Short-Term Effects of Heart Rate Variability Biofeedback on Working Memory

Drawing upon the well-documented impact of long-term heart rate variability biofeedback (HRVB) on psychophysiological responses, this study seeks to explore the short-term effects arising from a single HRVB session during and after paced breathing exercise. The research aligns with the neurovisceral integration model, emphasizing the link between heart rate variability (HRV) levels and cognitive performance. Therefore, a randomized controlled trial employing a between-subjects design was conducted with 38 participants. Each participant was assigned to either the paced breathing intervention group or the spontaneous breathing control group. The study assessed various parameters such as cardiac vagal tone, evaluated through vagally mediated HRV measures, and working memory, measured using the N-back task. Additionally, participants' affective states were assessed through self-reported questionnaires, specifically targeting attentiveness, fatigue, and serenity. The results notably reveal enhancements in the working memory task and an elevated state of relaxation and attention following the HRVB session, as evidenced by higher averages of correct responses, serenity and attentiveness scores. However, the findings suggest that this observed improvement is not influenced by changes in cardiac vagal tone, as assessed using a simple mediation analysis. In conclusion, this study presents promising insights into the impact of a single HRVB session, laying the foundation for future research advancements in this domain.

Remote Short Sessions of Heart Rate Variability Biofeedback Monitored With Wearable Technology: Open-Label Prospective Feasibility Study

BACKGROUND

Heart rate variability (HRV) biofeedback is often performed with structured education, laboratory-based assessments, and practice sessions. It has been shown to improve psychological and physiological function across populations. However, a means to remotely use and monitor this approach would allow for wider use of this technique. Advancements in wearable and digital technology present an opportunity for the widespread application of this approach.

OBJECTIVE

The primary aim of the study was to determine the feasibility of fully remote, self-administered short sessions of HRV-directed biofeedback in a diverse population of health care workers (HCWs). The secondary aim was to determine whether a fully remote, HRV-directed biofeedback intervention significantly alters longitudinal HRV over the intervention period, as monitored by wearable devices. The tertiary aim was to estimate the impact of this intervention on metrics of psychological well-being.

METHODS

To determine whether remotely implemented short sessions of HRV biofeedback can improve autonomic metrics and psychological well-being, we enrolled HCWs across 7 hospitals in New York City in the United States. They downloaded our study app, watched brief educational videos about HRV biofeedback, and used a well-studied HRV biofeedback program remotely through their smartphone. HRV biofeedback sessions were used for 5 minutes per day for 5 weeks. HCWs were then followed for 12 weeks after the intervention period. Psychological measures were obtained over the study period, and they wore an Apple Watch for at least 7 weeks to monitor the circadian features of HRV.

RESULTS

In total, 127 HCWs were enrolled in the study. Overall, only 21 (16.5%) were at least 50% compliant with the HRV biofeedback intervention, representing a small portion of the total sample. This demonstrates that this study design does not feasibly result in adequate rates of compliance with the intervention. Numerical improvement in psychological metrics was observed over the 17-week study period, although it did not reach statistical significance (all P>.05). Using a mixed effect cosinor model, the mean midline-estimating statistic of rhythm (MESOR) of the circadian pattern of the SD of the interbeat interval of normal sinus beats (SDNN), an HRV metric, was observed to increase over the first 4 weeks of the biofeedback intervention in HCWs who were at least 50% compliant.

CONCLUSIONS

In conclusion, we found that using brief remote HRV biofeedback sessions and monitoring its physiological effect using wearable devices, in the manner that the study was conducted, was not feasible. This is considering the low compliance rates with the study intervention. We found that remote short sessions of HRV biofeedback demonstrate potential promise in improving autonomic nervous function and warrant further study. Wearable devices can monitor the physiological effects of psychological interventions.

The International Performance, Resilience and Efficiency Program Protocol for the Application of HRV Biofeedback in Applied Law Enforcement Settings

Law enforcement officers are routinely exposed to high-threat encounters that elicit physiological stress responses that impact health, performance, and safety. Therefore, self-regulation using evidence-based approaches is a priority in police research and practice. This paper describes a five-module heart rate variability biofeedback (HRVB) protocol that is part of a larger resilience program (the International Performance Resilience and Efficiency Program - iPREP) established in 2014. Supported by 10 years of user-informed research and development, our methods are tailored to address occupational stressors and the practical realities of training and resource availability in operational settings. Building on existing clinical methods that comprise five to six weekly sessions and up to 40-min of daily practice, our iPREP HRVB protocol is typically delivered in a condensed format across 2-3 days and is seamlessly integrated with reality-based training scenarios commonly employed in policing. By combining best practices in clinical HRVB with police-specific pedagogical frameworks, officers receive accelerated and job-relevant training to adaptively modulate autonomic responses to acute and chronic stress. Efficacy of the iPREP HRVB protocol is supported by several research studies of various methodological designs (i.e., randomized control trial, longitudinal cohort) that demonstrate immediate and sustained improvements in police performance and physiological health outcomes. We conclude with a critical appraisal of the available empirical evidence contrasting common and emerging breathing techniques proposed for use in operational policing contexts. The critical appraisal guide is intended to serve as a resource for law enforcement agencies, governing bodies, and operators when choosing appropriate and effective self-regulation training approaches.

Digital mental health interventions as stand-alone vs. augmented treatment as usual

BACKGROUND

Smartphone-based digital mental health interventions (DMHI) have been described as a purported solution to meet growing healthcare demands and lack of providers, but studies often don't account for whether patients are concurrently in another treatment modality.

METHODS

This preregistered quasi-experimental intent-to-treat study with 354 patients enrolled in a therapist-supported DMHI examined the treatment effectiveness of the Meru Health Program (MHP) as a stand-alone treatment as compared to the MHP in combination with any other form of treatment, including (1) in-person therapy, (2) psychotropic medication use, and (3) in-person therapy and psychotropic medication use.

RESULTS

Patients with higher baseline depressive and anxiety symptoms were more likely to self-select into multiple forms of treatment, an effect driven by patients in the MHP as adjunctive treatment to in-person therapy and psychotropic medication. Patients in combined treatments had significantly higher depressive and anxiety symptoms across treatment, but all treatment groups had similar decreasing depressive and anxiety symptom trajectories. Exploratory analyses revealed differential treatment outcomes across treatment combinations. Patients in the MHP in combination with another treatment had higher rates of major depressive episodes, psychiatric hospitalization, and attempted death by suicide at baseline.

CONCLUSIONS

Patients with higher depressive and anxiety symptoms tend to self-select into using DMHI in addition to more traditional types of treatment, rather than as a stand-alone intervention, and have more severe clinical characteristics. The use the MHP alone was associated with improvement at a similar rate to those with higher baseline symptoms who are in traditional treatments and use MHP adjunctively.

An open trial of biofeedback for long COVID

OBJECTIVE

Biofeedback is a therapeutic treatment model that teaches self-regulation of autonomic functions to alleviate stress-related symptoms. "Long COVID" refers to chronic physical and cognitive sequelae post-SARS-CoV-2 infection. This study examined the efficacy of a six-week intervention, consisting of weekly one-hour sessions combining heart rate variability and temperature biofeedback, for alleviating mood symptoms, somatic symptoms and sleep disturbance of patients diagnosed with long COVID.

METHODS

Data were collected from 20 adult participants aged 22-63 (Mage = 44.1, SDage = 12.2) with varying long COVID symptoms. Within this single arm design, 16 of the 20 participants completed all six sessions of biofeedback; 14 completed an assessment at the three-month post-treatment time point.

RESULTS

Participants self-reported significant improvements in somatic, anxiety, and depressive symptoms, sleep quality, quality of life, and number of "bad days" immediately after the intervention and three months later (Cohen's d effect size (ES) = 1.09-0.46). Reduced number of medical doctor visits (ES = 0.85) and prescription drug use over the last month (odds ratio = 0.33), as well as improved emotional wellbeing (ES = 0.97) were observed at the three-month time point only.

CONCLUSION

Results suggest that this short, readily scalable intervention can be potentially efficacious in alleviating symptoms of long COVID. Despite notable improvements, the major limitation of this study is its lack of control group. While a randomized trial merits study, biofeedback appears to be a brief, effective, non-invasive, and low-cost treatment option for patients with chronic somatic symptoms secondary to SARS-CoV-2 infection.

CLINICALTRIALS

govID: NCT05120648.

The Physiological and Clinical-Behavioral Effects of Heart Rate Variability Biofeedback in Adolescents with Autism: A Pilot Randomized Controlled Trial

Adolescents with autism present lower levels of cardiac vagal modulation. It was hypothesized that Heart Rate Variability Biofeedback (HRVB) increases cardiac vagal modulation in adolescents with autism, resulting in positive effects on physiological and psychosocial parameters. It was also hypothesized that home-based HRVB training is feasible. In a single-blind, randomized sham-controlled pilot trial, adolescents with autism performed supervised HRVB (n = 24) or sham training (n = 20). Subsequently, half of the adolescents received HRVB training at home, whereas the other subset did not practice. Physiological, cortisol and behavioral data were collected during stress-provoking assessments before and after each training period. Supervised HRVB resulted in a late increase in cardiac vagal modulation in adolescents with autism. Heart rate increased and cortisol decreased significantly immediately after supervised HRVB, but none of these effects remained after follow-up. Following supervised HRVB, no significant change in psychosocial functioning was found. Home-based HRVB was feasible, adolescents reported lower symptoms of stress, but a significant decrease in compliance rate was found. HRVB is feasible and effective in adolescents with autism given the late-emerging increases in cardiac vagal modulation and decrease in stress symptoms. Replicating this study with a larger sample and further exploration of the working mechanisms of HRVB are recommended. ClinicalTrials.gov , NCT04628715.

