Respiratory sinus arrhythmia (RSA) is a phenomenon representing cardiorespiratory interaction. The magnitude of RSA is quantified as the power of high frequency (HF) component of heart rate variability (HRV). Although RSA has been used as an index of cardiac vagal function, it is thought to be an intrinsic cardiorespiratory resting function (Hayano and Yasuma 2003). Sakakibara et al. (2008) have studied the impact of college examinations on cardiorespiratory resting function among students during sleep. They demonstrated that HF component of pulse rate variability decreased during sleep on the day before the examinations, and suggested that real-world stress may interfere with the restorative function of sleep in daily life. HRV biofeedback (HRV-BF) refers to a technique for increasing HRV, both its time and frequency domain parameters. A number of HRV-BF studies have demonstrated that the technique used with paced breathing at a rate 0.1 Hz has clinical utility for the treatments of physical and mental disorders which involve autonomic nervous system dysregulation. Recent studies have also suggested that HRV-BF can help ameliorate sleep disturbance. Sakakibara et al. (2013) have examined the effect of HRV-BF on the cardiorespiratory resting function during sleep. Forty five healthy young adults were randomly assigned to one of three groups: HRV-BF, Autogenic Training (AT), and no-treatment control. Participants in the HRV-BF used a handheld HRV-BF device before their habitual bed time, those in the AT were asked to listen to an audiotaped instruction before bedtime. HF component increased during sleep in the HRV-BF group, although it remained unchanged in the AT and control groups. These results suggest that HRV-BF before sleep may improve cardiorespiratory resting function during sleep. Although growing evidence to support the efficacy of HRV-BF has led to an increased interest of clinical application in psychosomatic medicine and clinical psychology, further study for basic examination and construction of the theory for HRV-BF are warranted.
In this study, we developed a contactless biofeedback system for depressed patients as a relaxation aid. In our previous research, we developed a contactless heart rate measurement system that monitors the micro-vibrations of the body surface using microwave radars (24GHz). Using that system as the basis, we developed a new system that was able to conduct heart rate variability (HRV) biofeedback in accordance with the patient's relaxation state. The system was constructed as follows: we used "LabVIEW" for programming the real-time HRV measurement and calculation, and "Processing" for the visual representation to give the biofeedback to patients. The biofeedback system uses High-Frequency (HF) HRV components that reflect the parasympathetic activity as a relaxation index. We also created an animation that changes depending on the value of HF as the biofeedback for the patient. We conducted the verification experiment to gauge the amount of relaxation caused by this biofeedback system. There were two conditions in the experiment: (1) using the proposed system, and (2) without using the proposed system. The experiment was conducted with eight people in their twenty's. In each condition, they spent 10 minutes with 2-minute breaks before and after each condition. We measured the change in HF during the experiment, and compared the results of each condition. There was not a significant change in HF in condition (2), whereas in condition (1), there was a significant increase in HF after the use of our biofeedback system (t=-2.52, df=7, p<.05). Thus, induction of the relaxed state by the use of this system was confirmed.
After natural disasters and accidents and incidents, a certain percentage of children suffer from post traumatic stress disorder (PTSD) by those influences. So, many children need mental care. To prevent PTSD, learning the respiration control method, which relaxes the body and mind, is supposed to be efficient. Therefore, we developed a respiration leading stuffed toy, which leads children's respiration by the up-and-down movement of abdomen and help them relax. We executed a preliminary experiment to study the effects of respiration guidance by it. The participants were 48 children (26 boys and 22 girls) aged 4-12 years. Pulse waves and respiration waves were obtained as physiological measures. Overlap ratios were analyzed from respiration periods of respiration leading stuffed toy and of each participants. The results show that children were categorized into 2 groups; the well-synchronized group (20 children) and the poor-synchronized group (28 children). There are differences among age and sex. Age under 6 years and boys showed the trend not to be leaded. Further evaluation whether children can be relaxed by the respiration leading is needed.
In recent years, biofeedback has become recognized as a helpful tool not only in a medical setting, but in the field of sports performance enhancement as well (Muench, 2008). The aim of this study is to explore the effectiveness of biofeedback on breathing exercise as part of mental support for elite athletes. Four Japanese national team members participated in mental training to acquire breathing techniques as one of the relaxation skills. Stress Eraser manufactured by Helicor Inc, a small real-time biofeedback device, was used to visualize the transition of parasympathetic nerve predominant points during intervention. The athletes' reflections were also recorded over the course of 10 sessions. In the analysis, the relationships between the effects of acquiring breathing techniques, performance results and how the athletes actually applied breathing techniques into their sports were also examined. The results showed that 3 out of 4 athletes, who were first-time users of breathing exercise, consistently improved their parasympathetic nerve predominant points. Most likely, the key factor in these results may be the monitoring of their progress with real-time biofeedback and making modifications to their breathing approach such as the rhythm or length of the breathing. The athletes' reflections showed that they all realized the advantage of using real-time biofeedback while acquiring a breathing skill during mental training. These results suggest that real-time biofeedback could become a very powerful tool for visualizing the effects of mental training for both athletes and consultants in mental support.