Heart rate variability biofeedback in chronic disease management: A systematic review

Assessment and Correlates of Different Phenotypical Characteristics of Psychological Flexibility in Adapting to Chronic Pain: A Feasibility Study

OBJECTIVES

This study examined the feasibility of a research protocol for assessing psychological flexibility in patients with chronic pain to gain insight into the uniqueness of different phenotypes of psychological flexibility and to tentatively test whether psychological flexibility is associated with effective adaptation to chronic pain.

METHODS

In a cross-sectional study, in twenty patients with chronic pain, different phenotypes of psychological flexibility and a variety of positive and negative health indicators were assessed. Correlations were explored to determine the unicity of the different phenotypes of psychological flexibility and to test their associations with chronic pain.

RESULTS

All phenotypes of psychological flexibility could be assessed reliably in this patient group. Preliminary findings suggest that all phenotypes assess unique flexibility aspects (79% of the intercorrelations were less than moderate; > -0.30, < 0.30). Higher levels of different psychological flexibility phenotypes were generally associated with higher positive health indicators and lower negative health indicators (70% of the moderate correlations; ≤ -0.30 or ≥ 0.30 were in the expected direction).

CONCLUSIONS

Results confirm that the protocol is feasible for large-scale research in patients with chronic pain and that it is useful to further investigate the different phenotypes of psychological flexibility in relation to optimal adaptation to chronic pain in a longitudinal study.

PRACTICE IMPLICATIONS

Psychological flexibility is a potentially important future target in the treatment (e.g., biofeedback, cognitive behavioral therapy, mindfulness) of patients with chronic pain.

Interoception after frontal brain injury: A systematic review

OBJECTIVE

Interoception is crucial for emotional processing. It relies on the bidirectional connections between the insula, a crucial structure in interoception, and the frontal lobe, which is implicated in emotional experiences. Acquired frontal brain injury often leads to emotional disorders. Our goal was to explore the interoceptive profiles of patients with frontal lesions with or without insular involvement.

METHOD

Given the neuroanatomical links between interoception and emotions, we conducted a systematic Preferred Reporting Items for Systematic Reviews and Meta-analyses guided review of studies assessing at least one dimension of interoception in adults with acquired frontal injuries, with or without associated insular lesions.

RESULTS

Seven articles were included. The review indicated that interoceptive accuracy declines after frontal injuries. The two studies that investigated interoceptive sensitivity found lower scores in patient groups. Finally, inconsistent results were found for interoceptive metacognition after frontal damage.

CONCLUSIONS

This review is the first to explore interoceptive disorders after acquired frontal brain injury. The findings reveal deficits in cardiac interoceptive accuracy and interoceptive sensitivity following frontal damage. Inconsistent results were observed for interoceptive metacognition. Further research is needed to confirm the presence of interoceptive deficits following a frontal lesion. Additionally, the relationship between interoceptive deficits and emotional disorders, often reported after frontal brain injury, should be investigated.

Combined Proxies for Heart Rate Variability as a Global Tool to Assess and Monitor Autonomic Dysregulation in Fibromyalgia and Disease-Related Impairments

BACKGROUND

Heart rate variability (HRV) provides both linear and nonlinear autonomic proxies that can be informative of health status in fibromyalgia (FM), where sympatho-vagal abnormalities are common. This retrospective observational study aims to: 1. detect differences in correlation dimension (D2) between FM patients and healthy controls (HCs); 2. correlate D2 with standard HRV parameters; 3. correlate the degree of HRV changes using a global composite parameter called HRV grade, derived from three linear indices (SDNN = intervals between normal sinus beats; RMSSD = mean square of successive differences; total power), with FM clinical outcomes; 4. correlate all linear and nonlinear HRV parameters with clinical variables in patients.

METHODS

N = 85 patients were considered for the analysis and compared to 35 healthy subjects. According to standard diagnostic protocol, they underwent a systematic HRV protocol with a 5-min paced breathing task. Disease duration, pain intensity, mood, sleep, fatigue, and quality of life were assessed. Non-parametric tests for independent samples and pairwise correlations were performed using JMP (all p < 0.001).

RESULTS

Mann-Whitney U found a significant difference in D2 values between FM patients and HCs (p < 0.001). In patients, D2 was associated with all HRV standard indices (all p < 0.001) and FM impairment (FIQ = -0.4567; p < 0.001). HRV grade was also associated with FM impairment (FIQ = 0.5058; p < 0.001).

CONCLUSION

Combining different HRV measurements may help understand the correlates of autonomic dysregulation in FM. Specifically, clinical protocols could benefit from the inclusion and validation of D2 and HRV parameters to target FM severity and related dysautonomia.

The Physiological Component of the BOLD Signal: Impact of Age and Heart Rate Variability Biofeedback Training

Aging is associated with declines in autonomic nervous system (ANS) function, including reduced heart rate variability (HRV), impaired neurovascular coupling, and diminished cerebrovascular responsiveness-factors that may contribute to cognitive decline and neurodegenerative diseases. Understanding how aging alters physiological signal integration in the brain is crucial for identifying potential interventions to promote brain health. This study examines age-related differences in how cardiac and respiratory fluctuations influence the blood oxygenation level-dependent (BOLD) signal, using two independent resting-state fMRI datasets with concurrent physiological recordings from younger and older adults. Our findings reveal significant age-related reductions in the percent variance of the BOLD signal explained by heart rate (HR), respiratory variation (RV), and end-tidal CO 2 , particularly in regions involved in autonomic regulation, including the orbitofrontal cortex, anterior cingulate cortex, insula, basal ganglia, and white matter. Cross-correlation analysis also revealed that younger adults exhibited stronger HR-BOLD coupling in white matter, as well as a more rapid BOLD response to RV and CO 2 in gray matter. Additionally, we investigated the effects of heart rate variability biofeedback (HRV-BF) training, a non-invasive intervention designed to modulate heart rate oscillations. The intervention altered physiological-BOLD coupling in an age- and training-dependent manner: older adults who underwent HRV-BF to enhance HR oscillations exhibited a shift toward younger-like HR-BOLD coupling patterns, while younger adults who trained to suppress HR oscillations showed increased CO 2 -BOLD coupling. These findings suggest that HRV-BF may help mitigate age-related declines in autonomic or cerebrovascular function. Overall, this study underscores the role of physiological dynamics in brain aging and highlights the importance of considering autonomic function when interpreting BOLD signals. By demonstrating that HRV-BF can modulate physiological-BOLD interactions, our findings suggest a potential pathway for enhancing cerebrovascular function and preserving brain health across the lifespan.

Autonomic dysfunction after stroke: an overview of recent clinical evidence and perspectives on therapeutic management

PURPOSE

Central autonomic dysfunction is common in acute stroke and is associated with cardiovascular complications and increased mortality. The aim of this review is to present novel diagnostic and therapeutic approaches to the management of this disorder and the latest data on its impact on the clinical outcome after stroke.

METHODS

We performed a narrative review of recent literature, with a particular focus on articles related to underlying pathophysiological mechanisms of cardiac autonomic dysregulation, the role of cardiac autonomic dysregulation in the activation of neuroinflammatory response and the development of cardiovascular, respiratory and metabolic complications in patients with ischemic and hemorrhagic stroke.

RESULTS

The assessment of central autonomic dysfunction by non-invasive diagnostic techniques, including heart rate variability and baroreflex sensitivity, has gained wide practical application in recent years, and they may have a predictive role for evaluating disease prognosis. The emerging evidence derived from recent trials demonstrates that the presence of autonomic imbalance may lead to increased mortality and have an adverse effect on post-stroke rehabilitation.

CONCLUSION

The early detection and treatment of central autonomic system dysfunction may lead to improved survival of patients with stroke. Among the available therapeutic approaches, neuromodulatory techniques and pharmacological interventions are promising strategies which may be implemented as part of standard acute stroke care to improve patient recovery. Future studies are warranted to address the long-term effects of potential therapeutic agents on the modulation of cardiovascular autonomic function in stroke survivors.

The effects of paced breathing on psychological distress vulnerability and heart rate variability in adults sustaining traumatic injury

BACKGROUND

Traumatic physical injuries can lead to psychological distress and increased risk of psychiatric disorders, often reflected in dysregulated autonomic responses measurable through heart rate variability (HRV). Slow-paced breathing has shown potential in enhancing HRV, but its effectiveness in injured survivors remains unexplored. This study investigates the effect of slow-paced breathing on HRV among injured survivors compared to non-injured individuals and explores the influence of psychological distress and spontaneous respiratory rate on this effect.

