The physiological effects of slow breathing in the healthy human

Camera-based evaluation of deep breathing effects on plantar foot microcirculation - A pilot study on young healthy

BACKGROUND

Microvascular function, particularly of the plantar foot, reflects overall vascular health and is influenced by physiological oscillators such as heart rate, respiratory, myogenic, and neurogenic rhythms. Slow deep breathing modulates autonomic nervous system activity and affects peripheral microcirculation. This study investigates the effects of slow deep breathing on plantar foot perfusion using photoplethysmography imaging (PPGI).

METHODS

Twenty healthy young adults participated in a four-stage protocol: baseline, deep breathing test (DBT), and two recovery stages (REST1 and REST2). PPGI was used to measure changes in plantar foot perfusion, focusing on energy, amplitude, and phase synchronization within frequency bands corresponding to key physiological oscillators. Time-frequency analyses and advanced signal processing were applied to assess these parameters.

RESULTS

Significant increases in energy were observed in all frequency bands during DBT, with slow frequency oscillators (SFOs) maintaining elevated activity up to 5 min after DBT. Amplitude analysis revealed a significant decrease in the first and second harmonic components of the heart rate signals during DBT. Phase synchronization between medial and lateral foot regions improved for respiratory, myogenic, and neurogenic frequency bands during DBT, with myogenic synchronization persisting for up to 2.5 min after DBT.

CONCLUSIONS

Slow deep breathing enhances microvascular perfusion and synchronizes autonomic oscillators in healthy individuals. PPGI proved effective in capturing these dynamics, indicating its potential as a non-invasive tool for assessing autonomic and microvascular function. Future research should explore its applicability in detecting early autonomic or vascular dysfunction in clinical populations.

Breathe better, live better: the science of slow breathing and heart rate variability

BACKGROUND

Slow breathing and heart rate variability (HRV) biofeedback have gained attention as non-invasive methods for enhancing autonomic regulation and promoting vagal tone. These techniques are associated with improvements in cardiovascular, respiratory, and neural outcomes, offering potential therapeutic applications for stress-related and chronic conditions.

METHODS

A scoping review was conducted by analyzing six studies focusing on slow breathing and HRV biofeedback. The included studies involved healthy adults aged between 18 and 60 years, free from major cardiovascular, respiratory, or neurological disorders. Studies were identified through systematic searches in MEDLINE (PubMed), Scopus, Web of Science, and other databases. Population characteristics, intervention protocols, and outcomes related to HRV, respiratory sinus arrhythmia (RSA), baroreflex sensitivity, and neural synchronization were extracted and synthesized. Interventions were applied both acutely (single or short-term sessions) and chronically (ranging from daily sessions over 4-8 weeks).

RESULTS

All six studies demonstrated significant improvements in HRV parameters, particularly the high-frequency (HF) band, reflecting enhanced parasympathetic activity. RSA increased significantly in studies utilizing tailored breathing patterns, especially those emphasizing longer exhalations. Baroreflex sensitivity improved in interventions combining HRV biofeedback and slow breathing, indicating better cardiovascular adaptability. One study reported neural synchronization between HRV and cortical potentials with decelerated breathing. Across studies, these interventions promoted relaxation, enhanced autonomic flexibility, and stabilized cardiovascular function. Autonomic flexibility refers to the dynamic ability of the autonomic nervous system to adapt to internal and external stressors by shifting between sympathetic and parasympathetic dominance.

CONCLUSIONS

Slow breathing and HRV biofeedback are effective, non-invasive interventions for improving autonomic regulation, vagal tone, and stress resilience. These techniques hold promise for managing chronic conditions and enhancing cardiovascular and mental health. Standardization of protocols and long-term evaluations are needed to optimize clinical implementation.

Decreased CO2 saturation during circular breathwork supports emergence of altered states of consciousness

Altered states of consciousness (ASCs), induced e.g. during psychedelic-assisted therapy, show potential to treat prevalent mental health disorders like depression and posttraumatic stress disorder. However, access to such treatments is restricted by legal, medical, and financial barriers. Circular breathwork may present a non-pharmacological and hence more accessible alternative to engage similar therapeutic processes. Scientific studies of breathwork are only just emerging and its physiological and psychological mechanisms are largely unknown. Here, we track physiological and experiential dynamics throughout a breathwork session, comparing two forms of breathwork: Holotropic and Conscious-Connected breathwork. We show that a reduction in end-tidal CO2 pressure due to deliberate hyperventilation is significantly correlated to ASC onset (r = -0.46; p < 0.001). Based on standard questionnaires (MEQ-30 and 11-DASC), the ASCs evoked by breathwork resembled those produced by psychedelics across several experiential domains such as ego dissolution, and their depth predicted psychological and physiological follow-on effects, including improved well-being and reduced depressive symptoms. Further analysis showed that different breathwork approaches produced highly similar outcomes. Our findings identify physiological boundary conditions for ASCs to arise in a non-pharmacological context, shedding light on the functional mechanisms of breathwork as well as its potential as a psychotherapeutic tool.

A proof of concept study on digital interventions for reducing socio-evaluative stress and anxiety in youth

Youth often struggle with heightened sensitivity to social judgement, increasing their vulnerability to fear in social situations. This study investigates brief digital interventions aimed at regulating cognitive and affective disturbances related to social anxiety, specifically focusing on fear responses in a social-evaluative threat context. One-hundred-twenty healthy youth were randomly assigned to one of four conditions: attention training, detached mindfulness, slow breathing, or an active control condition. To induce social-evaluative threat, participants delivered a public speech after a 12-min video intervention. We assessed subjective anxiety levels, metacognition, heart rate variability (HRV), and subjective and objective performance ratings throughout the experiment. Results indicated that the slow breathing intervention significantly increased HRV immediately after the intervention, during the public speaking task, and during the recovery and reduced state anxiety immediately after the intervention. In contrast, attention training and detached mindfulness did not yield significant effects, although detached mindfulness did increase HRV immediately post-intervention. These preliminary findings suggest that brief digital interventions, especially slow breathing, may effectively alleviate fear responses in youth during social-evaluative contexts, highlighting their potential as accessible support tools.

Autonomic Nervous System Control in Male and Female Elite Soccer Players: Importance of Different Training Routines and Perceived Stress

The assessment of cardiac autonomic regulation (CAR) with non-invasive techniques, such as heart rate variability (HRV), might be of practical interest in elite sports, considering its importance in determining training. We studied 117 soccer players (74 male and 43 female) from three First Division European soccer teams. We used a ranked Autonomic Nervous System Index (ANSI, resulting from the combination of multivariate statistical methodologies applied to HRV-derived indices) to assess CAR. We hypothesized that ANSI might differentiate playing positions, considering goalkeepers, defenders, midfielders, and forwards. We also assessed the perception of somatic symptoms and stress. We observed in male athletes that ANSI was significantly greater in males as compared to females (p < 0.001), being higher in midfielders and defenders (p = 0.035), who usually sustain the greatest external load. Interestingly, this result was not observed in female athletes, who, instead, reported a significantly higher perception of somatic symptoms (p = 0.018) and stress (p = 0.049), the latter being particularly high in midfielders and forwards (p = 0.045). This approach might represent a convenient model to study the effects of long-term physical exercise on CAR in soccer, even to unveil possible differences due to sex, different playing positions characterized by distinct exercise routines, or stress perception.

Advanced and long-term meditation and the autonomic nervous system: A review and synthesis

Meditation has become prominent in both clinical and non-clinical applications for its effects on psychological and physical well-being. Long-term meditators, who have dedicated extensive time to their practice, present a unique opportunity to explore the effects of prolonged meditation training on the autonomic nervous system. Research has reported concomitant activation of both sympathetic (aroused) and parasympathetic (relaxed) branches of the autonomic nervous system during some forms of meditation, leading to the term 'relaxed alertness.' However, findings are not consistent, with reports of both sympathetic and parasympathetic activation, sympathetic-only, parasympathetic-only, or temporally variable activations, depending on several factors. This review synthesizes these heterogeneous and seemingly inconsistent results in relation to three explanatory factors: (1) specific classification of style or type of meditation; (2) specific definition of the level of expertise of the meditators; and (3) intra-individual variations within a given meditation practice. When these factors are considered, convergent and meaningful patterns emerge, allowing for a shift from the broad notion of 'long-term' meditation to a more precise characterization of 'advanced' meditation, highlighting skills, states, and stages of mastery developed over time. Our synthesis is particularly useful for understanding both long-term and advanced meditation, as it reveals specific heart rate variability patterns, including very low and low-frequency spectral power peaks, along with cardiac and respiratory coupling. Better characterization of the role of the autonomic nervous system in the context of advanced meditation promises to inform improved meditation training, including training assisted by technology, toward more impactful outcomes.

