Effects of heart rate variability biofeedback training in athletes exposed to stress of university examinations

Effects of Heart Rate Variability Biofeedback Training on Anxiety Reduction and Brain Activity: a Randomized Active-Controlled Study Using EEG

Heart rate variability biofeedback (HRVBF) is a promising anxiety-reducing intervention that increases vagally-mediated heart rate variability (vmHRV) through slow-paced breathing and feedback of heart rhythm. Several studies have reported the anxiety-reducing effects of HRVBF; however, some studies have reported such training as ineffective. Furthermore, the effects of training and underlying brain activity changes remain unclear. This study examined the anxiety-reducing effects of HRVBF training and related brain activity changes by randomly assigning participants, employing an active control group, and measuring anxiety-related attentional bias using the emotional Stroop task and electroencephalography (EEG). Fifty-five healthy students with anxiety were randomly assigned to the HRVBF or control groups, and 21 in the HRVBF group and 19 in the control group were included in the analysis. Both groups performed 10 training sessions of 20 min each within 3 weeks. They were assessed using resting vmHRV, event-related potential (ERP), time-frequency EEG, attentional bias, and the State-Trait Anxiety Inventory-JYZ (STAI-JYZ) before and after training. The results demonstrated increased resting vmHRV in the HRVBF group compared to the control group after training. However, no differences were observed in ERP, time-frequency EEG, attentional bias, and STAI-JYZ. Participants with higher pre-training resting vmHRV achieved higher heart rhythm coherence in HRVBF training and had reduced attentional bias. This study suggests that individuals with higher resting vmHRV are more likely to be proficient in HRVBF training and benefit from its anxiety-reducing effects. The findings contribute to participant selection to benefit from HRVBF training and modification of the training protocols for non-responders.Clinical trial registrationOrganization: University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR), JapanRegistration number: UMIN000047096Registration date: March 6, 2022.

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 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.

A Pilot Study of the Biofeedback Training to Reduce Salivary Cortisol Level and Improve Mental Health in Highly-Trained Female Athletes

Biofeedback (BFB) training can provide a useful resource for athletes to cope with stress. However, the effects of BFB training on acute and chronic endocrine stress responses, parasympathetic activity, and mental health in competitive athletes have not been explored yet. This pilot study examined the effects of a 7-week BFB training on psychophysiological parameters in highly trained female athletes. Six highly trained female volleyball players (mean age: 17.50 ± 1.05 years) volunteered to participate in the study. Athletes individually attended 21-session heart rate variability (HRV)-BFB training consisting of six minutes for 7 weeks. A BFB device (Nexus 10) was used to measure the athletes' physiological responses reflecting HRV. To assess the cortisol awakening response (CAR), saliva samples were collected immediately after awakening and 15 min, 30 min, and 60 min post-awakening. The Depression Anxiety Stress Scale-21 was filled out before and after the intervention to assess mental health. Furthermore, athletes provided saliva samples during eight sessions pre- and immediately post-session. Mid-day cortisol levels decreased significantly after the intervention. No significant change was observed in CAR and physiological responses after the intervention. A significant decrease in cortisol level was observed in BFB sessions in which cortisol level was assessed, except for two sessions. We concluded that short sessions of 7-week HRV-BFB training could be used as an effective method to control autonomic functions and stress of female athletes. Although the present study provides strong evidence for the psychophysiological well-being of athletes, further investigations with larger samples are needed.

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.

Asynchronous Heart Rate Variability Biofeedback Protocol Effects on Adolescent Athletes' Cognitive Appraisals and Recovery-Stress States

This study examined the effect of an asynchronous heart rate variability biofeedback (HRV-BFBasync) protocol on national-level adolescent swimmers' cognitive appraisals and recovery-stress states during a six-week ecological training period. A polynomial mixed-effects multilevel regression analysis approach was used with 27 adolescent national-level swimmers randomly assigned to an intervention group (n = 14) and a control group (n = 13). Six waves of assessments of cognitive appraisals and recovery-stress states were completed during six weeks of training preparation in ecological conditions. The results revealed that the HRV-BFBasync protocol significantly predicts lower levels of biopsychosocial stress states and cognitive stress. However, no significant effects were found for biopsychosocial recovery scales and cognitive perceived control. The results suggested that total stress states, sport-specific stress, and cognitive perceived stress evolutions are a function of polynomial time third-degree interactions with HRV-BFB protocol. Overall, this study suggested that the HRV-BFBasync protocol leads adolescent athletes to experience lower biopsychosocial and cognitive stress levels during training periodization. Our results also suggest that HRV-BFB induces complex evolutions over time for stress and recovery states but does not have a predictive function for the recovery states and perceived control.