METHODS

The study involved 120 injured individuals and 112 non-injured controls with similar age, sex, and education levels. Injured participants with minor-to-moderate injuries from traffic crashes were assessed 3-6 weeks post-injury. Psychological distress was defined as the risk of post-traumatic stress disorder and/or major depression. Physiological assessment (HRV) included a 2-min resting baseline and a 2-min slow-paced breathing session (6 breaths/min). Repeated measure MANCOVA assessed HRV changes between groups, while correlation analyses examined the relationship between these changes.

RESULTS

Injured survivors had significantly lower HRV than non-injured controls. Both groups showed notable HRV increases during slow-paced breathing. Among injured individuals, those with higher psychological distress exhibited greater HRV increases, particularly in parasympathetic activity and overall variability. Higher spontaneous respiratory rates were associated with greater HRV changes, especially in non-injured individuals.

CONCLUSION

Slow-paced breathing demonstrated significant physiological effects for injured survivors, particularly those with higher psychological distress, and supports its potential in improving stress regulation post-injury. Future research should examine the long-term effects of sustained breathing practice and clinical applicability in reducing psychological distress and disability post-injury.

Heart Rate Variability Biofeedback Training Can Improve Menopausal Symptoms and Psychological Well-Being in Women with a Diagnosis of Primary Breast Cancer: A Longitudinal Randomized Controlled Trial

Breast cancer survivors experience numerous chronic symptoms linked to autonomic dysfunction including anxiety, stress, insomnia, menopausal symptoms, and cognitive impairment. Effective non-pharmacological solutions to address these are currently lacking.

METHODS

Our three-armed longitudinal randomized controlled trial assessed the effectiveness of a 4-week remote smartphone-based heart rate variability biofeedback intervention which involved daily paced breathing at 6 breaths p/min; active (12 breaths p/min) and waitlist controls were included. Heart rate variability and self-reported cancer-related symptoms were assessed at baseline, post-, and 6 months-post intervention. Participants were 60 UK-based women with primary breast cancer history (6 to 60 months post-active treatment).

RESULTS

The intervention group showed significant increases in low-frequency heart rate variability over time (F (4, 103.89) = 2.862, p = 0.027, d = 0.33), long-lasting improvement in sleep quality (F (4, 88.04) = 4.87, p = 0.001, d = 0.43) and cessations in night sweats (X2 (2, N = 59) = 6.44, p = 0.04, Cramer's V = 0.33), and reduced anxiety post-intervention compared to the active and waitlist controls (F (4, 82.51) = 2.99, p = 0.023, d = 0.44). Other findings indicated that the intervention and active control participants reported lasting improvements in cognitive function, fatigue, and stress-related symptoms (all ps < 0.05). The waitlist group reported no symptom changes across time.

CONCLUSION

Heart rate variability biofeedback is a feasible intervention for addressing diverse chronic symptoms commonly reported by breast cancer survivors.

Designing and developing a prescription digital therapeutic for at-home heart rate variability biofeedback to support and enhance patient outcomes in post-traumatic stress disorder treatment

Post-traumatic stress disorder (PTSD) is a psychiatric condition producing considerable distress, dysfunction, and impairment in affected individuals. While various forms of psychotherapy are commonly utilized in PTSD treatment, the known neurological pathologies associated with PTSD are insufficiently addressed by these conventional approaches. Heart rate variability biofeedback (HRV-BFB) is a promising tool for correcting autonomic dysfunction in PTSD, with subsequent changes in clinically significant outcome measures. This paper outlines a systematic approach for the development, distribution, and implementation of a prescription at-home HRV-BFB digital therapeutic. We provide recommendations for evidence-generation strategies and propose appropriate regulatory pathways within existing frameworks. Widespread access to HRV-BFB could potentially reduce the distress, disability, and healthcare burden associated with PTSD. Promoting HRV-BFB as a primary intervention could also serve to reduce the stigma associated with "mental" illness and increase health literacy regarding the neuroimmune impacts of psychosocial factors. These processes might in turn improve treatment-seeking, adherence, and supported self-management of these conditions.

Comparing autonomic nervous system function in patients with functional somatic syndromes, stress-related syndromes and healthy controls

BACKGROUND

The goal of this study was to examine autonomic nervous system function by measuring heart rate (HR), heart rate variability (HRV), skin conductance levels (SCL), and peripheral skin temperature (ST) in response to and during recovery from psychosocial stressors in patients with functional somatic syndromes (FSS; fibromyalgia and/or chronic fatigue syndrome), stress-related syndromes (SRS; overstrain or burn-out), and healthy controls (HC).

METHODS

Patients with FSS (n = 26), patients with SRS (n = 59), and HC (n = 30) went through a standardized psychosocial stress test consisting of a resting phase (120 s), the STROOP color word task (120 s), a mental arithmetic task (120 s) and a stress talk (120 s), each followed by a 120 s recovery period. HR, HRV, SCL, and ST were monitored continuously.

RESULTS

Average HR and SCL were higher, and HRV was lower, in both patient groups compared to HC during rest (0.50 < Cohen's d < 0.97). A larger SC response to psychosocial stress was found in FSS compared to HC (d = 0.71). However, HR increased less during psychosocial stress and showed a smaller reduction during recovery in both patient groups compared to HC (0.68 < d < 0.98). HRV was lower in both patient groups compared to HC during recovery (0.91 < d < 0.98). There were no differences in ST levels or responses between groups.

CONCLUSIONS

Our results indicate a dominance of the sympathetic nervous system in both patient groups compared to controls, suggesting that autonomic nervous system dysfunction is a transdiagnostic feature for stress-related and functional somatic syndromes.

Implementation of Wearable Technology for Remote Heart Rate Variability Biofeedback in Cardiac Rehabilitation

Cardiovascular diseases pose a significant threat to global health, and cardiac rehabilitation (CR) has become a critical component of patient care. Heart Rate Variability Biofeedback (HRVB) is a non-invasive approach that helps modulate the Autonomic Nervous System (ANS) through Resonance Frequency (RF) breathing, supporting CR for cardiovascular patients. However, traditional HRVB techniques rely heavily on manual RF selection and face-to-face guidance, limiting their widespread application, particularly in home-based CR. To address these limitations, we propose a remote human-computer collaborative HRVB system, "FreeResp", which features autonomous RF adjustment through a simplified cognitive computational model, eliminating the reliance on therapists. Furthermore, the system integrates wearable technology and the Internet of Things (IoT) to support remote monitoring and personalized interventions. By incorporating tactile guidance technology with an airbag, the system assists patients in performing diaphragmatic breathing more effectively. FreeResp demonstrated high consistency with conventional HRVB methods in determining RF values (22/24) from 24 valid training samples. Moreover, a one-month home-based RF breathing training using FreeResp showed significant improvements in Heart Rate Variability (HRV) (p < 0.05). These findings suggest that FreeResp is a promising solution for home-based CR, offering timely and precise interventions and providing a new approach to long-term cardiovascular health management.

The Impact of Autonomic Nervous System Modulation on Heart Rate Variability and Musculoskeletal Manifestations in Chronic Neck Pain: A Double-Blind Randomized Clinical Trial

Background: The role of autonomic nervous system (ANS) modulation in chronic neck pain remains elusive. Transcutaneous vagus nerve stimulation (t-VNS) provides a novel, non-invasive means of potentially mitigating chronic neck pain. This study aimed to assess the effects of ANS modulation on heart rate variability (HRV), pain perception, and neck disability. Methods: In this double-blind randomized clinical trial, 102 participants with chronic neck pain were randomly allocated to one of three groups: t-VNS plus standard-care physiotherapy (SC-PT), heart rate variability biofeedback (HRV-BF) with SC-PT, or SC-PT alone. Interventions were administered three times weekly for 6 weeks. The following outcome measures were assessed at baseline and after 6 weeks: HRV, the visual analog scale (VAS), the pressure pain threshold (PPT), and the neck disability index (NDI). Results: The t-VNS group exhibited significant improvements compared to the HRV-BF and SC-PT groups. Specifically, t-VNS increased the RR interval (mean difference [MD] = 35.0 ms; p = 0.037) and decreased the average heart rate (MD = -5.4 bpm; p = 0.039). Additionally, t-VNS reduced the VAS scores (versus HRV-BF: MD = -0.8 cm, p = 0.044; SC-PT: MD = -0.9 cm, p = 0.018), increased the PPT (versus HRV-BF: MD = 94.4 kPa, p < 0.001; SC-PT (MD = 56.2 kPa, p = 0.001)), and lowered the NDI scores (versus HRV-BF: MD = -4.0, p = 0.015; SC-PT: MD = -5.9, p < 0.001). Conclusions: t-VNS demonstrated superior effectiveness compared to HRV-BF and SC-PT in regulating HRV, alleviating pain, and enhancing functional capabilities in individuals with chronic neck pain.