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 a 12-week lower limb resistance training with breathing regulation in patients with diabetes-related foot ulcers: A randomized controlled trial

Patients with diabetes-related foot ulcers may require hospitalization and face an increased risk of amputation, which can significantly impact their quality of life. One potential solution is exercise, which can regulate blood glucose levels, improve wound healing, and enhance overall well-being. This randomized controlled trial aimed to evaluate the impact of a lower limb resistance training program combined with breathing-regulation techniques on glycemic control, wound healing, and quality of life in patients with diabetes-related foot ulcers. Patients hospitalized for type 2 diabetes-related foot ulcers were recruited from a single medical center and randomly divided into two groups. The control group (n = 31) received standard treatment, while the exercise group (n = 28) received standard treatment along with lower limb resistance training and breathing-regulation techniques. Assessments of fasting blood glucose levels, hemoglobin A1c (HbA1c) levels, wound healing, and quality of life were carried out at the start of the study and week 4, week 8, and week 12 of the intervention. The exercise group demonstrated significant improvements in fasting blood glucose and HbA1c levels, as well as in physical health, psychological well-being, social relationships, and environmental aspects of quality of life over the 12 weeks compared to both the control group and the baseline (p < .05). However, no significant change was observed in wound healing (p > .05). The resistance training program for the lower limbs, combined with breathing-regulation techniques, is recommended for improving blood glucose levels and quality of life over 12 weeks.

The Constrained Disorder Principle: Beyond Biological Allostasis

The constrained disorder principle (CDP) defines complex biological systems based on inherent variability. Allostasis refers to the physiological processes that help maintain stability in response to changing environmental demands. Allostatic load describes the cumulative wear and tear on the body resulting from prolonged exposure to stress, and it has been suggested to mediate the relationship between stress and disease. This study presents the concepts of CDP and allostasis while discussing their similarities and differences. We reviewed the current literature on the potential benefits of introducing controlled doses of biological noise into interventions, which may enhance the effectiveness of therapies. The paper highlights the promising role of variability provided by a CDP-based second-generation artificial intelligence system in improving health outcomes.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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

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

METHODS

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

RESULTS

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

CONCLUSION

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

Changes in cognition, coping, pain and emotions after 12-months access to the digital self-management program EPIO

Background

Psychosocial pain self-management interventions can be of support for people living with chronic pain. Since psychosocial support is not always accessible, digital health interventions may increase outreach of these types of evidence-based interventions.

Objectives

To explore participants' experiences from 12-month access to the digital pain self-management program EPIO, particularly in terms of any behavioral and/or psychological changes experienced.

Methods

Participants (N = 25) engaged in individual semi-structured interviews following 12-month access to the EPIO intervention. Qualitative thematic analyses were conducted seeking to identify any behavioral and/or psychological changes experienced through intervention use, and what contributed to these changes.

Results

Participants were predominantly women (72%), median age 46 (range 26-70), with a range of self-reported pain conditions and the majority reporting pain duration >10 years (64%). Analyses identified three main themes and subsequent sub-themes: (1) Changes in Cognition; insight and self-awareness, acceptance and shifting focus, (2) Changes in Coping; pain, emotions, and activity pacing, and (3) Content and Functionality Specific Engagement; breathing and other mind-body exercises, thought-reflection exercises, and functionalities.

Conclusions

People with chronic pain experienced positive behavioral and/or psychological changes in terms of cognition and coping after 12 months access to the EPIO digital pain self-management program. The most prominent changes included increased understanding of the connection between own thoughts, feelings, and behavior, gaining concrete strategies to cope with everyday life living with pain, and utilizing these strategies to reduce pain and interference of pain, as well as to improve emotion regulation and psychological wellbeing.

The impact of alternate nostril breathing on the severity and frequency of migraine attacks: a randomized control trial

BACKGROUND

Migraine is a prevalent and debilitating neurological disorder that significantly affects quality of life. While pharmacological treatments exist, they can have limitations such as side effects, contraindications, and incomplete relief, prompting interest in non-pharmacological approaches for better symptom management.

OBJECTIVE

This study aimed to assess the effectiveness of alternate nostril breathing (ANB) as a non-pharmacological intervention to reduce the frequency and severity of migraine attacks and associated disability in adult patients.

METHODS

A single-center, open-label, two-arm, parallel-group randomized controlled trial was conducted at six Family Health Centers (FHCs) of Dokuz Eylul University, Izmir, Turkey. A total of 86 migraine patients aged 18-50 years, diagnosed with migraine based on ICD-10 criteria, were randomized into control (n = 43) and intervention (n = 43) groups. The intervention group practiced ANB three times daily for three months, while the control group continued their usual care. The primary outcomes were changes in migraine frequency and severity. Secondary outcomes included changes in migraine-related disability, both outcomes measured using the Migraine Disability Assessment Scale (MIDAS).

RESULTS

The intervention group showed a significant reduction in migraine attack frequency (P = 0.002) and MIDAS scores (P = 0.003) compared to the control group. Both groups experienced a reduction in attack severity (P = 0.001), though no significant difference was observed between the groups (P = 0.074). Within-group comparisons showed significant improvements in attack frequency, severity, and MIDAS scores in the intervention group (P = 0.001 for all).

CONCLUSION

ANB significantly reduced migraine frequency and disability, making it a promising non-invasive and accessible treatment option for migraine management. Further research with longer follow-up periods is needed to explore its long-term effects and broader applicability.

Prospective Evaluation of Autonomic Function and Intestinal Blood Flow in Health and Irritable Bowel Syndrome Shows Differences Limited to Patients With Constipation Predominance

BACKGROUND

Autonomic dysfunction may contribute to symptom generation in irritable bowel syndrome (IBS), possibly driven by psychological morbidity and activation of the hypothalamic-pituitary-adrenal axis. Previous data are conflicting, perhaps due to lack of accounting for differential bowel patterns in IBS (constipation vs. diarrhea) or by diverse methodologies used to measure autonomic function. Our aim was to determine if autonomic response differed between IBS subtypes and healthy controls.

METHODS

Forty female volunteers (20 IBS and 20 healthy) underwent comprehensive autonomic testing, fasting and postprandially, and in response to cold pressor and deep breathing challenges. Pulse transit time (PTT) and ultrasound measurements of intestinal blood flow were used as measures of systemic and local autonomic function, respectively. Outcomes were adjusted for baseline psychological comorbidities and gastric emptying (measured concurrently with scintigraphy).

KEY RESULTS

Findings, confined to IBS patients with predominant constipation (IBS-C), included (1) lower fasting and a trend to larger postprandial increase in superior mesenteric artery end-diastolic velocity; (2) lower fasting PTT, suggesting higher sympathetic tone, but no difference in postprandial PTT change; and (3) attenuated increase in postprandial aortic peak systolic velocity. Response to systemic autonomic challenges did not differ between IBS and health. Some psychological factors mediated differences between groups in the fasting, but not postprandial, state.

CONCLUSIONS AND INFERENCES

IBS-C patients display systemic and local autonomic imbalance providing some support for recent therapies aimed at modulating autonomic state specifically in this patient group (e.g., acustimulation).

Exhaled Breath Analysis: From Laboratory Test to Wearable Sensing

Breath analysis and monitoring have emerged as pivotal components in both clinical research and daily health management, particularly in addressing the global health challenges posed by respiratory and metabolic disorders. The advancement of breath analysis strategies necessitates a multidisciplinary approach, seamlessly integrating expertise from medicine, biology, engineering, and materials science. Recent innovations in laboratory methodologies and wearable sensing technologies have ushered in an era of precise, real-time, and in situ breath analysis and monitoring. This comprehensive review elucidates the physical and chemical aspects of breath analysis, encompassing respiratory parameters and both volatile and non-volatile constituents. It emphasizes their physiological and clinical significance, while also exploring cutting-edge laboratory testing techniques and state-of-the-art wearable devices. Furthermore, the review delves into the application of sophisticated data processing technologies in the burgeoning field of breathomics and examines the potential of breath control in human-machine interaction paradigms. Additionally, it provides insights into the challenges of translating innovative laboratory and wearable concepts into mainstream clinical and daily practice. Continued innovation and interdisciplinary collaboration will drive progress in breath analysis, potentially revolutionizing personalized medicine through entirely non-invasive breath methodology.

