The physiological effects of slow breathing in the healthy human

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.

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.

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.

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.

Effect of adding systematic desensitization to goal-directed paradigm on risk of falling in patients with stroke: a randomized controlled trial

Background

Improvement in rehabilitation outcomes for patients suffering from chronic stroke can be attained through systematic desensitization of their fear of falling, which in turn reduces the risk of falling.

Purpose

This study aimed to examine the effect of adding systematic desensitization to a goal-directed paradigm on functional performance, balance, risk of falling, and fear of falling among chronic ischemic stroke patients.

Methodology

Two equally sized groups, each comprising 40 stroke patients of both sexes, were randomly divided. For 8 weeks, Group A received three sessions per week of combined treatment consisting of systematic desensitization and a goal-directed paradigm, while Group B received only the goal-directed paradigm. The Timed Up and Go (TUG) test and Dynamic Gait Index (DGI) were used to assess function performance; the Berg Balance Scale (BBS) and the Biodex Fall Risk Index (FRI) were used to evaluate balance; and the 16-item Fall Efficacy Scale-International (FES-I) was used to evaluate fear of falling. At baseline and after the treatment, all measurements were obtained.

Results

Both groups (A and B) revealed a substantial increase in functional performance through a decrease in TUG scores and an increase in DGI. Additionally, there was a decrease in the risk of falling through an increase in the BBS scores and a decrease in the FRI. Furthermore, there was a decrease in the fear of falling, as measured using the FES-I, after treatment, with superior improvement in Group A with a p-value of <0.001.

Conclusion

Systematic desensitization combined with a goal-directed paradigm has a superior effect on improving functional performance and reducing the risk of falling and the fear of falling in patients with stroke compared to a goal-directed paradigm alone.

ECG-based estimation of respiration-induced autonomic modulation of AV nodal conduction during atrial fibrillation

Introduction: Information about autonomic nervous system (ANS) activity may offer insights about atrial fibrillation (AF) progression and support personalized AF treatment but is not easily accessible from the ECG. In this study, we propose a new approach for ECG-based assessment of respiratory modulation in atrioventricular (AV) nodal refractory period and conduction delay. Methods: A 1-dimensional convolutional neural network (1D-CNN) was trained to estimate respiratory modulation of AV nodal conduction properties from 1-minute segments of RR series, respiration signals, and atrial fibrillatory rates (AFR) using synthetic data that replicates clinical ECG-derived data. The synthetic data were generated using a network model of the AV node and 4 million unique model parameter sets. The 1D-CNN was then used to analyze respiratory modulation in clinical deep breathing test data of 28 patients in AF, where an ECG-derived respiration signal was extracted using a novel approach based on periodic component analysis. Results: We demonstrated using synthetic data that the 1D-CNN can estimate the respiratory modulation from RR series alone with a Pearson sample correlation of r = 0.805 and that the addition of either respiration signal (r = 0.830), AFR (r = 0.837), or both (r = 0.855) improves the estimation. Discussion: Initial results from analysis of ECG data suggest that our proposed estimate of respiration-induced autonomic modulation, a resp, is reproducible and sufficiently sensitive to monitor changes and detect individual differences. However, further studies are needed to verify the reproducibility, sensitivity, and clinical significance of a resp.

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

OBJECTIVES

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Mental Skills for Orthopaedic Surgery

Orthopaedic surgery training focuses primarily on the knowledge base and surgical techniques that comprise the fundamental and physical pillars of performance. It also pays much less attention to the mental pillar of performance than does the training of other specialists such as aviators, elite athletes, musicians, and Special Forces operators. However, mental skills optimize the ability to achieve the ideal state during surgery that includes absolute focus with the right amount of confidence and stress. The path to this state begins before surgery with visualization of the surgical steps and potential complications. On the day of surgery, the use of compartmentalization, performance aspirations, performance breathing, and keeping the team focused facilitates achieving and maintaining the proper mental state. Considering the similarities between surgery and other fields of expertise that do emphasize the mental pillar, including this training in orthopaedic residencies, is likely beneficial.

The effectiveness of an osteopathic manual technique compared with a breathing exercise on vagal tone as indicated by heart rate variability, a crossover study

INTRODUCTION

Parasympathetic nervous system (PSNS) function can be inferred by heart rate variability (HRV) providing indications about an individual's health. Manual therapy may influence PSNS function, however the research outcomes in this regard are equivocal. This study explored the PSNS effect of a measured breathing technique with suboccipital balanced ligamentous tension, an osteopathic manipulative therapy technique.