Guiding Breathing at the Resonance Frequency with Haptic Sensors Potentiates Cardiac Coherence

Cardiac coherence is a state achieved when one controls their breathing rate during the so-called resonance frequency breathing. This maneuver allows respiratory-driven vagal modulations of the heart rate to superimpose with sympathetic modulations occurring at 0.1 Hz, thereby maximizing autonomous power in heart-to-brain connections. These stimulations have been shown to improve vagal regulations, which results in obvious benefits for both mental and organic health. Here, we present a device that is able to deliver visual and haptic cues, as well as HRV biofeedback information to guide the user in maintaining a 0.1 Hz breathing frequency. We explored the effectiveness of cardiac coherence in three guidance conditions: visual, haptic and visuo-haptic breathing. Thirty-two healthy students (sixteen males) were divided into three groups that experienced five minutes of either visual, haptic and visuo-haptic guided breathing at 0.1 Hz. The effects of guidance on the (adequate) breathing pattern and heart rate variability (HRV) were analyzed. The interest of introducing haptic breathing to achieve cardiac coherence was shown in the haptic and visuo-haptic groups. Especially, the P_0.1 index, which indicates how the autonomous power is 'concentrated' at 0.1 Hz in the PSD spectrum, demonstrated the superiority of combining haptic with visual sensory inputs in potentiating cardiac coherence (0.55 ± 0.20 for visuo-haptic vs. 0.28 ± 0.14 for visual only guidance; p < 0.05) haptic-induced effectiveness could be an asset for a more efficient and time-saving practice, allowing improved health and well-being even under tight time constraints.

Single-lead ECG based autonomic nervous system assessment for meditation monitoring

We propose a single-lead ECG-based heart rate variability (HRV) analysis algorithm to quantify autonomic nervous system activity during meditation. Respiratory sinus arrhythmia (RSA) induced by breathing is a dominant component of HRV, but its frequency depends on an individual's breathing speed. To address this RSA issue, we designed a novel HRV tachogram decomposition algorithm and new HRV indices. The proposed method was validated by using a simulation, and applied to our experimental (mindfulness meditation) data and the WESAD open-source data. During meditation, our proposed HRV indices related to vagal and sympathetic tones were significantly increased (p < 0.000005) and decreased (p < 0.000005), respectively. These results were consistent with self-reports and experimental protocols, and identified parasympathetic activation and sympathetic inhibition during meditation. In conclusion, the proposed method successfully assessed autonomic nervous system activity during meditation when respiration influences disrupted classical HRV. The proposed method can be considered a reliable approach to quantify autonomic nervous system activity.

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, perceived stress and willingness to seek counselling in undergraduate students

OBJECTIVE

The primary aim was to determine the level of stress in Czech pharmacy students using both subjective and physiological markers of stress throughout their study. The secondary aim was to investigate association of stress with sociodemographic and clinical characteristics, and to determine the predictors of the likelihood of enrolling in psychotherapy counselling.

METHODS

Design: A prospective observational study.

SETTING

Faculty of Pharmacy in Hradec Kralove, Czech Republic.

SUBJECTS

175 s-year pharmacy students in 2016, 149 students in 2017, and 51 students in 2018.

OUTCOME MEASURES

Perceived stress scale (PSS-10), heart rate variability (HRV, emWavePro), a self-administered survey (sociodemographic and clinical data, likelihood of enrolling in psychotherapy counselling).

RESULTS

The average PSS score was 18.3 ± 6.7. There were no significant changes in PSS-10 and HRV parameters between 2016 and 2018. There was a significant negative correlation between PSS-10 and LF power (p = 0.012). Female gender and poor health status were more frequently observed among the respondents with impaired HRV (p = 0.026 for female gender and p = 0.025 and p = 0.042 for poor health status). Fifty-nine percent of students would be likely to enroll in psychotherapy counselling, with men being significantly less inclined to participate compared to women (p = 0.01).

CONCLUSION

Czech pharmacy students experience moderate levels of stress throughout their studies, which correlates with physiological markers of stress as well as their overall health. Push and pull factors of using mind-body interventions to manage stress should be further examined, especially in high risk groups.

