### Abstract

A new method of estimating the number and the size of active motor units by processing mass electromyogram (EMG) has been devised. This method is based on a model of mass EMG generation, which is founded on the knowledge of the motor unit activities. This model is described as follows: (1) Mass EMG is the sum of all active motor unit action potential trains. (2) An input of each motor unit is a statistically independent random pulse train. (3) Motor units are divided into groups by their threshold force for recruitment. N(j) denotes the number of motor units belonging to group j, K(j) denotes the size, and f(j)(Pi) denotes the firing rate. (4) The firing rate f(j)(Pi) is a function of force. By using the theory of shot noise, the number N(j) and the size K(j) of motor units of each group are expressed as a function of the second and fourth moments of mass EMG (m_{2} and m_{4}) and the firing rate f(j)(Pi). This estimation starts from the lowest threshold force group, using m_{2}, m_{4}, and f(j)(Pi). This method has been applied to the human brachialis muscle and the human extensor digitorum communis muscle. The estimated results agree with the size principle and the physiological knowledge of the relation between the threshold force and the number of motor units. This agreement confirms the propriety of this estimation method. The estimation accuracy, that is, the relation between the observed period of mass EMG, which means the integration time for the calculation of moments, and the deviation of estimated values, is elucidated theoretically.

Original language | English |
---|---|

Pages (from-to) | 187-194 |

Number of pages | 8 |

Journal | Japanese Journal of Medical Electronics and Biological Engineering |

Volume | 19 |

Issue number | 3 |

Publication status | Published - 1981 |

Externally published | Yes |

### Fingerprint

### ASJC Scopus subject areas

- Electrical and Electronic Engineering

### Cite this

*Japanese Journal of Medical Electronics and Biological Engineering*,

*19*(3), 187-194.

**Estimation of the number of motor units by processing mass electromyogram.** / Yoshida, M.; Kanosue, Kazuyuki; Akazawa, K.; Fujii, K.

Research output: Contribution to journal › Article

*Japanese Journal of Medical Electronics and Biological Engineering*, vol. 19, no. 3, pp. 187-194.

}

TY - JOUR

T1 - Estimation of the number of motor units by processing mass electromyogram

AU - Yoshida, M.

AU - Kanosue, Kazuyuki

AU - Akazawa, K.

AU - Fujii, K.

PY - 1981

Y1 - 1981

N2 - A new method of estimating the number and the size of active motor units by processing mass electromyogram (EMG) has been devised. This method is based on a model of mass EMG generation, which is founded on the knowledge of the motor unit activities. This model is described as follows: (1) Mass EMG is the sum of all active motor unit action potential trains. (2) An input of each motor unit is a statistically independent random pulse train. (3) Motor units are divided into groups by their threshold force for recruitment. N(j) denotes the number of motor units belonging to group j, K(j) denotes the size, and f(j)(Pi) denotes the firing rate. (4) The firing rate f(j)(Pi) is a function of force. By using the theory of shot noise, the number N(j) and the size K(j) of motor units of each group are expressed as a function of the second and fourth moments of mass EMG (m2 and m4) and the firing rate f(j)(Pi). This estimation starts from the lowest threshold force group, using m2, m4, and f(j)(Pi). This method has been applied to the human brachialis muscle and the human extensor digitorum communis muscle. The estimated results agree with the size principle and the physiological knowledge of the relation between the threshold force and the number of motor units. This agreement confirms the propriety of this estimation method. The estimation accuracy, that is, the relation between the observed period of mass EMG, which means the integration time for the calculation of moments, and the deviation of estimated values, is elucidated theoretically.

AB - A new method of estimating the number and the size of active motor units by processing mass electromyogram (EMG) has been devised. This method is based on a model of mass EMG generation, which is founded on the knowledge of the motor unit activities. This model is described as follows: (1) Mass EMG is the sum of all active motor unit action potential trains. (2) An input of each motor unit is a statistically independent random pulse train. (3) Motor units are divided into groups by their threshold force for recruitment. N(j) denotes the number of motor units belonging to group j, K(j) denotes the size, and f(j)(Pi) denotes the firing rate. (4) The firing rate f(j)(Pi) is a function of force. By using the theory of shot noise, the number N(j) and the size K(j) of motor units of each group are expressed as a function of the second and fourth moments of mass EMG (m2 and m4) and the firing rate f(j)(Pi). This estimation starts from the lowest threshold force group, using m2, m4, and f(j)(Pi). This method has been applied to the human brachialis muscle and the human extensor digitorum communis muscle. The estimated results agree with the size principle and the physiological knowledge of the relation between the threshold force and the number of motor units. This agreement confirms the propriety of this estimation method. The estimation accuracy, that is, the relation between the observed period of mass EMG, which means the integration time for the calculation of moments, and the deviation of estimated values, is elucidated theoretically.

UR - http://www.scopus.com/inward/record.url?scp=0019870064&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0019870064&partnerID=8YFLogxK

M3 - Article

C2 - 7328879

AN - SCOPUS:0019870064

VL - 19

SP - 187

EP - 194

JO - Japanese Journal of Medical Electronics and Biological Engineering

JF - Japanese Journal of Medical Electronics and Biological Engineering

SN - 0021-3292

IS - 3

ER -