METHODS

Healthy adult participants in this crossover study (n = 18) were randomly allocated into two groups with differing order of interventions. A 1:1 breathing rate of 6 breaths per minute maintained for 5 min was compared to the osteopathic intervention. HRV was measured for 5 min before and after each intervention and analysed using the root mean square of successive differences (RMSSD) between normal heartbeats and high frequency normalised units (HFnu).

RESULTS

The RMSSD data demonstrated no significant difference between groups or within groups (p > 0.05) over time. HFnu results showed a significant between-group difference over the four time points (p = 0.004) with a medium effect size (ηp2 = 0.240), and no significant within-group difference (p > 0.05).

DISCUSSION

The osteopathic intervention raised HRV to a small extent, however measured breathing lowered HRV. In the group that received the osteopathic technique first, HFnu values continued to rise post-osteopathic treatment possibly indicating an increasing parasympathetic effect over time. Recommendations for future studies include changing the breathing ratio to ensure parasympathetic response, take into account potential delayed effects of interventions, consider outcome measures less variable than HRV, and longer follow up times.

CONCLUSION

This study suggests parasympathetic stimulation may occur with the application of suboccipital balanced ligamentous tension and sympathetic stimulation from measured breathing.

What do brain oscillations tell about the human sense of smell?

Brain activity may manifest itself as oscillations which are repetitive rhythms of neuronal firing. These local field potentials can be measured via intracranial electroencephalography (iEEG). This review focuses on iEEG used to map human brain structures involved in olfaction. After presenting the methodology of the review, a summary of the brain structures involved in olfaction is given, followed by a review of the literature on human olfactory oscillations in different contexts. A single case is provided as an illustration of the olfactory oscillations. Overall, the timing and sequence of oscillations found in the different structures of the olfactory system seem to play an important role for olfactory perception.

Assessment of cardiovascular functioning following sport-related concussion: A physiological perspective

There is still much uncertainty surrounding the approach to diagnosing and managing a sport-related concussion (SRC). Neurobiological recovery may extend beyond clinical recovery following SRC, highlighting the need for objective physiological parameters to guide diagnosis and management. With an increased understanding of the connection between the heart and the brain, the utility of assessing cardiovascular functioning following SRC has gained attention. As such, this review focuses on the assessment of cardiovascular parameters in the context of SRC. Although conflicting results have been reported, decreased heart rate variability, blood pressure variability, and systolic (ejection) time, in addition to increased spontaneous baroreflex sensitivity and magnitude of atrial contraction have been shown in acute SRC. We propose that these findings result from the neurometabolic cascade triggered by a concussion and represent alterations in myocardial calcium handling, autonomic dysfunction, and an exaggerated compensatory response that attempts to maintain homeostasis following a SRC. Assessment of the cardiovascular system has the potential to assist in diagnosing and managing SRC, contributing to a more comprehensive and multimodal assessment strategy.

Vocal Effort and Acoustic Analysis of Gargle Phonation Versus Water Swallow in Patients With Muscle Tension Dysphonia: A Clinical Trial

PURPOSE

To determine the effects of gargle phonation (GP) on self-perceived vocal improvement, vocal effort, acoustic parameters, and speech rate in patients with muscle tension dysphonia (MTD). We hypothesized that GP would improve voice, reduce phonatory effort, and alter acoustic and speech measures.

STUDY DESIGN

Prospective randomized, single-blind cross-over clinical trial METHODS: Thirty-four participants (26 females, 8 males; average age 53 years) who were diagnosed with MTD completed the Voice Handicap Index-10 (VHI-10) and were assigned three study conditions: Baseline (B), GP, and Water Swallow (WS; sham), presented in one of two counterbalanced orders B-WS-GP (WS1st) or B-GP-WS (GP1st). Participants recorded stimuli from the Consensus Auditory-Perceptual Evaluation of Voice (CAPE-V) and rated their perceived vocal effort and vocal improvement. F0, vocal intensity, cepstral peak prominence (CPP), and speaking rate were measured.

