2013 Fiscal Year Final Research Report

Applying NIRS in physiology of locomotion - with a focus on muscle activities

Research Project

Project/Area Number	24657169
Research Category	Grant-in-Aid for Challenging Exploratory Research
Allocation Type	Single-year Grants
Research Field	Physical anthropology
Research Institution	Kyoto University
Principal Investigator	HIRASAKI Eishi 京都大学, 霊長類研究所, 准教授 (70252567)
Co-Investigator(Kenkyū-buntansha)	MORI Futoshi 教授, 保健福祉学部, 教授 (50301726)
Project Period (FY)	2012-04-01 – 2014-03-31
Keywords	生体機構 / ロコモーション
Research Abstract	NIRS technology has mainly been used to visualize cortical activities of the brain. Although one- or two-channel cw (continuous waveform) system is now increasingly used for muscle activity measurements, those studies mostly aim to elucidate muscles' physiological property. In this study, we recorded NIRS signals from human subjects during their motor tasks, and investigated potential benefits of NIRS technique in locomotion analysis. Results showed that the cwNIRS signals sampled at 60Hz corresponded well to the muscle activities; the oxyhemoglobulin (O2Hb) concentration decreased when muscles were recruited. The baseline of modulation was lowered as muscle activity continued, corresponding to muscle fatigue. However, reaction rate seemed low. Muscle contraction itself becomes an artifact by inducing perstriction. Although the NIRS signal is potentially useful as measure of fatigue and exercise intensity, there are several issues which require to be addressed in future studies.