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Titolo:
Effects of acute hypoxemia on force and surface EMG during sustained handgrip
Autore:
Dousset, E; Steinberg, JG; Balon, N; Jammes, Y;
Indirizzi:
Univ Mediterranee, Inst Jean Roche, Fac Med, Lab Physiopathol Resp,Unite Propre Rech Enseignem, F-13916 Marseille, France Univ Mediterranee Marseille France F-13916 em, F-13916 Marseille, France
Titolo Testata:
MUSCLE & NERVE
fascicolo: 3, volume: 24, anno: 2001,
pagine: 364 - 371
SICI:
0148-639X(200103)24:3<364:EOAHOF>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
MOTONEURON FIRING RATES; MAXIMAL VOLUNTARY CONTRACTIONS; M-WAVE; ISOMETRIC CONTRACTION; REFLEX INHIBITION; SKELETAL-MUSCLES; FATIGUE; ELECTROMYOGRAM; PERFORMANCE; ALTITUDE;
Keywords:
electrical stimulation; hypoxia; MVC; M wave; static contraction;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
32
Recensione:
Indirizzi per estratti:
Indirizzo: Jammes, Y Univ Mediterranee, Inst Jean Roche, Fac Med, Lab Physiopathol Resp,Unite Propre Rech Enseignem, Blvd Pierre Dramard, F-13916 Marseille, France Univ Mediterranee Blvd Pierre Dramard Marseille France F-13916
Citazione:
E. Dousset et al., "Effects of acute hypoxemia on force and surface EMG during sustained handgrip", MUSCLE NERV, 24(3), 2001, pp. 364-371

Abstract

Data on the consequences of acute hypoxemia on the strength of contractionare often contradictory. In healthy subjects, we tested the effects of hypoxemia (PaO2 = 56 mmHg), maintained for a 30-min period, on static handgripelicited by voluntary effort or direct electrical muscle stimulation, in order to separate the consequences of hypoxemia on central or peripheral factors, respectively. Force was measured during maximal voluntary contractions (MVCs), 60% MVCs sustained until exhaustion, and 1-min periods of electrical muscle stimulation at 60 Hz. The evoked compound muscle action potential (M wave) was recorded in resting muscle and after each period of 60-Hz stimulation or sustained 60% MVC. Power spectrum analysis of surface electromyogram (EMG) was performed during sustained 60% MVC. Compared to normoxemia, acute hypoxemia lowered MVC (-12%, P < 0.01) but enhanced (+38%, P < 0.01) the peak force elicited by electrical muscle stimulation. In resting muscle, hypoxemia had no influence on the M-wave amplitude but lengthened the neuromuscular transmission time(+740 us, P < 0.05). Hypoxemia did not alter the M wave measured after 60 Hz stimulation and 60% MVC, During sustained 60% MVC, hypoxemia markedly depressed the EMG changes, abolishing the leftward shift of power spectra. These data show that acute hypoxemia reduces MVCthrough depression of the central drive, whereas it improves the peripheral muscle response to electrical stimulation. In addition, hypoxemia reducesthe recruitment of slow firing motor unit, which are highly oxygen-dependent. This could constitute an adaptative muscle response to a reduced oxygensupply. (C) 2001 John Wiley & Sons, Inc.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 30/03/20 alle ore 11:16:19