Emotional Self-Regulation in Primary Education: A Heart Rate-Variability Biofeedback Intervention Programme

This study investigated the benefits of using a biofeedback intervention programme to train children in controlling their heart rate variability (HRV) through slow-paced breathing in real time. HRV biofeedback interventions focused on showing subjects to breathe such that their HRV numbers rise, improving their self-regulation. The HRV biofeedback intervention, focused on breathing, was conducted with primary education students aged between 7 and 11 years. The programme consisted of five biofeedback sessions, where students were taught to breathe six long and slow pairs of breaths per minute, to increase their HRV. After participation in the programme, students, regardless of gender, increased their HRV in a statistically significant fashion with a large effect, but this effect was not the same for all ages. HRV biofeedback interventions are rarely applied in schools and given the effectiveness of the intervention to improve HRV in children, the applied implications of our results in educational settings are discussed, especially taking into account the children’s ages.

Measuring Heart Rate Variability in Patients Admitted with ST-Elevation Myocardial Infarction for the Prediction of Subsequent Cardiovascular Events: A Systematic Review

Background and objectives: Ischemic heart disease represents the leading cause of death, emphasizing risk stratification and early therapeutic intervention. Heart rate variability (HRV), an indirect marker of autonomic nervous system activity, was investigated extensively as a risk factor for adverse cardiovascular events following acute myocardial infarction. Thus, we systematically reviewed the literature to investigate the association of HRV parameters with mortality and adverse cardiovascular events in patients presenting with ST-elevation myocardial infarction (STEMI). Materials and methods: Following the search process in the MEDLINE (PubMed), Embase, and Cochrane databases, nine studies were included in the final analysis. Results: Lower time-domain HRV parameters and a higher ratio between power in the low-frequency (LF) band and power in the high-frequency (HF) band (LF/HF) were associated with higher all-cause mortality during follow-up, even in patients treated mainly with percutaneous coronary interventions (PCI). Although most studies measured HRV on 24 h ECG recordings, short- and ultra-short-term measures (1 min and 10 s, respectively) were also associated with an increased risk of all-cause mortality. Although data were discrepant, some studies found an association between HRV and cardiac mortality, reinfarction, and other major adverse cardiovascular events. Conclusions: In conclusion, HRV measurement in patients with STEMI could bring crucial prognostic information, as it was associated with an increased risk of all-cause mortality documented in clinical studies. More and larger clinical trials are required to validate these findings in contemporary patients with STEMI in the context of the new generation of drug-eluting stents and current antithrombotic and risk-modifying therapies.

Can HRV Biofeedback Improve Short-Term Effort Recovery? Implications for Intermittent Load Sports

As intensity and physical demands continue to rise in sport competition, faster and better recovery becomes essential. The aim of this study was to assess the effects of HRV biofeedback (HRVB) while recovering from a submaximal aerobic exercise. Ten physically-active graduate students participated in the study, which was conducted in four sessions: exercise with free-breathing recovery, first resonance frequency (RF) detection, second RF detection, and exercise applying HRVB during recovery. Measurements included time spent running and recovering, HRV parameters, and recovery/exertion perceptions. The results indicate that using HRVB during recovery improves cardiac variability (RRmean, SDNN, RMSSD and LF; p < 0.01). HRVB also lowers recovery time (p < 0.05) and seems to be improving the perception of recovery (p = 0.087). Moreover, time spent exercising (p < 0.01) and perceived physical exertion (p < 0.05) were higher when applying HRVB. The improvement in the psychophysiological adaptation after intensive aerobic exercise provided by the HRVB is a valuable benefit, not only for competition-driven athletes, but also for the general population.

How everyday sounds can trigger strong emotions: ASMR, misophonia and the feeling of wellbeing

We propose that synesthetic cross-activation between the primary auditory cortex and the anatomically adjacent insula may help explain two puzzling conditions-autonomous sensory meridian response (ASMR) and misophonia-in which quotidian sounds involuntarily trigger strong emotional responses. In ASMR the sounds engender relaxation, while in misophonia they trigger an aversive response. The insula both plays an important role in autonomic nervous system control and integrates multiple interoceptive maps representing the physiological state of the body to substantiate a dynamic representation of emotional wellbeing. We propose that in ASMR cross-activation of the map for affective (sensual) touch leads to an increase in subjective wellbeing and parasympathetic activity. Conversely, in misophonia the effect of the cross-activation is to decrease emotional wellbeing and increase sympathetic activity. Our hypothesis also illuminates the connection between hearing and wellbeing more broadly and helps explain why so many people experience decreased wellbeing from modern urban soundscapes.

