Task Force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. Circulation. 1996;93:1043-1065. [PMID: 8598068 DOI: 10.1161/01.cir.93.5.1043]

C. P. Long-term cognitive and autonomic effects of COVID-19 in young adults: a cross-sectional study at 28 months

OBJECTIVES

The COVID-19 pandemic, caused by SARS-CoV-2, has had profound global impacts since its emergence in late 2019. Whilst acute symptoms are well-documented, increasing evidence suggests long-term consequences extending beyond the acute phase. This study aimed to investigate the long-term cognitive and autonomic effects of COVID-19 in young adults.

MATERIALS AND METHODS

We conducted a cross-sectional study comparing young adults with a history of COVID-19 (n = 34) to matched controls (n = 34). Cognitive function was assessed using the Sternberg Task, Stroop Task, and Go/No-Go Task (GNG). Autonomic function was evaluated using heart rate variability (HRV) parameters.

RESULTS

The average time interval between COVID-19 infection and testing was 28.2 months. The COVID-19 group showed significantly increased reaction time in the 2-item absent condition (p = 0.044) and errors in the 4-item present condition (p = 0.012) of the Sternberg Task and increased neutral response time (p = 0.028) and the normalized time for completing the task (p = 0.022) in the Stroop Task. No significant differences were found in the GNG Task. HRV parameters did not differ significantly between groups, although trends toward higher overall HRV were observed in the COVID-19 group.

CONCLUSION

Young adults who had COVID-19 infection approximately 28 months ago show minimal long-term impact on cognitive function and autonomic regulation. However, subtle cognitive inefficiencies persist, particularly in working memory and executive function tasks. These findings suggest a generally favorable long-term prognosis for young adults following mild to moderate COVID-19 but highlight the need for further investigation into persistent subtle cognitive effects and autonomic effects.

Heart rate variability in patients with atrial fibrillation of sinus rhythm or atrial fibrillation: chaos or merit?

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia characterized by consistently irregular atrial and ventricular contractions. Heart rate variability (HRV) refers to the changes in the intervals between consecutive ventricular heartbeats. In sinus rhythm, HRV may be subtle and is quantitatively reflecting the dynamic interplay of the cardiac autonomic nervous system, which plays a crucial role in the onset, development, and maintenance of AF. HRV metrics, consisting of time-domain, frequency-domain, and nonlinear parameters, have been verified to vary significantly before and after AF episodes, and AF treatment-related procedures such as electrical cardioversion, ablation, and surgery of AF. Therefore, HRV may serve as a digital biomarker in predicting AF risk in long-term and acute risk period, identification of patients with AF risk in sinus rhythm and recurrence risk stratification after procedures. HRV in AF rhythm, predominantly influenced by dynamic atrioventricular node conduction under the onslaught of irregular atrial impulses, shows a huge disparity compared to that in sinus rhythm. Despite this, HRV in AF rhythm still provides valuable prognostic information, as reduced HRV may indicate a poor heart function and outcomes in patients with AF. Despite being influenced by lots of variables, HRV can still serve as an independent digital biomarker in the clinical management of AF throughout its entire lifecycle.

Malignant tumors in vagal-innervated organs: Exploring its homeostatic role

Cancer remains a significant global health challenge, with its progression shaped by complex and multifactorial mechanisms. Recent research suggests that the vagus nerve could play a critical role in mediating communication between the tumor microenvironment and the central nervous system (CNS). This review highlights the diversity of vagal afferent receptors, which could position the vagus nerve as a unique pathway for transmitting immune, metabolic, mechanical, and chemical signals from tumors to the CNS. Such signaling could influence systemic disease progression and tumor-related responses. Additionally, the vagus nerve's interactions with the microbiome and the renin-angiotensin system (RAS)-both implicated in cancer biology-further underscore its potential central role in modulating tumor-related processes. Contradictions in the literature, particularly concerning vagal fibers, illustrate the complexity of its involvement in tumor progression, with both tumor-promoting and tumor-suppressive effects reported depending on cancer type and context. These contradictions often overlook certain experimental biases, such as the failure to distinguish between vagal afferent and efferent fibers during vagotomies or the localized parasympathetic effects that cannot always be extrapolated to the systemic level. By focusing on the homeostatic role of the vagus nerve, understanding these mechanisms could open the door to new perspectives in cancer research related to the vagus nerve and lead to potential therapeutic innovations.

Investigating phase coupling of respiratory sinus arrhythmia and slow wave sleep in obstructive sleep apnea patients with and without depression

Phase coherence (λ) between respiratory sinus arrhythmia (RSA) and respiration has emerged as a promising metric for assessing the role of autonomic nervous system (ANS) activity and slow wave sleep (SWS) activities in healthy subjects. This study aims to investigate how λ and SWS activity differ between Obstructive Sleep Apnea (OSA) patients with and without major depressive disorder (MDD) during overnight sleep and explore whether the correlation between λ and SWS activity exists among those OSA patients compared to healthy individuals. Overnight electroencephalogram (EEG), electrocardiograms (ECG), and breathing using plethysmography were recorded from 104 subjects, including 35 healthy individuals (control), 34 OSA subjects with MDD (OSAD+) and 35 OSA subjects without MDD (OSAD+). Slow wave activity was computed by the amplitude envelope of the EEG δ-wave (0.5-4 Hz). The interbeat intervals (RRI) and respiratory movement were derived from ECG. RRI and respiration were resampled at a frequency of 10 Hz, and the band passed filtered within the range of 0.1-0.4 Hz before the Hilbert transform was used to extract instantaneous phases of the RSA and respiration. From the analytical signal of the Hilbert transform, the phase coherence (λ) and amplitude of RSA (ARSA) were quantified. Additionally, the heart rate variability (HRV) features were calculated. Our results showed that overnight λ was significantly greater, while the Low Frequency (LF) and High Frequency (HF) components of the HRV were significantly lower in OSAD+ compared to OSAD-. In addition, overnight δ-wave activity was greater in OSAD- compared to both OSAD+ and control groups. Using auto- and cross-correlation analyses, we found that overnight profiles of λ and δ-wave were correlated only in healthy individuals compared to OSAD+ and OSAD-, indicating that sleep apnea may only have an impact on this cortical-cardiorespiratory correlation rather than depression. Our findings suggest that λ and SWS activity appear to be biomarkers for assessing depression in OSA patients, whereas their correlation pattern may serve as a marker for only OSA. This could enhance diagnostic precision and provide valuable insights into the complex physiological mechanisms underlying the corambid of OSA and MDD.

Cardiac Vagal Efficiency Is Enhanced by Percutaneous Auricular Neurostimulation in Adolescents With Nausea: Moderation by Antidepressant Drug Exposure

OBJECTIVES

Percutaneous electrical nerve field stimulation (PENFS) is an effective treatment for disorders of gut-brain interaction (DGBI), proposed to influence vagal pathways. Cardiac metrics such as respiratory sinus arrythmia (RSA) and vagal efficiency (VE) can noninvasively assess parasympathetic output. Commonly used antidepressant drugs inhibit vagal signaling and may interfere with PENFS. This study examined immediate effects of active compared to sham PENFS on cardiac vagal function in adolescents with chronic nausea with and without concurrent drug therapy.

MATERIALS AND METHODS

Participants (n = 84) were randomized to active (3.2 V, 1-10 Hz) or sham PENFS within an 8-week prospective, double-blind clinical trial. Subjects underwent posture challenges to elicit a vagal response before and after PENFS device placement mid-way through the study. RSA, mean heart period (HP), and VE were calculated from electrocardiogram recordings. Exposure to antidepressant drugs was recorded.

RESULTS

The mean (SD) age was 15.61 (2.07) years (83% female). Fifty percent were treated with antidepressants. PENFS neurostimulation enhanced VE in patients without antidepressant exposure (mean increase after PENFS stimulation =7.56 [95% CI: 0.26, 14.86], d = 0.30, 17% increase) but not in those treated with antidepressants (mean change = -5.30 [95% CI:-14.28, 3.68]). Sham PENFS did not produce significant VE changes regardless of medication use (both p > 0.40). There were no significant effects on RSA or HP.

CONCLUSIONS

Acute enhancement of cardiac VE is demonstrated with PENFS in patients not exposed to chronic antidepressant drug therapy. Findings indicate that VE is a sensitive metric for rapid assessment of PENFS effects but raise concern for possible interaction or interference by standard of care medications.

TRIAL REGISTRATION

Clinicaltrials.gov #: 1064187-2.

Impact of a music intervention on heart rate variability in very preterm infants

AIM

Infants born very preterm spend their early postnatal life in a neonatal intensive care unit, where irregular and unpredictable sounds replace the structured and familiar intrauterine auditory environment. Music interventions may contribute to alleviate these deleterious effects by reducing stress and providing a form of environmental enrichment.

MATERIAL AND METHODS

This was an ancillary study as part of a blinded randomised controlled clinical trial entitled the effect of music on preterm infant's brain development. It measured the impact of music listening on the autonomic nervous system (ANS), we assessed heart rate variability (HRV) through high-resolution recordings of heart rate monitoring, at three specific postmenstrual ages in premature infants.

RESULTS

From 29 included subjects, 18 were assessed for complete HRV dataset, including nine assigned to the music intervention and nine to the control group. Postmenstrual age appeared to be the main factor influencing HRV from 33 weeks to term equivalent age. Further analyses did not reveal any detectable effect of music intervention on ANS response.

CONCLUSION

This study found that ANS responses were not modified by recorded music intervention in very preterm infants during wakefulness or sleep onset. Further research is warranted to explore other factors influencing ANS development in this population.

Heart Rate Variability Modulation Through Slow-Paced Breathing in Health Care Workers with Long COVID: A Case-Control Study

BACKGROUND

Long COVID is a syndrome persisting 12+ weeks after COVID-19 infection, impacting life and work ability. Autonomic nervous system imbalance has been hypothesized as the cause. This study aims to investigate cardiovascular autonomic function in health care workers (HCWs) with Long COVID and the effectiveness of slow-paced breathing (SPB) on autonomic modulation.

METHODS

From December 1, 2022 to March 31, 2023, 6655 HCWs of the University Hospitals of Trieste (Northeast Italy) were asked to participate in the study by company-email. Inclusion/exclusion criteria were assessed. Global health status and psychosomatic disorders were evaluated through validated questionnaires. Heart rate variability was assessed by finger-photoplethysmography during spontaneous breathing and SPB, which stimulate vagal response. Long COVID HCWs (G1) were contrasted with Never infected (G2) and Fully recovered COVID-19 workers (G3).

