Age‐related change in motor unit activation strategy in force production: A mechanomyographic investigation

Akataki, Kumi; Mita, Katsumi; Watakabe, Makoto; Ito, Kunihiko

doi:10.1002/mus.10076

Cited by 48 publications

(69 citation statements)

References 42 publications

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“…4 and Tables 2 and 3). This result has to be discussed when MMG signals are used as indicators of muscle activity or MU recruitment strategies (ORIZIO et al, 2003;AKATAKI et al, 2002;YOSHITAKE and MORITANI, 1999). Moreover, it indicates that models of generation of MMG signals should account for the non-linearity of the generation system and that this nonlinearity is not negligible, even at low forces.…”

Section: Example Of Emg and Mmg Responses Of A Mu Detected During Thrmentioning

confidence: 88%

Non-invasive assessment of single motor unit mechanomyographic response and twitch force by spike-triggered averaging

Cescon

Gazzoni

Gobbo

et al. 2004

Med. Biol. Eng. Comput.

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A method for non-invasive assessment of single motor unit (MU) properties from electromyographic (EMG), mechanomyographic (MMG) and force signals is proposed. The method is based on the detection and classification of single MU action potentials from interference multichannel surface EMG signals and on the spike-triggered average of the MMG (detected by an accelerometer) and force signals. The first dorsal interosseous (FDI) and abductor digiti minimi (ADM) muscles were investigated at contraction levels of 2% and 5% of the maximum voluntary contraction (MVC) force. A third contraction was performed by selective activation of a single MU with surface MU action potential visual feedback provided to the subject. At 5% MVC, the mean (+/-standard error) single MU MMG peak-to-peak value was 11.0+/-1.8 mm s(-2) (N= 17) and 32.3+/-6.5 mm s(-2) (N=20) for the FDI and ADM muscles, respectively. The peak of the twitch force was, at the same contraction level, 7.41+/-1.34 mN and 14.42+/-2.92 mN, for the FDI and ADM muscles, respectively. The peak-to-peak value of the MMG was significantly different for the same MU at different contraction levels, indicating a non-linear summation of the single MU contributions. For the FDI muscle, the MMG peak-to-peak value of individual MUs was 21.5+/-7.8 mm s(-2), when such MUs were activated with visual feedback provided to the subject, whereas, for the same MUs, it was 11.8+/-3.8 mm s(-2), when the subject maintained a constant force level of 2% MVC. The method proposed allows the non-invasive assessment of single MU membrane and contractile properties during voluntary contractions.

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Section: Example Of Emg and Mmg Responses Of A Mu Detected During Thrmentioning

confidence: 88%

Non-invasive assessment of single motor unit mechanomyographic response and twitch force by spike-triggered averaging

Cescon

Gazzoni

Gobbo

et al. 2004

Med. Biol. Eng. Comput.

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show abstract

“…There is a limit in the force resolution of the MMG/force relationship obtained by the separate protocol. We have recently reported (Akataki et al 2001(Akataki et al , 2002 that time-frequency analysis of nonstationary MMG during continuous ramp contractions enables a high resolution of the MMG/force relationship and provides more detailed and reliable information on the MU activation strategy.…”

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

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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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“…Dessa forma, as fibras antes inervadas por NM com propriedades anaeróbias, sofrem um processo de remodelagem da unidade motora, e passam a ser inervadas por NM com propriedades oxidativas, alterando as propriedades das fibras tipo II para fibras tipo I 26 , o que pode influenciar diretamente a velocidade da geração de força no início da contração muscular.…”

Section: Discussionunclassified

Taxa De Desenvolvimento De Força E Ativação Neural Em Mulheres Pós-Menopausadas

Pereira

Araújo

Oliveira

et al. 2016

Rev Bras Med Esporte

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Introdução: O envelhecimento associa-se à redução da velocidade de contração e ativação das fibras musculares, influenciando a aptidão física e o desempenho funcional. Objetivo: Verificar o comportamento da taxa de desenvolvimento de força (TDF) e ativação neural em mulheres pós-menopausadas. Métodos: Vinte e quatro mulheres pós-menopausadas (63,2 ± 5,6 anos; 154,5 ± 7,3 cm e 64,7 ± 7,6 kg), funcionalmente independentes e fisicamente ativas, foram submetidas simultaneamente, à mensuração da força isométrica máxima e dos sinais eletromiográficos (EMG) dos seguintes músculos: vasto lateral (VL), reto femoral (RF) e vasto medial (VM), durante uma extensão unilateral do joelho do membro dominante. Tais resultados foram utilizados para calcular a TDF, o impulso contrátil, em intervalos de 20 ms nos primeiros 200 ms da contração muscular pelo uso da curva força/tempo, a taxa de ativação EMG (TAE) e a amplitude média EMG, em intervalos de 40 a 80 ms do início da integração EMG pelo uso da curva EMG/tempo. 29.19 to 86.04Nm; the RFD varied from 1459.42 to 430.21N.m.s-1 in 20ms and 200ms, respectively, indicating

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Age‐related change in motor unit activation strategy in force production: A mechanomyographic investigation

Cited by 48 publications

References 42 publications

Non-invasive assessment of single motor unit mechanomyographic response and twitch force by spike-triggered averaging

Non-invasive assessment of single motor unit mechanomyographic response and twitch force by spike-triggered averaging

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

Taxa De Desenvolvimento De Força E Ativação Neural Em Mulheres Pós-Menopausadas

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