An Estimation Formula for Resonance Frequency Using Sex and Height for Healthy Individuals and Patients with Incurable Cancers

Resonance frequency breathing is a technique that involves breathing that maximizes heart rate variability. It is specific to individuals and is determined through a procedure taking approximately 30 min, using a procedure that is often best carried out at specialized medical institutions. This is a physical and time-consuming burden because of hospital visits and measurements, particularly for patients with cancer. Therefore it would be beneficial if a procedure can be found to determine resonance frequency from the patient's physical characteristics, without the need for special assessment procedures. This exploratory cross-sectional study examined the correlation between individual characteristics and resonance frequency in healthy volunteers. Multiple regression analysis was performed with the measured resonance frequency as the target variable and individual characteristic parameters as explanatory variables. The study aims to build an estimation formula for resonance frequency with some of these parameters and assess its validity. In addition, the validity of the formula's applicability to patients with incurable cancers is assessed. A total of 122 healthy volunteers and 32 patients with incurable cancers were recruited as participants. The median resonance frequency of 154 participants was six breaths per min. Sex and height were selected as explanatory variables associated with the measured resonance frequency in the volunteers. The estimation formula for resonance frequency using individual characteristics was 17.90-0.07 × height for men and 15.88-0.06 × height for women. Adjusted R-squared values were 0.55 for men and 0.47 for women. When the measured resonance frequency in patients with incurable cancers was six breaths per minute or less, the resonance frequency estimated by this formula was slightly larger than the measured ones. Information on individual characteristics, such as sex and height, which can be easily obtained, was useful to construct an estimation formula for resonance frequency.

A Comparison Between Pre-Sleep Heart Rate Variability Biofeedback and Electroencephalographic Biofeedback Training on Sleep in National Level Athletes with Sleep Disturbances

The current study compared the effects of heart rate variability biofeedback (HRV-BF) and electroencephalographic biofeedback (EEG-BF) on sleep, mood, and reaction time. Fourteen highly trained male athletes with sleep disturbances participated in this randomised crossover study. Participants took part in HRV-BF and EEG-BF training, with each condition consisting of eight sessions over 15 days. Polysomnography (PSG) and the Pittsburgh sleep quality index (PSQI) were used to assess sleep quality, the profile of mood states (POMS) questionnaire to monitor mood, and reaction time to measure performance pre and post intervention. HRV-BF training improved PSG sleep efficiency (SE) (P = 0.022, d = 0.35, 95% CI 0.01 to 0.16) and subjective sleep duration (P = 0.011, ES = 0.40) when compared to EEG-BF. Only HRV-BF reduced reaction time pre to post biofeedback training (P = 0.020, d = 0.75, 95% CI 0.006 to 0.059). The PSQI showed that both HRV-BF (P = 0.025, ES = 0.31) and EEG-BF (P = 0.003, ES = 0.32) resulted in improved global PSQI scores. Total mood disturbance was also reduced though HRV-BF (P = 0.001, ES = 0.40) and EEG-BF (P = 0.001, ES = 0.30). HRV-BF and EEG-BF enhanced some subjective parameters of sleep and mood. HRV-BF increased PSG SE and subjective sleep duration more than EEG-BF in highly trained athletes with sleep disturbances.

Influence of Respiratory Frequency of Slow-Paced Breathing on Vagally-Mediated Heart Rate Variability

Breathing techniques, particularly slow-paced breathing (SPB), have gained popularity among athletes due to their potential to enhance performance by increasing cardiac vagal activity (CVA), which in turn can help manage stress and regulate emotions. However, it is still unclear whether the frequency of SPB affects its effectiveness in increasing CVA. Therefore, this study aimed to investigate the effects of a brief SPB intervention (i.e., 5 min) on CVA using heart rate variability (HRV) measurement as an index. A total of 75 athletes (22 female; Mage = 22.32; age range = 19-31) participated in the study, attending one lab session where they performed six breathing exercises, including SPB at different frequencies (5 cycles per minute (cpm), 5.5 cpm, 6 cpm, 6.5 cpm, 7 cpm), and a control condition of spontaneous breathing. The study found that CVA was significantly higher in all SPB conditions compared to the control condition, as indexed by both root mean square of the successive differences (RMSSD) and low-frequency HRV (LF-HRVms2). Interestingly, LF-HRVms2 was more sensitive in differentiating the respiratory frequencies than RMSSD. These results suggest that SPB at a range of 5 cpm to 7 cpm can be an effective method to increase CVA and potentially improve stress management and emotion regulation in athletes. This short SPB exercise can be a simple yet useful tool for athletes to use during competitive scenarios and short breaks in competitions. Overall, these findings highlight the potential benefits of incorporating SPB into athletes' training and competition routines.

Feasibility of a remote heart rate variability biofeedback intervention for reducing anxiety in cardiac arrest survivors: A pilot trial

Background

Heart rate variability biofeedback (HRVB) is a promising non-pharmacologic approach for reducing anxiety. This intervention's feasibility needs testing in psychologically distressed cardiac patients for whom heart-related anxiety is a core concern. To enhance scalability and convenience, remote delivery of HRVB also needs to be assessed. Accordingly, we evaluated the feasibility of remote HRVB in survivors of cardiac arrest (CA) with elevated CA-related psychological distress.

Methods

The intervention was comprised of daily sessions of diaphragmatic paced breathing and real-time monitoring of cardiac activity guided by a smartphone app and heart rate monitor. This single-arm feasibility trial assessed the percentage of eligible contacted patients who consented and engaged in the study and the self-reported acceptability, feasibility, appropriateness, and usability of the intervention. Exploratory analyses assessed pre-to-post changes in trait anxiety, negative affect, cardiac-related interoceptive fear, and resting-state HRV.

Results

Of 12 eligible CA survivors contacted, 10 enrolled. All 10 patients completed the virtual study visits and the majority (>50 %) of prescribed training sessions. Ninety percent reported good scores for intervention acceptability and feasibility, and 80 % reported good scores for its appropriateness and usability for reducing fear. Trait anxiety decreased significantly pre-to-post intervention. There were no changes in negative affect, interoceptive fear, or resting state HRV.

Conclusion

A remotely delivered HRVB intervention was acceptable, feasible, and useable for cardiac patients with CA-related psychological distress. A phase 2 randomized controlled trial evaluating the efficacy of HRVB on cardiac patients' psychological distress, health behaviors, and autonomic dysfunction may be warranted.

Mobile resonance frequency breathing smartphone application to support recovery among people with opioid use disorder: Study protocol for feasibility study

BACKGROUND

Experiencing drug cravings is an aspect of substance use disorders that frequently compromises the recovery efforts of people who use drugs. Most treatment approaches that address drug cravings either involve cognitive strategies or medication. Few interventions directly address the physiological aspects of craving, such as increased heart rate. Previous research has demonstrated that slow-paced breathing may be effective in managing drug cravings by manipulating an individual's heart rate. The purpose of this paper is to describe a study protocol for an intervention that offers resonance frequency breathing training for managing cravings via a smartphone application (app).

METHODS

This trial is registered in ClinicalTrials.gov (Identifier: NCT05830773). The intervention focuses on persons in recovery from opioid use disorder who receive services from the Texas Health and Human Service Commission Recovery Support Services division. Participants will be trained to use Camera Heart Rate Variability (CHRV), a resonance frequency breathing app. The CHRV app measures heart rate and the volumetric variations of blood circulation. When experiencing stress, anxiety, or cravings, participants will use the app to practice breathing exercises. Participants (N = 60) will also complete surveys at baseline, 4 weeks, and 8 weeks; the survey questions, covers demographic characteristics, personal trauma history, substance use experience, and utilization of substance use treatment services. The surveys will also include psychosocial measures of craving, stress, and anxiety to allow the study team to assess changes between baseline and study completion. Participants who complete the full 8-week intervention will be invited to participate in a 30-minute interview about their experience with the app. Interviews will provide details on implementation outcomes, including acceptability, appropriateness, and feasibility.

CONCLUSION

Many evidence-based interventions for opioid use require interpersonal communication with individuals in one's recovery network. However, individuals may be unable to engage others in their recovery network in the moments when they are experiencing cravings or stress- and anxiety-related triggers. Therefore, recovery support interventions that emphasize individual self-management of cravings, stress, and anxiety when they occur can empower individuals in recovery and enhance existing interventions.

HEART Rate Variability Biofeedback for LOng COVID Dysautonomia (HEARTLOC): Results of a Feasibility Study

Introduction

Post-COVID-19 syndrome, or Long Covid (LC) refers to symptoms persisting 12 weeks after the COVID-19 infection. LC comprises a wide range of dysautonomia symptoms, including fatigue, breathlessness, palpitations, dizziness, pain and brain fog. This study tested the feasibility and estimated the efficacy, of a Heart Rate Variability Biofeedback (HRV-B) programme via a standardised slow diaphragmatic breathing technique in individuals with LC.