RESULTS

There were 126 HCWs evaluated. The 58 Long COVID were assessed at a median time because COVID-19 of 419.5 days (interquartile range 269-730) and had significantly more psychosomatic symptoms and lower detectability of spontaneous systolic pressure oscillation at 0.1 Hz (Mayer wave - baroreflex arc) during spontaneous breathing compared with 53 never-infected and 14 fully-recovered HCWs (19%, 42%, and 40%, respectively, P = .027). During SPB, the increase in this parameter was close to controls (91.2%, 100%, and 100%, respectively, P = .09). No other differences in heart rate variability parameters were found among groups.

CONCLUSIONS

Resting vascular modulation was reduced in Long COVID, while during SPB, baroreflex sensitivity effectively improved. Long-term studies are needed to evaluate whether multiple sessions of breathing exercises can restore basal vascular reactivity and reduce cardiovascular risk in these patients.

Interplay of Weight Status and Sleep Autonomic Function in Mediating and Moderating the Link Between Disease Severity and Blood Pressure in Paediatric Obstructive Sleep Apnoea

INTRODUCTION

Obstructive sleep apnoea (OSA) in children is associated with numerous adverse outcomes, including elevated blood pressure. While the associations between OSA, obesity, and autonomic dysfunction are recognised, the precise mechanisms linking these factors and their relationship with elevated blood pressure in children remain unclear.

METHODS

This retrospective case series included 76 children with OSA. The relationships between night-time systolic and diastolic blood pressures, body mass index, and clinical, polysomnographic, and sleep heart rate variability variables were investigated. Mediation and moderation analyses were performed.

RESULTS

Correlation analyses revealed significant associations between both systolic and diastolic blood pressures with body mass index, age, sex, adenoidal-nasopharyngeal ratio, apnoea-hypopnoea index, and sleep low frequency/high frequency (LF/HF) ratio. In multivariable linear regression models, body mass index, adenoidal-nasopharyngeal ratio, and LF/HF ratio were independently associated with systolic blood pressure, while body mass index and adenoidal-nasopharyngeal ratio were independently associated with diastolic blood pressure. Mediation and moderation analyses identified a conceptual mediation with a moderated direct path model in which body mass index mediated, and the LF/HF ratio moderated, the relationship between apnoea-hypopnoea index and systolic blood pressure. Additionally, children with concomitant OSA and attention deficit hyperactivity disorder had a significantly higher LF/HF ratio than those with OSA alone.

CONCLUSION

In children with OSA, the relationship between apnoea-hypopnoea index and systolic blood pressure was mediated by weight status and modulated by sleep sympathovagal balance. Children with OSA and attention deficit hyperactivity disorder exhibited greater disturbances in sympathovagal balance. Further research is warranted to explore these associations.

Under the surface: Low cardiac vagal tone and poor interoception in young adults with subclinical depressive symptoms

INTRODUCTION

Depressive symptoms are associated with alterations in central and autonomic nervous system activity, including misperception of bodily activity (e.g., low interoception), somatic symptoms and decreased vagally mediated heart rate variability (vmHRV). However, there is a lack of studies that examine both perception of bodily activity and autonomic function in depression. The present study investigated the association between interoception, vmHRV, and subclinical depressive symptoms.

METHOD

Eighty-eight students were enrolled and vmHRV was calculated from a 5-minute resting electrocardiogram. Interoceptive accuracy (heartbeat tracking task; heartbeat discrimination task), interoceptive sensibility (Body Perception Questionnaire), and depressive symptoms (Depression, Anxiety and Stress Scale - 21 Items) were assessed.

RESULTS

Interoceptive accuracy and sensibility positively correlated with vmHRV and negatively correlates with depressive symptoms. Cluster analysis performed on vmHRV, interoceptive accuracy, and sensibility provided two clusters: the first characterized by a pattern of low interoceptive accuracy, sensibility, and decreased resting vmHRV, the second characterized by an opposite pattern. Regression analyses showed that the first cluster was characterized by significantly higher depressive symptoms compared to the second (β = 1.97; pBonferroni = 0.04), even after controlling for sex, BMI, anxiety, and stress levels.

CONCLUSIONS

Subclinical depressive symptoms are associated with a consistent impairment in the perception and interpretation of bodily activity and altered regulatory function of the autonomic nervous system. The present results suggest that the alteration of brain-body communication could be involved in subclinical depressive symptoms. Early identification of such alterations could help with targeted preventive strategies.

The usefulness of heart rate variability in adolescents with tic disorder: Focused on interplay with quality of life

BACKGROUND

Tic disorders, characterized by involuntary movements or vocalizations, are influenced by neurological and psychological factors. Although an imbalance in neurotransmitter systems, genetic factors, and environmental influences play a significant role in the expression of tic disorders, the precise mechanisms through which autonomic changes influence tic production are not fully understood yet. This study investigates the relationship between tic disorders and heart rate variability (HRV), a physiological marker of autonomic nervous system function. The study sought to identify correlations among tic symptoms, HRV indices, and perceived quality of life.

METHODS

In a cohort of 69 participants (39 with tic disorders and 30 controls), we assessed tic severity using the Yale Global Tic Severity Scale (YGTSS) and quality of life through the KIDSCREEN-27 instrument. HRV parameters were measured to evaluate autonomic nervous system activity.

RESULTS

Patients with tic disorders exhibited significant differences in HRV measures compared to the control group, indicating altered autonomic nervous system functioning. Our findings revealed notable differences in HRV, especially lower Low Frequency (LF) power in the patient group, suggesting altered autonomic responses potentially linked to chronic stress. Correlations between HRV metrics (notably SDNN and RMSSD) and various life quality dimensions were observed in the patient group. These results underscore a potential interplay between tic symptoms, autonomic balance, and adolescents' perceived quality of life.

CONCLUSION

The study highlights the importance of considering autonomic nervous system functioning in tic disorders, particularly in the context of stress and perceived quality of life. Our findings, which provide insights into tic disorders' physiological and psychological aspects, have important implications for developing more holistic treatment approaches that consider tic patients' mental and physical well-being.

Nocturnal short-term heart rate variability reflects impaired daytime vigilance better than overnight heart rate variability in suspected obstructive sleep apnea patients

In obstructive sleep apnea (OSA), heart rate variability (HRV) decreases and performance in psychomotor vigilance task (PVT) worsens with more severe hypoxic load. Nevertheless, the association between HRV and PVT performance is poorly understood. Thus, we hypothesize that nocturnal short-term HRV is better related to daytime psychomotor vigilance compared with overnight HRV. To investigate this hypothesis, we retrospectively analyzed the electrocardiograms from polysomnographies of 546 consecutive patients with suspected OSA. We determined overnight HRV and short-term HRV in nonoverlapping 5-min segments and performed stepwise linear regression analyses to associate HRV with the median reaction time (RT) in the PVT. The short-term decrease in the median interval between two successive normal R peaks (NN interval), root mean square of successive NNs, and normalized high-frequency band power were all significant (p < 0.001) indicators of longer median RTs. However, the overnight HRV parameters did not indicate worsening median RT. Instead, increased hypoxic load and N3 duration were associated with longer median RT in men but not in women. The association of HRV and cardiorespiratory coupling with PVT performance was generally weak. Nocturnal short-term HRV evaluation reflected a state of vigilance better than the average overnight HRV. Thus, the overnight HRV analysis might not be optimal for patients with OSA. Utilizing the HRV analysis in a time-series manner and combined with the hypoxic load and sleep stages could bring new aspects to the health assessment of patients with OSA.

Change of heart rate variability in children and adolescent with drug resistant epilepsy

Heart rate variability (HRV) has been examined and employed as a predictive biomarker for epilepsy. Patients with epilepsy exhibit reduced HRV as a result of heightened sympathetic activity. Reductions in HRV are observed in patients with sudden unexpected death in epilepsy (SUDEP). Our study aims to determine the change in HRV among children and adolescents with drug-resistant epilepsy (DRE) and advocate for its use as a biomarker to assess cardiovascular health in this population. Fifty-four children and adolescents, aged between 6 and 20 years, were enrolled and divided into two groups: the epilepsy group comprised 27 children diagnosed with DRE. Thirty minutes of HRV measurements were performed on both patients and controls. The median age was 12 years old. Malnutrition was the most common comorbidity in the epilepsy group. 75% have been diagnosed with DRE for more than 10 years. 44% had daily seizures. Generalized tonic-clonic seizures (GTCs) were the most common seizure type, accounting for 55.6% of cases. The most frequent cause of epilepsy was structural brain lesions (55.6%), followed by genetic disorders (18.5%). Patients with DRE had a significant reduction in both HRV's time domain (RMSSD and pNN50) and frequency domain (HF and LF). Patients who had GTC and had epilepsy for more than 10 years had a significant reduction in the low-frequency domain of HRV, according to the subgroup analysis. Children and adolescents with DRE exhibited a marked decrease in HRV measures, thereby increasing the likelihood of cardiovascular health issues in these patients. HRV can be used as a biomarker to effectively assess cardiovascular health in DRE patients.

Relationship between heart rate variability traits and stroke: A Mendelian randomization study

BACKGROUND

Previous observational studies have suggested a potential association between heart rate variability (HRV) and cerebrovascular disease. However, a causal relationship between the two has not yet been established.

AIMS

The objective of this study was to determine the causal relationship between heart rate variability (HRV) and stroke through a two-sample Mendelian randomization analysis.

METHODS

Three genetic predictive traits of heart rate variability standard deviation of the normal-to-normal interbeat intervals (SDNN), the root mean square of the successive differences of interbeat intervals (RMSSD), and the peak-valley respiratory sinus arrhythmia or high-frequency power (pvRSA/HF) were collected from publicly available genome-wide association studies (IEU Open GWAS). Additionally, stroke (STROKE) and its sub-types: ischemic stroke (IS), cardioembolic stroke (CES), small vessel stroke (SVS), large artery stroke (LAS), lacunar stroke (LS), and intracerebral hemorrhage (ICH)were also from this database. Two-sample Mendelian randomization and various sensitivity analyses were employed to explore the causal relationship between HRV and stroke and its sub-types. Inverse-variance weighted (IVW) was the primary method via which Mendelian randomization (MR) was conducted, and for the causal estimates determined by IVW, a series of sensitivity analyses were performed to assess the reliability of the results. (i) Four additional MR methods that complement IVW were utilized; (ii) Cochran's Q-test was employed for assessing heterogeneity; (iii) the MR-Egger's intercept test and MR-PRESSO global test were applied to assess the level of multivariate validity, and (iv) the "leave-one-out" method was utilized to assess stability.