Clinical application of respiratory-gated auricular vagal afferent nerve stimulation

Vagus nerve stimulation (VNS) has garnered significant attention as a promising bioelectronic therapy. In recent years, respiratory-gated auricular vagal afferent nerve stimulation (RAVANS), a novel non-invasive vagus nerve stimulation technique, has emerged. RAVANS integrates respiration with transcutaneous auricular vagus nerve stimulation (taVNS) and shares a similar mechanism of action to traditional VNS. Similar to conventional Vagus Nerve Stimulation (VNS), RAVANS may mitigate brain injury through three primary pathways: reducing neuronal apoptosis, modulating neurotransmitter release, and influencing inflammatory factor pathways. In this paper, we emphasize how RAVANS enhances the activation of nucleus of the solitary tract （NTS）and the locus coeruleus by regulating the monoaminergic and GABA systems through respiratory control. Additionally, it leverages the beneficial effects of respiration on the central nervous system. In this review, we delineate the potential mechanisms of action of RAVANS, provide a comprehensive overview of its clinical applications in chronic low back pain, migraine, depression, hypertension, and cognitive disorders. Furthermore, we offer future perspectives on optimizing the parameters of RAVANS and its application in post-stroke dysphagia. This will pave the way for new avenues in RAVANS research.

Effects of Breathing Exercises on Neck Pain Management: A Systematic Review with Meta-Analysis

Background: Given the relationship between reduced pulmonary and respiratory muscle function in neck pain, incorporating breathing exercises into neck pain management may be beneficial. Purpose: The purpose of this study was to investigate the benefits of breathing exercises for treating neck pain. Methods: We searched PubMed (MEDLINE), PEDro, CINAHL, Scopus, and EMBASE databases, up to the 28 of February 2024. Randomized controlled trials evaluating the impact of breathing exercises on reducing pain and disability in both persistent and recent neck pain were selected. A meta-analysis was conducted for each outcome of interest; however, if quantitative methods were not possible, a qualitative synthesis approach was used. The risk of bias was assessed using the Cochrane RoB 2.0 Tool (version 22 August 2019). We used the GRADE approach to judge the certainty of the evidence. Results: Five studies were included. Meta-analysis showed a statistically significant reduction in pain (standardized mean difference (SMD), -10.16; 95% CI: -14.82, -5.50) and disability (SMD, -0.80; 95% CI: -1.49, -0.11), in favor of breathing exercises. Qualitative synthesis for pulmonary functional parameters resulted in a statistically significant improvement for FVC, MIP, MEP, and MVV, in favor of breathing exercises. Conclusions: Breathing exercises showed significant short-term effects in reducing pain and disability for persistent neck pain. They also provided benefits for functional respiratory parameters. However, the evidence certainty is low.

Peculiarities of cardio-respiratory relationships in qualified athletes with different types of heart rhythm regulation according to respiratory maneuver data

INTRODUCTION

Our goal was to determine the differences in changes in cardiovascular and cardiorespiratory interaction indicators during a respiratory maneuver with a change in breathing rate in athletes with different types of heart rate regulation.

METHODS

The results of a study of 183 healthy men aged 21.2 ± 2.3 years, who were systematically involved in various sports, were analyzed. According to the results of the analysis of the HRV study during spontaneous breathing, the athletes were divided into 4 groups taking into account the type of heart rate regulation (HRR). Group 1 (with type I) consisted of 53 people, group 2 (with type II)-29 people, group 3 (with type III)-85 people, group 4 (with type IV)-16 people. The methodology for studying the cardiorespiratory system included combined measurements of the respiratory and cardiovascular system activity indicators in a sitting position using a spiroarteriocardiorhythmograph. The duration of the study was 6 min.

RESULTS

According to changes in cardiorespiratory and cardiovascular interaction indicators during controlled breathing with a frequency of 6 and 15 per minute (CR6 and CR15), it is shown that with a pronounced predominance of parasympathetic influences (type IV) in conditions of excessive cardiorespiratory control and moderate hyperventilation, differences in changes in arterial baroreflex sensitivity (δBRLF and δBRHF) are noted in comparison with other HRR. Athletes with type IV at CR6 in δBRLF significantly differ from athletes with type III (p = 0.026) and do not differ from athletes with type II (p = 0.141). In δBRHF significantly (p = 0.038 and p = 0.043)-from athletes with types I and II. It is shown that with the predominance of sympathetic influences (types I and II), the reactivity of BRS (δBRLF and δBRHF) in response to moderate hyperventilation (CR15) is significantly lower. Changes in the Hildebrandt index and the volume synchronization index additionally differentiate HRR associated with a moderate and pronounced predominance of sympathetic and parasympathetic influences.

CONCLUSION

The use of a respiratory maneuver in a combined study of the cardiorespiratory system in the conditions of current control of athletes showed informativeness in the differentiation of HRR types and states of functional overstrain.

The Effect of Diaphragmatic Breathing as a Complementary Therapeutic Strategy in Stress of Children and Teenagers 6-18 Years Old

BACKGROUND

Few studies are reported on interventions that have been carried out in children and adolescents using diaphragmatic breathing (DB) together with methods like counseling, muscle relaxation, therapeutic exercise, and music therapy.

OBJECTIVE

The goal of the review is to evaluate the effectiveness of DB as complementary therapy in the stress of the pediatric population (6-18 years old).

METHODS

Detailed research was carried out in the current literature to find relevant studies published from 2010 to October 2024 in PubMed and Cochrane Library. Thirteen studies that fulfilled the inclusion criteria were included in the study. Nine studies involved obese and overweight pediatric populations and the other four involved pediatric patients.

RESULTS

The interventions comprised two 8-week studies in an obese pediatric population, seven studies in healthy children and adolescents with normal weight. The studies were based on DB, muscle relaxation, nutrition, counseling, music therapy, and slow breathing exercises. The participants in the intervention group improved in comparison to those in the control group in terms of stress and depression in most included studies, in terms of school performance in two studies, in terms of better family relationships in one study, and showed improvement in anthropometric indicators in two studies. In four studies that involved pediatric patients, stress and fear of medical procedures were reduced.

CONCLUSIONS

DB can effectively contribute on its own or in combination with other therapeutic methods to improving physiological and psychological indicators in the pediatric population. It is useful to integrate stress management programs that include DB training as clinical practice in primary healthcare and in school schedules for elementary and high-school students.

A pilot study of trauma-sensitive yoga and Breathe2Relax among service members in an intensive outpatient program

Emerging research indicates that yoga is a promising adjunct to psychological trauma treatment. The current pilot study examined the associations between psychophysiological stress, diaphragmatic breathing (DB), and a trauma-sensitive yoga (TSY) regimen developed specifically for trauma-exposed service members in alignment with recent calls for precision in reporting therapeutic yoga protocols. Participants were 31 service members enrolled in a trauma-focused intensive outpatient program (IOP). Service members participated in a brief diaphragmatic breathing (DB) session using the Breathe2Relax (B2R) app followed by the TSY session. Heart rate (HR) and perceived stress were measured at baseline and after both the DB practice and the TSY session. We assessed Yoga and DB expectancies at baseline and post TSY. Participants also rated the acceptability and usability of the B2R app. Results of linear mixed effects regression models showed decreases in HR and perceived stress, compared to baseline, following DB (HR, b = -8.68, CI 95% = -13.34, -4.02; perceived stress, b = -1.77, CI 95% = -2.35, -1.18) and TSY (HR, b = -12.44, CI 95% = -17.15, -7.73; perceived stress b = -3.69, CI 95% = -4.29, -3.08). Higher levels of expectancies, compared to lower levels, related to stronger decreases in HR and perceived stress, particularly after TSY. Overall, participants rated the B2R usability as high; virtually all participants reported that "most would learn to use the app quickly," and 76.6% reported that they would use it frequently.

Neurocardiology: Major mechanisms and effects

Neurocardiology is a broad interdisciplinary specialty investigating how the cardiovascular and nervous systems interact. In this brief introductory review, we describe several key aspects of this interaction with specific attention to cardiovascular effects. The review introduces basic anatomy and discusses physiological mechanisms and effects that play crucial roles in the interaction of the cardiovascular and nervous systems, namely: the cardiac neuraxis, the taxonomy of the nervous system, integration of sensory input in the brainstem, influences of the autonomic nervous system (ANS) on heart and vasculature, the neural pathways and functioning of the arterial baroreflex, receptors and ANS effects in the walls of blood vessels, receptors and ANS effects in excitable cells in the heart, ANS effects on heart rate and sympathovagal balance, endo-epicardial inhomogeneity, ANS effects with a balanced vagal and sympathetic stimulation, sympathovagal interaction, arterial baroreflex, baroreflex sensitivity and heart rate variability, arrhythmias and the arterial baroreflex, the cardiopulmonary baroreflex, the exercise pressor reflex, exercise-recovery hysteresis, mental stress, cardiac-cardiac reflexes, the cardiac sympathetic afferent reflex (CSAR), and neuromodulation. Also, the potential role of the discussed mechanisms in cardiovascular disorders will be touched upon.

From the latin "re-cordis, passing through the heart": autonomic modulation differentiates migraineurs from controls when recounting a significant life event

OBJECTIVE

The literature on clinical psychophysiology highlights the possibility of using Heart Rate Variability (HRV) as an index of psychophysical balance and resilience to stress. This study investigates the differences in stress reactivity and subsequent recovery between a group of migraineurs and healthy controls.

