Morphological and electromyographical studies of trapezius myalgia in cleaners
(2001)- Abstract
- Pathomechanisms of work-related myalgia are poorly understood. Myalgia is caused by exitation of nociceptors present in the muscular tissue but not in the muscle fibres themselves. Morphological analysis can contribute to knowledge of excitation of nociceptors. Surface EMG is a widely used method in the research field of ergonomics. Knowledge of influence of myalgia, occupation, age and intrinsic properties on the surface EMG is limited. Twenty-five female cleaners with long standing work related myalgia, 25 female cleaners without trapezius myalgia and 21 healthy teachers participated in the study. All participants were clinically examined to reach the diagnosis trapezius myalgia. Surface EMG was recorded during an isokinetic endurance... (More)
- Pathomechanisms of work-related myalgia are poorly understood. Myalgia is caused by exitation of nociceptors present in the muscular tissue but not in the muscle fibres themselves. Morphological analysis can contribute to knowledge of excitation of nociceptors. Surface EMG is a widely used method in the research field of ergonomics. Knowledge of influence of myalgia, occupation, age and intrinsic properties on the surface EMG is limited. Twenty-five female cleaners with long standing work related myalgia, 25 female cleaners without trapezius myalgia and 21 healthy teachers participated in the study. All participants were clinically examined to reach the diagnosis trapezius myalgia. Surface EMG was recorded during an isokinetic endurance test of shoulder forward flexors. Biomechanical output and the EMG parameters mean power frequency and root mean square (RMS) were calculated. The RMS ratio between passive and active phases of contractions were calculated to assess the ability to relax between contractions. Surgical trapezius muscle biopsies were obtained from all subjects. Enzym- and immunohistochemical stainings were performed to visualize different fibre types, capillary density, fibres with subsarcolemmal accumulations of mitochondria, cytochrome oxidase deficient fibres and fibres with a disorganization of mitochondrial distribution. Occupational cleaning work, myalgia and age contributed to the total variation of biomechanical output and EMG parameters. Histopathological findings and the relative distribution of myosin heavy chains in the trapezius muscle influenced the surface EMG signal. The capillary supply but not the morphological characteristics and functional properties of the trapezius muscle may be associated with myalgia. Histochemical and enzym histochemical alterations indicating a disturbed oxidative metabolism were linked to heavy work load on the trapezius muscle. (Less)
- Abstract (Swedish)
- Popular Abstract in Swedish
Sammanfattning på svenska Avhandlingen är en sammanläggningsavhandling, bestående av fem delarbeten. I avhandlingen studeras yrkesrelaterad muskelvärk (myalgi) i kappmuskeln (trapezius) ur framförallt morfologiska, histopatologiska och elektromyografiska aspekter hos en förhållande stor grupp av försökspersoner. Försökspersonerna består av städerskor med och utan yrkesrelaterad trapeziusmyalgi samt friska kontroller utan påfallande fysisk belastning av trapeziusmuskulaturen (lärarinnor).
Den viktigaste målsättningen har varit att analysera om det finns förändringar i muskulaturen vid yrkesrelaterad trapeziusmyalgi. Tidigare studier av yrkesrelaterad trapeziusmyalgi har gällt... (More) - Popular Abstract in Swedish
Sammanfattning på svenska Avhandlingen är en sammanläggningsavhandling, bestående av fem delarbeten. I avhandlingen studeras yrkesrelaterad muskelvärk (myalgi) i kappmuskeln (trapezius) ur framförallt morfologiska, histopatologiska och elektromyografiska aspekter hos en förhållande stor grupp av försökspersoner. Försökspersonerna består av städerskor med och utan yrkesrelaterad trapeziusmyalgi samt friska kontroller utan påfallande fysisk belastning av trapeziusmuskulaturen (lärarinnor).
Den viktigaste målsättningen har varit att analysera om det finns förändringar i muskulaturen vid yrkesrelaterad trapeziusmyalgi. Tidigare studier av yrkesrelaterad trapeziusmyalgi har gällt förhållandevis små grupper av personer. En viss osäkerhet har därför funnits huruvida det finns t.ex. muskelmorfologiska och histopatologiska avvikelser i muskulaturen vid sådan muskelvärk.