RESULTS

Two of the genetically predictive traits of HRV (standard deviation of the normal-to-normal interbeat intervals [SDNN]) and (the peak-valley respiratory sinus arrhythmia or high-frequency power [pvRSA/HF]) were associated with IS (OR 0.63,95 %CI 0.42-0.95, P = 0.03), (OR 0.84, 95 %CI: 0.72-1.00; P = 0.04), and LAS (OR 135.93, 95 %CI: 7.19-2569.22; P = 0.05), (OR 1.42, 95 %CI: 1.02-1.98; P = 0.04) were significantly correlated in addition to (pvRSA/HF) and LS (OR 0.84, 95 %CI: 0.72-1.00; P = 0.04) were also causally associated. Neither was causally associated with other sub-types of stroke or hemorrhagic stroke. Another genetically predictive trait of HRV (the root mean square of the successive differences of interbeat intervals [RMSSD]) was not found to be significantly associated with stroke, its subtypes, or Intracerebral hemorrhage.

CONCLUSION

This study provides genetic evidence supporting the causal effects of HRV (SDNN) on ischemic stroke (IS) and large artery stroke (LAS), as well as (pvRSA/HF) on ischemic stroke (IS), large artery stroke (LAS), and lacunar stroke (LS).

The dynamics of cyclic-periodic phenomena during non-rapid and rapid eye movement sleep

Sleep is a complex physiological state characterized by distinct stages, each exhibiting unique electroencephalographic patterns and physiological phenomena. Sleep research has unveiled the presence of intricate cyclic-periodic phenomena during both non-rapid eye movement and rapid eye movement sleep stages. These phenomena encompass a spectrum of rhythmic oscillations and periodic events, including cyclic alternating pattern, periodic leg movements during sleep, respiratory-related events such as apneas, and heart rate variability. This narrative review synthesizes empirical findings and theoretical frameworks to elucidate the dynamics, interplay and implications of cyclic-periodic phenomena within the context of sleep physiology. Furthermore, it invokes the clinical relevance of these phenomena in the diagnosis and management of sleep disorders.

A New Heartbeat-Respiration Coupling Metric for Relaxation/Stress Monitoring

OBJECTIVE

Identification and continuous monitoring of relaxation/stress level through easily measurable physiological signals has become an urgent need. Relaxation/stress is mainly mediated by autonomic nervous system (ANS) which can hardly be noninvasively-measured, but can be reflected in heartbeat and respiration because the human body is a strongly coupling system. However, existing metrics based on heart rate and respiration present low accuracy for relaxation assessment. Our main objective is to propose a reliable metric for relaxation/stress monitoring.

METHODS

By improving the quantification of Respiratory Sinus Arrhythmia (RSA) and introducing the phase difference between heart rate and respiration, we construct a new metric called Heart-Breath Coherence (HBC) based on heart rate and respiration collected synchronously. Firstly, its practical performance is examined by the multi-scenario experiment with 34 volunteers, which contains four scenarios: smelling odors, listening to sounds, emotional evocations, and watching videos. Then, the synthetic data are employed to test the precision of RSA quantification by HBC.

RESULTS

Comparing with 26 existing metrics, HBC shows the highest accuracy 91% (p-value 0.01 and effect size 0.8) in the multi-scenario experiment. The introduction of magnitude of phase difference is crucial for the success. Synthetic studies show that HBC improves the RSA quantification with the minimum error comparing to other metrics.

CONCLUSION

HBC is a reliable metric for relaxation/stress monitoring and RSA quantification.

SIGNIFICANCE

HBC can provide the real-time monitoring of relaxation/stress level and reflect the ANS balance, which is meaningful for healthcare and may be used for psychology and clinical practice.

Effects of different postures on the hemodynamics and cardiovascular autonomic control responses to exercise in postural orthostatic tachycardia syndrome

PURPOSE

To assess the effects of two different body positions on the cardiovascular autonomic profile during a single bout of exercise in patients with postural orthostatic tachycardia syndrome (POTS).

METHODS

Thirteen patients with POTS and thirteen healthy controls (C) participated in the study. ECG, respiration, beat-by-beat arterial pressure and O2 consumption (VO2) were continuously recorded while on a cycle ergometer in supine and upright positions, before and during exercise (6 min, 50 Watts). Spectral analysis of RR intervals and systolic arterial pressure (SAP) variability provided indexes of cardiac sympathovagal interaction (LF/HF ratio), cardiac vagal modulation (HFRR, high-frequency component of RR variability, ~ 0.25 Hz), sympathetic vasomotor control (LFSAP, low-frequency component of SAP variability, 0.1 Hz) and baroreflex sensitivity (BRS, αLF).

RESULTS

While supine, patients with POTS showed lower HFRR and αLF, greater heart rate (HR), LF/HF and LFSAP, compared with C, suggesting cardiovascular sympathetic over-activity and reduced BRS. While sitting upright, POTS showed greater HR and reduced HFRR and αLF compared with C. During supine exercise, SAP, HR, LF/HF increased and HFRR and αLF decreased similarly in POTS and C. In POTS, upright sitting exercise was associated with slightly higherV ˙ O 2 , a greater increase in HR whereas LFSAP was lower than in C.

CONCLUSION

Upright exercise was associated with excessive enhancement of HR and a blunted increase of the sympathetic vasomotor control in POTS. Conversely, supine exercise-induced hemodynamic and autonomic changes similar in POTS and C, thus making supine exercise potentially more suitable for physical rehabilitation in POTS.

Attenuated cardiac autonomic function in patients with long-COVID with impaired orthostatic hemodynamics

PURPOSE

Long-coronavirus disease (long-COVID) is associated with initial orthostatic hypotension and postural orthostatic tachycardia syndrome. Whether altered autonomic tone underlies these abnormalities is unknown. We compared autonomic function between patients with long-COVID and healthy controls, and within patients with long-COVID with different orthostatic hemodynamic phenotypes.

METHODS

Patients with long-COVID (n = 94; F = 76; 42 years [36, 53 years] with initial orthostatic hypotension: n = 40; F = 32; 49 years [39, 57 years]; postural orthostatic tachycardia syndrome: n = 29; F = 26; 39 years [33, 47 years]; or no abnormalities: n = 25; F = 18; 42 years [35, 49 years]), and healthy controls (n = 33; F = 25; 49 years [30, 62 years]) completed a 10-min active stand with beat-to-beat hemodynamics. Heart rate variability, blood pressure variability, and baroreflex sensitivity were calculated as indirect measures of cardiovascular autonomic health. Continuous data (median [95% confidence interval]) were analyzed with Mann-Whitney U tests or Kruskal-Wallis tests with Dunn's corrections.

RESULTS

Patients with long-COVID had lower upright high frequency heart rate variability (p = 0.04) and low frequency blood pressure variability (p = 0.001) than controls. Patients with initial orthostatic hypotension had lower supine baroreflex sensitivity compared with patients without abnormalities (p = 0.01), and lower supine baroreflex sensitivity (p = 0.001) and high frequency heart rate variability (p = 0.03) than patients with postural orthostatic tachycardia syndrome. Patients with postural orthostatic tachycardia syndrome had lower upright high frequency heart rate variability (p < 0.001) and baroreflex sensitivity (p < 0.001) compared with patients without abnormalities and lower upright low frequency blood pressure variability (p = 0.04) compared with controls.

CONCLUSIONS

Patients with long-COVID have attenuated cardiac autonomic function. Patients with initial orthostatic hypotension have lower supine baroreflex sensitivity. Patients with postural orthostatic tachycardia syndrome have lower upright vascular sympathetic and cardiac parasympathetic modulation. Long-COVID subgroups do not present with homogeneous pathophysiology, necessitating targeted treatment strategies.

A machine learning-based Coagulation Risk Index predicts acute traumatic coagulopathy in bleeding trauma patients

BACKGROUND

Acute traumatic coagulopathy (ATC) is a well-described phenomenon known to begin shortly after injury. This has profound implications for resuscitation from hemorrhagic shock, as ATC is associated with increased risk for massive transfusion (MT) and mortality. We describe a large-data machine learning-based Coagulation Risk Index (CRI) to test the early prediction of ATC in bleeding trauma patients.

METHODS

Coagulation Risk Index was developed using continuous vital signs (VSs) available during the first 15 minutes after admission at a single trauma center over 4 years. Data to compute the CRI were derived from continuous features of photoplethymographic and electrocardiographic waveforms, oximetry values, and blood pressure trends. Two groups of patients at risk for ATC were evaluated: critical administration threshold and patients who received an MT. Acute traumatic coagulopathy was evaluated in separate models and defined as an international normalized ratio (INR) >1.2 and >1.5 upon arrival. The CRI was developed using 2 years of cases for training and 2 years for testing. The accuracy of the models is described by area under the receiver operator curve with 95% confidence intervals.

RESULTS

A total of 17,567 patients were available for analysis with continuous VS data, 52.8% sustained blunt injury, 30.2% were female, and the mean age was 44.6 years. The ability of CRI to predict ATC in critical administration threshold patients was excellent. The true positive and true negative rates were 95.6% and 88.3%, and 94.9% and 89.2% for INR >1.2 and INR >1.5, respectively. The CRI also demonstrated excellent accuracy in patients receiving MT; true positive and true negative rates were 92.8% and 91.3%, and 100% and 88.1% for INR >1.2 and INR >1.5, respectively.

CONCLUSION

Using continuous VSs and large-data machine learning capabilities, the CRI accurately predicts early ATC in bleeding patients. Clinical application may guide early hemostatic resuscitation. Extension of this technology into the prehospital setting could provide earlier treatment of ATC.

LEVEL OF EVIDENCE

Diagnostic Tests/Criteria; Level III.