Interventions to improve pharmacists' competency in chronic disease management: a systematic review of randomized controlled trials

INTRODUCTION

Effective chronic disease management (CDM) is vital for addressing chronic disease challenges. Given the importance of ensuring pharmacists' competence in CDM, interventions targeting knowledge, skills, and attitudes are essential. Therefore, a comprehensive and up-to-date study is needed to analyze these interventions' effect and potential development. Categorizing the interventions based on the Effective Practice and Organization of Care (EPOC) taxonomy is essential for better informing policymakers. The objectives of this systematic review were to identify interventions to improve pharmacists' competency in chronic disease management based on the EPOC taxonomy and summarize their effectiveness.

METHODS

Following methods in the Cochrane Handbook, a systematic search was conducted up to April 2024 on MEDLINE and Scopus. The inclusion criteria were an intervention study with a randomized controlled trial (RCT) design published in English, targeting pharmacists, and measuring knowledge, skills, and attitudes in aspects of CDM. The risk of bias was assessed using Cochrane's RoB 2 tool for either randomized or cluster-randomized trials. Findings are reported narratively and align with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement.

RESULTS

We included 11 RCT studies that focused on various aspects of CDM among community and hospital pharmacists. Implementation strategies and combined implementation strategies-delivery arrangements interventions were identified. Six implementation strategies interventions consistently yielded effective results, with scores ranging from 0.99 to 9.17 (p < 0.05). However, the other two implementation strategies interventions reported mixed results, with no significant improvements in knowledge or skills. Two implementation strategies-delivery arrangements interventions showed improvements, with score differences ranging from 4.5% (95% CI: 1.6%-7.4%) to 30% (95% CI: 29%-40%). Conversely, one implementation strategies-delivery arrangements intervention showed no significant improvement. The risk of bias assessment revealed varying levels of bias across the studies.

CONCLUSIONS

Implementation strategies and combined implementation strategies-delivery arrangements interventions improved pharmacists' competency in CDM. Most interventions consistently resulted in significant improvements in pharmacists' knowledge, skills, and attitudes. These findings underscore the potential of tailored, competency-based interventions to improve pharmacist competencies in CDM. Policymakers can use these insights to create guidelines and policies that promote ongoing professional development for pharmacists.

Vagally Mediated Heart Rate Variability and Mood States in Patients with Chronic Pain Receiving Prolonged Expiration Regulated Breathing: A Randomized Controlled Trial

Reduced vagally mediated heart rate variability (VmHRV) has been reported in patients with chronic pain. In healthy persons, breathing with longer expiration relative to inspiration increases VmHRV at 12 breaths per minute. The present study aimed to determine the immediate effect of breathing with longer expiration relative to inspiration on VmHRV and mood states in patients with chronic pain. Fifty patients with chronic pain aged between 20 and 67 years were prospectively randomized as two groups with an allocation ratio of 1:1. The interventional group practiced breathing with metronome based visual cues, maintaining an inspiration to expiration ratio of 28:72 (i/e ratio, 0.38) at a breath rate of 12 breaths per minute. The average i/e ratio they attained based on strain gauge respiration recording was 0.685 (SD 0.48). The control group, which looked at the metronome without conscious breath modification had an average i/e ratio of 0.745 (SD 0.69). The VmHRV, respiration and self-reported mood states (using the Brief Mood Introspection Scale (BMIS)) were assessed. There was a significant increase in HF-HRV and RMSSD during low i/e breathing (repeated measures ANCOVA, Bonferroni adjusted post-hoc test, p < 0.05; in all cases). Self-reported mood states changed as follows: (i) following low i/e breathing positive-mood states increased while the aroused mood state decreased whereas (ii) following the control intervention the aroused mood state increased (repeated measure ANOVA, p < 0.05; in all cases). Hence breathing with prolonged expiration is possibly useful to increase VmHRV and improve self- reported mood states in patients with chronic pain.

Laryngeal Recalibration Therapy Improves Laryngopharyngeal Symptoms in Patients With Suspected Laryngopharyngeal Reflux Disease

INTRODUCTION

Laryngopharyngeal symptoms such as cough, throat clearing, voice change, paradoxic vocal fold movement, or laryngospasm are hyper-responsive behaviors resulting from local irritation (e.g., refluxate) and heightened sympathetic tone. Laryngeal recalibration therapy (LRT) guided by a speech-language pathologist (SLP) provides mechanical desensitization and cognitive recalibration to suppress hyper-responsive laryngeal patterns. The aim of this study was to assess symptom response to LRT among patients with chronic laryngopharyngeal symptoms undergoing evaluation of gastroesophageal reflux disease (GERD).

METHODS

Adults with chronic laryngopharyngeal symptoms referred for evaluation of GERD to a single center were prospectively followed. Inclusion criteria included ≥2 SLP-directed LRT sessions. Data from endoscopy, ambulatory reflux monitoring, and patient-reported outcomes were collected when available. The primary outcome was symptom response.

RESULTS

Sixty-five participants completed LRT: mean age 55.4 years (SD 17.2), 46 (71%) female, mean body mass index 25.6 kg/m 2 (6.8), and mean of 3.7 (1.9) LRT sessions. Overall, 55 participants (85%) met criteria for symptom response. Specifically, symptom response was similar between those with isolated laryngopharyngeal symptoms (13/15, 87%) and concomitant laryngopharyngeal/esophageal symptoms (42/50, 84%). Among participants who underwent reflux monitoring, symptom response was similar between those with proven, inconclusive for, and no GERD (18/21 [86%], 8/9 [89%], 10/13 [77%]).

DISCUSSION

Eighty-five percent of patients with chronic laryngopharyngeal symptoms referred for GERD evaluation who underwent LRT-experienced laryngeal symptom response. Rates of symptom response were maintained across patients with or without proven GERD and patients with or without concomitant esophageal reflux symptoms. SLP-directed LRT is an effective approach to incorporate into multidisciplinary management of chronic laryngopharyngeal symptoms/laryngopharyngeal reflux disease.

The Effect of a Biofeedback-Based Integrated Intervention for Older Adults with Orthostatic Hypotension: A Secondary Analysis on Psychological Health Outcomes in a Non-Randomized Pilot Trial

BACKGROUND/OBJECTIVES

Aging-related physical changes and dysfunctions in the autonomic nervous system (ANS) often lead to orthostatic hypotension (OH) in older adults. OH negatively impacts both the physical and psychological well-being of those affected. Previous studies have demonstrated that the biofeedback-based integrated program (BBIP), a multicomponent intervention focused on heart rate variability biofeedback, effectively improves OH, as well as symptoms related to ANS function. This substudy aims to examine the effects of the BBIP on psychological health outcomes among community-dwelling older adults with OH.

METHODS

This study employed a non-randomized controlled trial design with a convenience sampling strategy. A total of 51 older adults with OH were recruited from two senior welfare centers and randomly assigned to either the intervention group (n = 27) or the control group (n = 24). The intervention group participated in a 12-week BBIP, which included weekly biofeedback sessions and group education on lifestyle modification to alleviate OH. Telephone counseling was also provided to promote compliance.

RESULTS

The intervention group showed significant improvements in health-related quality of life, depression, anxiety, and fall efficacy after the 12-week BBIP, whereas the control group exhibited no significant changes. There was a significant reduction in the percentage of participants in the intervention group reporting problems in all five dimensions of the EQ-5D (mobility, self-care, usual activities, pain/discomfort, and anxiety/depression).

CONCLUSIONS

The BBIP was effective in improving the psychological health outcomes of older adults with OH. Future studies should explore the long-term effects of the BBIP using a larger sample size and a randomized controlled trial design.

Slow-Paced Breathing Intervention in Healthcare Workers Affected by Long COVID: Effects on Systemic and Dysfunctional Breathing Symptoms, Manual Dexterity and HRV

BACKGROUND

Many COVID-19 survivors still experience long-term effects of an acute infection, most often characterised by neurological, cognitive and psychiatric sequelae. The treatment of this condition is challenging, and many hypotheses have been proposed. Non-invasive vagus nerve stimulation using slow-paced breathing (SPB) could stimulate both central nervous system areas and parasympathetic autonomic pathways, leading to neuromodulation and a reduction in inflammation. The aim of the present study was to evaluate physical, cognitive, emotional symptoms, executive functions and autonomic cardiac modulation after one month of at-home slow breathing intervention.