METHODS

Socio-demographic (i.e., sex, age, profession, marital status, and level of education) and psychophysiological (HR and HRV) measures of a group of thirty subjects with migraine (26 migraineurs without aura (86.7%), 2 migraineurs with aura (6.7%), and 2 migraineurs with and without aura (6.7%)) and from thirty healthy control subjects were collected. In particular, HRV was analyzed through frequency-domain parameters, including Low-Frequency (LF; 0.04-0.15 Hz) and High-Frequency (HF; 0.15-0.4 Hz) bands as well as LF/HF ratio during a Psychophysiological Stress Profile (PSP) structured in seven phases: (1) Baseline, (2) Objective stressor 1 (Stroop Test), (3) Rest 1, (4) Objective stressor 2 (Mental Arithmetic Task), (5) Rest 2, (6) Subjective stressor (recount a significant life event), and (7) Rest 3. The LF, HF, and LF/HF ratio values were transformed into a logarithmic scale (i.e., log-LF, log-HF, and log LF/HF ratio). Additionally, LF and HF were converted into normalized units (0-100) (i.e., LF% and HF%) which, in turn, were used to obtain reactivity and recovery to stress through delta values (Δ) calculation.

RESULTS

Subjects with migraine reported greater ΔLF% levels of reactivity and recovery to subjective stressor, demonstrating a prevalence of sympathetic activity while recounting a personal life event. At the same time, a lowering of the same values was found in the subjects of the group control.

DISCUSSION

Our results underline the importance of conducting a psychophysiological assessment in patients with headaches because reduced stress management skills could influence the clinical manifestations of the disease, considering stress as one of the most common triggers for migraine patients.

Towards constructing a generalized structural 3D breathing human lung model based on experimental volumes, pressures, and strains

Respiratory diseases represent a significant healthcare burden, as evidenced by the devastating impact of COVID-19. Biophysical models offer the possibility to anticipate system behavior and provide insights into physiological functions, advancements which are comparatively and notably nascent when it comes to pulmonary mechanics research. In this context, an Inverse Finite Element Analysis (IFEA) pipeline is developed to construct the first continuously ventilated three-dimensional structurally representative pulmonary model informed by both organ- and tissue-level breathing experiments from a cadaveric human lung. Here we construct a generalizable computational framework directly validated by pressure, volume, and strain measurements using a novel inflating apparatus interfaced with adapted, lung-specific, digital image correlation techniques. The parenchyma, pleura, and airways are represented with a poroelastic formulation to simulate pressure flows within the lung lobes, calibrating the model's material properties with the global pressure-volume response and local tissue deformations strains. The optimization yielded the following shear moduli: parenchyma (2.8 kPa), airways (0.2 kPa), and pleura (1.7 Pa). The proposed complex multi-material model with multi-experimental inputs was successfully developed using human lung data, and reproduced the shape of the inflating pressure-volume curve and strain distribution values associated with pulmonary deformation. This advancement marks a significant step towards creating a generalizable human lung model for broad applications across animal models, such as porcine, mouse, and rat lungs to reproduce pathological states and improve performance investigations regarding medical therapeutics and intervention.

Inspiration Time: The Ultrasound Variable Necessary to Study the Diaphragm Functionality. A Cross-Sectional Controlled Study

Introduction

The diaphragm is considered the main inspiratory muscle, and as such, its assessment is crucial in patients with respiratory pathology. It is known that the contractile capacity of a muscle is determined by strength, length, and the duration of contraction. Although transdiaphragmatic pressure is the gold standard test for its study, ultrasound has been confirmed as a useful tool in clinical practice. Thanks to it, both the strength (diaphragmatic thickness) and the length of movement (diaphragmatic excursion) can be evaluated. This study aims to investigate the relationship between the inspiratory time and the diaphragmatic contraction.

Design

Cross-sectional controlled study.

Methodology

Eighty healthy subjects, yoga practitioners, with no previous respiratory pathology participated in this study. They were asked to take three different types of deep breaths: diaphragmatic with nasal inspiration, pursed-lip inspiration, and ujjayi (nasal inspiration with slight contraction of the glottis). The variables of thickness, excursion, and inspiratory contraction time were taken for each of them by ultrasound.

Results

Diaphragmatic contraction time is the only variable that shows a significant correlation with the other two. Thus, the correlation between inspiratory time and diaphragmatic thickness is significant (p < .001) for the three breaths: diaphragmatic (0.60), ujjayi (0.67), and pursed lips (0.39) and the correlation between inspiratory time and diaphragmatic excursion is significant for diaphragmatic breaths (-0.24, p = .035) and ujjayi (0.27, p = .017), but not in pursed lips (-0.01, p = .90).

Conclusion

The inspiratory contraction time and the diaphragmatic excursion are two essential variables in the dynamic functional evaluation of the diaphragm, compared to the diaphragmatic thickness measurement that only reports its strength.

Body Positions and Physical Activity Levels Modulate the Ratio of Abdominal to Thoracic Breathing and Respiratory Rate in Young Individuals

Background/Objectives: The COVID-19 pandemic highlighted that body positions substantially affected the mortality rate. We hypothesized that body position modulates the contribution of abdominal (AB) and thoracic breathing (TB) to the breathing cycle (BC), as well as respiratory rate (RR). In addition, we hypothesized that physical activity level can increase the contribution of abdominal breathing. Methods: Thus, we used plethysmography respiratory belts to measure changes in abdominal (AB) and thoracic (TB) circumferences, their ratio (AB/TB), and respiratory rate (RR) under resting conditions. Measurements were taken in four body positions-standing (St), sitting (Si), supine (Su), and prone (Pr)-for two groups of young adults (aged 21 ± 2 years) with different physical activity levels (low and high PA). Results: The AB/TB ratios significantly differed between the body positions (Si: 45.5/54.5%, St: 40.5/59.5%, Su: 56.8/43.2%, Pr: 52.2/47.8% (p < 0.001)). AB was significantly the highest in Su and lowest in Si and St (p < 0.001). There was a significant difference in respiratory rate (RR) between the four body positions (p = 0.005). RR in the four body positions was the following: Si: 15.1, St: 15.0, Su: 13.7, and Pr: 14.4. RR was the lowest in Su (13.7), where AB was the highest (56.8%), and RR was the highest in Si (15.1) and St (15.0), where TB was higher compared to Su (p < 0.001). PA significantly affected the various body positions' AB/TB ratio and RR. The high PA group showed a significant difference in the AB/TB ratio between the body positions (p < 0.001). The low PA group showed a significant difference in RR between the body positions (p = 0.025). Conclusions: In young, healthy adults, we found that body position significantly influenced the abdominal/thoracic breathing ratio during the breathing cycle. The supine position showed the highest contribution of abdominal breathing, which correlated with the lowest respiratory rate. Additionally, a higher level of physical activity increased the contribution of abdominal breathing in the Si, Su, and St positions, suggesting a more energy-efficient breathing pattern. These findings suggest the potentials for breathing pattern monitoring and position-based interventions to improve healthcare outcomes and enhance sports performance and recovery.

Whole-Body Cold Stimulation Improves Cardiac Autonomic Control Independently of the Employed Temperature

Background/Objectives: The autonomic nervous system (ANS) is considered one of the mechanisms mediating the benefits of whole-body cold stimulation (WBC). Nevertheless, different treatment protocols, different methodologies employed to assess the ANS, and, in particular, difficulties in interpreting the numerous variables obtained represent important barriers to understanding the effects of WBC on the ANS. The present study aimed to explore the effects of WBC on cardiac autonomic control (CAR) as assessed using a single composite percentile-ranked proxy of autonomic balance (ANSI), considering two different WBC temperatures and the same WBC protocol. Methods: Heart rate variability (HRV) was employed to assess the ANS in 23 subjects with obesity who underwent 10 WBC sessions, studied before and after 2 min WBC at -55 °C (15 subjects) or 2 min WBC at -110 °C (8 subjects) both at the first session (T1) and the last one (T10). To overcome some important barriers in data interpretation and age/sex bias, we considered the Autonomic Nervous System Index (ANSI), a single composite percentile-ranked proxy of autonomic control. Results: We observed an improvement in CAR independently of the employed temperature. Both treatments, without distinction, caused a significant increase in the ANSI post-WBC treatment both at T1 and T10 and a significant betterment of the total power of the RR interval variability from pre- to post-treatment at T1 and overall from T1 to T10. Conclusions: WBC was capable of inducing an immediate change in the ANS control (pre- vs. post-treatment both at T1 and T10) and a long-term modulation in cardiac autonomic control (T1-pre vs. T10-pre).