Methods

LC patients underwent a 4-week HRV-B intervention for 10 minutes twice daily for 4 weeks using the Polar H10 ECG (Electrocardiogram) chest strap and Elite HRV phone application. Outcome measures C19-YRSm (Yorkshire Rehabilitation Scale modified), Composite Autonomic Symptom Score (COMPASS-31), WHO Disability Assessment Schedule (WHODAS), EQ5D-5L (EuroQol 5 Dimensions) and Root Mean Square of Successive Differences between heartbeats (RMSSD) using a Fitbit device were recorded before and after the intervention. The study was pre-registered at clinicaltrials.gov NCT05228665.

Results

A total of 13 participants (54% female, 46% male) completed the study with high levels of independent use of technology, data completeness and intervention adherence. There was a statistically significant improvement in C19YRS-m (P = .001), COMPASS-31 (P = .007), RMSSD (P = .047), WHODAS (P = .02) and EQ5D Global Health Score (P = .009). Qualitative feedback suggested participants could use it independently, were satisfied with the intervention and reported beneficial effects from the intervention.

Conclusion

HRV-B using diaphragmatic breathing is a feasible intervention for LC. The small sample size limits generalisability. HRV-B in LC warrants further exploration in a larger randomised controlled study.

Heart Rate Variability Biofeedback in Adults with a Spinal Cord Injury: A Laboratory Framework and Case Series

Heart rate variability biofeedback (HRV-F) is a neurocardiac self-regulation therapy that aims to regulate cardiac autonomic nervous system activity and improve cardiac balance. Despite benefits in various clinical populations, no study has reported the effects of HRV-F in adults with a spinal cord injury (SCI). This article provides an overview of a neuropsychophysiological laboratory framework and reports the impact of an HRV-F training program on two adults with chronic SCI (T1 AIS A and T3 AIS C) with different degrees of remaining cardiac autonomic function. The HRV-F intervention involved 10 weeks of face-to-face and telehealth sessions with daily HRV-F home practice. Physiological (HRV, blood pressure variability (BPV), baroreflex sensitivity (BRS)), and self-reported assessments (Fatigue Severity Scale, Generalised Anxiety Disorder Scale, Patient Health Questionnaire, Appraisal of Disability and Participation Scale, EuroQol Visual Analogue Scale) were conducted at baseline and 10 weeks. Participants also completed weekly diaries capturing mood, anxiety, pain, sleep quality, fatigue, and adverse events. Results showed some improvement in HRV, BPV, and BRS. Additionally, participants self-reported some improvements in mood, fatigue, pain, quality of life, and self-perception. A 10-week HRV-F intervention was feasible in two participants with chronic SCI, warranting further investigation into its autonomic and psychosocial effects.

Heart Rate Variability Measurement through a Smart Wearable Device: Another Breakthrough for Personal Health Monitoring?

Heart rate variability (HRV) is a measurement of the fluctuation of time between each heartbeat and reflects the function of the autonomic nervous system. HRV is an important indicator for both physical and mental status and for broad-scope diseases. In this review, we discuss how wearable devices can be used to monitor HRV, and we compare the HRV monitoring function among different devices. In addition, we have reviewed the recent progress in HRV tracking with wearable devices and its value in health monitoring and disease diagnosis. Although many challenges remain, we believe HRV tracking with wearable devices is a promising tool that can be used to improve personal health.

Effect of cardiovascular biofeedback on nursing staff stress: a randomized controlled clinical trial

OBJECTIVE

to assess the effect of cardiovascular biofeedback on nursing staff stress when compared to an activity without self-monitoring.

METHOD

a randomized controlled clinical trial, carried out with nursing professionals from a university hospital. The intervention group (n=58) performed cardiovascular biofeedback, and the control (n=57) performed an online puzzle without self-monitoring, totaling nine meetings over three weeks. The outcome was assessed using the Stress Symptoms and Work-Related Stress scales, and the biological marker heart rate variability. The generalized estimating equations method was used.

RESULTS

the intervention had no effect on self-reported instruments (p>0.050). However, there was an effect of time (p<0.050) on all heart rate variability indicators, demonstrating changes over the sessions.

CONCLUSION

cardiovascular biofeedback showed promising results in the biological marker, suggesting that it can be used in nursing staff as a complementary therapy by promoting better autonomic nervous system regulation.

The effect of a single-session heart rate variability biofeedback on attentional control: does stress matter?

Introduction

Vagally mediated heart rate variability is an index of autonomic nervous system activity that is associated with a large variety of outcome variables including psychopathology and self-regulation. While practicing heart rate variability biofeedback over several weeks has been reliably associated with a number of positive outcomes, its acute effects are not well known. As the strongest association with vagally mediated heart rate variability has been found particularly within the attention-related subdomain of self-regulation, we investigated the acute effect of heart rate variability biofeedback on attentional control using the revised Attention Network Test.

Methods

Fifty-six participants were tested in two sessions. In one session each participant received a heart rate variability biofeedback intervention, and in the other session a control intervention of paced breathing at a normal ventilation rate. After the biofeedback or control intervention, participants completed the Attention Network Test using the Orienting Score as a measure of attentional control.

Results

Mixed models revealed that higher resting baseline vagally mediated heart rate variability was associated with better performance in attentional control, which suggests more efficient direction of attention to target stimuli. There was no significant main effect of the intervention on attentional control. However, an interaction effect indicated better performance in attentional control after biofeedback in individuals who reported higher current stress levels.

Discussion

The results point to acute beneficial effects of heart rate variability biofeedback on cognitive performance in highly stressed individuals. Although promising, the results need to be replicated in larger or more targeted samples in order to reach stronger conclusions about the effects.

Preliminary Effectiveness of a Therapist-Supported Digital Mental Health Intervention in Reducing Suicidal Ideation

Suicidal ideation (SI) is a significant public health concern with increasing prevalence. Therapist-supported digital mental health interventions (DMHI) are an emergent modality to address common mental health problems like depression and anxiety, although less is known about SI. This study examined SI trajectories among 778 patients who participated in a therapist-supported DMHI using multilevel models during and up to 6-months post-treatment. Estimates of associated suicide attempts and deaths by suicide were calculated using published data linking PHQ-9-assessed SI to records of suicide attempts and deaths by suicide. The proportion of participants reporting no SI significantly increased between baseline and end-of-treatment (78.02% to 91.00%). Effect sizes of SI changes between baseline and end-of-treatment, 3-month, and 6-month follow-ups were 0.33 (95%CI = 0.27-0.38), 0.32 (95%CI = 0.27-0.38), and 0.32 (95%CI = 0.27-0.38), respectively. Results also indicated an estimated 30.49% reduction (95%CI = 25.15%-35.13%) in suicide attempts and death by suicide across treatment. This study provides preliminary evidence of the effectiveness of a therapist-supported DMHI in reducing SI.

Using the Research Domain Criteria as a framework to integrate psychophysiological findings into stress management and psychotherapy interventions

Research on the psychophysiology of stress is expanding rapidly, but the field lacks a clear integrative framework to help translate research findings into empirically supported stress interventions. The Research Domain Criteria (RDoC) is an excellent candidate to explore as a framework to integrate stress research. The RDoC framework is a dimensional, multi-modal approach to psychopathology proposed as an alternative to categorical approaches used by the International Classification of Diseases (ICD) and the Diagnostic and Statistical Manual (DSM). The goal of this paper is to explore the RDoC as a framework to integrate psychophysiology research into therapeutic interventions for stress. The RDoC consists of six domains: negative valence systems, positive valence systems, cognitive systems, social processes systems, arousal/regulatory systems, and sensorimotor systems, and provides an excellent structure for integrating information from multiple levels of functioning including physiology, behavior, and self-report, as well as genes, molecules, cells, and brain circuits. Integrating psychophysiological research on stress using the RDoC framework can direct and amplify stress management and psychotherapeutic interventions. First, the RDoC provides a clear foundation for conceptualizing the stress response in terms of important concepts such as allostasis and adaptation. In this perspective, the terms "allostatic response" or "adaptation response" are more descriptive terms than "stress response" in understanding bodily responses to life threats and challenges. Second, psychophysiological approaches can be used in the context of modalities such as biofeedback and mindfulness to both collect psychophysiological data and then integrate that data into a broader therapeutic framework. Heart rate variability (HRV) biofeedback is being used more frequently as part of a therapeutic intervention package with stress management and psychotherapy, and HRV data is also used to provide outcome evidence on the efficacy of treatment. Mindfulness practices are commonly used in combination with stress management and psychotherapy, and psychophysiological data (HRV, EEG, blood pressure, etc.) is often collected to explore and understand mind/body relationships. In conclusion, the lack of a clear framework to assess and understand mind/body functioning limits current stress research and interventions. The RDoC provides a strong framework to assess and integrate physiological and psychological data and improve stress interventions.

Validation of Photoplethysmography Using a Mobile Phone Application for the Assessment of Heart Rate Variability in the Context of Heart Rate Variability-Biofeedback

OBJECTIVE

Heart rate variability-biofeedback (HRV-BF) is an effective intervention to reduce stress and anxiety and requires accurate measures of real-time HRV. HRV can be measured through photoplethysmography (PPG) using the camera of a mobile phone. No studies have directly compared HRV-BF supported through PPG against classical electrocardiogram (ECG). The current study aimed to validate PPG HRV measurements during HRV-BF against ECG.