METHODS

6655 healthcare workers (HCWs) were contacted via a company email in November 2022, of which N = 58 HCWs were enrolled as long COVID (cases) and N = 53 HCWs as controls. A baseline comparison of the two groups was performed. Subsequently each case was instructed on how to perform a resonant SPB using visual heart rate variability (HRV) biofeedback. They were then given a mobile video tutorial breathing protocol and asked to perform it three times a day (morning, early afternoon and before sleep). N = 33 cases completed the FU. At T0 and T1, each subject underwent COVID-related, psychosomatic and dysfunctional breathing questionnaires coupled with heart rate variability and manual dexterity assessments.

RESULTS

After one month of home intervention, an overall improvement in long-COVID symptoms was observed: confusion/cognitive impairment, chest pain, asthenia, headache and dizziness decreased significantly, while only a small increase in manual dexterity was found, and no relevant changes in cardiac parasympathetic modulation were observed.

The duration discrimination respiratory task: A new test to measure respiratory interoceptive accuracy

Interoception, which refers to the perception of body's internal state, is implicated in emotional processes and psychopathological disorders. Over the last decades, different tools have been developed to measure interoceptive accuracy, or the ability to accurately perceive physiological signals. Most of these tools have focused on cardiac interoception, but respiratory interoception has been less investigated due to the more complex and less portable equipment required. In this study, we suggest a new duration discrimination respiratory (DDR) task that does not require complex equipment. Using an adaptive staircase procedure, this task aims to determine an individual's ability to detect exhalation longer than their resting reference duration. One hundred and twenty-three healthy subjects completed the DDR task, an interoceptive task of heart rate discrimination, and filled out questionnaires on interoceptive awareness (Multidimensional Assessment of Interoceptive Awareness), alexithymia (Toronto Alexithymia Scale [TAS]), affects (Positive and Negative Affect Scale [PANAS]), and anamnestic. Results demonstrated a good internal consistency (Cronbach's alpha = .93) of the DDR task. On average, subjects needed 99.22% (SD = 36.38) of their reference exhalation time in addition to reference exhalation to detect a prolonged exhalation. Higher self-reported fitness levels, not counting during the DDR task and lower difficulty in describing feelings (TAS subscale), predicted higher respiratory discrimination duration. In conclusion, this study demonstrates the utility of the DDR task as a valid measure of interoception.

Heart rate variability biofeedback enhances cognitive, motor, psychological, and autonomic functions in post-stroke rehabilitation

Post-stroke patients often experience psychological distress and autonomic nervous system (ANS) dysregulation, impacting their well-being. This study evaluated the effectiveness of heart rate variability (HRV) biofeedback on cognitive, motor, psychological, and ANS functions in sixty-two ischemic stroke patients (43 males, mean age = 60.1) at a Medical Center in southern Taiwan. To prevent interaction, we allocated patients to the HRV biofeedback or control (usual care) group based on their assigned rehabilitation days, with 31 patients in each group. Assessments conducted at baseline, three, and six months included the Montreal Cognitive Assessment (MoCA), Fugl-Meyer Assessment for Upper Extremities (FMA-UE), Perceived Stress Scale, Hospital Anxiety and Depression Scales (HADS), and HRV indices. Mixed-effect models were used to analyze Group by Time interactions. The results revealed significant interactions across all functions. At 3 months, significant improvements in the HRV biofeedback group were observed only in MoCA, FMA-UE, and HADS-depression scores compared to the control group. By 6 months, all measured outcomes demonstrated significant improvements in the biofeedback group relative to the control group. These results suggest that HRV biofeedback may be an effective complementary intervention in post-stroke rehabilitation, warranting further validation.

Blood Pressure Variability is Better Associated with Acute Relative Hyperglycemia Than the Heart Rate Variability in Healthy Young Adults

BACKGROUND

Deranged cardiovascular autonomic functions are well-reported complications of diabetes mellitus, where chronic hyperglycemia is an important factor. The role of acute relative hyperglycemia on cardiovascular autonomic functions, particularly on blood pressure variability in healthy subjects, has been rarely explored. Therefore, this study aimed to examine the effect of acute relative hyperglycemia on cardiovascular autonomic functions in healthy young adults.

METHODS

Beat-to-beat blood pressure and electrocardiogram were recorded to assess the heart rate variability and blood pressure variability in 42 young, healthy subjects during fasting and relative hyperglycemic states. Recorded cardiovascular parameters were analyzed in time and frequency domains. Correlations among analyzed parameters of cardiovascular autonomic variabilities were explored during fasting and relative hyperglycemic state.

RESULTS

A few of the systolic, mean, and diastolic blood-pressure-variability parameters were significantly altered during acute relative hyperglycemia when compared to the fasting state. However, no significant changes were observed in any of the heart-rate-variability parameters. Also, novel significant correlations were found among many of the parameters of cardiovascular autonomic variabilities during fasting and relative hyperglycemic states.

CONCLUSIONS

The blood pressure variability is affected significantly during acute relative hyperglycemia in healthy young adults; however, the heart rate variability does not show such changes. Also, many blood pressure variability parameters show significant correlations with heart rate variability and baroreflex sensitivity. It may be hypothesized that although the variabilities in heart rate and blood pressure assess cardiovascular autonomic functions, blood pressure variability is a better indicator of cardiovascular autonomic effects of acute relative hyperglycemia.

Non-pharmacological interventions for the treatment of post-stroke fatigue: A systematic review

BACKGROUND

Post-stroke fatigue (PSF) affects 50% of stroke survivors. Current guidance on management of this condition is limited.

AIMS

This systematic review and meta-analysis aimed to identify and analyze all randomized clinical trials (RCTs) of non-pharmacological interventions for the treatment of PSF.

SUMMARY OF REVIEW

Six electronic databases were searched from inception to January 2023 for English-language RCTs investigating the efficacy of non-pharmacological interventions versus passive controls in patients with PSF. The primary outcome was fatigue severity at the end of the intervention. The Cochrane risk-of-bias (ROB)2 tool was used to assess evidence quality. A total of 7990 records were retrieved, 333 studies were scrutinized, and 13 completed RCTs (484 participants) were included. Interventions included psychological therapies, physical therapies, and brain stimulation. Nine studies provided sufficient data for meta-analysis, of which seven also had follow-up data. Fatigue severity was lower in the intervention groups at the end of the intervention compared with control (participants = 310, standardized mean difference (SMD) = -0.57, 95% confidence intervals (CIs) (-0.87 to -0.28)) and at follow-up (participants = 112, SMD = -0.36, 95% CIs (-0.83 to 0.10)). Certainty in the effect estimate was downgraded to low for a serious ROB and imprecision. Subgroup analysis revealed significant benefits with physical therapy and brain stimulation but not psychological therapies, though sample sizes were low.

CONCLUSION

Non-pharmacological interventions improved fatigue but the quality of evidence was low. Further RCTs are needed for PSF management.

Real-time heart rate variability biofeedback amplitude during a large-scale digital mental health intervention differed by age, gender, and mental and physical health

Heart rate variability biofeedback (HRVB) is an efficacious treatment for depression and anxiety. However, translation to digital mental health interventions (DMHI) requires computing and providing real-time HRVB metrics in a personalized and user-friendly fashion. To address these gaps, this study validates a real-time HRVB feedback algorithm and characterizes the association of the main algorithmic summary metric-HRVB amplitude-with demographic, psychological, and health factors. We analyzed HRVB data from 5158 participants in a therapist-supported DMHI incorporating slow-paced breathing to treat depression or anxiety symptoms. A real-time feedback metric of HRVB amplitude and a gold-standard research metric of low-frequency (LF) power were computed for each session and then averaged within-participants over 2 weeks. We provide HRVB amplitude values, stratified by age and gender, and we characterize the multivariate associations of HRVB amplitude with demographic, psychological, and health factors. Real-time HRVB amplitude correlated strongly (r = .93, p < .001) with the LF power around the respiratory frequency (~0.1 Hz). Age was associated with a significant decline in HRVB (β = -0.46, p < .001), which was steeper among men than women, adjusting for demographic, psychological, and health factors. Resting high- and low-frequency power, body mass index, hypertension, Asian race, depression symptoms, and trauma history were significantly associated with HRVB amplitude in multivariate analyses (p's < .01). Real-time HRVB amplitude correlates highly with a research gold-standard spectral metric, enabling automated biofeedback delivery as a potential treatment component of DMHIs. Moreover, we identify demographic, psychological, and health factors relevant to building an equitable, accurate, and personalized biofeedback user experience.