Predictive Modeling of Heart Rate from Respiratory Signals at Rest in Young Healthy Humans

Biological signals such as respiration (RSP) and heart rate (HR) are oscillatory and physiologically coupled, maintaining homeostasis through regulatory mechanisms. This report models the dynamic relationship between RSP and HR in 45 healthy volunteers at rest. Cross-correlation between RSP and HR was computed, along with regression analysis to predict HR from RSP and its first-order time derivative in continuous signals. A simulation model tested the possibility of replicating the RSP-HR relationship. Cross-correlation results showed a time lag in the sub-second range of these signals (849.21 ms ± SD 344.84). The possible modulation of HR by RSP was mediated by the RSP amplitude and its first-order time derivative (in 45 of 45 cases). A simulation of this process allowed us to replicate the physiological relationship between RSP and HR. These results provide support for understanding the dynamic interactions in cardiorespiratory coupling at rest, showing a short time lag between RSP and HR and a modulation of the HR signal by the first-order time derivative of the RSP. This dynamic would optionally be incorporated into dynamic models of resting cardiopulmonary coupling and suggests a mechanism for optimizing respiration in the alveolar system by promoting synchrony between the gases and hemoglobin in the alveolar pulmonary system.

A slow diaphragmatic breathing intervention for anxiety: How do respiration rate and inhalation/exhalation ratio influence self-reported anxiety?

The primary aim was to investigate how respiration rate and inhalation/exhalation ratio influence self-reported state anxiety during a single slow diaphragmatic breathing exercise session. Eight hundred and twenty-eight participants completed the study at two separate geographical locations (Poland and Spain). Participants performed a 10-min online guided breathing exercise. Respiration rates were sampled from a continuous uniform distribution (ranging from 6 to 12 breaths/min). Similarly, inhalation/exhalation ratios were treated as continuous variables and sampled from a uniform distribution for each participant. An application programed for this experiment displayed visual and auditory cues adjusted for each participant. Before and after the breathing exercise, each participant filled in the Current Anxiety Level Measure questionnaire. Self-trait anxiety was measured with the Clinically Useful Anxiety Outcome Scale. A linear regression model showed that respiration rate, trait anxiety, pre-test anxiety, and nationality (Polish/Spanish) were positively related to post-test anxiety levels. Adding quadratic terms of respiration rate and inhalation/exhalation ratio did not improve model fit. Polish participants exhibited higher post-test anxiety levels compared with the Spanish subsample. Age was negatively associated with post-test anxiety. No significant relationships between inhalation/exhalation ratio and post-test anxiety level were found. Slower respiration rates during a single-session breathing exercise are linearly associated with lower post-test anxiety levels in a large and varied sample. This study is the largest to date and may offer further guidance for predicting expected effect sizes for the relationships between anxiety and respiratory dynamics.

Immediate effects of structured and natural deep breathing on heart rate variability and blood pressure in community-dwelling older adults

BACKGROUND

This study investigated the immediate effects of structured deep breathing (SDB) and natural deep breathing (NDB) on heart rate variability (HRV) and blood pressure (BP) in community-dwelling older adults.

METHODS

Twenty-six participants were randomly assigned to SDB (n = 14) or NDB (n = 12) groups. HRV parameters (time domain: standard deviation of normal-to-normal intervals [SDNN], root mean square of successive differences [RMSSD]; frequency domain: low frequency [LF], high frequency [HF], LF/HF ratio, total power [TP], normalized low frequency [LFnu], normalized high frequency [HFnu]) and BP were assessed during spontaneous breathing, DB, and post DB.

RESULTS

Both groups showed significant increases during DB in SDNN (p < 0.001), RMSSD (p = 0.021), LF power (p < 0.001), LFnu (p < 0.001), TP (p < 0.001), and LF/HF ratio (p < 0.001). HFnu decreased significantly during DB (p < 0.001) with no group differences. HF power showed no significant effect in group and time. BP remained stable throughout the protocol, with no significant changes in either systolic or diastolic BP across time points or between groups.

CONCLUSIONS

This first direct comparison of structured versus natural DB in healthy older adults demonstrates that both approaches effectively enhance parasympathetic activity. These findings support DB as a cost-effective, accessible intervention for promoting autonomic balance in healthy aging, without requiring specialized equipment or instruction.

Flexible Pressure, Humidity, and Temperature Sensors for Human Health Monitoring

The rapid advancements in artificial intelligence, micro-nano manufacturing, and flexible electronics technology have unleashed unprecedented innovation and opportunities for applying flexible sensors in healthcare, wearable devices, and human-computer interaction. The human body's tactile perception involves physical parameters such as pressure, temperature, and humidity, all of which play an essential role in maintaining human health. Inspired by the sensory function of human skin, many bionic sensors have been developed to simulate human skin's perception to various stimuli and are widely applied in health monitoring. Given the urgent requirements for sensing performance and integration of flexible sensors in the field of wearable devices and health monitoring, here is a timely overview of recent advances in pressure, humidity, temperature, and multi-functional sensors for human health monitoring. It covers the fundamental components of flexible sensors and categorizes them based on different response mechanisms, including resistive, capacitive, voltage, and other types. Specifically, the application of these flexible tactile sensors in the area of human health monitoring is highlighted. Based on this, an extended overview of recent advances in dual/triple-mode flexible sensors integrating pressure, humidity, and temperature tactile sensing is presented. Finally, the challenges and opportunities of flexible sensors are discussed.

Music alters heart rate and psychological responses but not muscle activation during light-intensity isometric exercise

Listening to music manipulates attention to be more externally focused, which has the potential to improve muscular efficiency. This study aimed to determine the effect of listening to music on muscle activation during an isometric exercise task, and compare this effect to those of other attentional focus conditions. Apparently healthy subjects (n = ​35; 16 men/19 women) completed an isometric elbow flexion task for 1 ​min in three randomized and counterbalanced conditions: internal focus (INT), external focus with a simple distraction task (EXT), or listening to music (MUS). Muscle activation of the biceps and triceps brachii and heart rate (HR) were recorded throughout the exercise tasks. Ratings of perceived exertion (RPE), affective valence, and motivation were measured at the end of each trial. There was no difference in muscle activation measures among the three conditions. HR during MUS was lower than EXT at 15 ​s ([89.4 ​± ​11.8] beats/min vs. [93.1 ​± ​12.9] beats/min; p ​= ​0.018) and 30 ​s ([90.6 ​± ​12.4] beats/min vs. [94.2 ​± ​12.5] beats/min; p ​= ​0.026), and lower than INT at 60 ​s ([93.3 ​± ​13.3] beats/min vs. [96.7 ​± ​12.0] beats/min; p ​= ​0.016). Overall RPE was higher for INT (13.4 ​± ​2.2) than for MUS ([12.6 ​± ​2.0]; p ​= ​0.020) and EXT ([11.94 ​± ​2.22]; p ​< ​0.001). Affective valence was higher for MUS than for INT ([2.7 ​± ​1.4] vs. [2.1 ​± ​1.5]; p ​= ​0.011). Manipulating attentional focus did not alter muscle activation for a light-intensity isometric muscular endurance task, though MUS was reported as more positive and requiring less exertion to complete than INT. Using music can therefore be recommended during light-intensity isometric exercise based on the psychological benefits observed.

What can the psychoneuroimmunology of yoga teach us about depression's psychopathology?

Depression, the most prevailing mental health condition, remains untreated in over 30% of patients. This cluster presents with sub-clinical inflammation. Investigations trialling anti-inflammatory medications had mixed results. The lack of results may result from inflammation's complexity and targeting only a few of depression's abnormal pathways. Mind-body therapies' biological and neuro-imaging studies offer valuable insights into depression psychopathology. Interestingly, mind-body therapies, like yoga, reverse the aberrant pathways in depression. These aberrant pathways include decreased cognitive function, interoception, neuroplasticity, salience and default mode networks connectivity, parasympathetic tone, increased hypothalamic-pituitary-adrenal (HPA) axis activity, and metabolic hyper/hypofunction. Abundant evidence found yogic techniques improving self-reported depressive symptoms across various populations. Yoga may be more effective in treating depression in conjunction with pharmacological and cognitive therapies. Yoga's psychoneuroimmunology teaches us that reducing allostatic load is crucial in improving depressive symptoms. Mind-body therapies promote parasympathetic tone, downregulate the HPA axis, reduce inflammation and boost immunity. The reduced inflammation promotes neuroplasticity and, subsequently, neurogenesis. Improving interoception resolves the metabolic needs prediction error and restores homeostasis. Additionally, by improving functional connectivity within the salience network, they restore the dynamic switching between the default mode and central executive networks, reducing rumination and mind-wandering. Future investigations should engineer therapies targeting the mechanisms mentioned above. The creation of multi-disciplinary health teams offering a combination of pharmacological, gene, neurofeedback, behavioural, mind-body and psychological therapies may treat treatment-resistant depression.

