Quantification of forearm muscle activation by ultrasound imaging and high-density electromyography

Abstract

Assessment of skeletal muscle function is an active research area in rehabilitation and sports medicine. An effective assessment methodology can be used to evaluate muscle recovery or response to treatments or interventions, and for early diagnosis of skeletal muscle diseases when combined with corresponding biomarkers. The main objective of this study is to develop an engineering technique for detecting muscle activation by combined ultrasound imaging and high-density electromyography (HDEMG). An ultrasound speckle tracking algorithm was employed to measure the impulsive kinetic energy released by muscle contraction while the processed HDEMG depicted the spatial-temporal electrical response of the activated muscle. The location and time course of the muscle activation can then be quantified by detecting the precise onset of the mechanical and electrical signals from ultrasound imaging and HDEMG, respectively. To demonstrate the conceptual feasibility, experiments were performed, with synchronized dual-probe ultrasound imaging and HDEMG recorded, on the forearm of one human participant without an injury or disability. To test detections of different activation patterns, single electrical pulses were sent to the flexor carpi radialis (FCR), flexor digitorum superficialis (FDS) and the median nerve, respectively, to intentionally create cases where FCR and FDS can contract individually or simultaneously.