Effects of Postural Resonance on Skin Sympathetic Nerve Activity and Blood Pressure: A Pilot Study Evaluating Vascular Tone Baroreflex Stimulation Through Biofeedback

Heart rate and vascular tension baroreflex exhibit resonance characteristics at approximately 0.1 and 0.03 Hz. In this study, we aimed to induce postural resonance (PR) through rhythmic postural adjustments. To assess the viability of this technique, we investigated the acute impacts of postural resonance on blood pressure, sympathetic nerve activity, and mood. Fifteen healthy study participants, consisting of 8 males and 7 females, were selected for this self-controlled study. Skin sympathetic nerve activity was continuously monitored during both the intervention and stress test on the experimental day. After PR intervention, the diastolic blood pressure and mean arterial pressure in the PR group exhibited significant reductions compared to the CON group (P = 0.032, CON = 71.67 ± 2.348, PR = 64.08 ± 2.35; P = 0.041, CON = 75.00 ± 2.17, PR = 81.67 ± 2.17). After PR intervention both left brachial ankle pulse wave velocity and right brachial ankle pulse wave velocity exhibited a significant reduction compared to pre-intervention levels (from 1115.86 ± 150.08 to 1048.43 ± 127.40 cm/s, p < 0.001; 1103.86 ± 144.35 to 1060.43 ± 121.35 cm/s, p = 0.018). PR intervention also led to a significant decrease in burst frequency and duration (P = 0.049; CON = 8.96 ± 1.17, PR = 5.51 ± 1.17) and a noteworthy decrease in burst amplitude and burst threshold during the cold-pressor test (P = 0.002; P = 0.002). Additionally, VAS scores exhibited a substantial increase following PR (P = 0.035, CON = 28.4 ± 4.49, PR = 42.17 ± 4.10). PR can induce resonance effects within the cardiovascular system, resulting in the effective reduction of blood pressure, skin sympathetic nerve activity and pulse wave velocity, and decreased burst amplitude and burst threshold of the sympathetic nerve during the cold-pressor test.

Effects of Exercise Training on Heart Rate Variability in Healthy Adults: A Systematic Review and Meta-analysis of Randomized Controlled Trials

This meta-analysis was conducted to investigate the effects of exercise training on heart rate variability (HRV) parameters associated with the autonomic nervous system (ANS) activity. Randomized controlled trials (RCTs) involving healthy adults (aged ≥ 18 years) were included. We searched PubMed, Scopus, Web of Science, and EBSCO databases to identify relevant studies. A random-effects meta-analysis was performed using the standardized mean difference (SMD) and 95% confidence interval (CI). Sixteen RCTs with a total of 623 participants were selected for the final analysis. The analysis showed that exercise training improved the standard deviation of normal-to-normal intervals (SDNN) (SMD: 0.58 (0.16, 1.00); p = 0.007), the root mean square of successive differences in heart period series (RMSSD) (SMD: 0.84 (0.36, 1.31); p = 0.0005), and the absolute power of high-frequency band (HF) (SMD: 0.89 (0.27, 1.51); p = 0.005) parameters compared to the control group. Analysis of the moderator variables showed that the effect of exercise on HRV indices may be influenced by sex, age, and type of exercise used, specifically in HF band, absolute power of low-frequency band (LF), and LF/HF ratio parameters. Despite the limited number of existing RCTs related to the subject, the results suggest that exercise training enhances HRV parameters associated with vagal-related activity (RMSSD and HF) and both sympathetic and parasympathetic activities (SDNN). This study overcomes the lack of meta-analyses on the effects of exercise training on autonomic modulation among healthy adults and may bridge the gap in understanding the potential physiological underpinnings of the acknowledged positive health benefits of exercise.

Facilitating ambulatory heart rate variability analysis using accelerometry-based classifications of body position and self-reported sleep

Objective.This study aimed to examine differences in heart rate variability (HRV) across accelerometer-derived position, self-reported sleep, and different summary measures (sleep, 24 h HRV) in free-living settings using open-source methodology.Approach.HRV is a biomarker of autonomic activity. As it is strongly affected by factors such as physical behaviour, stress, and sleep, ambulatory HRV analysis is challenging. Beat-to-beat heart rate (HR) and accelerometry data were collected using single-lead electrocardiography and trunk- and thigh-worn accelerometers among 160 adults participating in the SCREENS trial. HR files were processed and analysed in the RHRV R package. Start time and duration spent in physical behaviours were extracted, and time and frequency analysis for each episode was performed. Differences in HRV estimates across activities were compared using linear mixed models adjusted for age and sex with subject ID as random effect. Next, repeated-measures Bland-Altman analysis was used to compare 24 h RMSSD estimates to HRV during self-reported sleep. Sensitivity analyses evaluated the accuracy of the methodology, and the approach of employing accelerometer-determined episodes to examine activity-independent HRV was described.Main results.HRV was estimated for 31 289 episodes in 160 individuals (53.1% female) at a mean age of 41.4 years. Significant differences in HR and most markers of HRV were found across positions [Mean differences RMSSD: Sitting (Reference) - Standing (-2.63 ms) or Lying (4.53 ms)]. Moreover, ambulatory HRV differed significantly across sleep status, and poor agreement between 24 h estimates compared to sleep HRV was detected. Sensitivity analyses confirmed that removing the first and last 30 s of accelerometry-determined HR episodes was an accurate strategy to account for orthostatic effects.Significance.Ambulatory HRV differed significantly across accelerometry-assigned positions and sleep. The proposed approach for free-living HRV analysis may be an effective strategy to remove confounding by physical activity when the aim is to monitor general autonomic stress.

Designing and developing a nature-based virtual reality with heart rate variability biofeedback for surgical anxiety and pain management: evidence from total knee arthroplasty patients

OBJECTIVES

Total knee arthroplasty (TKA) is one of the most common joint surgeries, with over a million procedures performed annually in the US. Over 70% of patients report moderate to high pain and anxiety surrounding TKA surgery, and 96% are discharged with an opioid prescription. This population requires special attention as approximately 90% of TKA patients are older adults and one of the riskiest groups prone to misusing opioids. This study aimed to develop and compare the efficacy of nature-based virtual reality (VR) with heart rate variability biofeedback (HRVBF) to mitigate surgical pain and anxiety.

METHODS

This randomized control trial recruited 30 patients (mean age = 66.3 ± 8.2 years, 23 F, 7 M) undergoing TKA surgery and randomly assigned to a control, 2D video with HRVBF, or VR with HRVBF group. A visual analog scale (VAS) was used to measure pain levels before and after the intervention. In addition, a second VAS and the State-Trait Anxiety Inventory (STAI) were used to measure anxiety before and after the intervention. Electrocardiogram (ECG) was used to continuously measure HRV and respiration rate in preoperative and postoperative settings.

RESULTS

VR and 2D-video with HRVBF decreased pain and anxiety post-intervention compared with the control group, p's <.01. On analyzing physiological signals, both treatment groups showed greater parasympathetic activity levels, and VR with HRVBF reduced pain more than the 2D video, p < .01.

CONCLUSIONS

Nature-based VR and 2D video with HRVBF can mitigate surgical pain and anxiety. However, VR may be more efficacious than 2D video in reducing pain.

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.

Comorbid anxiety is associated with more changes in the Management of Postural Orthostatic Tachycardia Syndrome

OBJECTIVE

Postural Orthostatic Tachycardia Syndrome (POTS) is not an anxiety disorder, but it shares similar symptomatology. The impact of this comorbidity on management is unknown. This information may lead to better strategies to improve the care of this subgroup.

METHOD

The electronic medical records of 322 patients seen at our institution between 2018 and 2022 with confirmed POTS diagnoses were analyzed. Demographics, anxiety comorbidities, questionnaire responses, and treatment course changes were collected. Negative binomial regression models examined if the presence of an anxiety disorder was associated with the number of POTS treatment course changes offset by observation time.

RESULTS

When adjusted for sex, age, baseline GAD-7 score, and baseline PROMIS global mental health score, those with a diagnosis of an anxiety disorder had2.6 times the incident rate of treatment changes for POTS management (IRR = 2.66 (95% CI: 1.43-4.95)).

CONCLUSION

Individuals carrying the diagnosis of an anxiety disorder had an increase in the incident rate of treatment changes for POTS therapy. This finding may be due to the underlying pathophysiology and treatment of anxiety disorders, the effect of bias, and difficulty with symptom differentiation. More work needs to be done to determine how to best care for POTS patients with comorbid anxiety.

Sleep disorders and cancer incidence: examining duration and severity of diagnosis among veterans

Introduction

Sleep disruption affects biological processes that facilitate carcinogenesis. This retrospective cohort study used de-identified data from the Veterans Administration (VA) electronic medical record system to test the hypothesis that patients with diagnosed sleep disorders had an increased risk of prostate, breast, colorectal, or other cancers (1999-2010, N=663,869). This study builds upon existing evidence by examining whether patients with more severe or longer-duration diagnoses were at a greater risk of these cancers relative to those with a less severe or shorter duration sleep disorder.