A review of automatic sleep stage classification using machine learning algorithms based on heart rate variability

Over the past few decades, the use of heart rate variability (HRV) has expanded significantly due to its ease of collection, affordability, and its clinical relevance to psychophysiological processes and psychopathological disorders. This study aims to demonstrate the effectiveness of an artificial intelligence approach based on HRV signals for automatic sleep stage classification. This review examines machine learning algorithms for HRV-based sleep stage classification over the past 15 years. It also compares the HRV features extracted, the classification algorithms used, and the evaluation parameters employed. Existing studies indicate that with advances in technology, machine learning algorithms utilizing HRV features for sleep staging achieve high accuracy, sensitivity, and specificity. The use of HRV for sleep analysis via machine learning algorithms is an active area of research with broad application potential. As technology progresses and data accumulation increases, this approach is expected to offer more accurate and personalized solutions for sleep medicine and health management.

African Americans with a family history of cardiovascular disease show lower endothelial-dependent vasodilation

Normotensive African Americans (AAs) show attenuated vascular responses and reduced nitric oxide (NO) bioavailability compared to European Americans (EAs). Few studies have used diverse measures to examine differences in macrovascular function and structure in individuals with a family history of CV disease (CVD). We assessed 150 AAs (Mage, 23.57 ± 2.73 yr) and 104 EAs (Mage, 22.70 ± 2.86) with a confirmed family history of CVD. Age, sex, body mass index, and father's education were used as covariates, hemodynamic measures (heart-rate [HR], stroke volume [SV], cardiac output [CO], total peripheral resistance [TPR], mean arterial pressure [MAP], systolic and diastolic blood pressure [SBP/DBP], and pulse pressure [PP]), high-frequency heart-rate variability [HF-HRV], and endothelial-dependent arterial dilation [EDAD] were the dependent variables. AA's had lower EDAD (11.64 vs. 13.20%) and higher HF-HRV (7.31 vs. 7.11 ms2), TPR (17.60 vs. 15.93 mmHg/L/min), TPI (33.72 vs. 30.09 mmHg/L/min/m2), MAP (83.60 vs. 78.36 mmHg), SBP (115.44 vs. 110.23 mmHg), and DBP (65.35 vs. 60.57 mmHg). Lower EDAD alongside no ethnic differences in PP, HR, or SV suggests early onset endothelial dysfunction (lower NO availability) rather than inherited pathophysiological structural characteristics (arterial stiffness) in AAs. Future prospective studies are needed and should consider measures of sympathetic activity and potential moderators, including discrimination.

Dynamical instability is a major cause of cardiac action potential variability

Increased beat-to-beat QT interval variability (QTV) in the electrocardiogram is strongly associated with ventricular arrhythmias and sudden cardiac death, yet its origins remain poorly understood. While heart rate variability decreases with deteriorating cardiac health, QTV increases, suggesting distinct underlying mechanisms. The stochastic nature of ion channel gating is a potential source of cardiac variability. However, the law of large numbers suggests that, with billions of channels in the heart, this stochasticity should be minimized. In this study, we tested the hypothesis that dynamical instability amplifies stochastic ion channel fluctuations, leading to increased action potential (AP) variability. Using a mathematical model of ventricular myocytes, we investigated the relationship between AP variability and voltage instability. Our results demonstrate that stochastic gating alone cannot cause large AP variability, but dynamical instability significantly amplifies this variability. We found a positive correlation between voltage instability, indicated by the slope of the AP duration restitution curve, and AP duration variability. Notably, the largest variability occurred at the onset of alternans when considering every other beat. These findings provide a mechanistic explanation for increased QTV in pathological conditions and suggest that measuring QTV using every other beat may predict the onset of alternans and severity of alternans. Our study highlights the critical role of dynamical instability in cardiac electrical variability and offers new insights into the mechanisms underlying arrhythmogenesis.

Acute exercise impacts heart rate variability but not cognitive flexibility during subsequent simulated firefighter occupational tasks

PURPOSE

Acute exercise can transiently enhance cognitive flexibility. The cognitive demand of firefighters makes it relevant to understand if on-shift exercise could produce similar improvements in cognitive performance during subsequent occupational tasks. Metrics of heart rate variability (HRV), such as time- and frequency-domain outcomes, may shed light upon the influence exercise has on cognition, as they discern information related to cardiac autonomic (sympathetic/parasympathetic) function. We aimed to determine if acute resistance and aerobic exercise impact cognitive flexibility during occupational tasks and its relation to HRV.

METHODS

32 participants completed a baseline Wisconsin Card Sorting Task (WCST) and three experimental trials: resistance exercise (RE), aerobic exercise (AE), or a rested control (CON). An occupational task assessment (OTA) including four rounds of 10 deadlifts and a 0.15-mile sandbag carry in an environmental chamber (35 °C/50% humidity) was completed after each trial. The second round was followed by the WCST. Repeated measures ANOVAs were used to analyze differences by condition.

RESULTS

For the WCST, total, perseverative, and non-perseverative errors did not differ (ps > 0.39). Time-domain HRV metrics were not different (ps > 0.05). All frequency-domain metrics, other than low-frequency power, were not different (ps > 0.24). Low-frequency power was lower based on condition (p = 0.03). Post hoc analysis showed low-frequency power was lower following AE compared to RE and CON.

CONCLUSION

Results suggest an acute bout of on-shift aerobic or resistance exercise may not impact cognitive flexibility during subsequent simulated occupational tasks, despite depressed metrics of heart rate variability following aerobic exercise.

Inhibitory effect of exercise on elevated blood pressure and fetal growth restriction during pregnancy in Dahl salt-sensitive rats

Exercise is effective in preventing gestational hypertension, but its mechanism remains unclear. This study investigates the effects of exercise on Dahl salt-sensitive (DSS) rats, which develop elevated blood pressure and fetal growth restriction during pregnancy. DSS rats were divided into exercise and non-exercise groups, with Sprague-Dawley rats as controls. Exercise consisted of voluntary running, starting 4 weeks prior to pregnancy until the last trimester. Cardiovascular parameters, molecular characteristics of the brain and placenta, and fetal conditions were evaluated. Exercise significantly improved elevated blood pressure at early pregnancy and was associated with improved baroreceptor reflex gain. Gene expression analysis in the rostral ventrolateral medulla (RVLM) showed exercise-induced downregulation of nitric oxide synthase and upregulation of superoxide dismutase. These genetic changes suggest that exercise impacts circulatory regulation mechanisms, contributing to blood pressure improvement. In addition, placental analysis revealed a marked increase in placental growth factor expression due to exercise. In conclusion, exercise alleviates elevated blood pressure at early gestation and fetal growth restriction in DSS rats. Genetic modifications in the RVLM may play a critical role in exercise-induced cardiovascular improvements. This study highlights the potential of exercise as a therapeutic approach for managing gestational elevated blood pressure and fetal growth restriction and provides insights into its underlying mechanisms.

Vagal nerve activity and cancer prognosis: a systematic review and meta-analysis

BACKGROUND

The prognostic significance of vagal nerve (VN) activity, as measured by heart rate variability (HRV) in cancer patients remains a subject of debate. The aim of this meta-analysis was to evaluate the association between various HRV parameters and cancer prognosis.

METHODS

We conducted an extensive search of the PubMed, Embase, Cochrane, and Web of Science databases and compared the overall survival (OS) of cancer patients with high and low HRV. The data type was unadjusted hazard ratio (HR). Random or fixed-effects models were used to calculate the pooled HR along with the 95% Confidence Interval (CI). We used funnel plot analysis to evaluate potential publication bias.

RESULTS

A total of 11 cohort studies were included with 2539 participants. The methodological quality of the included studies is generally high. Compared with low standard deviation of normal-to-normal intervals (SDNN) group, higher SDNN was a protective factor for OS in patients with cancer (I2 = 66%, HR = 0.59, 95% CI: 0.46-0.75, P < 0.0001). Compared with low root mean square of successive differences (RMSSD) group. The prognostic value of RMSSD did not reach statistical significance (I2 = 0%, HR = 0.85, 95% CI: 0.70-1.03, P = 0.11). Among the frequency domain indicators, higher high-frequency power HRV (HF-HRV) and low-frequency power HRV (LF-HRV) were associated with significantly longer overall survival compared to the low HF-HRV and LF-HRV groups (I2 = 6%, HR = 0.59, 95% CI: 0.43-0.80, P = 0.006 and I2 = 74%, HR = 0.45, 95% CI: 0.22-0.93, P = 0.03). In the nonlinear indicators, higher maximal diagonal line length (Lmax), mean diagonal line length (Lmean), percent of recurrence (REC), and determinism (DET) were associated with poorer tumor OS. The funnel plot shows that there is no publication bias in the study.

CONCLUSIONS

The findings of this study demonstrate that HRV parameters, particularly SDNN, HF-HRV, and nonlinear indices, exhibit predictive value for prognosis in cancer. Furthermore, it can be inferred that elevated VN activity may predict prolonged survival outcomes. However, these findings should be interpreted with caution due to the heterogeneity observed across included studies. Future research should prioritize prospective studies with standardized measurement protocols to validate these associations.

The short-term relation between load and acute psychophysiological responses in football: a meta-analysis and methodological considerations

Relations between load and acute psychophysiological responses have been widely studied in football. However, due to the large heterogeneity in contexts, operationalization, and results, the direction and strength of these relations remain unclear. In this meta-analysis, we examine the relation between load and typical acute (i.e. within one week) responses - wellbeing, recovery, and heart rate measures - in football players from all football codes (soccer, rugby, futsal, American football, and Australian rules football). We consulted PubMed, Web of Science, and CINAHL up to the 19th of June 2024, and included 62 articles and 1,474 participants in the meta-analysis. Subsequently, we estimated 12 meta-analysis models and applied meta-regression models to explore the influence of several moderators. Significant relations were found between load and overall wellbeing (r = -0.33 [95%CI: -0.48; -0.19]), muscle soreness (r = -0.36 [95%CI: -0.49; -0.24]), fatigue (r = -0.41 [95%CI: -0.56; -0.26]), sleep quality (r = -0.21 [95%CI: -0.31; -0.10]), and stress (r = -0.16 [95%CI: -0.26; -0.06]). Given the high risk of bias, inconsistency (wide prediction intervals), and imprecision, the certainty in these findings based on the GRADE assessment is very low. Additionally, the high risk of bias scores indicates that the overall quality of the included studies is low. In conclusion, this meta-analysis provides comprehensive information on the acute responses of the athlete to load, and directions for improvement of the quality of future studies.

