Biomechanical analysis of human movements has been conducted in various fields in order to aid the comprehension and evaluation of essential human motions. In the fields of sports and medical rehabilitation, biomechanics is recently being considered as an indispensable field of study. In particular, electromyography (EMG) is extensively being considered as an effective way of understanding human muscle dynamics. An electromyogram provides a real-time representation of muscle activity and is commonly used with the aim of performance improvement in electrophysiological study and rehabilitation. Although existing methods provide some benefits, they still have drawbacks with respect to spatial and time consistency, which are important elements of biofeedback. In other words, simultaneous understanding of the relationship between muscle activity and body motion is difficult and requires appropriate equipment and suitable training of the subject.

In recent years, sonification and visualization have attracted attention, as they enable an intuitive understanding of muscle activity. Sonification is an effective method of presenting the variation in muscle activity with respect to time, while visualization is effective for presenting multichannel muscle activity information, thereby facilitating an easy understanding of the interaction between multiple muscles. Although these methods aim at providing an intuitive understanding of muscle activity, they require an LCD display or large-scale equipments such as a motion capture device, thereby limiting the range of the application considerably.

We developed a wear-type interface that allows users to perceive muscle activity in an intuitive manner while providing an unrestricted system. Muscle activity or muscular tension are visualized on the surface of the body in the shape and position of the muscle in real time; this interface aids an intuitive understanding of multichannel muscle activity. It is designed as a wearable, thin, and light interface device, which enables a wide range of uses. Several experiments were conducted to evaluate the system performance. In addition, an experiment was conducted to investigate the possible applications of the interface to neurorehabilitation; this experiment involved the use of the interface in combination with an exoskeleton.