On the Time-frequency Analysis of Trunk Muscles During Sudden Release of Load

This paper studies the time-frequency analysis of trunk response based on surface electromyography (EMG) under an experimental protocol of sudden load release. Due to difficulties in feature extraction of surface EMG in short-time muscular reflex using conventional time-frequency analysis algorithms, a novel method called adaptive Lomb periodogram (ALP) is employed to improve the time and frequency resolutions by adaptively selecting the window sizes. Experimental results demonstrate the improved time-frequency resolution of the ALP in analyzing the EMG signals compared with conventional methods using scalogram. The findings of this study would provide important information in devising objective and quantitative protocol for neuromuscular function assessment, which are applicable to rehabilitation of low back pain patients, motor control and training, elderly fall prevention and ergonomic studies.