Heart rate variability tests for diagnosing cardiovascular autonomic neuropathy in patients with type 2 diabetes mellitus in advanced stages of kidney disease

Cardiovascular Autonomic Neuropathy (CAN) is one of the most devastating complications of Diabetes Mellitus (DM) and presents high morbidity and mortality. Its association with diabetic kidney disease (DKD) worsens the condition even further. CAN diagnosis remains a challenge and is being based on reflex tests which are laborious, risky and difficult to perform. Heart Rate Variability (HRV) tests has been suggested as having high utility in diagnosing CAN, but this issue remains controversial. The aim is to evaluate the sensitivity and specificity of HRV tests to diagnose CAN in patients with type 2 diabetes mellitus (T2DM) and DKD with severely increased albuminuria. This is a cross-sectional study in patients with T2DM and DKD with severely increased albuminuria. A total of 48 subjects were recruited and underwent laboratory and neuropathy assessment. The diagnosis of CAN was first confirmed in 75% (36/48) of patients based on cardiovascular autonomic reflex tests (CARTs). HRV tests (VLF, LF, TP and SDNN) differed between groups with and without CAN (212 vs. 522 ms2, p = 0.024; 57 vs. 332 ms2, p = 0.025; 359.5 vs. 2733 ms2, p = 0.007; 20 vs. 48 ms, p = 0.012), respectively. The best cut-off points based on ROC curve were < 1,117 ms2, < 152.5 ms2, < 1,891 ms2 and < 46.5 ms, respectively. VLF and TP reached highest sensitivity values (97% and 92%) and F1 Score of 90%, while LF had best specificity (75%) and TP had best accuracy (85%). Our best model of serial algorithm using VLF as first screening test and TP in sequency obtained a sensitivity of 97% and accuracy of 90%, reducing in 90% the need to perform CARTs. Our findings suggest that it is possible to achieve high sensitivity and accuracy using an algorithm with VLF and TP parameters analyzed in series. It could enable a simpler and early diagnosis, avoiding CARTs complications.

Psychophysiological correlates of science communicators

We conducted a study in an ecological setting to evaluate the heart rate variability (HRV) of expert communicators during a live national primetime video interview. The study involved 32 expert science communicators, all with mid- to long-term experience in public speaking and outreach work, who were evaluated by an external jury to assess their communication skills. Prior to the experiment, participants completed an online survey to gather socio-demographic data, work-related information, and psychological profiles. The six indices of communication abilities assessed by jury were: Interest, Agreement, Engagement, Authoritativeness learning, and Clarity. HRV acquisitions were divided into three phases: baseline pre-interview, during the interview, and another baseline recording after the interview. Science communicators were characterized by high levels of self-esteem and prosociality, which were positively correlated with communication indices and inversely correlated with age. Evaluation of physiological responses showed that the total power and low-frequency components of HRV were significantly higher in the post-interview phase compared to both the interview and pre-interview phases. However, when we divided the entire group according to high and low Authoritativeness and Clarity indices, significant interactive effects were detected. Indeed, for the low Authoritativeness and Clarity subgroups, significant differences among all phases were observed, with total power decreasing from the pre-interview to the interview phase and increasing in the post-interview phase. This indicates a clear pattern of stress response and recovery. In contrast, the high Authoritativeness and Clarity subgroup showed less variation across phases, suggesting better stress regulation or less perceived stress during the interview. We provided the psychophysiological basis of science communication expertise that can affect the control of stress regulation during public speaking.

Orthostatic cardiovascular responses to postural sway and discreet counterpressure maneuvers

Counterpressure maneuvers (CPM) are movements used to delay or abort syncope, but may have practical barriers to use. We recently showed exaggerated postural sway produces protective responses against syncope. Accordingly, we aimed to evaluate a series of discreet, accessible movements as novel preventative CPM. We tested 26 healthy adults (12 female) aged 28.9 ± 1.2 years. Participants performed a baseline stand (BL), followed by three randomized CPM trials (exaggerated anteroposterior sway, AP; toe clenching, TC; gluteal muscle clenching, GC). Non-invasive beat-to-beat systolic arterial pressure (SAP), heart rate, stroke volume (SV), cardiac output (CO), total peripheral resistance (TPR), mean middle cerebral artery blood velocity (mMCAv), and total path length moved (TPL) were measured. Muscularity was assessed using bioelectrical impedance. All discreet CPM augmented orthostatic SV (p < 0.001) and CO (p < 0.001), while reducing TPR (p < 0.001). SAP increased during AP (p < 0.001) and GC (p < 0.001), but not TC. GC responses were unstable, with increased standard deviation of SAP (p = 0.002) and SV (p = 0.022) that may predispose syncope. Only AP improved mMCAv (p = 0.005) and sympathovagal balance (p < 0.001). Responses were largest in those with greater initial cardiovascular instability (p < 0.003), larger leg muscle mass (p < 0.02), and where TPL was greater (p < 0.002). These novel CPM hold clinical potential for the prevention of orthostatic syncope and presyncope, while addressing real-world patient-reported barriers to CPM. Exaggerated AP sway was most robust and stable at improving orthostatic hemodynamics in healthy controls, with reduced reliance on sympathetic baroreflex-mediated vasoconstriction during enhanced muscle pumping activity. Accordingly, AP shows the most promise as a simple and discrete CPM.

Describing the Impact of Physician End-of-Life Communication Training on Simulated Stress Using a Novel Stress Marker

IntroductionEmpathetic end-of-life (EOL) communication is important for high quality pediatric patient and family outcomes. Trainees may have limited exposure and training in caring for patients at EOL which may impact communication-related stress. This study had 2 aims: (1) describe pediatric resident physician EOL exposure and training (2) measure objective and subjective stress during simulated critical communication encounters and the impact of prior communication training/exposures on stress responses.MethodsWe performed a prospective, pilot observational cohort study measuring physician exposure to caring for patients/families at EOL and simulated communication stress. Simulated stress was measured subjectively using the state-trait anxiety inventory (STAI) and objectively using heart rate variability (HRV) during a communication training intervention.Results85.7% (18/21) of residents reported seldom/never caring for patients at EOL and universally felt ill-prepared to provide care. Subjective and objective stress increased when directly communicating with the simulated parent/patient actor compared to baseline in all HRV domains. Residents with limited exposure to patients/families at EOL had a smaller stress response than those who cared for a substantial number.ConclusionsPediatric residents report limited opportunities to communicate with patients/families at EOL, which may impact stress responses when communicating life-altering news to families. Simulated communication encounters can be designed to evoke subjective and objective stress which can be measured using novel technology and may help address limited EOL opportunities.

A Scoping Review of Studies Reporting Heart Rate Variability Measurement Among Pregnant and Postpartum People Using Wearable Technology

Maternal mental health conditions significantly contribute to pregnancy-related mortality in the United States. Approximately 20-25% of postnatal women exhibit symptoms of depressive and anxiety disorders. Mental health is influenced by stress, which affects mood, cognition, and behavior. Heart rate variability (HRV), the time interval between consecutive heartbeats, is a physiological marker for assessing stress levels, providing critical insights into the body's autonomic responses. Wearable devices measuring HRV offer a non-invasive method to monitor stress and mental health, enabling early detection of maternal stress dynamics to facilitate timely interventions. In this scoping review, we aimed to capture the current state of science on two areas of focus: (1) utilization of wearable technology for HRV monitoring in pregnant and postpartum women, (2) findings from these perinatal HRV studies, including observed HRV trends throughout pregnancy and postpartum, as well as the association between HRV, perinatal stress, and mental health. The six included perinatal HRV studies employed five fitness tracking wearables, utilizing either periodic or continuous 24-h monitoring. Findings include evidence that HRV declines during pregnancy, with a return to normal levels postpartum. Associations between HRV and stress were inconsistent across studies, with some demonstrating correlations and others reporting no relationship. Postpartum HRV measurements effectively differentiated between women with postpartum depression (PPD) versus those with adjustment disorder (AJD), demonstrating high diagnostic accuracy. In this scoping review, HRV shows promise as a stress biomarker among pregnant/postpartum people, although more work is needed to standardize optimal methods of wearable HRV measurement in this population.

The restorative effects of working individually in a vegetated office space: A crossover controlled experimental study in real-life workplace setting

BackgroundExamining the restorative effects of indoor nature exposure that can be controlled through management and design in work settings is crucial for public health. However, concerns about the external validity of existing findings persist due to insufficiency of studies with ecologically sound experimental designs.ObjectiveThrough an experiment that prioritized higher ecological validity, this study aimed to explore the effects of working in an office room vegetated with green plants on employees' physiological and psychological well-being, and their attentional performance.MethodsThis controlled experimental study employed a crossover design in real-life work environments, involving 40 working individuals. It assessed changes in perceived fatigue, psychological and physiological stress, and attentional performance after individual work in either a vegetated or plant-free office room, with other environmental factors kept constant.ResultsAfter an hour of individual work in a vegetated room, participants reported decreased perceived stress and fatigue, supported by changes in measures of systolic blood pressure and heart rates when compared to a plant-free room. Gender differences emerged, with females experiencing greater relief in perceived stress and males showing more noticeable reductions in stress-related physiological indicators. Enhanced attentional reactions were noted solely among males.ConclusionsThis study accentuated the immediate emotional well-being benefits of indoor plants at work, highlighting the importance of considering diverse user groups in indoor workspace design. It also proposes potential explanations for how indoor plants induce restorative effects on working individuals, suggesting further research.

Pubertal developmental, body mass index, and cardiovascular autonomic function in children and adolescents with and without autism spectrum disorder: a four-time point accelerated longitudinal study

BACKGROUND

The Autonomic Nervous System (ANS) regulates 'automatic' functions such as heart rate, and alterations may have significant impacts on health outcomes. Cardiovascular measures of autonomic function such as heart rate variability are of interest as biological markers in autism spectrum disorder (ASD). The interplay between the ANS and physical health establishes a need to examine cardiovascular autonomic functioning in youth with and without ASD over development. The current study aimed to identify change in autonomic function and balance across the parasympathetic and sympathetic branches over time as a function of diagnosis, age, pubertal development, and physical health status.

