In vivo behavior of human muscle during contraction: A multimodal investigation with real-time ultrasonography

The in vivo behavior of human muscle during contraction is a complicated process, and some commonly-used research techniques include electromyography (EMG), mechanomyography (MMG), and ultrasonography (US). This study proposed a new multi-model method which integrated EMG, MMG and US together to investigate the muscle activities. An acquisition system was developed to simultaneously collect US images and other signals in real-time; and an image tracking algorithm was implemented to automatically extract the muscle boundary in US. This study examined the responses of human rectus femoris muscle during voluntary isometric ramp contraction for knee extension. The collected signals were analyzed and three parameters extracted from EMG, MMG and US were combined to estimate the torque. The results show that there are significant multiple linear relationships between the three parameters and torque. The R2 of the regression was 0.99 which was much better than the linear regressions with single parameter. In conclusion, this multi-model method can provide more information about the muscle activities, and further research will be conducted for better understanding of the muscle contraction mechanism.