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Titolo:
Effect of step and ramp static contractions on the median frequency of electromyograms of back muscles in humans
Autore:
Lariviere, C; Arsenault, AB; Gravel, D; Gagnon, D; Loisel, P;
Indirizzi:
Univ Montreal, Sch Rebahil, Montreal, PQ H3C 3J7, Canada Univ Montreal Montreal PQ Canada H3C 3J7 il, Montreal, PQ H3C 3J7, Canada Previcap, Longueuil, PQ J4K 5G4, Canada Previcap Longueuil PQ Canada J4K 5G4 vicap, Longueuil, PQ J4K 5G4, Canada Univ Sherbrooke, Dept Kinanthropol, Sherbrooke, PQ J1K 2R1, Canada Univ Sherbrooke Sherbrooke PQ Canada J1K 2R1 erbrooke, PQ J1K 2R1, Canada Univ Sherbrooke, Fac Med, Dept Surg, Sherbrooke, PQ J1K 2R1, Canada Univ Sherbrooke Sherbrooke PQ Canada J1K 2R1 erbrooke, PQ J1K 2R1, Canada
Titolo Testata:
EUROPEAN JOURNAL OF APPLIED PHYSIOLOGY
fascicolo: 6, volume: 85, anno: 2001,
pagine: 552 - 559
SICI:
1439-6319(200110)85:6<552:EOSARS>2.0.ZU;2-4
Fonte:
ISI
Lingua:
ENG
Soggetto:
EMG POWER SPECTRUM; SINGLE MOTOR UNITS; DORSAL INTEROSSEOUS MUSCLE; ISOMETRIC CONTRACTIONS; FIBER-TYPE; HEALTHY-SUBJECTS; ERECTOR SPINAE; BALLISTIC CONTRACTIONS; CONDUCTION-VELOCITY; PAIN;
Keywords:
electromyography; power spectrum analysis; back muscles; median frequency; ramp and step contractions;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
44
Recensione:
Indirizzi per estratti:
Indirizzo: Lariviere, C Univ Montreal, Sch Rebahil, CP 6128,Succursale Ctr Ville, Montreal, PQ H3C3J7, Canada Univ Montreal CP 6128,Succursale Ctr Ville Montreal PQ Canada H3C 3J7
Citazione:
C. Lariviere et al., "Effect of step and ramp static contractions on the median frequency of electromyograms of back muscles in humans", EUR J A PHY, 85(6), 2001, pp. 552-559

Abstract

The purpose of this study was to compare the electromyogram median frequency (MF) values from two contraction modes (ramp vs step) at different forcelevels of eight back muscles. A group of 20 healthy male subjects stood ina dynamometer with the trunk in a vertical position and performed trunk extension contractions using the displayed L5/S1 extension moment as visual feedback. The electromyogram (EMG) signals from four pairs of back muscles were collected at 4.096 Hz using active surface electrodes during two 7 s static ramp contractions ranging from 0% to 100% of the maximal voluntary contraction (MVC) and two 5 s static step contractions performed at five forces (10%, 20%, 40%, 60% and 80% MVC). The root mean square (RMS) and MF of the EMG signals corresponding to 250 ins windows were computed at each force level for both contraction modes. The RMS from the ramp contractions were significantly higher than from the step contractions in six muscles. The corresponding MF showed a significant (alpha =0.05) contraction modexforce interaction in four muscles. A significant contraction mode main effect was obtained in four muscles having higher MF during step than during ramp contractions. These differences were more obvious (10-15 Hz) and more frequent atthe lower (10%, 20% and 40% MVC) forces. It was suggested that mechanisms not related to motor unit recruitment mi-ht influence MF in contraction modes. These unknown mechanisms contaminate any possible relationship between the MF measurements and muscle composition.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 28/01/20 alle ore 14:55:12