METHODS

The study included 244 ASD (N = 140) or neurotypical (NT) (N = 104) youth, ages 10 to 13 years at enrollment and followed over four years. Resting state autonomic functioning was measured using respiratory sinus arrhythmia (RSA; parasympathetic) and pre-ejection period (PEP; sympathetic). Autonomic balance and regulation were also examined as outcomes. Linear mixed models tested between- and within-group differences in the primary autonomic outcomes as well as the influence of pubertal development, body weight, and medication use.

RESULTS

Baseline models showed diagnostic differences, with lower parasympathetic regulation, in youth with ASD, but no differences were observed for the other three outcomes. Adding body mass index (BMI) percentile and medication use removed the statistically significant diagnostic effect, while both variables were significantly related to lower RSA and overall autonomic regulation. Parasympathetic function (RSA) was stable over age and pubertal stage, while a notable decrease in sympathetic control (increased PEP) was found for age and pubertal stage. BMI percentile at enrollment significantly predicted autonomic function, while change in BMI over time did not.

CONCLUSIONS

Minimal research to date has explored physical health (e.g., BMI) and autonomic outcomes in ASD. The current study observed few group differences yet demonstrates important effects of physical health on ANS function in both ASD and neurotypical youth. Findings further emphasize a need to focus on individual traits such as BMI and medication use to elucidate the extent to which autonomic differences are related to health status, irrespective of diagnostic category, across the lifespan.

Analysis of changes in heart rate variability after prolonged ultra-high plateau residence in young healthy population: a cross-sectional study

Objective

This study aims to investigate changes in the autonomic nervous system (ANS) by analyzing the characteristics of heart rate variability (HRV).

Methods

A portable 3-lead dynamic electrocardiogram monitoring device was used to collect HRV data from the participants. Based on the inclusion and exclusion criteria, a total of 52 volunteers from the Xinjiang Hetian area (ultra-high plateau group, approximately 5300 m altitude) and 56 volunteers from the Sichuan Chengdu area (plain group, approximately 500 m altitude) were enrolled for the 24-hour long-term HRV data collection. A cross-sectional comparison was made between the groups in terms of various HRV time-domain, frequency-domain, and nonlinear indices. The diurnal and nocturnal variations in HRV and ANS after prolonged residence in the ultra-high plateau were further explored by dividing the day into daytime and nighttime periods and calculating the ΔHRV values. Additionally, the participants' heart rate and sleep conditions were analyzed.

Results

Compared to the plain group, the ultra-high plateau group showed a significant reduction in overall HRV, with decreased indices of vagal activity (RMSSD, NN50, pNN50, HF, HF norm, and SD1) and increased indices of sympathetic activity (LF norm). The ANS balance indices were increased (LF/HF) and decreased (SD1/SD2), respectively. More importantly, although the diurnal and nocturnal trends of various HRV indices in the ultra-high plateau group were consistent with the plain group, the △HRV value analysis indicated that the ultra-high plateau group had increased △LF (95% CI: 10.20 to 271.60, P = 0.031) and △LF/HF (95% CI: -2.23 to -0.49, P < 0.001), and decreased △HF (95% CI: -383.10 to -35.50, P = 0.012) and △S (95% CI: -12149.47 to -2759.29, P = 0.001). Additionally, in the ultra-high plateau group, both the mean and minimum heart rates were elevated compared to the plain group (84.67 ± 1.37 vs. 73.2 ± 0.93 beats/min and 52.9 ± 1.37 vs. 47.57 ± 0.73 beats/min, respectively, P < 0.001), while the maximum heart rate was reduced (135.21 ± 1.63 vs. 144.43 ± 3.22 beats/min, P = 0.012). Furthermore, the ultra-high plateau group had a significant increase in the number of awakenings (18.27 ± 1.14 vs. 15.34 ± 1.43, P = 0.046) and the Apnea-Hypopnea Index (AHI) (20.14 ± 2.47 vs. 11.36 ± 0.76, P < 0.001).

Conclusion

Prolonged residence in the ultra-high plateau reduces HRV, cardiac reserve capacity, and sleep quality in healthy young adults, diminishes the diurnal recovery capacity of the vagal nerve, and leads to a shift in ANS balance towards reduced vagal activity and enhanced sympathetic activity.

Radiology AI Lab: Evaluation of Radiology Applications with Clinical End-Users

Despite the approval of over 200 artificial intelligence (AI) applications for radiology in the European Union, widespread adoption in clinical practice remains limited. Current assessments of AI applications often rely on post-hoc evaluations, lacking the granularity to capture real-time radiologist-AI interactions. The purpose of the study is to realise the Radiology AI lab for real-time, objective measurement of the impact of AI applications on radiologists' workflows. We proposed the user-state sensing framework (USSF) to structure the sensing of radiologist-AI interactions in terms of personal, interactional, and contextual states. Guided by the USSF, a lab was established using three non-invasive biometric measurement techniques: eye-tracking, heart rate monitoring, and facial expression analysis. We conducted a pilot test with four radiologists of varying experience levels, who read ultra-low-dose (ULD) CT cases in (1) standard PACS and (2) manually annotated (to mimic AI) PACS workflows. Interpretation time, eye-tracking metrics, heart rate variability (HRV), and facial expressions were recorded and analysed. The Radiology AI lab was successfully realised as an initial physical iteration of the USSF at a tertiary referral centre. Radiologists participating in the pilot test read 32 ULDCT cases (mean age, 52 years ± 23 (SD); 17 male; 16 cases with abnormalities). Cases were read on average in 4.1 ± 2.2 min (standard PACS) and 3.9 ± 1.9 min (AI-annotated PACS), with no significant difference (p = 0.48). Three out of four radiologists showed significant shifts (p < 0.02) in eye-tracking metrics, including saccade duration, saccade quantity, fixation duration, fixation quantity, and pupil diameter, when using the AI-annotated workflow. These changes align with prior findings linking such metrics to increased competency and reduced cognitive load, suggesting a more efficient visual search strategy in AI-assisted interpretation. Although HRV metrics did not correlate with experience, when combined with facial expression analysis, they helped identify key moments during the pilot test. The Radiology AI lab was successfully realised, implementing personal, interactional, and contextual states of the user-state sensing framework, enabling objective analysis of radiologists' workflows, and effectively capturing relevant biometrics. Future work will focus on expanding sensing of the contextual state of the user-state sensing framework, refining baseline determination, and continuing investigation of AI-enabled tools in radiology workflows.

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.

The use of heart rate variability, oxygen saturation, and anthropometric data with machine learning to predict the presence and severity of obstructive sleep apnea

Introduction

Obstructive sleep apnea (OSA) is a prevalent sleep disorder with a high rate of undiagnosed patients, primarily due to the complexity of its diagnosis made by polysomnography (PSG). Considering the severe comorbidities associated with OSA, especially in the cardiovascular system, the development of early screening tools for this disease is imperative. Heart rate variability (HRV) is a simple and non-invasive approach used as a probe to evaluate cardiac autonomic modulation, with a variety of newly developed indices lacking studies with OSA patients.

Objectives

We aimed to evaluate numerous HRV indices, derived from linear but mainly nonlinear indices, combined or not with oxygen saturation indices, for detecting the presence and severity of OSA using machine learning models.

Methods

ECG waveforms were collected from 291 PSG recordings to calculate 34 HRV indices. Minimum oxygen saturation value during sleep (SatMin), the percentage of total sleep time the patient spent with oxygen saturation below 90% (T90), and patient anthropometric data were also considered as inputs to the models. The Apnea-Hypopnea Index (AHI) was used to categorize into severity classes of OSA (normal, mild, moderate, severe) to train multiclass or binary (normal-to-mild and moderate-to-severe) classification models, using the Random Forest (RF) algorithm. Since the OSA severity groups were unbalanced, we used the Synthetic Minority Over-sampling Technique (SMOTE) to oversample the minority classes.

Results

Multiclass models achieved a mean area under the ROC curve (AUROC) of 0.92 and 0.86 in classifying normal individuals and severe OSA patients, respectively, when using all attributes. When the groups were dichotomized into normal-to-mild OSA vs. moderate-to-severe OSA, an AUROC of 0.83 was obtained. As revealed by RF, the importance of features indicates that all feature modalities (HRV, SpO2, and anthropometric variables) contribute to the top 10 ranks.

Conclusion

The present study demonstrates the feasibility of using classification models to detect the presence and severity of OSA using these indices. Our findings have the potential to contribute to the development of rapid screening tools aimed at assisting individuals affected by this condition, to expedite diagnosis and initiate timely treatment.

Self-compassion modulates autonomic and psychological responses to stress among adults with generalized anxiety disorders

Background

Self-compassion is associated with emotional well-being, yet its benefits in generalized anxiety disorder (GAD) patients remain unclear. This study investigated the impact of self-compassion on emotional and physiological stress responses in individuals diagnosed with GAD.

Methods

Seventy-seven GAD patients were categorized into high (n = 39) and low (n = 38) self-compassion groups using the Self-Compassion Scale. Electrocardiograms were recorded during a stress-inducing task, in which negative feedback was provided on personal intelligence and career development. Participants reported state anxiety and perceived stress pre- and post-task.

Results

When exposed to a stressor, individuals with higher self-compassion had lower heart rates (t (75) = -2.06, p = 0.043), higher heart rate variability (t (75) = 2.73, p = 0.04), and lower anxiety (t (75) = -2.07, p = 0.041) compared to the lower self-compassion group. Moreover, heart rate variability was negatively correlated with anxiety across patients (r = -0.31, df = 75, p = 0.03).

Conclusion

These results highlight the role of self-compassion in managing psychological and physiological responses to stress in GAD patients and indicate the potential of self-compassion interventions in GAD treatments.

Identifying Cardiovascular Risk by Nonlinear Heart Rate Dynamics Analysis: Translational Biomarker from Mice to Humans

BACKGROUND

The beat-by-beat fluctuation of heart rate (HR) in its temporal sequence (HR dynamics) provides information on HR regulation by the autonomic nervous system (ANS) and its dysregulation in pathological states. Commonly, linear analyses of HR and its variability (HRV) are used to draw conclusions about pathological states despite clear statistical and translational limitations.

OBJECTIVE

The main aim of this study was to compare linear and nonlinear HR measures, including detrended fluctuation analysis (DFA), based on ECG recordings by radiotelemetry in C57BL/6N mice to identify pathological HR dynamics.

