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

近红外光谱技术主要用于显示大脑皮层的活动。虽然单通道或双通道连续波形系统越来越多地用于肌肉活动测量，但这些研究主要是为了阐明肌肉的生理特性。在这项研究中，我们记录了近红外光谱信号从人类受试者在他们的运动任务，并探讨了潜在的好处，近红外光谱技术在运动分析。结果表明：60Hz频率下采集的cwNIRS信号与肌肉活动有较好的对应关系，肌肉活动时O2 Hb浓度降低。随着肌肉活动的继续，调制的基线降低，对应于肌肉疲劳。然而，反应速率似乎很低。肌肉收缩本身通过诱发收缩而成为一种伪影。虽然近红外光谱信号作为疲劳和运动强度的测量是潜在有用的，但有几个问题需要在未来的研究中解决。

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.