Efficacy of Visual Biofeedback with Surface Electromyography During the Forehead Exercise for Suprahyoid Muscles

<p>　Objective:　The forehead exercise for suprahyoid muscles (FESM, “Enge-Odeko-Taiso” in Japanese) is a popular method for training the suprahyoid muscles. This is a simple head-and-neck flexion technique in which resistance is applied by placing the hand on the forehead. However, because the angle of neck bending and application of resistance are left to the practitioner, the suprahyoid muscles may not be fully activated. These challenges may be mitigated by incorporating participant feedback (FB) information regarding the muscle contractions associated with neck movements. This study investigated the usefulness of visual feedback by using surface electromyography (sEMG) during the FESM.</p><p>　Methods:　Thirty-two healthy young adults with an average age of 24.0±3.6 years participated in this study. The participants were divided into two groups, with and without visual feedback, and were assigned to perform the FESM. The experiment was conducted in the following order: (1) practice; (2) first trial; (3) second trial; (4) third trial (after 15 min); (5) fourth trial (after one week). The group with feedback used sEMG as visual feedback in the second trial step (3) of this process. The measurement time per FESM was 5 s, and a total of three measurements were recorded during each trial. We assessed the electromyographic activity of the suprahyoid muscles in the study participants while they were performing the FESM. The analysis interval of the electromyographic waveform was 3 s, ranging from 1 s to 4 s after the start of the exercise. The representative value for each trial was determined as the average of the three calculated amplitude values.</p><p>　Results:　The analysis comprised 15 participants in each experimental group. A simple main effect test with the trial time as a factor showed a significant difference in the group with feedback. Furthermore, multiple comparison tests per trial showed a significant increase in the mean amplitude of the second, third, and fourth trials compared to that in the first trial. However, the simple main effect of the without-feedback group was not significantly different.</p><p>　Conclusion:　Our results show that the combined use of real-time FB with sEMG during the FESM helps increase the electromyographic amplitude in the suprahyoid muscles. The results also suggest that the effect was retained after one week.</p>