Validity of delay time identification during standing based on steady-state response

Abstract

Delay time of reflection is widely used to evaluate neurological disorders and child development. The delay time is generally measured from a button press to a visual stimulus or from surface electromyography (EMG) response to an external stimulus. Due to its variability, however, it is not easy to estimate accurately. In the previous study, we proposed a delay time estimation method from steady-state response based on a delayed feedback control model during standing. The method allows us to estimate the delay time with reproducibility. The purpose of this study is to verify the validity of the delay times estimated from the steady-state response analysis by comparing it with the response of surface EMG to impulse stimulation. In addition, we investigated time delay changes according to the degree of tension by varying the magnitude of the external stimulus. From the validation experiments involving 10 young healthy subjects, no correlation was found between the delay times estimated from the steady-state response and the EMG responses. Furthermore, there was no change in the delay time with the degree of tension caused by the magnitude of support surface sway. Since the delay time estimated from EMG measurement according to impulse stimulus has a high variable, it is necessary to improve the estimation method.