healthy controls. Muscle contractility was reduced (P<0.01) in three of four patient muscle groups. In conclusion, muscle contractility was reduced in patients with congenital myopathy, across different diagnoses, and was independent of the level of muscle fat fraction, suggesting that intrinsic defects of the myocyte are responsible for reduced contractility.",
keywords = "Congenital myopathy, Contractile cross-sectional area, Dixon technique, Muscle contractility",
author = "Eisum, {Anne-Sofie Vib{\ae}k} and Freja Fornander and Poulsen, {Nanna Scharff} and Andersen, {Annarita Ghosh} and Julia Dahlqvist and Andersen, {Linda Kahr} and Nanna Witting and John Vissing",
note = "Copyright {\textcopyright} 2020 Elsevier B.V. All rights reserved.",
year = "2020",
month = aug,
doi = "10.1016/j.nmd.2020.06.007",
language = "English",
volume = "30",
pages = "649--655",
journal = "Neuromuscular Disorders",
issn = "0960-8966",
publisher = "Elsevier Ltd",
number = "8",

}

RIS

TY - JOUR

T1 - Contractile properties are impaired in congenital myopathies

AU - Eisum, Anne-Sofie Vibæk

AU - Fornander, Freja

AU - Poulsen, Nanna Scharff

AU - Andersen, Annarita Ghosh

AU - Dahlqvist, Julia

AU - Andersen, Linda Kahr

AU - Witting, Nanna

AU - Vissing, John

N1 - Copyright © 2020 Elsevier B.V. All rights reserved.

PY - 2020/8

Y1 - 2020/8

N2 - The ratio between muscle strength and muscle cross-sectional area is called the specific force. Fatty replacement of muscles is seen in many myopathies, affecting the specific force, without necessarily affecting the ability of the remaining muscle fibers to contract. This ability is called the contractility and is the ratio between muscle strength and the lean muscle cross-sectional area, i.e. the contractile cross-sectional area. We hypothesized that contractility is disrupted in patients with congenital myopathy, because of defects in contractile proteins of the sarcomere. Peak torque across ankle and knee joints was measured by isokinetic dynamometry in 16 patients with congenital myopathy and 13 healthy controls. Five patients only participated partially in the dynamometer measurements due to severe muscle weakness. Dixon MRI technique was used to quantify muscle fat fractions and calculate cross-sectional area. Patients with congenital myopathy had lower cross-sectional area in all muscle groups (P<0.01), higher fat fraction (P<0.01) and less strength (P<0.005) in all studied muscle groups. Their fat content was more than doubled and peak torque lower than half that in healthy controls. Muscle contractility was reduced (P<0.01) in three of four patient muscle groups. In conclusion, muscle contractility was reduced in patients with congenital myopathy, across different diagnoses, and was independent of the level of muscle fat fraction, suggesting that intrinsic defects of the myocyte are responsible for reduced contractility.

AB - The ratio between muscle strength and muscle cross-sectional area is called the specific force. Fatty replacement of muscles is seen in many myopathies, affecting the specific force, without necessarily affecting the ability of the remaining muscle fibers to contract. This ability is called the contractility and is the ratio between muscle strength and the lean muscle cross-sectional area, i.e. the contractile cross-sectional area. We hypothesized that contractility is disrupted in patients with congenital myopathy, because of defects in contractile proteins of the sarcomere. Peak torque across ankle and knee joints was measured by isokinetic dynamometry in 16 patients with congenital myopathy and 13 healthy controls. Five patients only participated partially in the dynamometer measurements due to severe muscle weakness. Dixon MRI technique was used to quantify muscle fat fractions and calculate cross-sectional area. Patients with congenital myopathy had lower cross-sectional area in all muscle groups (P<0.01), higher fat fraction (P<0.01) and less strength (P<0.005) in all studied muscle groups. Their fat content was more than doubled and peak torque lower than half that in healthy controls. Muscle contractility was reduced (P<0.01) in three of four patient muscle groups. In conclusion, muscle contractility was reduced in patients with congenital myopathy, across different diagnoses, and was independent of the level of muscle fat fraction, suggesting that intrinsic defects of the myocyte are responsible for reduced contractility.

KW - Congenital myopathy

KW - Contractile cross-sectional area

KW - Dixon technique

KW - Muscle contractility

UR - http://www.scopus.com/inward/record.url?scp=85087985825&partnerID=8YFLogxK

U2 - 10.1016/j.nmd.2020.06.007

DO - 10.1016/j.nmd.2020.06.007

M3 - Journal article

C2 - 32675003

VL - 30

SP - 649

EP - 655

JO - Neuromuscular Disorders

JF - Neuromuscular Disorders

SN - 0960-8966

IS - 8

ER -

ID: 61072352