Early life adversity blunts the subjective and physiological relaxation response in healthy adults

While Early Live Adversity (ELA) is a known risk factor for mental and physical diseases, the investigation into the mechanisms behind this connection is ongoing. In the present study, we investigated whether ELA blunts the relaxation response in healthy adults. Using a within-subjects design, we employed a paced breathing exercise (four seconds inhale, six seconds exhale) and a 360° nature video as relaxation interventions while measuring physiological relaxation using heart rate variability and subjective relaxation using the Relaxation State Questionnaire. A total of 103 participants (63.11% female; agemean = 22.73 ± 3.43 years) completed the Parental Bonding Instrument and the Childhood Trauma Questionnaire to assess ELA retrospectively. For subjective relaxation, a blunted relaxation reaction was associated with lower scores of paternal care and higher scores of paternal overprotection, physical abuse, physical neglect, and emotional abuse. For heart rate variability emotional abuse in interaction with nicotine consumption was related to a blunted relaxation response. This indicates that experiencing ELA negatively affects the relaxation capability in a healthy sample and emphasizes the importance of assessing relaxation at a physiological and subjective level.

A Respiratory Sensor-Based Study of the Relationship between Voluntary Breathing Patterns and Aerobic and Anerobic Exercise Capacity-An Exploratory Applied Study

(1) Background: Exploring the relationship between spontaneous breathing patterns and aerobic and anerobic running exercise performance can greatly improve our understanding of optimizing physical fitness. Spontaneous breathing patterns refer to how the rhythm and depth of breathing affect performance and physical adaptation during exercise. (2) Methods: This study aimed to investigate this relationship by enrolling 240 college students (120 males and 120 females, aged 18-22). We evaluated their resting respiratory rate (RR), the combined total of abdominal and thoracic movements (AM+TM), the proportion of abdominal movement to the overall respiratory movement (AM/(AM+TM)), and the inhalation to exhalation ratio (I/E ratio). Additionally, their performance in a 50 m sprint (measuring anerobic capability), an 800- or 1000 m run (assessing mixed aerobic and anerobic capacity), and a 12 min distance run (evaluating aerobic capacity) was recorded. (3) Results: Our findings, through both correlational and comparative analyses, indicate that a larger AM+TM is predictive of a greater distance covered in the 12 min run, suggesting enhanced aerobic capacity. Interestingly, among female participants, a lower body mass index (BMI) coupled with a higher proportion of abdominal movement (AM/(AM+TM)) was linked to better performance in the 800 m run, indicative of superior mixed aerobic and anerobic capacities. These results imply that women with a larger tidal volume and those with a lower BMI but higher abdominal contribution to breathing at rest may exhibit better aerobic and mixed exercise capacities, respectively. (4) Conclusions: Based on these findings, we recommend that healthcare professionals and physical education instructors incorporate respiratory pattern assessments into their practices to potentially improve the physical health of their clients and students, with a particular emphasis on female populations. This study underscores the importance of understanding the intricate relationship between spontaneous respiratory patterns and exercise capabilities in enhancing overall physical fitness and health.

PDMS/CNT electrodes with bioamplifier for practical in-the-ear and conventional biosignal recordings

Objective.Potential usage of dry electrodes in emerging applications such as wearable devices, flexible tattoo circuits, and stretchable displays requires that, to become practical solutions, issues such as easy fabrication, strong durability, and low-cost materials must be addressed. The objective of this study was to propose soft and dry electrodes developed from polydimethylsiloxane (PDMS) and carbon nanotube (CNT) composites.Approach.The electrodes were connected with both conventional and in-house NTAmp biosignal instruments for comparative studies. The performances of the proposed dry electrodes were evaluated through electromyogram, electrocardiogram, and electroencephalogram measurements.Main results.Results demonstrated that the capability of the PDMS/CNT electrodes to receive biosignals was on par with that of commercial electrodes (adhesive and gold-cup electrodes). Depending on the type of stimuli, a signal-to-noise ratio of 5-10 dB range was achieved.Significance.The results of the study show that the performance of the proposed dry electrode is comparable to that of commercial electrodes, offering possibilities for diverse applications. These applications may include the physical examination of vital medical signs, the control of intelligent devices and robots, and the transmission of signals through flexible materials.

Perspectives on the Toxic Effects of Micro- and Nanoplastics on the Environment: A Bibliometric Analysis of the 2014 to 2023 Period

Over the past decade, micro- and nanoplastics (MNPs) have garnered significant attention due to their frequent detection in and potential toxic effects on the environment and organisms, making them a serious threat to human health. To comprehensively understand the research on MNPs' toxicity, we employed the R language-based Bibliometrix toolkit (version 4.3.0), VOSviewer (version 1.6.11) and CiteSpace (version 6.3.R1) to perform statistical and visual analyses of 3541 articles pertaining to MNPs' toxicity between 2014 and 2023, which were retrieved from the Web of Science Core Collection (WOSCC) database. The analysis revealed that research related to MNPs' toxicity has experienced a rapid increase in recent years. China's particularly prominent influence in the field of MNPs' toxicity is evidenced by its academic exchanges and the establishment of a mature cooperation system with other countries (regions), such as the USA and Germany. Studies related to MNPs' toxicity are primarily published in leading journals, including the Science of the Total Environment, Environmental Pollution, and the Journal of Hazardous Materials. The Chinese Academy of Sciences was identified as the leading institution in terms of research on MNPs' toxicity, contributing 203 papers to the total number of studies published. Keyword co-occurrence and burst analyses indicated that the current research on MNPs' toxicity mainly focuses on the toxic effects of MNPs on aquatic organisms, the combined toxicity of MNPs and other contaminants, and the toxic effects and mechanisms of MNPs. Future research should integrate computational toxicology and toxicomics to enhance our understanding of MNPs' toxicity mechanisms and assess the potential health risks posed by atmospheric MNPs.

Sensing, feeling and regulating: investigating the association of focal brain damage with voluntary respiratory and motor control

Breathing is a complex, vital function that can be modulated to influence physical and mental well-being. However, the role of cortical and subcortical brain regions in voluntary control of human respiration is underexplored. Here we investigated the influence of damage to human frontal, temporal or limbic regions on the sensation and regulation of breathing patterns. Participants performed a respiratory regulation task across regular and irregular frequencies ranging from 6 to 60 breaths per minute (bpm), with a counterbalanced hand motor control task. Interoceptive and affective states induced by each condition were assessed via questionnaire, and autonomic signals were indexed via skin conductance. Participants with focal lesions to the bilateral frontal lobe, right insula/basal ganglia and left medial temporal lobe showed reduced performance relative to individually matched healthy comparisons during the breathing and motor tasks. They also reported significantly higher anxiety during the 60 bpm regular and irregular breathing trials, with anxiety correlating with difficulty in rapid breathing specifically within this group. This study demonstrates that damage to frontal, temporal or limbic regions is associated with abnormal voluntary respiratory and motor regulation and tachypnoea-related anxiety, highlighting the role of the forebrain in affective and motor responses during breathing. This article is part of the theme issue 'Sensing and feeling: an integrative approach to sensory processing and emotional experience'.

A Systematic Review of Breathing Exercise Interventions: An Integrative Complementary Approach for Anxiety and Stress in Adult Populations

Aim: Nurses are well-qualified to deliver integrative complementary therapy interventions, a holistic approach to assist individuals experiencing anxiety and stress. Self-regulated, controlled breathing exercises (a clinical approach) are reported to decrease anxiety and increase stress tolerance. The aim of this systematic review was to evaluate the effectiveness of breathing exercise interventions on the psychological and physiologic outcomes of anxiety and stress among adults and assess the state of the science in the post-COVID-19 population. Methods: A systematic review was conducted, and four scientific databases were searched: PubMed, CINAHL, EMBASE, and Web of Science. Inclusion criteria included: (1) peer-reviewed studies, (2) adults over 18, (3) breathing exercise interventions, and (4) anxiety or stress as outcomes. Results: Out of 309 studies identified, 19 were included. Twelve reported significant improvements in anxiety and nine reported significant improvements in stress following varying breathing exercise interventions (p < .05). No adverse events were reported. Conclusions: Breathing exercises were found to be effective in reducing anxiety and stress in adults, however, there continues to be limited evidence that includes large randomized controlled trials. Breathing exercises are a holistic care approach that can be safely implemented by nurses to decrease symptomatology among adults, including the post-COVID population.

