2004 Fiscal Year Final Research Report Summary

Elucidation of the Motor unit firing behaviors in various human muscles

Research Project

Project/Area Number	14580066
Research Category	Grant-in-Aid for Scientific Research (C)
Allocation Type	Single-year Grants
Section	一般
Research Field	体育学
Research Institution	Meiji University
Principal Investigator	MIZUMURA Shinji Meiji University, School of Arts and Letters, Associate Professor, 文学部, 助教授 (50267358)
Project Period (FY)	2002 – 2004
Keywords	Motor unit / recruitment threshold / firing rate / Vastus medialis muscle / Quadrifilar wire electrode
Research Abstract	Purpose of the present research was to elucidate the motor unit firing behaviors in various human muscles during voluntary isometric force exertion. First, I improved the quadrifilar needle electrode which is used in the precision decomposition technique. As a result, the quadrifilar wire electrode which can detect the intra-muscular myoelectric signal of vastus medialis muscle was produced. Next, the recruitment threshold, the de-recruitment threshold, and the firing rate of the motor unit in the vastus medialis muscle were verified. The positive correlation was observed between the recruitment and de-recruitment threshold of the motor units. The negative correlation was observed between the recruitment threshold and the firing frequency of the motor units. These results indicate that the concept of the "Onion skin phenomenon" is also adapted in the vastus medialis muscle.