Entropy in Heart Rate Dynamics Reflects How HRV-Biofeedback Training Improves Neurovisceral Complexity during Stress-Cognition Interactions

Despite considerable appeal, the growing appreciation of biosignals complexity reflects that system complexity needs additional support. A dynamically coordinated network of neurovisceral integration has been described that links prefrontal-subcortical inhibitory circuits to vagally-mediated heart rate variability. Chronic stress is known to alter network interactions by impairing amygdala functional connectivity. HRV-biofeedback training can counteract stress defects. We hypothesized the great value of an entropy-based approach of beat-to-beat biosignals to illustrate how HRVB training restores neurovisceral complexity, which should be reflected in signal complexity. In thirteen moderately-stressed participants, we obtained vagal tone markers and psychological indexes (state anxiety, cognitive workload, and Perceived Stress Scale) before and after five-weeks of daily HRVB training, at rest and during stressful cognitive tasking. Refined Composite Multiscale Entropy (RCMSE) was computed over short time scales as a marker of signal complexity. Heightened vagal tone at rest and during stressful tasking illustrates training benefits in the brain-to-heart circuitry. The entropy index reached the highest significance levels in both variance and ROC curves analyses. Restored vagal activity at rest correlated with gain in entropy. We conclude that HRVB training is efficient in restoring healthy neurovisceral complexity and stress defense, which is reflected in HRV signal complexity. The very mechanisms that are involved in system complexity remain to be elucidated, despite abundant literature existing on the role played by amygdala in brain interconnections.

Effect of an eight-week smartphone-guided HRV-biofeedback intervention on autonomic function and impulsivity in healthy controls

A large body of scientific studies suggest a close relationship between increased vagal function and better cognitive performance.

OBJECTIVE

In the current study, we investigated the association between autonomic function and behavioral impulsivity. We hypothesized that heart rate variability (HRV) biofeedback training increases HRV and enhances inhibitory control.

APPROACH

A total of 28 healthy participants were recruited. After drop-out, 14 participants completed an eight-week HRV biofeedback training with five training sessions per week including one session at the clinic's laboratory and four sessions at home using a mobile application running on their smartphone. Ten control subjects matched with respect to age and gender played a mobile game according to the same schedule as the biofeedback group. The assessment of autonomic status and the stop-signal task were conducted before the beginning of the training (T1) and after finishing the schedule (T2).

MAIN RESULTS

We found a relationship of reaction times in the stop-signal task and standard HRV as well as cardiorespiratory indices. After biofeedback training, short-term HRV and baroreflex function significantly increased by 33% (CI [2%, 64%], p   <  0.05) and 21% (CI [5%, 36%], p   <  0.05), respectively. The performance in the stop-signal task was not affected by the biofeedback intervention. Compared to the changes of autonomic indices in the control group, only a decrease of skin conductance levels in the biofeedback group remained statistically significant.

SIGNIFICANCE

Our results indicate that a smartphone-based HRV biofeedback intervention can be applied to improve cardiovagal function in healthy subjects. Although higher HRV was associated with higher levels of inhibitory control, HRV biofeedback had no effect on measures of impulsivity.

An oculometrics-based biofeedback system to impede fatigue development during computer work: A proof-of-concept study

A biofeedback system may objectively identify fatigue and provide an individualized timing plan for micro-breaks. We developed and implemented a biofeedback system based on oculometrics using continuous recordings of eye movements and pupil dilations to moderate fatigue development in its early stages. Twenty healthy young participants (10 males and 10 females) performed a cyclic computer task for 31–35 min over two sessions: 1) self-triggered micro-breaks (manual sessions), and 2) biofeedback-triggered micro-breaks (automatic sessions). The sessions were held with one-week inter-session interval and in a counterbalanced order across participants. Each session involved 180 cycles of the computer task and after each 20 cycles (a segment), the task paused for 5-s to acquire perceived fatigue using Karolinska Sleepiness Scale (KSS). Following the pause, a 25-s micro-break involving seated exercises was carried out whether it was triggered by the biofeedback system following the detection of fatigue (KSS≥5) in the automatic sessions or by the participants in the manual sessions. National Aeronautics and Space Administration Task Load Index (NASA-TLX) was administered after sessions. The functioning core of the biofeedback system was based on a Decision Tree Ensemble model for fatigue classification, which was developed using an oculometrics dataset previously collected during the same computer task. The biofeedback system identified fatigue with a mean accuracy of approx. 70%. Perceived workload obtained from NASA-TLX was significantly lower in the automatic sessions compared with the manual sessions, p = 0.01 Cohen’s d_z = 0.89. The results give support to the effectiveness of integrating oculometrics-based biofeedback in timing plan of micro-breaks to impede fatigue development during computer work.