A systematic review, meta-analysis and meta-regression amalgamating the driven approaches used to quantify dynamic cerebral autoregulation

Numerous driven techniques have been utilized to assess dynamic cerebral autoregulation (dCA) in healthy and clinical populations. The current review aimed to amalgamate this literature and provide recommendations to create greater standardization for future research. The PubMed database was searched with inclusion criteria consisting of original research articles using driven dCA assessments in humans. Risk of bias were completed using Scottish Intercollegiate Guidelines Network and Methodological Index for Non-Randomized Studies. Meta-analyses were conducted for coherence, phase, and gain metrics at 0.05 and 0.10 Hz using deep-breathing, oscillatory lower body negative pressure (OLBNP), sit-to-stand maneuvers, and squat-stand maneuvers. A total of 113 studies were included, with 40 of these incorporating clinical populations. A total of 4126 participants were identified, with younger adults (18-40 years) being the most studied population. The most common techniques were squat-stands (n = 43), deep-breathing (n = 25), OLBNP (n = 20), and sit-to-stands (n = 16). Pooled coherence point estimates were: OLBNP 0.70 (95%CI:0.59-0.82), sit-to-stands 0.87 (95%CI:0.79-0.95), and squat-stands 0.98 (95%CI:0.98-0.99) at 0.05 Hz; and deep-breathing 0.90 (95%CI:0.81-0.99); OLBNP 0.67 (95%CI:0.44-0.90); and squat-stands 0.99 (95%CI:0.99-0.99) at 0.10 Hz. This review summarizes clinical findings, discusses the pros/cons of the 11 unique driven techniques included, and provides recommendations for future investigations into the unique physiological intricacies of dCA.

Etiology and treatment of cancer-related secondary lymphedema

Lymphedema and specifically cancer-related lymphedema is not the main focus for both patients and physicians dealing with cancer. Its etiology is an unfortunate complication of cancer treatment. Although lymphedema treatments have gained an appreciable consensus, many practitioners have developed and prefer their own specific protocols and this is especially true for conventional (manual) versus surgical treatments. This collection of presentations explores the incidence and genetics of cancer-related lymphedema, early detection and monitoring techniques, both conventional and operative treatment options, and the importance and role of exercise for patients with cancer-related lymphedema. These assembled presentations provide valuable insights into the challenges and opportunities presented by cancer-related lymphedema including the latest research, treatments, and exercises available to improve patient outcomes and quality of life.

Exploring heart rate variability in polycystic ovary syndrome: implications for cardiovascular health: a systematic review and meta-analysis

OBJECTIVES

Polycystic ovary syndrome (PCOS) is a prevalent and complex endocrine disorder that affects women of reproductive age. It has significant implications for female endocrine function, reproductive health, and metabolic disturbances, including insulin resistance, impaired glucose tolerance, and dyslipidemia. Studies have shown that decreased heart rate variability (HRV), a marker of autonomic dysfunction, is associated with adverse cardiovascular events. Recent research has focused on investigating autonomic function in PCOS, and some studies have suggested altered autonomic drive in these patients. The aim of this systematic review and meta-analysis was to evaluate cardiac autonomic function by analyzing HRV in women with PCOS.

METHODS

This systematic review was prepared using PRISMA reporting guidelines. The databases searched were PubMed, Scopus, Web of Science, and Cochrane. Risk of Bias was assessed using ROBINS-I for non-RCTs. The GRADE approach was employed to evaluate the level of certainty in the evidence for each outcome. In order to identify the underlying cause of high heterogeneity, a subgroup analysis was conducted. Sensitivity analysis was checked. A random effect model was used and calculated a pooled standardized mean difference (SMD) with a 95% confidence interval (CI).

RESULTS

Seventeen articles were included in the final analysis, varied in quality, ranging from a "low" to a "high risk of bias". Combined analyses indicated a notable decrease in HRV among individuals with PCOS compared to the control group. Significant changes were observed in SDNN (SMD: -0.763, 95%CI [-1.289 to -0.237], p=0.004), PNN50 (SMD: -1.245, 95%CI [-2.07, -0.419], p=0.003), LF/HF ratio (SMD: 0.670, 95%CI [0.248, 1.091], p=0.002), HFnu (SMD: -0.873, 95%CI [-1.257, -0.489], p=0.000), LFnu (SMD: 0.840, 95%CI [0.428, 1.251], p=0.000) and TP (SMD: -1.997, 95%CI [-3.306, -0.687], p=0.003). The heterogeneity was partially explained by types of study design. Subgroup analysis revealed significant alterations of HRV in normal-weighted and overweight PCOS cases. Conversely, no significant changes in HRV were observed in obese PCOS cases.

CONCLUSION

The findings of this meta-analysis provide evidence suggesting diminished HRV in individuals with PCOS compared to non-PCOS control group.

Volitionally Regulated Breathing with Prolonged Expiration Influences Food Craving and Impulsivity

INTRODUCTION

Previously, an intervention involving volitional slow breathing reduced trait food craving with protective effects on cardiac vagal activity (CVA). Breathing with a low inspiration-to-expiration (i/e) ratio also increases CVA. High CVA was separately associated with low unregulated eating and lesser impulsivity. Hence, the present study assessed breathing with a low i/e for effects on state food craving, hunger and satiety, state impulsivity, and heart rate variability (HRV) in healthy obese persons.

METHODS

Forty obese persons were randomized to two groups. The intervention group (mean age ± SD, 41.15 ± 12.63, M:F, 10:10) practiced metronome-regulated breathing with low i/e at 12 breaths per minute (expiration 72% of total breath duration) and attained expiration 55.8% of total breath duration, while the active control group (mean age ± SD, 44.45 ± 11.06, M:F, 13:07) sat motionless and directed their gaze and awareness to the stationary metronome without modifying their breath consciously. The HRV was recorded before, during, and after breathing intervention (or control) (standard limb lead I, acquisition at 2,000 Hz, with an LF filter = 0.5 Hz and HF filter = 50 Hz). Time-domain and frequency-domain HRV parameters were obtained with Kubios software. State food craving, and hunger and satiety were recorded before and after the intervention/control.

RESULTS

The intervention group decreased total state food craving scores and the sub-domains (i.e., desire to eat, positive reinforcement, lack of control and hunger), increased current satisfaction with food, decreased total state impulsivity (repeated measures ANOVA, p < 0.05 in all cases), increased HF-HRV and RMSSD (linear mixed model analyses with age and gender as fixed factors; p < 0.05 in all cases) during the intervention compared to the preceding baseline. The intervention group also showed an increase in positive mood and a decrease in aroused and negative mood states.

CONCLUSION

Changes in state food craving and impulsivity could be related to an increase in HRV or to changes in subjective relaxation and positive mood or to both.

Resonant breathing improves self-reported symptoms and wellbeing in people with Long COVID

Introduction

Long COVID involves debilitating symptoms, many of which mirror those observed with dysautonomia, and care must be taken with rehabilitation for autonomic dysfunction to avoid post-exertional malaise/post-exertional symptom exacerbation. Resonant breathing (breathing slowly at a defined rate of breaths per minute) requires less exertion and can potentially improve autonomic function. The objective of this work was to report on the impact of a resonant breathing program on self-reported symptoms and wellbeing in people with Long COVID.

Methods

A retrospective analysis of de-identified data was completed in a convenience sample of people with Long COVID, who participated in the Meo Health (formerly known as Stasis HP) resonant breathing program. Participants completed baseline and follow up surveys.

Results

Data were available for 99 participants. Most measures of symptoms and wellbeing improved at follow up, with the largest differences per participant seen in sense of wellness (47.3%, p < 0.0001), ability to focus (57.5%, p < 0.0001), ability to breathe (47.5%, p < 0.0001), ability to control stress (61.8%, p < 0.0001) and sleep quality (34.9%, p = 0.0002). Most (92%) participants reported improvement at follow up on the Patient Global Impression of Change Scale.

Conclusion

Self-reported symptoms and wellbeing improved in people with Long COVID completing resonant breathing. Resonant breathing can be considered as an option within the broader treatment plan of people with Long COVID.

Acute cardiac autonomic and hemodynamic responses to resistive breathing: Effect of loading type and intensity

OBJECTIVES

This study aimed to assess the acute impact of distinct loading breathing types and intensities on cardiac autonomic function and hemodynamic responses in healthy young adults.

METHODS

A randomized, crossover trial involved 28 participants who underwent inspiratory resistive breathing, expiratory resistive breathing (ERB) and combined resistive breathing, each at 30% and 60% of maximal respiratory pressures. Data on heart rate variability (HRV) and hemodynamic parameters were collected during each trial.

RESULTS

The study revealed significant main and interaction effects for both the performed task and the intensity across all measured variables (all p < 0.001). ERB at 60% load demonstrated significantly higher HRV values in the standard deviation of normal-to-normal RR intervals, the square root of the mean squared difference of successive normal-to-normal RR intervals and high-frequency power, as well as significantly lower values in heart rate, stroke volume, stroke volume index, cardiac output, cardiac index, end-diastolic volume and end-diastolic volume index, compared to other loaded protocols (all p < 0.001).