METHODS

We investigated different behavioral and a wide range of pharmacological interventions which alter ANS regulation through various peripheral and/or central mechanisms including receptors implicated in psychiatric disorders. This spectrum of interventions served as a reference system for comparison of linear and nonlinear HR measures to identify pathological states.

RESULTS

Physiological HR dynamics constitute a self-similar, scale-invariant, fractal process with persistent intrinsic long-range correlations resulting in physiological DFA scaling coefficients of α~1. Strongly altered DFA scaling coefficients (α ≠ 1) indicate pathological states of HR dynamics as elicited by (1) parasympathetic blockade, (2) parasympathetic overactivation and (3) sympathetic overactivation but not inhibition. The DFA scaling coefficients are identical in mice and humans under physiological conditions with identical pathological states by defined pharmacological interventions.

CONCLUSIONS

Here, we show the importance of tonic vagal function for physiological HR dynamics in mice, as reported in humans. Unlike linear measures, DFA provides an important translational measure that reliably identifies pathological HR dynamics based on altered ANS control by pharmacological interventions. Central ANS dysregulation represents a likely mechanism of increased cardiac mortality in psychiatric disorders.

Acute effects of commercial group exercise classes on arterial stiffness and cardiovagal modulation in healthy young and middle-aged adults: A crossover randomized trial

BACKGROUND

Arterial stiffness and cardiac autonomic function are crucial indicators of cardiovascular health. Acute exercise and age impact these parameters, but research often focuses on specific exercise activities, lacking ecological validity.

METHODS

We examined the acute effects of commercially available group fitness classes (indoor cycling, resistance training, combined exercise) on arterial stiffness and vagal-related heart rate variability (HRV) indices in twelve young and twelve middle-aged adults. Participants attended four sessions, including exercise and control conditions, with measurements taken at rest and during recovery.

RESULTS

Middle-aged, but not young adults, showed reductions in central and peripheral systolic blood pressure 20-min into recovery across all exercise modalities (range: -7 to -8 mmHg p < 0.05). However, arterial stiffness remained unchanged. Similarly, vagal-related HRV indices (range: -0.51 to -0.90 ms, p < 0.05) and BRS (-4.03, p < 0.05) were reduced immediately after exercise, with differences persisting 30 min into recovery only after indoor cycling. Resistance and combined exercise elicited similar cardiovagal modulation and delayed baroreflex sensitivity recovery to cycling exercise, despite higher energy expenditure during indoor cycling (+87 to +129 kcal, p < 0.05).

CONCLUSION

Acute group fitness classes induce age-dependent alterations in blood pressure, but not in arterial stiffness or cardiovagal modulation. While the overall cardiovascular effects were generally consistent, differences in autonomic recovery were observed between exercise modes, with prolonged effects seen after indoor cycling. This suggests that exercise prescription should consider both age and exercise modality, as well as recovery time. The findings also emphasize the importance of ecological validity in exercise interventions, highlighting that acute effects on cardiovascular health in real-world settings may differ from those observed in controlled laboratory environments (ID: NCT06616428).

The Effect of Electroencephalographic Biofeedback Therapy on Anxiety and Overall Well-being in Patients with Rectal Cancer

This study aimed to investigate the effectiveness of electroencephalographic (EEG) biofeedback therapy in reducing anxiety levels and improving overall well-being among patients diagnosed with rectal cancer. A randomised controlled trial was conducted with 150 patients with rectal cancer who were randomly assigned to either the intervention group (n = 75) or the control group (n = 75). The intervention group received 16 sessions of EEG biofeedback therapy over 8 weeks, whereas the control group received standard care. Anxiety levels were assessed using the State-Trait Anxiety Inventory at baseline, post-intervention, 3-month follow-up, 6-month follow-up and 12-month follow-up. Secondary outcomes, including quality of life, sleep quality, treatment adherence, cortisol levels and heart rate variability (HRV), were also evaluated. The intervention group showed significant reductions in state anxiety (p < 0.001) and trait anxiety (p < 0.001) compared with the control group at all post-intervention time points. Significant improvements were also observed in the intervention group for quality of life (p < 0.001), sleep quality (p < 0.001), treatment adherence (p < 0.001), cortisol levels (p < 0.01) and HRV (p < 0.01). The effects were maintained at the 12-month follow-up. Electroencephalographic biofeedback therapy is an effective non-pharmacological intervention for reducing anxiety levels and improving overall well-being in patients with rectal cancer. The findings suggest that incorporating EEG biofeedback therapy into the standard care of patients with rectal cancer may enhance their psychological well-being, quality of life, sleep quality, treatment adherence, physiological stress responses and autonomic function. Long-term benefits were observed, indicating the sustainability of the intervention's effects. Further research is warranted to investigate the underlying mechanisms and potential applications of EEG biofeedback therapy in other cancer populations.

The Effects of Commando Training on Stress, Cognitive Performance, and Group Behavior in Military Personnel: An Exploratory Study

BACKGROUND

Military personnel are exposed to a high level of operational stress that degrades their psychophysiological and cognitive performance and could impact the mission. Commando training is a unique opportunity to assess psychological, physiological, and cognitive performance in an ecological setting.

METHODS

Psychological, physiological, and cognitive performance were evaluated at baseline, and before and after a 1-week commando training course consisting of exercises and night walks. Psychological factors (anxiety, subjective stress), physiological measures (heart rate variability, electrodermal conductance), cognitive behavior (cognitive bias, risk-taking, decision-making), and cognitive performance (the MindPulse neurophysiological test) were assessed. Volunteers were 39 young (mean age 21.6 years) French army officers.

RESULTS

Blind spot bias was found in all participants before training, except for the action-inaction bias. We observed a deterioration in parasympathetic functioning (Root Mean Square of Successive Differences, P = .05), an increase in subjective fatigue (P < .001), and impaired cognitive performance: reaction time (P = .02, F = 5.77), errors (P = .03, F = 4.97). Post-training, we observed an emerging group dynamic, notably an increase in avoidance (buck-passing) (P = .002, F = 10,43), a reduction of the action-inaction bias (P = .009, F = 7.59), ostrich effect (P = .008, F = 7.83) and stereotyping bias (P = .03, F = 5.11).

CONCLUSION

Commando training increases stress and impacts the cognitive performance of military personnel. Pre-deployment preparation could consider the need for physiological recovery, and the impact of deployment on cognitive performance.

Heart rate variability as an early predictor for children with SARS-CoV-2-associated encephalopathy

BACKGROUND

Although encephalopathy and encephalitis are uncommon complications of SARS-CoV-2 infection in children, they can lead to significant morbidity and mortality. Therefore, the aim of the study is to assess heart rate variability in children with SARS-CoV-2 infection and determine those at risk of progressing to SARS-CoV-2-associated encephalopathy.

METHODS

Children with confirmed SARS-CoV-2 infection between September 1, 2022 and December 8, 2023 were prospectively enrolled and divided into encephalopathic and non-encephalopathic groups. The non-encephalopathic group was further classified into mild, moderate, and severe/critical disease groups. One-minute electrocardiography was recorded on the first day of admission. Heart rate variability indices were compared between the encephalopathic and non-encephalopathic groups.

RESULTS

A total of 72 children (30 girls [41.7 %] and 42 boys [58.3 %]) with SARS-CoV-2 infection were enrolled, with age ranging from 1 month to 18 years. Of these children, 15 (20.8 %) were classified into the encephalopathic group, and 57 (79.2 %) were classified into the non-encephalopathic group. We compared heart rate variability indices and found that both time domain analysis (SDNNc and RMSSDc) and nonlinear Poincaré plot analysis (SD1/SD2 ratio) were lower in the encephalopathic group and severe/critical disease group than in the mild and moderate severity non-encephalopathic groups.

CONCLUSIONS

Heart rate variability parameters were significantly lower in the severe/critical disease group and the encephalopathic group compared to the mild to moderate severity groups. The implications of heart rate variability, particularly when considering neurological symptoms, as a predictor of disease progression to encephalopathy require further evaluation.

Distress detection in VR environment using Empatica E4 wristband and Bittium Faros 360

Introduction

Distress detection in virtual reality systems offers a wealth of opportunities to improve user experiences and enhance therapeutic practices by catering to individual physiological and emotional states.

Methods

This study evaluates the performance of two wearable devices, the Empatica E4 wristband and the Faros 360, in detecting distress in a motion-controlled interactive virtual reality environment. Subjects were exposed to a baseline measurement and two VR scenes, one non-interactive and one interactive, involving problem-solving and distractors. Heart rate measurements from both devices, including mean heart rate, root mean square of successive differences, and subject-specific thresholds, were utilized to explore distress intensity and frequency.

Results

Both the Faros and E4 sensors adequately captured physiological signals, with Faros demonstrating a higher signal-to-noise ratio and consistency. While correlation coefficients were moderately positive between Faros and E4 data, indicating a linear relationship, small mean absolute error and root mean square error values suggested good agreement in measuring heart rate. Analysis of distress occurrence during the interactive scene revealed that both devices detect more high- and medium-level distress occurrences compared to the non-interactive scene.

Discussion

Device-specific factors in distress detection were emphasized due to differences in detected distress events between devices.

Classifying metro drivers' cognitive distractions during manual operations using machine learning and random forest-recursive feature elimination

Metro drivers are more likely to trigger accidents if they suffer from cognitive distractions during manual driving. However, identifying metro drivers' cognitive distractions faces challenges as generally no obvious behavior can be found during the distractions. To address the challenge, this paper identifies metro drivers' cognitive distractions based on Electrocardiogram (ECG) signals collected by wearable devices in simulated driving experiments. The ECG signals are processed to generate ultra-short-term heart rate and heart rate variability (HR-HRV) features. The HR-HRV features are extracted by 30-s and 60-s time-windows in driving phase, and 25-s time-windows in parking phase, respectively. Machine learning approaches are developed to identify distractions (binary) and distinguish the degrees of distractions (multi-class). The optimal input features are determined by a random forest and recursive feature elimination (RF-RFE) algorithm. Results show that the DT with only one HR-HRV feature extracted from 30-s time-windows and XGBoost with 20 h-HRV features extracted from 60-s time-windows are optimal models for binary and multi-class classification for distractions during driving phase, respectively. The features including NN20, pNN20, SD1/SD2, Max-HR, Min-HR, and MEDNN are the most critical HR-HRV features associated with distractions. Cognitive distractions in parking phase are difficult to be detected using HR-HRV features.