METHODS

Fifty-seven healthy participants (70% women) with a mean (standard deviation) age of 26.70 (9.86) years received HRV-BF in the laboratory. Participants filled out questionnaires and performed five times a 5-minute diaphragmatic breathing exercise at different paces (range, ~6.5 to ~4.5 breaths/min). Four HRV indices obtained through PPG, using the Happitech software development kit, and ECG, using the validated NeXus apparatus, were calculated and compared: RMSSD, pNN50, LFpower, and HFpower. Resonance frequency (i.e., optimal breathing pace) was also compared between methods.

RESULTS

All intraclass correlation coefficient values of the five different breathing paces were "near perfect" (>0.90) for all HRV indices: lnRMSSD, lnpNN50, lnLFpower, and lnHFpower. All Bland-Altman analyses (with just three incidental exceptions) showed good interchangeability of PPG- and ECG-derived HRV indices. No systematic evidence for proportional bias was found for any of the HRV indices. In addition, correspondence in resonance frequency detection was good with 76.6% agreement between PPG and ECG.

CONCLUSIONS

PPG is a potentially reliable and valid method for the assessment of HRV. PPG is a promising replacement of ECG assessment to measure resonance frequency during HRV-BF.

Methods for Heart Rate Variability Biofeedback (HRVB): A Systematic Review and Guidelines

Heart Rate Variability Biofeedback (HRVB) has been widely used to improve cardiovascular health and well-being. HRVB is based on breathing at an individual's resonance frequency, which stimulates respiratory sinus arrhythmia (RSA) and the baroreflex. There is, however, no methodological consensus on how to apply HRVB, while details about the protocol used are often not well reported. Thus, the objectives of this systematic review are to describe the different HRVB protocols and detect methodological concerns. PsycINFO, CINALH, Medline and Web of Science were searched between 2000 and April 2021. Data extraction and quality assessment were based on PRISMA guidelines. A total of 143 studies were finally included from any scientific field and any type of sample. Three protocols for HRVB were found: (i) "Optimal RF" (n = 37), each participant breathes at their previously detected RF; (ii) "Individual RF" (n = 48), each participant follows a biofeedback device that shows the optimal breathing rate based on cardiovascular data in real time, and (iii) "Preset-pace RF" (n = 51), all participants breathe at the same rate rate, usually 6 breaths/minute. In addition, we found several methodological differences for applying HRVB in terms of number of weeks, duration of breathing or combination of laboratory and home sessions. Remarkably, almost 2/3 of the studies did not report enough information to replicate the HRVB protocol in terms of breathing duration, inhalation/exhalation ratio, breathing control or body position. Methodological guidelines and a checklist are proposed to enhance the methodological quality of future HRVB studies and increase the information reported.

A Serious Game to Self-Regulate Heart Rate Variability as a Technique to Manage Arousal Level Through Cardiorespiratory Biofeedback: Development and Pilot Evaluation Study

BACKGROUND

Heart rate variability biofeedback (HRVB) is an established intervention for increasing heart rate variability (HRV) in the clinical context. Using this technique, participants become aware of their HRV through real-time feedback and can self-regulate it.

OBJECTIVE

The aim of this study was 2-fold: first, to develop a serious game that applies the HRVB technique to teach participants to self-regulate HRV and, second, to test the app with participants in a pilot study.

METHODS

An HRVB app called the FitLab Game was developed for this study. To play the game, users must move the main character up and down the screen, avoiding collisions with obstacles. The wavelength that users must follow to avoid these obstacles is based on the user's basal heart rate and changes in instantaneous heart rate. To test the FitLab Game, a total of 16 participants (mean age 23, SD 0.69 years) were divided into a control group (n=8) and an experimental group (n=8). A 2 × 2 factorial design was used in each session. Participants in the experimental condition were trained in breathing techniques.

RESULTS

Changes in the frequency and time domain parameters of HRV and the game's performance features were evaluated. Significant changes in the average RR intervals and root mean square of differences between adjacent RR intervals (RMSSD) were found between the groups (P=.02 and P=.04, respectively). Regarding performance, both groups showed a tendency to increase the evaluated outcomes from baseline to the test condition.

CONCLUSIONS

The results may indicate that playing different levels leads to an improvement in the game's final score by repeated training. The tendency of changes in HRV may reflect a higher activation of the mental system of attention and control in the experimental group versus the control group. In this context, learning simple, voluntary strategies through a serious game can aid the improvement of self-control and arousal management. The FitLab Game appears to be a promising serious game owing to its ease of use, high engagement, and enjoyability provided by the instantaneous feedback.

Multimodal neuroimaging data from a 5-week heart rate variability biofeedback randomized clinical trial

We present data from the Heart Rate Variability and Emotion Regulation (HRV-ER) randomized clinical trial testing effects of HRV biofeedback. Younger (N = 121) and older (N = 72) participants completed baseline magnetic resonance imaging (MRI) including T1-weighted, resting and emotion regulation task functional MRI (fMRI), pulsed continuous arterial spin labeling (PCASL), and proton magnetic resonance spectroscopy (1H MRS). During fMRI scans, physiological measures (blood pressure, pulse, respiration, and end-tidal CO2) were continuously acquired. Participants were randomized to either increase heart rate oscillations or decrease heart rate oscillations during daily sessions. After 5 weeks of HRV biofeedback, they repeated the baseline measurements in addition to new measures (ultimatum game fMRI, training mimicking during blood oxygen level dependent (BOLD) and PCASL fMRI). Participants also wore a wristband sensor to estimate sleep time. Psychological assessment comprised three cognitive tests and ten questionnaires related to emotional well-being. A subset (N = 104) provided plasma samples pre- and post-intervention that were assayed for amyloid and tau. Data is publicly available via the OpenNeuro data sharing platform.

Assessing effectiveness of heart rate variability biofeedback to mitigate mental health symptoms: a pilot study

Introduction: The increasing burden on mental health has become a worldwide concern especially due to its substantial negative social and economic impact. The implementation of prevention actions and psychological interventions is crucial to mitigate these consequences, and evidence supporting its effectiveness would facilitate a more assertive response. Heart rate variability biofeedback (HRV-BF) has been proposed as a potential intervention to improve mental wellbeing through mechanisms in autonomic functioning. The aim of this study is to propose and evaluate the validity of an objective procedure to assess the effectiveness of a HRV-BF protocol in mitigating mental health symptoms in a sample of frontline HCWs (healthcare workers) who worked in the COVID-19 pandemic. Methods: A prospective experimental study applying a HRV-BF protocol was conducted with 21 frontline healthcare workers in 5 weekly sessions. For PRE-POST intervention comparisons, two different approaches were used to evaluate mental health status: applying (a) gold-standard psychometric questionnaires and (b) electrophysiological multiparametric models for chronic and acute stress assessment. Results: After HRV-BF intervention, psychometric questionnaires showed a reduction in mental health symptoms and stress perception. The electrophysiological multiparametric also showed a reduction in chronic stress levels, while the acute stress levels were similar in PRE and POST conditions. A significant reduction in respiratory rate and an increase in some heart rate variability parameters, such as SDNN, LFn, and LF/HF ratio, were also observed after intervention. Conclusion: Our findings suggest that a 5-session HRV-BF protocol is an effective intervention for reducing stress and other mental health symptoms among frontline HCWs who worked during the COVID-19 pandemic. The electrophysiological multiparametric models provide relevant information about the current mental health state, being useful for objectively evaluating the effectiveness of stress-reducing interventions. Further research could replicate the proposed procedure to confirm its feasibility for different samples and specific interventions.

A Pilot Study of a Three-Session Heart Rate Variability Biofeedback Intervention for Veterans with Posttraumatic Stress Disorder

Many veterans do not complete traditional trauma treatments; others may continue to struggle with posttraumatic stress disorder (PTSD) even after completing a full course of therapy (Blasé et al., in Int J Environ Res Public Health 18(7):Article 3329, https://doi.org/10.3390/ijerph18073329 , 2016). Heart rate variability (HRV) biofeedback (HRVB) is a non-invasive, non-pharmacological, breathing-based cardiorespiratory training technique that can reduce trauma symptoms and improve HRV parameters. Prior studies have demonstrated HRVB is well-tolerated by veterans with PTSD symptoms (Tan et al., in Appl Psychophysiol Biofeedback 36(1):27-35, 10.1007/s10484-010-9141-y, 2011; Schuman and Killian, in Appl Psychophysiol Biofeedback 44(1):9-20, https://doi.org/10.1007/s10484-018-9415-3 , 2019). This randomized wait-list controlled pilot study tested a short mobile app-adapted HRVB intervention in combination with treatment as usual for veterans with military-related PTSD to determine if further investigation was warranted. We assessed veterans' military-related PTSD symptoms, depression symptoms, and HRV time and frequency domain measures at baseline, after three clinical sessions, and one month later. This study combined clinical training and home biofeedback with a smartphone app and sensor to reinforce training and validate adherence. In the intervention group, depression and SDNN significantly improved, and we observed marginally significant improvements for PTSD Cluster B (intrusion) symptoms, whereas no significant improvements were observed in the control group. In addition, the brief protocol was acceptable to veterans with PTSD with over 83% of participants completing the study. However, adherence to home practice was low. Findings suggest brief HRVB interventions can decrease comorbid depression and improve overall autonomic function in veterans with PTSD; however, additional research on home biofeedback is necessary to determine the best strategies to increase adherence and which veterans would benefit from brief HRVB interventions.

