When beginners play the piano, the activity of the forearm muscles tends to be greater than that of experts because beginners move their fingers with more force than necessary. Reducing forearm muscle activity is important for pianists to prevent fatigue and injury. However, it is difficult for beginners to learn how to do so by themselves. We propose using electrical muscle stimulation (EMS) to teach beginners how to reduce this muscle activity while playing a tremolo: a rapid alternation between two notes. Since experts use wrist rotation efficiently when playing tremolos, we propose an EMS-based support system that applies EMS not to muscles that are relevant to moving the fingers but to the supinator and pronator teres muscles, which are involved in wrist rotation. We conducted a user study with 16 beginners to investigate how the forearm muscle activity on the extensor pollicis longus and digitorum muscles changed when using our EMS-based support system. We divided the participants into two groups: an experimental group who practiced by themselves with EMS and a control group who practiced by themselves without EMS and then practiced with instruction. When practicing by themselves, practicing with EMS was more effective than that without EMS; the activity levels of the extensor pollicis longus and digitorum muscles were significantly lower with EMS, and the participants felt less fatigue when playing tremolos. By comparing the improvement in reducing muscle activity between practicing with EMS and practicing with instruction, there was no significant difference. The results suggest that our EMS-based support system can reduce target muscle activity by applying EMS to other muscles to teach beginners how to move limbs efficiently.
Electrical muscle stimulation intervention in the acute phase of neuromyelitis optica: Two case reports