Methods

Incident cancer cases were identified in the VA Tumor Registry and sleep disorders were defined by International Classification of Sleep Disorder codes. Analyses were performed using extended Cox regression with sleep disorder diagnosis as a time-varying covariate.

Results

Sleep disorders were present among 56,055 eligible patients (8% of the study population); sleep apnea (46%) and insomnia (40%) were the most common diagnoses. There were 18,181 cancer diagnoses (41% prostate, 12% colorectal, 1% female breast, 46% other). The hazard ratio (HR) for a cancer diagnosis was 1.45 (95% confidence interval [CI]: 1.37, 1.54) among those with any sleep disorder, after adjustment for age, sex, state of residence, and marital status. Risks increased with increasing sleep disorder duration (short [<1-2 years] HR: 1.04 [CI: 1.03-1.06], medium [>2-5 years] 1.23 [1.16-1.32]; long [>5-12 years] 1.52 [1.34-1.73]). Risks also increased with increasing sleep disorder severity using cumulative sleep disorder treatments as a surrogate exposure; African Americans with more severe disorders had greater risks relative to those with fewer treatments and other race groups. Results among patients with only sleep apnea, insomnia, or another sleep disorder were similar to those for all sleep disorders combined.

Discussion

The findings are consistent with other studies indicating that sleep disruption is a cancer risk factor. Optimal sleep and appropriate sleep disorder management are modifiable risk factors that may facilitate cancer prevention.

CVRanalysis: a free software for analyzing cardiac, vascular and respiratory interactions

Introduction: Simultaneous beat-to-beat R-R intervals, blood pressure and respiration signals are routinely analyzed for the evaluation of autonomic cardiovascular and cardiorespiratory regulations for research or clinical purposes. The more recognized analyses are i) heart rate variability and cardiac coherence, which provides an evaluation of autonomic nervous system activity and more particularly parasympathetic and sympathetic autonomic arms; ii) blood pressure variability which is mainly linked to sympathetic modulation and myogenic vascular function; iii) baroreflex sensitivity; iv) time-frequency analyses to identify fast modifications of autonomic activity; and more recently, v) time and frequency domain Granger causality analyses were introduced for assessing bidirectional causal links between each considered signal, thus allowing the scrutiny of many physiological regulatory mechanisms. Methods: These analyses are commonly applied in various populations and conditions, including mortality and morbidity predictions, cardiac and respiratory rehabilitation, training and overtraining, diabetes, autonomic status of newborns, anesthesia, or neurophysiological studies. Results: We developed CVRanalysis, a free software to analyze cardiac, vascular and respiratory interactions, with a friendly graphical interface designed to meet laboratory requirements. The main strength of CVRanalysis resides in its wide scope of applications: recordings can arise from beat-to-beat preprocessed data (R-R, systolic, diastolic and mean blood pressure, respiration) or raw data (ECG, continuous blood pressure and respiratory waveforms). It has several tools for beat detection and correction, as well as setting of specific areas or events. In addition to the wide possibility of analyses cited above, the interface is also designed for easy study of large cohorts, including batch mode signal processing to avoid running repetitive operations. Results are displayed as figures or saved in text files that are easily employable in statistical softwares. Conclusion: CVRanalysis is freely available at this website: anslabtools.univ-st-etienne.fr. It has been developed using MATLAB® and works on Windows 64-bit operating systems. The software is a standalone application avoiding to have programming skills and to install MATLAB. The aims of this paper area are to describe the physiological, research and clinical contexts of CVRanalysis, to introduce the methodological approach of the different techniques used, and to show an overview of the software with the aid of screenshots.

The Stress Phenotyping Framework: A multidisciplinary biobehavioral approach for assessing and therapeutically targeting maladaptive stress physiology

Although dysregulated stress biology is becoming increasingly recognized as a key driver of lifelong disparities in chronic disease, we presently have no validated biomarkers of toxic stress physiology; no biological, behavioral, or cognitive treatments specifically focused on normalizing toxic stress processes; and no agreed-upon guidelines for treating stress in the clinic or evaluating the efficacy of interventions that seek to reduce toxic stress and improve human functioning. We address these critical issues by (a) systematically describing key systems and mechanisms that are dysregulated by stress; (b) summarizing indicators, biomarkers, and instruments for assessing stress response systems; and (c) highlighting therapeutic approaches that can be used to normalize stress-related biopsychosocial functioning. We also present a novel multidisciplinary Stress Phenotyping Framework that can bring stress researchers and clinicians one step closer to realizing the goal of using precision medicine-based approaches to prevent and treat stress-associated health problems.

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.

The 24-Hour Cardiac Autonomic Activity in Patients With Allergic Rhinitis

BACKGROUND

Definitive knowledge of the 24-hour cardiac autonomic activity in patients with allergic rhinitis (AR) is lacking. Thus, we aimed to evaluate heart rate variability (HRV), which is used to measure cardiac autonomic activity by 24-hour Holter monitoring in patients with AR.

METHODS

We enrolled 32 patients who visited our clinic and were diagnosed with AR. The control group was selected four-fold (n = 128) by matching (age, sex, hypertension, and diabetes) in the AR group from a Holter registry in the cardiology department. The HRV results, which were measured using 24-hour Holter monitoring, were compared between the AR and control groups.

RESULTS

All time-domain parameters of HRV revealed no differences between the groups. However, among the frequency domain parameters of HRV, the low-frequency to high-frequency ratio and low-frequency power in normalized units were significantly lower in the AR group. Conversely, high-frequency power in normalized units was significantly higher in the AR group. In the multiple regression analysis, AR was independently associated with sympathetic withdrawal (adjusted odds ratio = 3.393, P = 0.020) after adjusting for age, sex, hypertension, diabetes mellitus, and hyperlipidemia.

CONCLUSIONS

The present findings suggest differences in cardiac autonomic activity which are related with sympathetic withdrawal in patients with AR compared with that in the normal population over 24 hours.

Dietary neoagarotetraose extends lifespan and impedes brain aging in mice via regulation of microbiota-gut-brain axis

INTRODUCTION

Dietary oligosaccharides can impact the gut microbiota and confer tremendous health benefits.

OBJECTIVES

The aim of this study was to determine the impact of a novel functional oligosaccharide, neoagarotetraose (NAT), on aging in mice.

METHODS

8-month-old C57BL/6J mice as the natural aging mice model were orally administered with NAT for 12 months. The preventive effect of NAT in Alzheimer's disease (AD) mice was further evaluated. Aging related indicators, neuropathology, gut microbiota and short-chain fatty acids (SCFAs) in cecal contents were analyzed.

RESULTS

NAT treatment extended the lifespan of these mice by up to 33.3 %. Furthermore, these mice showed the improved aging characteristics and decreased injuries in cerebral neurons. Dietary NAT significantly delayed DNA damage in the brain, and inhibited reduction of tight junction protein in the colon. A significant increase at gut bacterial genus level (such as Lactobacillus, Butyricimonas, and Akkermansia) accompanied by increasing concentrations of SCFAs in cecal contents was observed after NAT treatment. Functional profiling of gut microbiota composition indicated that NAT treatment regulated the glucolipid and bile acid-related metabolic pathways. Interestingly, NAT treatment ameliorated cognitive impairment, attenuated amyloid-β (Aβ) and Tau pathology, and regulated the gut microbiota composition and SCFAs receptor-related pathway of Alzheimer's disease (AD) mice.

CONCLUSION

NAT mitigated age-associated cerebral injury in mice through gut-brain axis. The findings provide novel evidence for the effect of NAT on anti-aging, and highlight the potential application of NAT as an effective intervention against age-related diseases.

Feasibility of a wrist-worn wearable device for estimating mental health status in patients with mental illness

Object

Real-world data from wearable devices has the potential to understand mental health status in everyday life. We aimed to investigate the feasibility of estimating mental health status using a wrist-worn wearable device (Fitbit Sense) that measures movement using a 3D accelerometer and optical pulse photoplethysmography (PPG).

Methods

Participants were 110 patients with mental illnesses from different diagnostic groups. The study was undertaken between 1 October 2020 and 31 March 2021. Participants wore a Fitbit Sense on their wrist and also completed the State-Trait Anxiety Inventory (STAI), Positive and Negative Affect Schedule (PANAS), and EuroQol 5 dimensions 5-level (EQ-5D-5L) during the study period. To determine heart rate (HR) variability (HRV), we calculated the sdnn (standard deviation of the normal-to-normal interval), coefficient of variation of R-R intervals, and mean HR separately for each sleep stage and the daytime. The association between mental health status and HR and HRV was analyzed.