Effects of a Randomised Trial of 5-Week Heart Rate Variability Biofeedback Intervention on Cognitive Function: Possible Benefits for Inhibitory Control

Previous research suggests that higher heart rate variability (HRV) is associated with better cognitive function. However, since most previous findings on the relationship between HRV and cognitive function were correlational in nature, it is unclear whether individual differences in HRV play a causal role in cognitive performance. To investigate whether there are causal relationships, we used a simple breathing manipulation that increases HRV through a 5-week HRV biofeedback intervention and examined whether this manipulation improves cognitive performance in younger and older adults (N = 165). The 5-week HRV biofeedback intervention did not significantly improve inhibitory control, working memory and processing speed across age groups. However, improvement in the Flanker score (a measure of inhibition) was associated with the amplitude of heart rate oscillations during practice sessions in the younger and older intervention groups. Our results suggest that daily practice to increase heart rate oscillations may improve inhibitory control, but future studies using longer intervention periods are warranted to replicate the present finding.

Increasing coordination and responsivity of emotion-related brain regions with a heart rate variability biofeedback randomized trial

Heart rate variability is a robust biomarker of emotional well-being, consistent with the shared brain networks regulating emotion regulation and heart rate. While high heart rate oscillatory activity clearly indicates healthy regulatory brain systems, can increasing this oscillatory activity also enhance brain function? To test this possibility, we randomly assigned 106 young adult participants to one of two 5-week interventions involving daily biofeedback that either increased heart rate oscillations (Osc+ condition) or had little effect on heart rate oscillations (Osc- condition) and examined effects on brain activity during rest and during regulating emotion. While there were no significant changes in the right amygdala-medial prefrontal cortex (MPFC) functional connectivity (our primary outcome), the Osc+ intervention increased left amygdala-MPFC functional connectivity and functional connectivity in emotion-related resting-state networks during rest. It also increased down-regulation of activity in somatosensory brain regions during an emotion regulation task. The Osc- intervention did not have these effects. In this healthy cohort, the two conditions did not differentially affect anxiety, depression, or mood. These findings indicate that modulating heart rate oscillatory activity changes emotion network coordination in the brain.

Efficacy of Heart Rate Variability Biofeedback for Somatic Symptom Disorder: A Pilot Randomized Controlled Trial

OBJECTIVE

Patients with somatic symptom disorder (SSD) often receive targeted intervention only after a long duration of illness. Moreover, the reported effect sizes of interventions for SSD are small. Therefore, improvement and evaluation of interventions are needed. Preliminary evidence suggests autonomic imbalance, for example, lower heart rate variability (HRV) in SSD. HRV biofeedback (HRV-BF) as a method for self-regulation shows initial positive effects in chronic pain and functional syndromes. The aim of this study was to evaluate the efficacy of a brief HRV-BF intervention for SSD.

METHODS

Of a total of 50 participants with SSD ( Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition ) who were recruited and randomly assigned to four sessions of HRV-BF ( n = 25) or autogenic training (AT; n = 25), 49 participants were analyzed (female, 77.6%; mean [standard deviation] age = 45.3 [14.4] years). The primary outcomes were somatic symptom severity (Screening for Somatoform Disorders, numeric rating scale) and HRV. Secondary outcomes were psychological characteristics of SSD (e.g., the Somatic Symptom Disorder 12 scale, health concerns, emotion regulation). The data were collected before and after intervention and were analyzed with repeated-measures analyses of variance and post hoc t tests.

RESULTS

Symptom severity improved after both, HRV-BF and AT. Standard Deviation of the NN Interval and psychological symptoms improved significantly more strongly in the HRV-BF than in the AT group (e.g., Standard Deviation of the NN Interval: ηp2 interaction = 0.10, p = .047).

CONCLUSIONS

The improvements in somatic symptoms, but specifically in cognitive-affective symptoms and autonomic regulation, suggest that HRV-BF with only four sessions is a potentially useful intervention option for SSD. Thus, adding this short HRV-BF intervention to existing psychological treatments for SSD may be promising.Trial Registration : German Clinical Trial Register identifier DRKS00017099 ( https://www.drks.de ).

Effects of a randomised trial of 5-week heart rate variability biofeedback intervention on mind wandering and associated brain function

Previous research suggests that excessive negative self-related thought during mind wandering involves the default mode network (DMN) core subsystem and the orbitofrontal cortex (OFC). Heart rate variability (HRV) biofeedback, which involves slow paced breathing to increase HRV, is known to promote emotional well-being. However, it remains unclear whether it has positive effects on mind wandering and associated brain function. We conducted a study where young adults were randomly assigned to one of two 5-week interventions involving daily biofeedback that either increased heart rate oscillations via slow paced breathing (Osc+ condition) or had little effect on heart rate oscillations (active control or Osc- condition). The two intervention conditions did not differentially affect mind wandering and DMN core-OFC functional connectivity. However, the magnitude of participants' heart rate oscillations during daily biofeedback practice was associated with pre-to-post decreases in mind wandering and in DMN core-OFC functional connectivity. Furthermore, the reduction in the DMN core-OFC connectivity was associated with a decrease in mind wandering. Our results suggested that daily sessions involving high amplitude heart rate oscillations may help reduce negative mind wandering and associated brain function.

Dynamics of Physiological, Biochemical and Psychological Markers during Single Session of Virtual Reality-Based Respiratory Biofeedback Relaxation

Psychological stress exposure is associated with long-lasting health effects including memory problems, depression, aches and pains, eating disorders, and alcohol or drug use. Thus, there is a need to develop effective stress management strategies that are easy to learn and practice. Respiratory biofeedback is an evidence-based stress management technique presenting breathing-related information to help subjects learn specific breathing skills for relaxation. It is suggested that the use of biofeedback techniques in conjunction with virtual reality makes biofeedback training an even more effective tool for stress management. The current study aimed to investigate dynamics of distinct stress indicators before, after, as well as during one brief virtual reality-based respiratory biofeedback session. Thirty-nine healthy volunteers participated in the study. Individuals provided their saliva samples and evaluated their mood status, fatigue, and strain level before and after the session. The subjects' heart and respiratory rate, heart rate variability, and galvanic skin response measures were recorded during the session. The results showed that after single 12 min relaxation session, there was a significant decrease in salivary cortisol concentration, heart and respiratory rate, as well as decrease in skin conductance values. Self-reported strain, fatigue level, and mood status also significantly improved. VR-based respiratory-biofeedback-assisted relaxation sessions might serve as an effective stress management strategy, as even single session had positive effects on subjects' autonomic nervous system (ANS) and hypothalamic-pituitary-adrenal (HPA) axis activity, as well as self-reported fatigue, strain level, and mood status.

HEART rate variability biofeedback for long COVID symptoms (HEARTLOC): protocol for a feasibility study

INTRODUCTION

Long COVID (LC), also known as post-COVID-19 syndrome, refers to symptoms persisting 12 weeks after COVID-19 infection. It affects up to one in seven people contracting the illness and causes a wide range of symptoms, including fatigue, breathlessness, palpitations, dizziness, pain and brain fog. Many of these symptoms can be linked to dysautonomia or dysregulation of the autonomic nervous system after SARS-CoV2 infection. This study aims to test the feasibility and estimate the efficacy, of the heart rate variability biofeedback (HRV-B) technique via a standardised slow diaphragmatic breathing programme in individuals with LC.

METHODS AND ANALYSIS

30 adult LC patients with symptoms of palpitations or dizziness and an abnormal NASA Lean Test will be selected from a specialist Long COVID rehabilitation service. They will undergo a 4-week HRV-B intervention using a Polar chest strap device linked to the Elite HRV phone application while undertaking the breathing exercise technique for two 10 min periods everyday for at least 5 days a week. Quantitative data will be gathered during the study period using: HRV data from the chest strap and wrist-worn Fitbit, the modified COVID-19 Yorkshire Rehabilitation Scale, Composite Autonomic Symptom Score, WHO Disability Assessment Schedule and EQ-5D-5L health-related quality of life measures. Qualitative feedback on user experience and feasibility of using the technology in a home setting will also be gathered. Standard statistical tests for correlation and significant difference will be used to analyse the quantitate data.

ETHICS AND DISSEMINATION

The study has received ethical approval from Health Research Authority (HRA) Leicester South Research Ethics Committee (21/EM/0271). Dissemination plans include academic and lay publications.

TRIAL REGISTRATION NUMBER

NCT05228665.

Heart rate variability (HRV) changes and cortical volume changes in a randomized trial of five weeks of daily HRV biofeedback in younger and older adults

Previous studies indicate that the structure and function of medial prefrontal cortex (PFC) and lateral orbitofrontal cortex (OFC) are associated with heart rate variability (HRV). Typically, this association is assumed to reflect the PFC's role in controlling HRV and emotion regulation, with better prefrontal structural integrity supporting greater HRV and better emotion regulation. However, as a control system, the PFC must monitor and respond to heart rate oscillatory activity. Thus, engaging in regulatory feedback during heart rate oscillatory activity may over time help shape PFC structure, as relevant circuits and connections are modified. In the current study with younger and older adults, we tested whether 5 weeks of daily sessions of biofeedback to increase heart rate oscillations (Osc+ condition) vs. to decrease heart rate oscillations (Osc- condition) affected cortical volume in left OFC and right OFC, two regions particularly associated with HRV in prior studies. The left OFC showed significant differences in volume change across conditions, with Osc+ increasing volume relative to Osc-. The volume changes in left OFC were significantly correlated with changes in mood disturbance. In addition, resting low frequency HRV increased more in the Osc+ than in the Osc- condition. These findings indicate that daily biofeedback sessions regulating heart rate oscillatory activity can shape both resting HRV and the brain circuits that help control HRV and regulate emotion.

