Conducting Wave Analysis of Temporal Changes in Multi-channel Surface EMG for Estimation of Mobilized Muscle Fibres

Skeletal muscle is a collection of motor units (MUs) composed of motoneurons and muscle fibres; muscle contraction is regulated by the number and type of MUs. Since sarcopenia and disuse atrophy are caused by atrophy of specific muscle fibre types, it is important to observe mobilized MUs for skeletal muscle diagnosis. In a previous study, we proposed a method to measure multi-channel surface electromyography (EMG) and quantitatively acquire conducting waves, which are potential waveforms propagating on the muscle surface. The mode of MU mobilization by prolonged muscle contraction is not well known. It is necessary to be able to estimate the mobilized MU over time to diagnose slow muscle fibres and to realize the evaluation of muscle activity during training. This study analyzed the conducting waves of multi-channel surface EMG during prolonged muscle contraction in 20 adult male subjects. The results of the changes in the conducting wave during long-duration muscle contractions at high and low loads showed different characteristics, suggesting the possibility of using the propagating wave to elucidate skeletal muscle.