Kinesiophysiological Analysis Associated with Changes in Subjective Intensities in Belt Electrode-skeletal Muscle Electrical Stimulation: a Prospective Exploratory Study

[Purpose] Belt electrode-skeletal muscle electrical stimulation (B-SES) is a novel electrical muscle stimulation treatment that causes less pain and discomfort and induces contraction in a wider skeletal muscle area than conventional electrodes. However, the stimulation intensity depends on patients' subjectivity. In the present study, B-SES and an expiratory gas device were combined to analyze the kinesiophysiological data associated with changes in subjective intensity. [Participants and Methods] Seventeen healthy participants were recruited. The subjective intensities were set to four conditions (weak, normal, strong, and maximum tolerated intensity), and the stimulation was performed in each condition in the "metabolic mode" (frequency, 4 Hz; pulse width, 250 µs). The primary outcome was metabolic equivalents (METs), and this data were compared for each condition. [Results] METs generated by B-SES were 2.0 (1.0) for weak intensity, 2.7 (1.2) for normal intensity, 3.9 (1.3) for strong intensity, and 5.0 (1.3) for the tolerance limit intensity; differences detected between all subjective intensities were statistically significant. [Conclusion] These findings show that objective intensities of >3 METs, as recommended in rehabilitation prescriptions, can be achieved when the subjective intensity is set at strong or maximum tolerated. Treatment with B-SES may provide a viable alternative to therapeutic exercise.