I avhandlingen visas bland annat att städerskor är starkare och har bättre uthållighet samt en bättre kärlförsörjning i trapeziusmuskulaturen än lärarinnor. Detta kan tolkas som en anpassning till de krav som ställs i städarbetet. Dock har städerskegruppens trapeziusmuskulatur enligt elektromyografiska registreringar sämre förmåga att utnyttja pauser i ett standardiserat skulder flexionsarbete. Förekomsten av avvikande muskelfibrer - t.ex. så kallade ragged red fibrer och malätna fibrer – var signifikant högre i städeskegrupperna än i lärarinnegruppen. Förekomsten av ragged red-fibrer sammanhängde i de multivariata analyserna bland.annat med ålder, arbete som städerska samt förekomsten av en öm punkt i trapeziusmuskulaturen (tender point). Den ökade förekomst av ragged red fibrer och malätna fibrer kan tyda på att ischemiska perioder i trapezius muskulaturen var mer frekventa i städerskegruppen än i lärarinnegruppen. Tolkningen att mikrocirkulationen kan spela ha en roll vid utvecklandet av myalgi understöddes av fyndet att städerskor med myalgi hade signifikant sämre kärlförsörjning än städerskor utan myalgi.
Utifrån förhållandet att yt-elektromyografi (EMG) ofta används vid ergonomiska studier har också analyserats huruvida morfologiska (t.ex. fiber proportioner och fiber areor) samt histopatologiska fynd kan tänkas påverka den registrerade EMG signalen. I avhandlingen visas bland annat att förmågan enligt yt-EMG att utnyttja pauser i ett standardiserat skulderflexionsarbete interkorrelerar med olika morfologiska och histopatologiska variabler. I det sista delarbetet användes förekomsten av tunga myosin kedjor som indikator på muskulaturens funktionella egenskaper. Vid de multivariata analyserna fann man att de tre grupperna av försökspersoner uppvisade olika mönster vad gällde relationen mellan å ena sidan tunga myosinkedjor och å andra sidan olika EMG variabler. Städerskegruppen utan myalgi avvek från de två övriga grupperna, vilket kan vara tecken på en höggradig anpassning till arbetets krav - utan utveckling av smärta - i denna grupp. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/42058
- author
- Larsson, Britt LU
- supervisor
- opponent
-
- Associate Professor Jörgensen, Kurt, August Krogh Institute Copenhagen
- organization
- publishing date
- 2001
- type
- Thesis
- publication status
- published
- subject
- keywords
- female cleaners, Trapezius myalgia, work-related, arbetsmiljömedicin, Yrkesmedicin, industrial medicine, Occupational health, morphological analysis and surface-EMG
- pages
- 77 pages
- publisher
- 1Department of Occupational and Environmental Medicine, University Hospital, 221 85 Lund
- defense location
- F1, University Hospital , Lund
- defense date
- 2001-11-30 13:15:00
- ISBN
- 91-628-5004-0
- language
- English
- LU publication?
- yes
- id
- d5a2c397-55a3-4f20-a439-8915efc02e41 (old id 42058)
- date added to LUP
- 2016-04-04 10:40:08
- date last changed
- 2018-11-21 21:00:06
@phdthesis{d5a2c397-55a3-4f20-a439-8915efc02e41,
abstract = {{Pathomechanisms of work-related myalgia are poorly understood. Myalgia is caused by exitation of nociceptors present in the muscular tissue but not in the muscle fibres themselves. Morphological analysis can contribute to knowledge of excitation of nociceptors. Surface EMG is a widely used method in the research field of ergonomics. Knowledge of influence of myalgia, occupation, age and intrinsic properties on the surface EMG is limited. Twenty-five female cleaners with long standing work related myalgia, 25 female cleaners without trapezius myalgia and 21 healthy teachers participated in the study. All participants were clinically examined to reach the diagnosis trapezius myalgia. Surface EMG was recorded during an isokinetic endurance test of shoulder forward flexors. Biomechanical output and the EMG parameters mean power frequency and root mean square (RMS) were calculated. The RMS ratio between passive and active phases of contractions were calculated to assess the ability to relax between contractions. Surgical trapezius muscle biopsies were obtained from all subjects. Enzym- and immunohistochemical stainings were performed to visualize different fibre types, capillary density, fibres with subsarcolemmal accumulations of mitochondria, cytochrome oxidase deficient fibres and fibres with a disorganization of mitochondrial distribution. Occupational cleaning work, myalgia and age contributed to the total variation of biomechanical output and EMG parameters. Histopathological findings and the relative distribution of myosin heavy chains in the trapezius muscle influenced the surface EMG signal. The capillary supply but not the morphological characteristics and functional properties of the trapezius muscle may be associated with myalgia. Histochemical and enzym histochemical alterations indicating a disturbed oxidative metabolism were linked to heavy work load on the trapezius muscle.}},
author = {{Larsson, Britt}},
isbn = {{91-628-5004-0}},
keywords = {{female cleaners; Trapezius myalgia; work-related; arbetsmiljömedicin; Yrkesmedicin; industrial medicine; Occupational health; morphological analysis and surface-EMG}},
language = {{eng}},
publisher = {{1Department of Occupational and Environmental Medicine, University Hospital, 221 85 Lund}},
school = {{Lund University}},
title = {{Morphological and electromyographical studies of trapezius myalgia in cleaners}},
year = {{2001}},
}