Development of chronaxie measurement system based on muscle vibration.

• OKA Hisao

  Faculty of Health Sciences, Okayama University Medical School

• MIYAJIMA Tomo

  Nissin Systems Co., Ltd.

Bibliographic Information

Other Title

• 筋の振動特性に着目したクロナキシー測定システムの開発

Abstract

Electro-stimulation of muscles is utilized in various fields, such as functional electric stimulation (FES), therapeutic electric stimulation (TES), chronaxie testing of muscle, etc. The chronaxie is examined to estimate the relative excitability of muscles in clinical practice. Chronax^TM (OG Giken Co., Ltd., CX-3) is a commercial instrument for this type of diagnosis. However, the time required to obtain a strength-duration curve and the chronaxie is relatively long. It is also difficult to get reproducible measurement results because the start of muscle vibration is detected visually and subjectively.<BR>We previously developed a computer-based chronaxie meter. It consisted of a notebook-type computer, an electrical interface circuit, and a set of stimulating electrode and accelerometer. The motor point of a muscle was stimulated with negative rectangular pulses. As the muscle vibration caused by stimulation was detected using an accelerometer, the measurement reproducibility of the meter became better. The measurement time also decreased, compared with that of the Chronax^TM. The application of our instrument to many subjects and muscles was difficult for two reasons: a) individual characteristics of muscles; and b) heart synchronous pulsatile noise was superimposed on the muscle vibrations. As a consequence, our former instrument was inadequate because of the long measurement time required, and the accuracy was not sufficient for clinical use.<BR>In the present study, the former chronaxie meter was improved for an increase in measurement accuracy and a decrease in measurement time. The improved chronaxie measurement system is characterized by a measurement/control programming design and a transducer for detecting a pulsatile blood flow, newly appended to the former meter. In order to apply this system to many kinds of muscles, two characteristic frequencies and the rheobase current of the S-D curve of the muscle are examined prior to the usual S-D curve measurement. In order to avoid muscle vibration with superposed cardiac synchronous pulsatile noise, the muscle is electrically stimulated just after the onset of the systolic phase of the photoplethysmogram, measured transdigitally. With this trigger method, the muscle vibration can be detected free from noise.<BR>The measurement time for an S-D curve has decreased to approximately 50%, compared with the Chronax^TM. The dispersion in the obtained chronaxies of ten measurements has become 3.3%, and in the rheobases, 1.3% (3.8% and 2.3%, respectively in the former meter). The improved measurement system will be applicable to many subjects and kinds of muscles in clinical examination.

Journal

• Biomechanisms

  Biomechanisms 16 37-46, 2002

  Society of Biomechanisms

Keywords

• General Engineering

Details

• CRID: 1390001205219208192
• NII Article ID: 110004695651
• NII Book ID: AN10286188
• DOI: 10.3951/biomechanisms.16.37
• ISSN: 1349497X
• ISSN: 13487116
• Text Lang: ja
• Data Source:
  • JaLC
  • Crossref
  • CiNii Articles
• Abstract License Flag: Disallowed