An Integrated Platform Combining Immersive Virtual Reality and Physiological Sensors for Systematic and Individualized Assessment of Stress Response (bWell): Design and Implementation Study

BACKGROUND

Stress is a pervasive issue in modern society, manifesting in various forms such as emotional, physical, and work-related stress, each with distinct impacts on individuals and society. Traditional stress studies often rely on psychological, performance, or social tests; however, recently, immersive virtual reality (VR), which provides a sense of presence and natural interaction, offers the opportunity to simulate real-world tasks and stressors in controlled environments. Despite its potential, the use of VR to investigate the multifaceted manifestations of stress has not been thoroughly explored.

OBJECTIVE

This study aimed to explore the feasibility of using a VR-based platform, bWell, to elicit multifaceted stress responses and measure the resulting behavioral and physiological changes. Specifically, we aimed to design various VR stress exercises based on neurocardiac models to systematically test cardiac functioning within specific contexts of self-regulation (executive functioning, physical efforts, and emotional regulation).

METHODS

The development process adhered to guidelines for VR clinical trials and complex health interventions, encompassing 3 phases: preparation, development, and verification. The preparation phase involved a comprehensive literature review to establish links between stress, the heart, and the brain, leading to the formulation of a conceptual model based on the Neurovisceral Integration Model (NVIM) and Vagal Tank Theory (VTT). The development phase involved designing VR exercises targeting specific stressors and integrating physiological sensors such as photoplethysmography (PPG) and electromyography (EMG) to capture heart rate variability (HRV) and facial expressions. The verification phase, conducted with a small number of trials, aimed to design a study and implement a workflow for testing the feasibility, acceptability, and tolerability of the VR exercises. In addition, the potential for capturing physiological measures along with subjective ratings of stress for specific dimensions was assessed.

RESULTS

Verification trials demonstrated that the VR exercises were well tolerated, with negligible cybersickness and high user engagement. The different VR exercises successfully elicited the intended stress demands, along with the physiological responses.

CONCLUSIONS

The study presents a novel VR-based experimental setup that allows a systematic and individualized assessment of stress responses, paving the way for future research to identify features that confer stress resilience and help individuals manage stress effectively. While our conceptual model highlights the role of HRV in providing valuable insights into stress responses, future research will involve multivariate and machine learning analyses to predict individual stress responses based on comprehensive sensor data, including EMG and the VR-based behavioral data, ultimately guiding personalized stress management interventions.

Physical activity, fitness, and cardiac autonomic function among adults born postterm

Recent studies have suggested that adverse outcomes of postterm birth (≥42 completed weeks of gestation), including increased cardiometabolic risk factors, impaired glucose metabolism, and obesity, may extend into adulthood. We studied interconnected determinants of cardiovascular health, including physical activity (PA; based on accelerometry for 2 weeks), muscular strength (measured by handgrip strength), cardiorespiratory fitness (CRF; measured by 4-min step test), and cardiac autonomic function (heart rate [HR] recovery, HR variability, and baroreflex sensitivity) among 46-year-old adults from the Northern Finland Birth Cohort born postterm (n = 805) and at term (n = 2645). Adults born postterm undertook vigorous PA 2.0 min day-1 (95% CI, 0.4-3.7) less than term-born adults when adjusted for sex, age, and maternal- and pregnancy-related covariates in multiple linear regression. Postterm birth was associated with reduced CRF, based on a higher peak HR (2.1 bpm; 95% CI, 0.9-3.4) and slower HR recovery 30 s after the step test (-0.7 bpm; 95% CI, -1.3 to -0.1). Postterm birth was associated with less PA of vigorous intensity and CRF and slower HR recovery in middle age. Our findings reinforce previous suggestions that postterm birth should be included as a perinatal risk factor for adult cardiometabolic disease.

'Hidden' anger as a risk factor for operational health: An exploratory approach among French military personnel

Military personnel are repeatedly exposed to multiple stressors, and are sometimes characterized by high levels of anger. Evidence suggests that this anger can become dysfunctional, and impact the health status of populations chronically exposed to stress. In particular, rumination (understood as perseverative thoughts about a past event), provides a theoretical framework for investigating how anger may impact stress regulation abilities in military personnel declared fit for deployment. This exploratory study aimed therefore to examine the impact of the anger profile on psychological suffering in terms of burnout and post-traumatic stress disorder (PTSD), along with the reactivity of the autonomic nervous system, measured as cardiac variability. One hundred and seventeen French soldiers were tested before deployment to Operation BARKHANE. Anger rumination, burnout, and PTSD symptoms were assessed using questionnaires, and cardiac variability was measured as the questionnaires were completed. The results revealed two profiles related to anger trait and anger rumination. Burnout and PTSD scores were higher among military personnel with high levels of anger trait and rumination, and this group also had lower parasympathetic activity and flexibility after completing the questionnaires. These results suggest that there may be a link between an angry profile and psychological suffering, notably burnout and PTSD. Rumination could be involved in this link, as it is associated with poor adaptation to stress in a military context. Prospective researches including post-deployment will establish whether this ruminative response can account for the relationship between problematic anger, stress regulatory capacities and psychological health in military populations.

Diaphragmatic Breathing Interfaces to Promote Relaxation for Mitigating Insomnia: Pilot Study

BACKGROUND

Brief behavioral treatment for insomnia is an effective short-term therapy focusing on stimulus control and sleep restriction to enhance sleep quality. As a crucial part of this therapy, diaphragmatic breathing is often recommended when patients fail to fall asleep within 30 minutes. With the rise of health apps and gamification, these tools are increasingly seen as effective ways to boost self-efficacy and user engagement; however, traditional games tend to increase attention, which can negatively impact sleep and contradicts the aim of sleep therapy. This study thus explored the potential for gamification techniques to promote relaxation without disrupting sleep processes.

OBJECTIVE

The study developed 4 breathing guidance mechanisms, ranging from concrete to abstract: number countdown, zoom-in/out, up/down, and color gradients. The objective was to explore the relationship between game mechanics, cognitive load, relaxation effects, and attention as well as to understand how different designs impact users with varying levels of insomnia.

METHODS

The study was conducted in 2 phases. The first phase involved a questionnaire on the 4 guidance mechanisms. In the second phase, 33 participants classified by insomnia severity completed a Sleep Self-Efficacy Scale. They then engaged in 5 minutes of diaphragmatic breathing using each of the 4 interfaces. Relaxation effects were measured using heart rate variability via a smartwatch, attention and relaxation levels via an electroencephalogram device, and respiratory rate via a smartphone. Participants also completed the Game Experience Questionnaire and NASA Task Load Index, followed by user interviews.

RESULTS

The results indicated that competence, immersion, and challenge significantly influenced cognitive load. Specifically, competence and immersion reduced cognitive load, while challenge, negative affect, and positive affect were correlated with relaxation. Negative affect showed a positive correlation with the mean root mean square of successive differences, while positive affect exhibited a negative correlation with the mean root mean square of successive differences. Cognitive load was found to affect both relaxation and attention, with a negative correlation between mental demand and attention and a positive correlation between temporal demand and respiratory rate. Sleep self-efficacy was negatively correlated with temporal demand and negative affect and positively correlated with competence and immersion.

CONCLUSIONS

Interfaces offering moderate variability and neither overly abstract nor too concrete guidance are preferable. The up/down interface was most effective, showing the best overall relaxation effect. Conversely, the number countdown interface was stress-inducing, while the zoom-in/out interface had a significant impact on insomnia-related issues, making them less suitable for insomnia-related breathing exercises. Participants showed considerable variability in their response to the color gradient interface. These findings underscore the importance of carefully considering game design elements in relaxation training. It is essential that breathing guidance designs account for the impact of the game experience to effectively promote relaxation in users.

Vascular mechanoreceptor magnetic activation, hemodynamic evidence and potential clinical outcomes

There is sufficient proof that static magnetic fields (SMFs) of different parameters have a significant effect on the cardiovascular system. The sometimes contradictory, opposite-directional nature of SMF's hemodynamic effect generates uncertainty; therefore, an explanation of the underlying mechanisms is required. Following SMF selective carotid baroreceptors or microvascular net exposure, both high and low blood pressure (BP)/vascular tone starting conditions showed a return to normal. Beyond the previous descriptions of SMF's simple hemodynamic results, the current study aims to clarify the physiology of the SMF BP/vascular tone normalizing effects. The examination of available literature and hemodynamic tracings provided strong evidence that mechanoreceptor magnetic activation is concealed behind SMF vascular tone adjustment (increasing or decreasing as needed), filling in the knowledge gap regarding SMF opposite directional vascular tone normalizing outcomes. It has been proposed that cytoskeletal actin filament rearrangement, mechanically-gated Ca2+ influx, and nitric oxide (NO) activity may strengthen SMF's vascular mechanoreceptor sensing/regulation ability, modifying BP and vascular tone features in a hemodynamic normalizing pattern. It is suggested that baro/mechanoreceptor magnetic activation physiology is a unique mechanism of the magneto-cardiovascular interaction with substantial potential for cardiovascular protection.

Acute psychological stress does not influence joint position reproduction performance in the elbow joint

BACKGROUND

Proprioceptive accuracy is an important aspect of motor functioning thus understanding how the stress response affects it can broaden our knowledge about the effects of stress on motor performance. There has been published only one quasi-experimental study on this topic to date, reporting a negative association between stress and proprioceptive accuracy. The aim of the present study was to explore whether the stress response influences proprioceptive accuracy in a randomized and controlled experimental setting.

METHOD

Participants (Mage =  20.4 yrs, SDage =  1.91 yrs) were randomly assigned to a stress (n =  29) and a control (n =  28) group. Psychological stress was induced via an online quiz involving time pressure and instant feedback on performance. Participants' perceived (state anxiety) and physiological (heart rate, heart rate variability, skin conductance level) stress response and proprioceptive accuracy (the active and passive version of the Joint Position Reproduction test for the elbow joint) were measured before and after the experimental manipulation.

RESULTS

The quiz substantially increased only participants' perceived stress however, proprioceptive accuracy was not impacted by the experimental manipulation.

CONCLUSION

Perceived stress does not impact proprioceptive accuracy.