Neuromodulation Applied to Diseases: The Case of HRV Biofeedback

The vagus or “wandering” nerve is the main branch of the parasympathetic nervous system (PNS), innervating most internal organs crucial for health. Activity of the vagus nerve can be non-invasively indexed by heart-rate variability parameters (HRV). Specific HRV parameters predict less all-cause mortality, lower risk of and better prognosis after myocardial infarctions, and better survival in cancer. A non-invasive manner for self-activating the vagus is achieved by performing a slow-paced breathing technique while receiving visual feedback of one’s HRV, called HRV-biofeedback (HRV-B). This article narratively reviews the biological mechanisms underlying the role of vagal activity and vagally mediated HRV in hypertension, diabetes, coronary heart disease (CHD), cancer, pain, and dementia. After searching the literature for HRV-B intervention studies in each condition, we report the effects of HRV-B on clinical outcomes in these health conditions, while evaluating the methodological quality of these studies. Generally, the levels of evidence for the benefits of HRV-B is high in CHD, pain, and hypertension, moderate in cancer, and poor in diabetes and dementia. Limitations and future research directions are discussed.

Dynamic Phase Extraction: Applications in Pulse Rate Variability

Pulse rate variability is a physiological parameter that has been extensively studied and correlated with many physical ailments. However, the phase relationship between inter-beat interval, IBI, and breathing has very rarely been studied. Develop a technique by which the phase relationship between IBI and breathing can be accurately and efficiently extracted from photoplethysmography (PPG) data. A program based on Lock-in Amplifier technology was written in Python to implement a novel technique, Dynamic Phase Extraction. It was tested using a breath pacer and a PPG sensor on 6 subjects who followed a breath pacer at varied breathing rates. The data were then analyzed using both traditional methods and the novel technique (Dynamic Phase Extraction) utilizing a breath pacer. Pulse data was extracted using a PPG sensor. Dynamic Phase Extraction (DPE) gave the magnitudes of the variation in IBI associated with breathing [Formula: see text] measured with photoplethysmography during paced breathing (with premature ventricular contractions, abnormal arrhythmias, and other artifacts edited out). [Formula: see text] correlated well with two standard measures of pulse rate variability: the Standard Deviation of the inter-beat interval (SDNN) (ρ = 0.911) and with the integrated value of the Power Spectral Density between 0.04 and 0.15 Hz (Low Frequency Power or LF Power) (ρ = 0.885). These correlations were comparable to the correlation between the SDNN and the LF Power (ρ = 0.877). In addition to the magnitude [Formula: see text], Dynamic Phase Extraction also gave the phase between the breath pacer and the changes in the inter-beat interval (IBI) due to respiratory sinus arrythmia (RSA), and correlated well with the phase extracted using a Fourier transform (ρ = 0.857). Dynamic Phase Extraction can extract both the phase between the breath pacer and the changes in IBI due to the respiratory sinus arrhythmia component of pulse rate variability ([Formula: see text], but is limited by needing a breath pacer.

An Undergraduate Program with Heart: Thirty Years of Truman HRV Research

This article celebrates the contributors who inspired Truman's heart rate variability (HRV) research program. These seminal influences include Robert Fried, Richard Gevirtz, Paul Lehrer, Erik Peper, and Evgeny Vaschillo. The Truman State University Applied Psychophysiology Laboratory's HRV research has spanned five arcs: interventions to teach diaphragmatic breathing, adjunctive procedures to increase HRV, HRV biofeedback (HRVB) training studies, the concurrent validity of ultra-short-term HRV measurements, and rhythmical skeletal muscle tension strategies to increase HRV. We have conducted randomized controlled trials, primarily using within-subjects and mixed designs. These studies have produced eight findings that could benefit HRVB training. Effortful diaphragmatic breathing can lower end-tidal CO2 through larger tidal volumes. A 1:2 inhalation-to-exhalation (I/E) ratio does not increase HRV compared to a 1:1 I/E ratio. Chanting "om," listening to the Norman Cousins relaxation exercise, and singing a fundamental note are promising exercises to increase HRV. Heartfelt emotion activation does not increase HRV, enhance the effects of resonance frequency breathing, "immunize" HRV against a math stressor, or speed HRV recovery following a math stressor. Resonance frequency assessment achieved moderate (r = 0.73) 2-week test-reliability. Four weeks of HRVB training increased HRV and temperature, and decreased skin conductance level compared with temperature biofeedback training. Concurrent-validity assessment of ultra-short-term HRV measurements should utilize rigorous Pearson r and limits of agreement criteria. Finally, rhythmical skeletal muscle tension can increase HRV at rates of 1-, 3-, and 6-cpm. We describe representative studies, their findings, significance, and limitations in each arc. Finally, we summarize some of the most interesting unanswered questions to enable future investigators to build on our work.

Evaluation of Heart Rate Variability and Application of Heart Rate Variability Biofeedback: Toward Further Research on Slow-Paced Abdominal Breathing in Zen Meditation

This review summarizes my own involvement in heart rate variability (HRV) and HRV biofeedback studies, as a tribute to the late Dr. Evgeny Vaschillo. I first review psychophysiological studies on behavioral stress and relaxation performed in my laboratory using an assessment of cardiac parasympathetic activity. Although magnitude of high-frequency (HF) component of HRV corresponding respiratory sinus arrhythmia (RSA) is widely used as an index of cardiac parasympathetic function, a respiratory confound during stress or relaxation may have interfered with the proper assessment of the HF HRV. An enhanced method under frequency-controlled respiration at 0.25 Hz provided a reliable assessment of cardiac parasympathetic activity. I then review findings from HRV biofeedback research in my laboratory. Based on the hypothesis that RSA measured as an HF component of HRV represents cardiorespiratory resting function, it was demonstrated that HRV biofeedback before sleep enhanced the magnitude of HF HRV during sleep, a cardiorespiratory resting function. Moreover, by focusing on the spectral peak of the low-frequency (LF) component of HRV, paced breathing at the LF-peak frequency was shown to increase baroreflex sensitivity. Finally, I describe the potential of slow-paced abdominal breathing (i.e., Tanden breathing) performed in Zen meditation. The concept of Tanden breathing as described in a regimen from early modern Japan is introduced, and recent research findings on slow-paced abdominal breathing are summarized. Future research directions of slow-paced abdominal breathing are also discussed.

Presentation and Evaluation of a Manual for Heart Rate Variability Biofeedback in Somatic Symptom Disorder

<b><i>Background:</i></b> There is initial evidence for the efficacy of heart rate variability biofeedback (HRV-BF) in depression, anxiety disorders, and functional somatic syndromes. In somatic symptom disorder (SSD), evidence is lacking. The aim of this study was to describe a newly developed HRV-BF brief intervention and to analyze HRV changes, and to examine the applicability and acceptance in SSD. <b><i>Methods:</i></b> We analyzed the data of the subsample of a pilot randomized controlled trial (22 subjects with SSD) who received HRV-BF over 4 sessions. We assessed HRV (SDNN: standard deviation of the NN interval, RMSSD: root mean square of successive differences between NN interval, LF: low frequency) and the subjective evaluation and acceptance of the intervention. <b><i>Results:</i></b> HRV analyses within therapy sessions showed that individuals learned to increase their HRV significantly during biofeedback sessions and were able to maintain it during self-regulation periods without feedback (SDNN, RMSSD, LF: 5.7 ≤ <i>F</i>_<i>t</i> ≤ 11.1). Moreover, HRV improved across sessions (SDNN). The majority of participants rated the intervention very positively (e.g., satisfaction, improvement in mood and physical well-being). <b><i>Conclusions:</i></b> HRV-BF can be learned within 4 sessions and shows positive effects in patients with SSD. Adding HRV-BF to existing treatments, e.g., psychotherapy, seems promising.

Effects of arousal modulation via resonance breathing on craving and affect in women with substance use disorder

BACKGROUND

Craving for alcohol and other drugs is a complex in-the-moment experience that involves within-person changes in physiological arousal and affect. We evaluated the utility of a just-in-time, self-administered resonance breathing smartphone application (app) to reduce craving and improve affect in women during outpatient treatment for substance use disorders (SUD).

METHODS

Women (N = 57) receiving outpatient addiction treatment were randomized to practice either cardiovascular resonance breathing (0.1 Hz/6 breaths per minute) or a sham (∼0.23 Hz/14 breaths per minute) in the face of urges over an 8-week intervention. Craving (Penn Alcohol Craving Scale) and affect (Positive and Negative Affect Scale) were collected weekly throughout the intervention. App data were uploaded weekly to assess frequency of use. Generalized Estimated Equations modeled craving and affect as a function of group randomization and app use frequency across the 8-week intervention.

FINDINGS

Higher levels of craving were associated with more frequent app use. The group X app use interaction was significant for craving. Frequent app use during the intervention phase was associated with lower craving levels in the resonance breathing group relative to the sham group over the 8-week intervention. There was no effect of app use frequency on affect measures.