Results

The following significant correlations were found in the wake after sleep onset stage within 3 days of mental health status assessment: sdnn, HR and STAI scores, HR and PANAS scores, HR and EQ-5D-5L scores. The association between mental health status and HR and HRV was stronger the closer the temporal distance between mental health status assessment and HR measurement.

Conclusion

A wrist-worn wearable device that measures PPG signals was feasible for use with patients with mental illness. Resting state HR and HRV could be used as an objective assessment of mental health status within a few days of measurement.

Induced Relaxation Enhances the Cardiorespiratory Dynamics in COVID-19 Survivors

Most COVID-19 survivors report experiencing at least one persistent symptom after recovery, including sympathovagal imbalance. Relaxation techniques based on slow-paced breathing have proven to be beneficial for cardiovascular and respiratory dynamics in healthy subjects and patients with various diseases. Therefore, the present study aimed to explore the cardiorespiratory dynamics by linear and nonlinear analysis of photoplethysmographic and respiratory time series on COVID-19 survivors under a psychophysiological assessment that includes slow-paced breathing. We analyzed photoplethysmographic and respiratory signals of 49 COVID-19 survivors to assess breathing rate variability (BRV), pulse rate variability (PRV), and pulse-respiration quotient (PRQ) during a psychophysiological assessment. Additionally, a comorbidity-based analysis was conducted to evaluate group changes. Our results indicate that all BRV indices significantly differed when performing slow-paced breathing. Nonlinear parameters of PRV were more appropriate for identifying changes in breathing patterns than linear indices. Furthermore, the mean and standard deviation of PRQ exhibited a significant increase while sample and fuzzy entropies decreased during diaphragmatic breathing. Thus, our findings suggest that slow-paced breathing may improve the cardiorespiratory dynamics of COVID-19 survivors in the short term by enhancing cardiorespiratory coupling via increased vagal activity.

Menstrual cycle symptomatology during the COVID-19 pandemic: The role of interoceptive sensibility and psychological health

The literature on the COVID-19 pandemic has shown the importance of investigating its impact on mental health during this sensitive period, also in relation to the female menstrual cycle. To this end, interceptive sensibility has emerged as a fundamental construct for studying the mind-body interaction among psychosomatic and pain symptoms, particularly through the distinction between two attentional styles (namely, a "mindful" and a "non-mindful" sensibility). The aim of the following study is to verify the role of mental health and interoceptive sensibility on menstrual symptoms in women of childbearing age, during the pandemic, as well as to identify the specific contribution of the existing dimensions of interoceptive sensibility in the prediction of symptoms' severity. Data were collected through an online survey, for which 5294 women responded on demographic information, menstrual history, symptoms' disturbance, and completed the Italian versions of the GHQ-12 and the MAIA. The analyses showed that symptoms were strongly correlated to either the GHQ-12 and the MAIA subscales Noticing, Emotional Awareness, Trusting and Not-Worrying. This result was further verified via a hierarchical regression, which revealed that the same interoceptive dimensions and mental health strongly predicted the intensity of menstrual symptoms (R² = 0.177, ΔR² = 0.143) compared to other considered dimensions (R² = 0.180, ΔR² = 0.002). Results are partially in line with the premises but suggest that mental health has a strong impact on the experience of the menstrual cycle and that only a few interoceptive dimensions may be relevant in explaining the severity of menstrual symptoms. It is here suggested that noticing internal bodily signals and being aware of emotional states might become dysfunctional if not reconciled with a good ability to self-regulate internal states, but may rather contribute to the perpetuation of the 'vicious cycle' of heightened affective and attentional reactions to interoceptive sensations.

Humming (Simple Bhramari Pranayama) as a Stress Buster: A Holter-Based Study to Analyze Heart Rate Variability (HRV) Parameters During Bhramari, Physical Activity, Emotional Stress, and Sleep

Objective In this study, our goal was to understand the comparative impact of humming, physical activity, emotional stress, and sleep on several heart rate variability (HRV) parameters, including the stress index (SI), and to assess the effectiveness of humming (simple Bhramari) as a stress buster based on the HRV parameters. Methods This pilot study assessed the long-term HRV parameters of 23 participants in terms of four activities: humming (simple Bhramari), physical activity, emotional stress, and sleep. The single-channel Holter device measured the readings, and data was analyzed using Kubios HRV Premium software for time and frequency-domain HRV parameters, including the stress index. Regarding statistical analysis, single-factor ANOVA followed by paired t-test was used to compare the results of HRV parameters "during" the four activities to understand if humming generates the outcome to enhance the autonomic nervous system. Results Our findings revealed that humming generates the lowest stress index compared to all three other activities (physical activity, emotional stress, and sleep). Several additional HRV parameters also supported the positive impact on the autonomic nervous, equivalent to stress reduction. Conclusions Humming (simple Bhramari) can be an effective stress-buster based on the assessment of several HRV parameters during its practice and in comparison with other activities. A regular daily humming routine can help enhance the parasympathetic nervous system and slow down sympathetic activation.

Biofeedback as an Adjunct or Alternative Intervention to Cognitive Behavioral Therapy for Insomnia

Insomnia is highly prevalent and comorbid with many disorders. However, insomnia is underdiagnosed and undertreated in many populations. Cognitive behavioral therapy for insomnia (CBT-I) is not appropriate or sufficient for some individuals. Biofeedback has demonstrated efficacy in a range of disorders, including insomnia. The authors discuss the history and rationale for the use of biofeedback in the treatment of insomnia and other comorbid disorders. The article also presents current research on biofeedback for insomnia and comorbid disorders with recommendations for using biofeedback as an adjunct or alternative intervention to CBT-I.

Measuring objective fatigability and autonomic dysfunction in clinical populations: How and why?

Fatigue is a major symptom in many diseases, often among the most common and severe ones and may last for an extremely long period. Chronic fatigue impacts quality of life, reduces the capacity to perform activities of daily living, and has socioeconomical consequences such as impairing return to work. Despite the high prevalence and deleterious consequences of fatigue, little is known about its etiology. Numerous causes have been proposed to explain chronic fatigue. They encompass psychosocial and behavioral aspects (e.g., sleep disorders) and biological (e.g., inflammation), hematological (e.g., anemia) as well as physiological origins. Among the potential causes of chronic fatigue is the role of altered acute fatigue resistance, i.e. an increased fatigability for a given exercise, that is related to physical deconditioning. For instance, we and others have recently evidenced that relationships between chronic fatigue and increased objective fatigability, defined as an abnormal deterioration of functional capacity (maximal force or power), provided objective fatigability is appropriately measured. Indeed, in most studies in the field of chronic diseases, objective fatigability is measured during single-joint, isometric exercises. While those studies are valuable from a fundamental science point of view, they do not allow to test the patients in ecological situations when the purpose is to search for a link with chronic fatigue. As a complementary measure to the evaluation of neuromuscular function (i.e., fatigability), studying the dysfunction of the autonomic nervous system (ANS) is also of great interest in the context of fatigue. The challenge of evaluating objective fatigability and ANS dysfunction appropriately (i.e.,. how?) will be discussed in the first part of the present article. New tools recently developed to measure objective fatigability and muscle function will be presented. In the second part of the paper, we will discuss the interest of measuring objective fatigability and ANS (i.e. why?). Despite the beneficial effects of physical activity in attenuating chronic fatigue have been demonstrated, a better evaluation of fatigue etiology will allow to personalize the training intervention. We believe this is key in order to account for the complex, multifactorial nature of chronic fatigue.

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.

The efficacy of heart rate variability biofeedback in patients with acute ischemic stroke: A protocol for systematic review and meta-analysis

BACKGROUND

Stroke is the most common serious neurological disorder, and in high-income countries, it is the fourth-leading cause of death, long-term disability, and reduced quality of life among adults. Heart rate variability (HRV) can improve autonomic dysfunction, cognitive impairment, and psychological distress in other patient populations, but its effect in patients with acute ischemic stroke is still unclear. We conducted a protocol for systematic review and meta-analysis to evaluate the efficacy of HRV biofeedback in patients with acute ischemic stroke.

METHODS

A computerized literature search will be performed in the following electronic databases from their inceptions to October 2022: PubMed, EMBASE, MEDLINE, Cochrane Central Register of Controlled Clinical Trials, China Knowledge Resource Integrated Database, Wanfang Data Information, and Weipu Database for Chinese Technical Periodicals. The risk of bias in the included articles is assessed according to the Risk of Bias Assessment Tool in Cochrane Handbook of Systematic Reviews. Data are analyzed with the Review Manager Version 5.3 software.

