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Titolo:
Recruitment of low threshold motor-units in the trapezius muscle in different static arm positions
Autore:
Kadefors, R; Forsman, M; Zoega, B; Herberts, P;
Indirizzi:
Lindholmen Dev, S-40275 Gothenburg, Sweden Lindholmen Dev Gothenburg Sweden S-40275 Dev, S-40275 Gothenburg, Sweden Chalmers Univ Technol, Dept Injury Prevent, S-41296 Gothenburg, Sweden Chalmers Univ Technol Gothenburg Sweden S-41296 41296 Gothenburg, Sweden Sahlgrens Univ Hosp, Div Orthopaed, S-41345 Gothenburg, Sweden Sahlgrens Univ Hosp Gothenburg Sweden S-41345 S-41345 Gothenburg, Sweden
Titolo Testata:
ERGONOMICS
fascicolo: 2, volume: 42, anno: 1999,
pagine: 359 - 375
SICI:
0014-0139(199902)42:2<359:ROLTMI>2.0.ZU;2-7
Fonte:
ISI
Lingua:
ENG
Soggetto:
WORK-RELATED MYALGIA; ELECTROMYOGRAPHIC EVALUATION; ACTION-POTENTIALS; FIRING PATTERN; DECOMPOSITION; CONTRACTIONS; TENSION; SIGNAL; TASKS;
Keywords:
trapezius myalgia; motor-unit recruitment; decomposition; electromyography;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Social & Behavioral Sciences
Engineering, Computing & Technology
Citazioni:
37
Recensione:
Indirizzi per estratti:
Indirizzo: Kadefors, R Lindholmen Dev, Box 8714, S-40275 Gothenburg, Sweden Lindholmen Dev Box 8714 Gothenburg Sweden S-40275 urg, Sweden
Citazione:
R. Kadefors et al., "Recruitment of low threshold motor-units in the trapezius muscle in different static arm positions", ERGONOMICS, 42(2), 1999, pp. 359-375

Abstract

A prevailing hypothesis for development of myalgia symptoms in the trapezius muscle is based on observations that in stereotypic activation of musclethe same low-threshold motor-units are the first ones to be recruited, andthat these units are active throughout the contraction, until total relaxation. The theory suggests that these units are the first ones in monotonousrepetitive work to be subject to degenerative processes, causing pain. Thepresent project was undertaken to evaluate to what extent recruitment of motor-units in the trapezius muscle is position-specific, i.e. if there are motor-units that are recruited over a wide range of arm postures. Fine wireelectrode pairs, inserted 2 cm lateral to the midpoint between the acromion and the C7 spinous processus, were used for signal acquisition. Methods for decomposition of the interference patterns were developed, allowing identification of single motor-units in signals registered in different arm positions. Voluntary recruitment of motor-units in the descending portion of the trapezius muscle was studied in 24 different arm positions (0-90 degreesshoulder flexion, 0-45 degrees humeral abduction, and 45 - 135 degrees elbow flexion) in three subjects. The results showed that the wire electrode technique and the signal processing algorithm employed allowed motor-unit identification in nonisometric conditions. It was found that low threshold motor-units in the trapezius muscle, active over a wide range of arm positions, could be identified in all three subjects. We refer to those as Cinderella, or C, units. These results support the research hypothesis addressed.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/09/20 alle ore 15:14:11