CONCLUSIONS

Women assigned to practice sham breathing who used the intervention frequently experienced elevations in craving that are commonly reported during outpatient SUD treatment. Women assigned to resonance breathing who used the intervention frequently did not experience such increases. Resonance breathing may be protective against triggers in outpatient treatment. Physiological mechanisms are discussed.

My Life in HRV Biofeedback Research

This paper reviews the published work of me along with my students and close colleagues on the topic of heart rate variability biofeedback (HRVB). It includes early research by Vaschillo documenting resonance characteristics of the baroreflex system that causes large oscillations in heart rate when breathing at resonance frequency, research on heart rate variability as a marker of parasympathetic stress response in asthma, and HRVB as a treatment for asthma and depression. Many questions about HRVB remain unresolved, and important questions for future research are listed.

Review of Perioperative Music Medicine: Mechanisms of Pain and Stress Reduction Around Surgery

Clinical-experimental considerations and an approach to understanding the autonomic basis of improved surgical outcomes using Perioperative Music Medicine (PMM) are reviewed. Combined surgical, psycho-physiological, and experimental perspectives on Music Medicine (MM) and its relationship to autonomic nervous system (ANS) function are discussed. Considerations are given to the inter-related perioperative effects of MM on ANS, pain, and underlying vagal and other neural circuits involved in emotional regulation and dysregulation. Many surgical procedures are associated with significant pain, which is routinely treated with post-operative opioid medications, which cause detrimental side effects and delay recovery. Surgical trauma shifts the sympathetic ANS to a sustained activation impairing physiological homeostasis and causing psychological stress, as well as metabolic and immune dysfunction that contribute to postoperative mortality and morbidity. In this article, we propose a plan to operationalize the study of mechanisms mediating the effects of MM in perioperative settings of orthopedic surgery. These studies will be critical for the implementation of PMM as a routine clinical practice and to determine the potential limitations of MM in specific cohorts of patients and how to improve the treatment.

A pilot study investigating the relationship between heart rate variability and blood pressure in young adults at risk for cardiovascular disease

Background

Cardiovascular disease is one of the leading causes of death globally with hypertension being a primary cause of premature death from this disease process. Individuals with a family history of cardiovascular disease and hypertension are at a greater risk for developing the same sequela. Autonomic cardiac control is important in the level of cardiac function. One intervention that is effective in improving cardiovascular function is heart rate variability biofeedback training. The purpose of our study was to determine the effectiveness of heart rate biofeedback training on HRV and blood pressure in individuals with a family history of cardiovascular disease.

Methods

Thirty-four participants (76.5% female, 22.7 ± 4.3 years) completed a baseline assessment and training using an established short-term HRV protocol followed by two weeks of at-home paced breathing employing a smartphone application. The participants were then reassessed in a biofeedback clinic.

Results

The participants physiological measures showed a significant increase in means between pre and post intervention of SDNN (t (32) = 2.177, p =.037) and TP, (t (32) = 2.327 p = .026). Correlation noted a medium effect on diastolic blood pressure and high frequency heart rate variability, F, r = .41, n =33, p < .05. A multiple regression with all predictor variables in the model found no significance with diastolic and systolic blood pressure.

Conclusions

The findings from this pilot study demonstrated that a two-week paced breathing intervention may assist in reducing heart rate and diastolic blood pressure while improving heart rate variability.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40885-021-00185-z.

Making the Best Out of IT: Design and Development of Exergames for Older Adults With Mild Neurocognitive Disorder - A Methodological Paper

Background: Utilizing information technology (IT) systems, for example in form of computerized cognitive screening or exergame-based (also called active videogames) training, has gained growing interest for supporting healthy aging and to detect, prevent and treat neurocognitive disorders (NCD). To ameliorate the effectiveness of exergaming, the neurobiological mechanisms as well as the most effective components for exergame-based training remain to be established. At the same time, it is important to account for the end-users' capabilities, preferences, and therapeutic needs during the design and development process to foster the usability and acceptance of the resulting program in clinical practice. This will positively influence adherence to the resulting exergame-based training program, which, in turn, favors more distinct training-related neurobiological effects. Objectives and Methods: This methodological paper describes the design and development process of novel exergame-based training concepts guided by a recently proposed methodological framework: The 'Multidisciplinary Iterative Design of Exergames (MIDE): A Framework for Supporting the Design, Development, and Evaluation of Exergames for Health' (Li et al., 2020). Case Study: A step-by-step application of the MIDE-framework as a specific guidance in an ongoing project aiming to design, develop, and evaluate an exergame-based training concept with the aim to halt and/or reduce cognitive decline and improve quality of life in older adults with mild neurocognitive disorder (mNCD) is illustrated. Discussion and Conclusion: The development of novel exergame-based training concepts is greatly facilitated when it is based on a theoretical framework (e.g., the MIDE-framework). Applying this framework resulted in a structured, iterative, and evidence-based approach that led to the identification of multiple key requirements for the exergame design as well as the training components that otherwise may have been overlooked or neglected. This is expected to foster the usability and acceptance of the resulting exergame intervention in "real life" settings. Therefore, it is strongly recommended to implement a theoretical framework (e.g., the MIDE-framework) for future research projects in line with well-known checklists to improve completeness of reporting and replicability when serious games for motor-cognitive rehabilitation purposes are to be developed.

Influencing Cardiovascular Outcomes through Heart Rate Variability Modulation: A Systematic Review

Psychological stress is a well-established risk factor for cardiovascular disease (CVD). Heart rate variability (HRV)-biofeedback could significantly reduce stress levels and improve autonomic nervous system function and cardiovascular endpoints. We aimed to systematically review the literature to investigate the impact of HRV modulation through HRV-biofeedback on clinical outcomes in patients with CVD. A literature search was performed in the following databases: MEDLINE (PubMed), Embase, and Cochrane from the inception until 1 October 2021. Patients in the HRV-biofeedback group had significantly lower rates of all-cause readmissions than patients who received psychological education (respectively, p = 0.028 and p = 0.001). Heart failure following HRV-biofeedback displayed an inverse association with stress and depression (respectively, p = 0.022 and p = 0.033). When stratified according to left ventricular ejection fraction (LVEF), patients with LVEF ≥ 31% showed improved values of the 6 min walk test after HRV-biofeedback interventions (p = 0.05). A reduction in systolic and diastolic blood pressure associated with HRV-biofeedback was observed (p < 0.01) in pre-hypertensive patients. HRV-biofeedback had beneficial effects on different cardiovascular diseases documented in clinical trials, such as arterial hypertension, heart failure, and coronary artery disease. A standard breathing protocol should be applied in future studies to obtain equivalent results and outcomes. However, data regarding mortality in patients with coronary artery disease are scarce and need further research.

Combining top-down and bottom-up interventions targeting the vagus nerve to increase resilience

Chronic stress has dramatically increased over the last years and is one of the major health concerns of the 21st century. Targeted interventions are traditionally based on inducing cognitive changes and enhancing control with the aim to promote adaptive emotion regulation, ultimately enhancing stress resilience. Crucially, bodily functions have received little attention in this quest, despite increasing evidence on the impact of mind-body interactions on resilience. An exemplary model is constituted by accumulating empirical support on the vagus nerve, which enables two-way communication between heart and brain, allowing to engage in an adaptive stress response in a context-appropriate manner. Yet, research on such bidirectional communication is mainly correlational. We propose to consider resonance breathing (bottom-up approach, heart > brain), and neuromodulation (top-down approach, brain > heart) as evidence-based ways to increase vagal nerve inhibitory control and hence increase stress resilience. These promising, likely cost-effective and easily employable techniques can be used alone or in combination, harnessing neurobiological scientific advances to select treatment options with the greatest likelihood of success.

Relationship between the proficiency level and anxiety-reducing effect in a one-time heart rate variability biofeedback: A randomized controlled trial

INTRODUCTION

Previous studies have reported that the proficiency level of heart rate variability biofeedback (HRVBF) contributes significantly to the anxiety-reducing effects in continuous HRVBF interventions. Meanwhile, anxiety-reducing effects have been confirmed in one-time HRVBF interventions as well as continuous HRVBF; however, no study has analyzed the relationship between the proficiency level of a one-time HRVBF and its anxiety-reducing effects. To pursuit the effectiveness of a one-time HRVBF intervention, it is necessary to clarify whether the proficiency level is an important predictor of anxiety-reducing effects from a dose-response relationship between these 2 variables. The purpose of this study was to examine the dose-response relationship between the proficiency level and anxiety-reducing effects of a one-time HRVBF.

METHODS

This study was a single-blinded, randomized, controlled trial with stratification based on trait anxiety of the State-Trait Anxiety Inventory-JYZ. In total, 45 healthy young males aged 20 to 30 years were allocated to the HRVBF or control group with simple breathing at rest. The intervention was performed for 15 minute in each group. The state anxiety score of the State-Trait Anxiety Inventory-JYZ was measured to evaluate the anxiety-reducing effect before and after training.

RESULTS

The results showed no significant linear relationship between the proficiency level and anxiety-reducing effect, and variations in the proficiency level were observed post-intervention in the HRVBF group. A significant anxiety-reducing effect was only observed in the HRVBF group (P = .001, effect size r = 0.62).

