Acoustic Signals from Skeletal Muscle

Dt, Barry

doi:10.1152/physiologyonline.1990.5.1.17

Cited by 8 publications

(8 citation statements)

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“…Stokes and Cooper (1992) have described a relevant relationship between PMG amplitude and stimulation frequency, PMG markedly decreasing with increasing tetanic frequency. This con®rmed what had been demonstrated in vitro for isolated frog muscles (Barry 1987;Frangioni et al 1987). On the other hand, the eect of recruitment on evoked PMG amplitude has been poorly documented.…”

Section: Introductionsupporting

confidence: 87%

“…Our band-pass ®lter (10 Hz±60 Hz) eliminated much of the lower frequencies of the signal, these latter being attributed by Barry (1991Barry ( , 1992 to the bulk movement of the muscle mass during the twitch. He has also interpreted the higher frequency components as the resonant frequency, con®rming in situ what he had demonstrated in vitro (Barry 1987).…”

Section: Evoked Pmg As a Summation Of Elementary Soundsmentioning

confidence: 67%

“…3, several points may be superimposed because the PMG or twitch latency values obtained for dierent stimulation were identical between PMG amplitude and diaphragm force. For every recorded PMG, it was possible to recognize an initial negative ®rst wave and to interpret it as the transverse latency relaxation (see Hufschmidt 1985;Barry 1987Barry , 1991Barry , 1992Bolton et al 1989). This initial wave was always present and of lower amplitude compared to the amplitude of the ®rst main peak.…”

Section: Evoked Pmg As a Summation Of Elementary Soundsmentioning

confidence: 99%

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Summation of elementary phonomyograms during isometric twitches in humans

Petitjean

Maton

Fourment

1998

European Journal of Applied Physiology

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To study its summation principle, the phonomyogram (PMG) from the first interosseus dorsalis muscle was recorded in five subjects during single twitches evoked by electrical stimulation over the motor point. By increasing the current pulse from threshold to maximal intensity, PMG amplitude increased linearly with motor unit recruitment. The twitch amplitude-intensity relationship was also linear. The PMG amplitude was therefore linearly related to the external force. For all these relationships highly significant correlation coefficients were found. These relationships were interpreted as being a consequence of an orderly recruitment, although, contrary to what happens during voluntary contraction, the largest and strongest motor units were recruited before the smallest and weakest ones during axon electrical stimulation. The PMG onset always preceded twitch onsets as indicated by latency measurements [mean 3.2 (SD 1.3) ms versus 11.5 (SD 3.9) ms, respectively]. Moreover, PMG and twitch latencies may have been significantly reduced by recruitment, suggesting that orderly recruitment influenced both PMG amplitude and occurrence. These results were interpreted as being the result of the summation of elementary PMG from every contracting motor unit and the stiffness change of the muscle medium occurring with recruitment.

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Section: Introductionsupporting

confidence: 87%

Section: Evoked Pmg As a Summation Of Elementary Soundsmentioning

confidence: 67%

Section: Evoked Pmg As a Summation Of Elementary Soundsmentioning

confidence: 99%

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Summation of elementary phonomyograms during isometric twitches in humans

Petitjean

Maton

Fourment

1998

European Journal of Applied Physiology

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“…A mechanical vibration on the skin overlying a contracting muscle is produced by lateral dimensional changes of a number of active muscle fibers (Barry 1987;Brozovich and Pollack 1983;Frangioni et al 1987;Gordon and Holbourn 1948;Oster and Jaffe 1980;Ouamer et al 1999). The recording of this vibration has recently been referred to as the mechanomyogram (MMG) because the signal reflects the mechanical activity of contracting muscle (Orizio 1993).…”

Section: Introductionmentioning

confidence: 99%

Mechanomyographic responses during voluntary ramp contractions of the human first dorsal interosseous muscle

Akataki

Mita

Watakabe

et al. 2003

European Journal of Applied Physiology

113

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The aim of this study was to examine the mechanomyogram (MMG) and force relationship of the first dorsal interosseous (FDI) muscle as well as the biceps brachii (BB) muscle during voluntary isometric ramp contractions, and to elucidate the MMG responses resulting from the intrinsic motor unit (MU) activation strategy of FDI muscle with reference to the MMG of BB muscle. The subjects were asked to exert ramp contractions of FDI and BB muscle from 5% to 70% of the maximal voluntary contraction (MVC) at a constant rate of 10% MVC/s. In FDI muscle, the root-mean-squared amplitude (RMS) of the MMG decreased slowly with force up to 21%, and then a progressive increase was followed by a relatively rapid decrease beyond 41% MVC. The RMS/%MVC relationship in BB muscle consisted of an initial slow increase followed by a rapid increase from 23% MVC and a progressive decrease beyond 61% MVC. With respect to the mean power frequency (MPF), FDI muscle demonstrated no obvious inflection point in the MPF/%MVC relationship compared with that in BB muscle. Namely, the MPF of FDI muscle increased linearly through the force levels exerted. In contrast to FDI muscle, the MPF/%MVC relationship in BB muscle was decomposed into four specific regions: (1) a relative rapidly increase (<34% MVC), (2) a slow increment (34-53% MVC), (3) a temporary reduction (53-62% MVC), and (4) a further rapid increase (>62% MVC). The different MMG responses between FDI and BB muscles are considered to reflect the fact that the MU activation strategy varies among different muscles in relation to their morphology and histochemical type. Namely, the rate coding of the MUs plays a more prominent role in force production in relatively small FDI muscle than does MU recruitment compared with their respective roles in the relatively large BB muscle.

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“…La industrialización creó una clase obrera más amplia y una clase media de profesionales, técnicos, pequeños empresarios y burócratas, pero también llevó a la destitución de campesinos que fueron desplazados de sus tierras cuando estas se convertían en modernas empresas agrícolas. 5 …”

Section: Bosquejo Históricounclassified

The family remittance from abroad: dependency or development for El Salvador

Ulloa¹

1996

Realidad, Rev. Ciencias Soc. y Hum.

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Durante los años ochenta, El Salvador experimentó una emigración significativa, efecto del creciente conflicto político que llevó al país a una guerra que duró doce años. El país perdió el 20% de su población, una fuente de trabajo bastante importante. En 1994, casi un millón de salvadoreños que residen principalmente en los Estados Unidos y Canadá, enviaron $958 millones en ayuda familiar a El Salvador. En 1993, la remesa familiar representó una proporción equivalente al 12% del Producto Interno Bruto (PIB) del país, sobrepasando el monto global de las exportaciones en un 20%. Como factor redistributivo, aproximadamente un tercio de todas las familias en El Salvador se beneficiaron de las remesas enviadas por parientes residentes en el extranjero, quienes luchan por aliviar la pobreza de sus familiares en El Salvador pese a que muchos también viven en de la pobreza en los Estados Unidos. No obstante la tendencia creciente del flujo de remesas, existen factores que pueden afectar la tendencia futura del emigrante a remitirlas. El objetivo de este estudio fue el de examinar los determinantes principales de las remesas y las implicaciones políticas de los resultados para la ciudadanía y para el Gobierno de El Salvador (GOES).Realidad: Revista de Ciencias Sociales y Humanidades No. 50, 1996: 213-240

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Acoustic Signals from Skeletal Muscle

Cited by 8 publications

References 0 publications

Summation of elementary phonomyograms during isometric twitches in humans

Summation of elementary phonomyograms during isometric twitches in humans

Mechanomyographic responses during voluntary ramp contractions of the human first dorsal interosseous muscle

The family remittance from abroad: dependency or development for El Salvador

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