To improve the efficiency of individualized resonance frequency search for heart rate variability biofeedback (HRV-BF), we focused on the phase match between respiratory and heart rate waveforms. The resonance frequencies of 32 male experimental participants were determined using BREASSIST^® (made by TOYOBO Co., Ltd.), an application that adjusts the time gap between the peak of successive heart rate changes and the peak of the respiratory waveform by simultaneously measuring heart rate and respiratory sensors. The results showed that the average determining time was 3 minutes 20 seconds, with the shortest taking 2 minutes 28 seconds and the longest 5 minutes 40 seconds. The average resonance frequency for each search time was 6.3 times a minute (0.105 Hz), with a mode and median of 6.5 times a minute. Resonance frequencies ranged from 5.0 to 7.5 times a minute, which tended to be slightly faster than the known resonance frequency range of 4.5 to 7.0 times a minute. Analysis of HRV-BF training conducted at the determined resonance frequencies (n＝30) showed a significant increase (p＜0.001) in RMSSD, which represents parasympathetic activity during paced breathing, compared to resting breathing, statistically confirming the increase in parasympathetic activity, and suggested that paced breathing with resonance frequency reduces mental stress. In addition, SDNN, which represents autonomic nervous activity, was significantly higher after the HRV-BF training than before the training, and the mean heart rate was also significantly lower in the same comparison. From the above results, it was found that the method of adjusting the time gap between the peak of heart rate change and the peak of respiratory waveform at the paced breathing by simultaneous measurement of the heart rate sensor and the respiratory sensor could efficiently determine the resonance frequency, and this method was comparable to the effects of conventional HRV-BF.

  In recent years, with the focus on preventative health approaches, there has been growing interest in health management using activity tracker (AT). This study investigated the impact of biofeedback using AT on physical activities, psychological aspects, and interest in health and sleep quality in healthy participants.

  Eleven participants (mean age＝42.9±12.1 years) wore AT and provided biometric data (steps, heart rate, sleep duration, sleep efficiency) for five two-week periods. Subjective happiness (SHS) and stress (K10) were assessed via questionnaires, and changes in health awareness were evaluated at the study’s conclusion. The analysis results showed that, compared to Period 1 (baseline), there was a significant increase in the average number of steps taken in all other periods. On the other hand, there was no significant difference in the average sleep time between the periods. Regarding the K10, the number of participants who scored above the cutoff value decreased at the end of the study compared to the beginning. In addition, 81.8％ of the participants said that their interest in health had increased, and 100％ said that their interest in sleep quality had increased.

  This study suggests that biofeedback using AT may increase the number of steps taken and improve awareness of health and sleep. However, there was no clear direct effect on sleep time or psychological indicators. On the other hand, the problem of low AT attachment rates was also identified, suggesting the need for a more convenient device.

  It is very important for the patients with psychosomatic disease to understand why their symptoms occur through the bio-psycho-social model. In this study, we examine two cases in which good progress was made when biofeedback (BF) was used to share the pathophysiology of psychosomatic disorders. The case 1 was a man in his 40’s with stomach pain which has been 8 years. We suspected aerophagy and performed radiographs before and after ingestion of barium sulfate as a physiologic indicator of gastric function. After providing feedback while viewing the images, the patient was able to visually understand the functional pathology that could be causing his symptoms, which gave him a sense of relief. Since then, we have continued to treat him for other symptoms, but he no longer complains of abdominal symptoms. Case 2 was a man in his late 50’s. He had been aware of his difficulty in speaking for 3 years and was referred to our department in October of the same year because the cause of his symptoms was unknown after a thorough examination. Physiological parameters were evaluated at rest and under stress, and a marked increase in oculomotor potential with stress was observed, along with an increase in subjective symptoms and a decrease in the responsiveness of trapezius muscle potential to stress. After providing feedback that muscle tension was affecting his symptoms and explaining that exercise therapy would be helpful, he felt reassured and confident that he could manage his symptoms on his own, and further visits to our department were no longer necessary. Through taking biofeedback, we found out how functional symptoms occurred and this helped patients get courage to deal with their symptoms, which means that the visualization with the biofeedback was useful for psychosomatic approach.