CONCLUSION

These findings highlight the acute effect of type-specific and load-dependent resistive breathing on cardiac autonomic and hemodynamic functions, where ERB at 60% intensity showed the most significant cardiovagal modulation while causing the least hemodynamic alterations.

The Effects of Slow Breathing during Inter-Set Recovery on Power Performance in the Barbell Back Squat

Slow breathing (SB) reduces sympathetic nervous system activity, the heart rate (HR), and blood pressure (BP) and increases parasympathetic nervous system activity, HR variability, and oxygen saturation which may lead to quicker recovery between bouts of exercise. Therefore, the purpose of this study was to examine whether a SB technique using the 4-7-8 method between sets of barbell back squats (SQs) would attenuate drops in power and bar velocity. In a randomized, crossover design, 18 healthy resistance-trained college-aged males (age: 20.7 ± 1.4 years, body height: 178.6 ± 6.4 cm, body mass: 82.2 ± 15.0 kg, 4.5 ± 2.4 years of experience) performed 5 sets of 3 repetitions of SQs with normal breathing (CON) or SB during the 3-min recovery between sets. Peak and average power and bar velocity were assessed using a linear positioning transducer. HR recovery (RHR), systolic BP recovery (RBP), the rating of perceived exertion (RPE) and the rating of perceived recovery score (RS) were assessed after each set. There were no significant differences between conditions for peak and average power and bar velocity, RBP, RPE, and RS (p > 0.211). SB led to a greater RHR after set 2 (SB: 51.0 ± 14.9 bpm vs. CON: 44.5 ± 11.5 bpm, p = 0.025) and 3 (SB: 48.3 ± 13.5 bpm vs. CON: 37.7 ± 11.7 bpm, p = 0.006) compared to the CON condition. SB was well tolerated, did not hinder nor improve training performance and improved RHR after the middle sets of SQs. Further investigations are warranted to examine the effects of other SB techniques and to determine SB's effects on different training stimuli as well as its effects over an entire workout and post-workout recovery metrics.

Tactile breathing guidance increases oxygen saturation but not alertness or hypoxia symptoms

We investigated the effect of tactile guided slow deep breathing compared with that of spontaneous breathing on blood oxygen saturation (SpO2), alertness, and hypoxia symptoms during acute hypobaric hypoxia. We also evaluated the usability of this tactile breathing guidance. Twelve male military pilots were exposed to a simulated altitude of 4,572 m (15,000 ft) in a repeated measures study while breathing spontaneously and during tactile guided slow deep breathing. Under both breathing conditions, measurements were performed at rest and during the performance of a cognitive task. The Stanford Sleepiness Scale was used to rate alertness, and hypoxia symptoms were reported using a list of general hypoxia symptoms. Usability was evaluated in a questionnaire. Tactile guidance of slow deep breathing significantly increased (p <.001) the SpO2 - 88% (95% confidence interval (CI) [84%, 91%]) at rest and 85% (95% CI [81%, 88%]) during the cognitive task - compared with spontaneous breathing - 78% (95% CI [75%, 81%]) at rest and 78% (95% CI [76%, 80%]) during the cognitive task. This increase in SpO2 had no effect on the level of alertness and number of hypoxia symptoms. Pilots were positive about the intensity and sensation of the vibration signal, but had difficulty following the vibration pattern during the cognitive task. Pre-training may improve slow deep breathing technique during performance of cognitive tasks.

Effect of Integrated Yoga as an add-on therapy in adults with clinical depression - A randomized controlled trial

BACKGROUND

Depression is a leading cause of disability and the conventional management has several limitations. Recent studies demonstrated the benefits of yoga in psychological disorders.

AIMS

To evaluate the efficacy of the Integrated Yoga Module (IYM) to standard care with added yogic education on lifestyle modification (YELM) in patients with clinical depression.

METHODS

A PROBE trial was conducted at a single tertiary care hospital in India. Adults aged 18 to 64 with clinical depression were randomized to either an IYM or an active control group using a computer-generated mixed block randomization sequence. Both groups received YELM in addition to standard care and the intervention group practiced IYM, for 8 weeks. The primary outcome was the reduction in depression symptoms assessed using the Beck Depression Inventory (BDI-II), and secondary outcomes involved self-compassion, brief resilience, positive and negative experiences, and quality of life, evaluated at 8 weeks.

RESULTS

The mean ± SD age of participants was 32.2 ± 10.0 and 54.3% were females. The IYM group showed statistically significant improvements in BDI-II scores β = -6.7 (95% CI [-10.8, -2.5]; p = .001), resilience β = 0.4 (95% CI [0.02, 0.80]; p = .037), physical health domain of WHOQOL - BREF β = 10.1 (95% CI [0.7, 19.5]; p = .035) and negative emotions (SPANE-N) β = 2.8 (95% CI [0.1, 5.4]; p = .037). However, no significant differences were found in SCS-SF β = -0.3 (95% CI [-0.7, 0.0]; p = .053).

CONCLUSIONS

IYM as an adjunct is superior to conventional medical management in reducing symptoms and improving positive psychological resources in clinical depression.

Impact of Loneliness on Training Gains with Heart Rate Variability Biofeedback in the Elderly: A Pilot Study

The negative impact of loneliness on the health of the elderly is particularly noticeable because of the effects of central control on the autonomic nervous system. Such an impact can be assessed through heart rate variability (HRV) analysis and can be modified using HRV biofeedback training. This study aimed to investigate the impact of different levels of social interaction reported by the elderly on HRV before and after training with HRV biofeedback and after a follow-up period. The participants of this pilot study comprised 16 elderly people of both sexes with a mean age of 71.20 ± 4.92 years. The participants were divided into two groups, the loneliness group (N = 8) and the no-loneliness group (N = 8), based on a combination of both criteria: the institutionalization condition (institutionalized or not) and the score on the loneliness scale (high or low). All participants had their HRV components recorded at baseline, after 14 training sessions with HRV biofeedback (three times a week, 15 min each for 4.5 weeks), and after 4.5 weeks of follow-up without training. After HRV biofeedback training, HRV components increased in both groups. However, the gains lasted at follow-up only in the no-loneliness group. In conclusion, loneliness can influence the maintenance of HRV after interruption of training with HRV biofeedback in the elderly. HRV biofeedback training can be an innovative and effective tool for complementary treatment of elderly individuals, but its effects on lonely elderly individuals need to be further investigated.

Evaluation of Lateral Radar Positioning for Vital Sign Monitoring: An Empirical Study

Vital sign monitoring is dominated by precise but costly contact-based sensors. Contactless devices such as radars provide a promising alternative. In this article, the effects of lateral radar positions on breathing and heartbeat extraction are evaluated based on a sleep study. A lateral radar position is a radar placement from which multiple human body zones are mapped onto different radar range sections. These body zones can be used to extract breathing and heartbeat motions independently from one another via these different range sections. Radars were positioned above the bed as a conventional approach and on a bedside table as well as at the foot end of the bed as lateral positions. These positions were evaluated based on six nights of sleep collected from healthy volunteers with polysomnography (PSG) as a reference system. For breathing extraction, comparable results were observed for all three radar positions. For heartbeat extraction, a higher level of agreement between the radar foot end position and the PSG was found. An example of the distinction between thoracic and abdominal breathing using a lateral radar position is shown. Lateral radar positions could lead to a more detailed analysis of movements along the body, with the potential for diagnostic applications.

The effect of breathing exercises on chemotherapy-induced nausea and vomiting in autologous hematopoietic stem cell transplantation patients: A randomized controlled trial

PURPOSE

This research was conducted as a randomized controlled study to examine the effect of breathing exercises on managing chemotherapy-related nausea and vomiting in patients who underwent autologous hematopoietic stem cell transplantation.

METHODS

A randomized controlled trial design was used, including an intervention group doing breathing exercises and a control group receiving standard care for chemotherapy-induced nausea and vomiting. The sample was selected from patients hospitalized in the bone marrow transplantation unit. A total of 70 autologous hematopoietic stem cell transplantation patients (35 intervention and 35 control participants). Several variables were evaluated, including the frequence and degree of nausea and vomiting, the patient's nutritional status, and the need for antiemetics. Data were analyzed and interpreted using Mann Whitney U, Pearson chi-square test, Independent t-test, Mann Whitney U, and multiple linear regression.

RESULTS

It was found that there was a negative relationship between the number of breathing exercises, the number of nausea and vomiting and the severity of nausea. As the number of breathing exercises increased, the number nausea and vomiting, and severity of nausea decreased significantly (p < 0.05). It was found that the use of antiemetics decreased in the intervention group. Furthermore, it was found that the intervention group had higher daily food consumption on the 3rd, 7th, and 9th days (p < 0.05).

CONCLUSION

Breathing exercises were a practical approach to managing chemotherapy-related nausea and vomiting.