RESULTS

This paper will provide high-quality synthesis to assess the efficacy of HRV biofeedback in patients with acute ischemic stroke.

CONCLUSION

HRV biofeedback may be a promising intervention for improving autonomic function, cognitive impairment, and psychological distress in patients with acute ischemic stroke.

Effects of trunk posture on cardiovascular and autonomic nervous systems: A pilot study

Objective: Although regular and moderate physical activity has been shown to improve the cardiovascular and autonomic nervous systems, little has been done to study the effects of postural changes in the movement on the heart and autonomic nervous system. To uncover changes in cardiac function and autonomic nerves induced by different underlying posture transitions and explore which trunk postures lead to chronic sympathetic activation. Therefore, this study investigated the effects of trunk posture on the cardiovascular and autonomic nervous systems. Methods: Twelve male subjects (age 24.7 ± 1.3) underwent this study. The non-invasive cardiac output NICOM monitoring equipment and the FIRSTBEAT system are used to dynamically monitor seven trunk postures in the sitting position simultaneously (neutral position, posterior extension, forward flexion, left lateral flexion, right lateral flexion, left rotation, right rotation). Each posture was maintained for 3 min, and the interval between each movement was 3 min to ensure that each index returned to the baseline level. Repeated analysis of variance test was used to compare and analyze the differences in human cardiac function, heart rate variability index, and respiratory rate under different postures. Results: Compared with the related indicators of cardiac output in a neutral trunk position: the cardiac index (CI) was significantly reduced in forwarding flexion and left rotation (3.48 ± 0.34 vs. 3.21 ± 0.50; 3.48 ± 0.34 vs. 3.21 ± 0.46, Δ L/(min/m2)) (p = 0.016, p = 0.013), cardiac output decreased significantly (6.49 ± 0.78 vs. 5.93 ± 0.90; 6.49 ± 0.78 vs. 6.00 ± 0.96, Δ L/min) (p = 0.006, p = 0.014), the stroke volume (stroke volume)decreased significantly (87.90 ± 15.10 vs. 81.04 ± 16.35; 87.90 ± 15.10 vs. 79.24 ± 16.83, Δ ml/beat) (p = 0.017, p = 0.0003); heart rate increased significantly in posterior extension (75.08 ± 10.43 vs. 78.42 ± 10.18, Δ beat/min) (p = 0.001); left rotation stroke volume index (SVI) decreased significantly (47.28 ± 7.97 vs. 46.14 ± 8.06, Δ ml/m2) (p = 0.0003); in the analysis of HRV-related indicators, compared with the neutral trunk position, the LF/HF of the posterior extension was significantly increased (1.90 ± 1.38 vs. 3.00 ± 1.17, p = 0.037), and the LF/HF of the forward flexion was significantly increased (1.90 ± 1.38 vs. 2.85 ± 1.41, p = 0.041), and the frequency-domain index LF/HF of right rotation was significantly increased (1.90 ± 1.38 vs. 4.06 ± 2.19, p = 0.008). There was no significant difference in respiratory rate (p > 0.05). Conclusion: A neutral trunk is the best resting position, and deviations from a neutral trunk position can affect the cardiovascular and autonomic nervous systems, resulting in decreased stroke volume, increased heart rate, and relative activation of sympathetic tone.

Heart Rate Variability Biofeedback in Cancer Patients: A Scoping Review

Heart Rate Variability (HRV) Biofeedback (BFB) has been shown to improve autonomic balance and wellbeing in chronic diseases. As cardiac variability represents an index of cognitive and emotional regulation, HRV-BFB has been shown to lead to improvements in physiological and psychological adaptability and quality of life. However, knowledge of HRV-BFB in cancer patients is lacking, and available results are diversified according to methods and outcomes. The present paper undertakes a scoping review, exploring the use of HRV-BFB to modulate autonomic balance, cancer symptom management, and quality of life in cancer. This scoping review analyzes empirical evidence considering study designs, BFB methods, and psychophysiological outcomes. Research that focused on HRV-BFB effects in cancer patients was selected (79%). In addition, a systematic review and meta-analysis (31%) focusing on HRV, or BFB in chronic conditions, including cancer, were considered. The studies examined BFB treatment for thyroid, lung, brain or colon cancer, hematologic cancer, and survivors or terminal cancer patients. Retrieved studies reported physiological and psychological indices as primary outcomes: they included HRV values, sleep, pain, fatigue, depression, anxiety, and quality of life. Although the heterogeneity of publications makes it difficult to generalize the effectiveness of HRV-BFB, the training has been proven to improve cancer symptoms and well-being.

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.

The Usefulness of Assessing Heart Rate Variability in Patients with Acute Myocardial Infarction (HeaRt-V-AMI)

BACKGROUND

Heart rate variability (HRV) could have independent and critical prognostic values in patients admitted for ST segment elevation myocardial infarction (STEMI). There are limited data in the literature regarding HRV assessment in STEMI setting. Thus, we aim to investigate the potential correlations between HRV and adverse outcomes in a contemporary cohort of patients presenting with STEMI undergoing primary percutaneous coronary intervention (PCI).

METHODS

We will perform a prospective, observational cohort study in a single healthcare center. Adult patients aged ≥18 years presenting with STEMI in sinus rhythm will be enrolled for primary PCI within 12 h from symptoms onset. Time domain, frequency domain, and nonlinear HRV parameters will be measured using a medically approved wrist-wearable device for 5 min segments during myocardial revascularization by primary PCI. Additional HRV measurements will be performed one and six months from the index event. The primary composite outcome will include all-cause mortality and major adverse cardiovascular events (during the hospital stay, one month, and one year following admission). Several secondary outcomes will be analyzed: individual components of the primary composite outcome, target lesion revascularization, hospitalizations for heart failure, ventricular arrhythmias, left ventricular ejection fraction, and left ventricular diastolic function.

CONCLUSIONS

Our study will enlighten the reliability and usefulness of HRV evaluation as a prognostic marker in contemporary patients with STEMI. The potential validation of HRV as a risk marker for adverse outcomes following STEMI will ensure a background for including HRV parameters in future risk scores and guidelines.

Adhésion et implémentation d’un programme de cohérence cardiaque visant à réduire l’anxiété de patients opérés pour une carcinose péritonéale : étude pilote randomisée

Objectif : Évaluer l’implémentation d’une pratique quotidienne de cohérence cardiaque chez des patients opérés pour une carcinose péritonéale.

Matériel et méthode : Étude pilote monocentrique, ouverte, contrôlée, randomisée non comparative, incluant 20 patients en soins courants vs 40 patients formés à la cohérence cardiaque avec biofeedback et guide respiratoire pour une pratique au domicile enregistrée.

Résultats attendus : Adhésion satisfaisante au programme, pouvant caractériser les éléments favorisant son implémentation avant et après chirurgie et évaluation de son impact sur l’anxiété.

Perspectives : Efficacité à déterminer pour transférer ce soin de support.

The Movesense Medical Sensor Chest Belt Device as Single Channel ECG for RR Interval Detection and HRV Analysis during Resting State and Incremental Exercise: A Cross-Sectional Validation Study

The value of heart rate variability (HRV) in the fields of health, disease, and exercise science has been established through numerous investigations. The typical mobile-based HRV device simply records interbeat intervals, without differentiation between noise or arrythmia as can be done with an electrocardiogram (ECG). The intent of this report is to validate a new single channel ECG device, the Movesense Medical sensor, against a conventional 12 channel ECG. A heterogeneous group of 21 participants performed an incremental cycling ramp to failure with measurements of HRV, before (PRE), during (EX), and after (POST). Results showed excellent correlations between devices for linear indexes with Pearson's r between 0.98 to 1.0 for meanRR, SDNN, RMSSD, and 0.95 to 0.97 for the non-linear index DFA a1 during PRE, EX, and POST. There was no significant difference in device specific meanRR during PRE and POST. Bland-Altman analysis showed high agreement between devices (PRE and POST: meanRR bias of 0.0 and 0.4 ms, LOA of 1.9 to -1.8 ms and 2.3 to -1.5; EX: meanRR bias of 11.2 to 6.0 ms; LOA of 29.8 to -7.4 ms during low intensity exercise and 8.5 to 3.5 ms during high intensity exercise). The Movesense Medical device can be used in lieu of a reference ECG for the calculation of HRV with the potential to differentiate noise from atrial fibrillation and represents a significant advance in both a HR and HRV recording device in a chest belt form factor for lab-based or remote field-application.