CONCLUSIONS

These results suggest that there is no close relationship between the proficiency level and anxiety-reducing effect in one-time HRVBF and that HRVBF is effective in reducing anxiety regardless of individual differences in the proficiency level. Therefore, a one-time HRVBF may be a useful breathing technique for reducing state anxiety without specific education and breathing techniques.

TRIAL REGISTRATION

University Hospital Medical Information Network Clinical Trial Registry (UMIN000041760).

Evaluating the potential of respiratory-sinus-arrhythmia biofeedback for reducing physiological stress in adolescents with autism: study protocol for a randomized controlled trial

Background

Prior evidence points towards lower cardiac vagal modulation in individuals with autism spectrum disorder (ASD) as compared to control groups. A cross-sectional phase in this study will gather more evidence concerning this topic. A longitudinal phase will explore the efficacy of a biofeedback intervention based on respiratory sinus arrhythmia (RSA) in adolescents with ASD. Finally, a feasibility study will focus on a non-supervised RSA biofeedback intervention in this population.

Methods

The cross-sectional phase includes the comparison of adolescents with ASD (n=38) and age- and gender-matched typically developing peers. A standardized assessment will be used which contains physiological, cortisol, and behavioral measurements. The longitudinal phase contains a randomized, single-blinded, and sham-controlled design to determine the efficacy of supervised RSA biofeedback in adolescents with ASD (n=128). A follow-up phase of 5 weeks is included to evaluate the presence of retention effects. During the latter, a feasibility study will focus on a non-supervised intervention (n=64). Assessments as described previously are scheduled after the intervention and the follow-up phase.

Discussion

First, more conclusive evidence will be provided for the presence of lower cardiac vagal modulation in adolescents with ASD as well as the association between these lower values and physiological and behavioral indices. Second, the supervised intervention in adolescents with ASD is hypothesized to upregulate this cardiac vagal modulation and positively change behavioral and physiological parameters. Third, evidence regarding the feasibility and acceptability of a non-supervised intervention may open novel avenues for home-based interventions in this population.

Trial registration

ClinicalTrials.govNCT04628715. Registered on 13 November 2020.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13063-021-05709-4.

Rehabilitation program combining physical exercise and heart rate variability biofeedback in hematologic patients: a feasibility study

Purpose

Hematologic patients have a poorer health-related quality of life due to the disease and its treatments. Non-pharmacological interventions represent an opportunity in tertiary cancer prevention to manage persistent symptoms and support patients in their return to active daily living. This interventional study aimed to evaluate the feasibility of a program combining physical exercise (PE) and heart rate variability biofeedback (HRVB) in hematologic patients.

Method

Hematologic patients in remission within 6 months participated in a 12-week rehabilitation program including 24 supervised sessions of PE associated with 10 supervised sessions of HRVB and daily home-based practice of paced breathing. We assessed patient adherence, fatigue, physical function, and heart rate variability.

Results

Twenty patients were included, 17 completed the protocol and 3 dropped out due to disease progression or time constraints; no adverse events or incidents were reported. Participation rates were 85% for PE and 98% for HRVB-supervised sessions. Significant improvements of physical capacity (6-min walk test, p < 0.001; 50-foot walk test, p < 0.001), muscle strength (grip force test, p < 0.01), and flexibility (toe-touch test, p < 0.001; back scratch test, p < 0.05) were measured. Coherence ratio (p < 0.001) and low-frequency spectral density of HRV signal (p < 0.003) increased significantly, suggesting improved autonomic function. Fatigue, static balance, and other time and frequency indicators of HRV were not improved (all p > 0.05).

Conclusion

A rehabilitation program combining PE and HRVB is feasible in hematologic patients and effective on physical function. Further research with a larger sample size is needed to investigate effectiveness on patients’ autonomic functions and their impacts on symptomatology.

Testing the Efficacy of a 1-Day Police Decision-Making and Autonomic Modulation Intervention: A Quasi-Random Pragmatic Controlled Trial

Contemporary discourse has identified several urgent priorities concerning police training and education, including: (a) empirically testing and validating the effectiveness of current programming in reducing lethal force decision-making errors; (b) integrating evidence-based content and pedagogical approaches into police curriculum; and (c) understanding the breadth and length of programming necessary to ensure learning and transfer of skills to operational field settings. Widespread calls to identify effective and actionable training programs have been met with numerous research studies, systematic reviews, and policy recommendations that reveal the need to train officers' internal physiological awareness, which is foundational in shaping cognitive decision-making, emotion regulation, and behavior under stressful conditions. Several investigations have shown improvements to both lethal force errors and physiological recovery following a multi-day autonomic modulation (AM) intervention. Immediate and sustained training gains are observed following repeated practice with clinically validated protocols integrated into training scenarios. Despite evidence-based support for AM in addressing the aforementioned priorities, police organizations are faced with limited time and funding for training and education. The goal of the current quasi-random pragmatic controlled trial was to evaluate the effectiveness of a modified 1-day version of an established AM intervention. A sample of active-duty police officers were quasi-randomly assigned to an AM intervention (n = 82) or waitlist control group (n = 105). Lethal force errors and objective measures of autonomic arousal and recovery were measured during reality-based scenarios pre- and post-training and at 12-month follow-up. In contrast to previous investigations of longer AM intervention protocols, no significant training-related improvements to behavioral or physiological outcomes were found immediately post-intervention or at follow-up. The current results suggest that single-day training is insufficient to learn the physiological awareness and regulation skills necessary to perform effectively during lethal force encounters, as demonstrated by a lack of immediate or sustained training effects. Practical considerations, such as resource allocation, that may undermine the effectiveness of implementing evidence-based police training are discussed.

A neuro-cardiac self-regulation therapy to improve autonomic and neural function after SCI: a randomized controlled trial protocol

BACKGROUND

Spinal cord injury (SCI) is associated with autonomic imbalance and significant secondary conditions, including cardiac and brain dysfunction that adversely impact health and wellbeing. This study will investigate the effectiveness (intention-to-treat) of a neuro-cardiac self-regulation therapy to improve autonomic and neural/brain activity in adults with SCI living in the community.

METHODS

A two-arm parallel, randomised controlled trial in which adults with SCI living in the community post-rehabilitation will be randomly assigned to a treatment or control group. The treatment group (N = 60) aged 18-70 years with a chronic traumatic or non-traumatic SCI, will receive intervention sessions once per week for 10 weeks, designed to regulate autonomic activity using computer-based feedback of heart rate variability and controlled breathing (called HRV-F). Comprehensive neurophysiological and psychological assessment will occur at baseline, immediate post-treatment, and 6 and 12-months post-treatment. Primary outcome measures include electrocardiography/heart rate variability (to assess autonomic nervous system function) and transcranial doppler sonography (to assess cerebral blood circulation in basal cerebral arteries). Secondary outcomes measures include continuous blood pressure, electroencephalography, functional near-infrared spectroscopy, respiration/breath rate, electrooculography, cognitive capacity, psychological status, pain, fatigue, sleep and quality of life. Controls (N = 60) will receive usual community care, reading material and a brief telephone call once per week for 10 weeks and be similarly assessed over the same time period as the HRV-F group. Linear mixed model analysis with repeated measures will determine effectiveness of HRV-F and latent class mixture modelling used to determine trajectories for primary and selected secondary outcomes of interest.

DISCUSSION

Treatments for improving autonomic function after SCI are limited. It is therefore important to establish whether a neuro-cardiac self-regulation therapy can result in improved autonomic functioning post-SCI, as well as whether HRV-F is associated with better outcomes for secondary conditions such as cardiovascular health, cognitive capacity and mental health.

TRIAL REGISTRATION

The study has been prospectively registered with the Australian and New Zealand Clinical Trial Registry ( ACTRN12621000870853 .aspx). Date of Registration: 6th July 2021. Trial Sponsor: The University of Sydney, NSW 2006. Protocol version: 22/07/2021.

Targeting autonomic flexibility to enhance cognitive training outcomes in older adults with mild cognitive impairment: study protocol for a randomized controlled trial

Importance

Cognitive training with components that can further enhance the transferred and long-term effects and slow the progress of dementia is needed for preventing dementia.

Objective

The goal of the study is to test whether improving autonomic nervous system (ANS) flexibility via a resonance frequency breathing (RFB) training will strengthen the effects of a visual speed of processing (VSOP) cognitive training on cognitive and brain function, and slow the progress of dementia in older adults with mild cognitive impairment (MCI).

Design

Stage II double-blinded randomized controlled trial. The study was prospectively registered at ClinicalTrials.gov, with registration approved on 21 August 2020 (No. NCT04522791).

Setting

Study-related appointments will be conducted on-site at University of Rochester Medical Center locations. Data collection will be conducted from August 2020 to February 2025.

Participants

Older adults with MCI (n = 114) will be randomly assigned to an 8-week combined intervention (RFB+VSOP), VSOP with guided imagery relaxation (IR) control, and a IR-only control, with periodical booster training sessions at follow-ups. Mechanistic and distal outcomes include ANS flexibility, measured by heart rate variability, and multiple markers of dementia progress. Data will be collected across a 14-month period.

Discussion

This will be among the first RCTs to examine in older persons with MCI a novel, combined intervention targeting ANS flexibility, an important contributor to overall environmental adaptation, with an ultimate goal for slowing neurodegeneration.

Trial registration

ClinicalTrials.gov NCT04522791. Registered on 21 August 2020

Protocol version: STUDY00004727; IRB protocol version 2, approved on 30 July 2020.