RESULTS

Average VHI-10 scores by group were 16 (min/max 2-29) for WS1st and 15 (min/max 3-40) for GP1st. About 73.5% reported more vocal improvement after GP, 17.65% after WS, and 8.8% noted no difference between conditions. Reduced effort was reported after GP, compared to B (P < 0.001) and WS (P = 0.005). Lower effort was also reported after the WS condition, compared to B (P = 0.011). Key acoustic findings included an increase in F0 after GP for sustained /i/ for females. CPP was significantly higher for females reading CAPE-V sentences after GP, when GP preceded WS, compared to B (P = 0.004) and WS (P = 0.003). Speech rate was faster for females after GP versus B (P = 0.029).

CONCLUSIONS

GP may be beneficial in the treatment of MTD. CPP may be a useful marker for vocal improvement after GP for women with mild MTD. Further studies would benefit from having more male participants and those with moderate and severe MTD.

Integrated use of biofeedback and neurofeedback techniques in treating pathological conditions and improving performance: a narrative review

In recent years, the scientific community has begun tо explore the efficacy оf an integrated neurofeedback + biofeedback approach іn various conditions, both pathological and non-pathological. Although several studies have contributed valuable insights into its potential benefits, this review aims tо further investigate its effectiveness by synthesizing current findings and identifying areas for future research. Our goal іs tо provide a comprehensive overview that may highlight gaps іn the existing literature and propose directions for subsequent studies. The search for articles was conducted on the digital databases PubMed, Scopus, and Web of Science. Studies to have used the integrated neurofeedback + biofeedback approach published between 2014 and 2023 and reviews to have analyzed the efficacy of neurofeedback and biofeedback, separately, related to the same time interval and topics were selected. The search identified five studies compatible with the objectives of the review, related to several conditions: nicotine addiction, sports performance, Autism Spectrum Disorder (ASD), and Attention Deficit Hyperactivity Disorder (ADHD). The integrated neurofeedback + biofeedback approach has been shown to be effective in improving several aspects of these conditions, such as a reduction in the presence of psychiatric symptoms, anxiety, depression, and withdrawal symptoms and an increase in self-esteem in smokers; improvements in communication, imitation, social/cognitive awareness, and social behavior in ASD subjects; improvements in attention, alertness, and reaction time in sports champions; and improvements in attention and inhibitory control in ADHD subjects. Further research, characterized by greater methodological rigor, is therefore needed to determine the effectiveness of this method and the superiority, if any, of this type of training over the single administration of either. This review іs intended tо serve as a catalyst for future research, signaling promising directions for the advancement оf biofeedback and neurofeedback methodologies.

Effect of "365 Breathing Technique" on Intraocular Pressure and Autonomic Functions in Patients With Glaucoma: A Randomized Controlled Trial

PRCIS

Patients with primary open angle glaucoma were advised to follow the "365 breathing technique" for 6 weeks in addition to their pharmacological glaucoma treatment. It helped to reduce intraocular pressure (IOP), stress biomarker-cortisol, and improve autonomic dysfunction.

OBJECTIVE

To study the effect of the "365 breathing technique" on IOP, autonomic functions, and stress biomarkers in patients with primary open angle glaucoma.

METHODS

In this randomized, controlled, interventional trial, after randomization, 40 patients in the intervention group followed "365 breathing" (three times a day, breathing rate: 6 cycles/min for 5 min) in addition to their pharmacological glaucoma treatment and 40 patients in the control group continued only with their pharmacological glaucoma treatment. IOP, serum cortisol, heart rate variability (HRV), and heart rate response to deep breathing test (DBT) were recorded at preintervention and 6 weeks postintervention.

RESULTS

The mean IOP, serum cortisol, parameters of the HRV test, and DBT were comparable between the two groups at baseline. At the 6-week follow-up, in the intervention group, mean IOP was significantly lower (16.09 ± 2.24 vs 18.38 ± 1.58 mm Hg, P = 0.03) and serum cortisol were significantly lower (13.20 ± 3.11 vs 14.95 ± 2.60 mcg/dL, P = 0.038) compared with the control group. In the HRV test, time domain analysis showed a significant difference in the root mean square of the successive difference between RR interval values between both groups at 6 weeks ( P = 0.015) pointing towards higher postintervention parasympathetic activation in the intervention group. In frequency domain analysis (HRV test), the ratio of the low-frequency component to the high-frequency component was significantly lower in the intervention group at 6 weeks (1.65 vs 1.79, P = 0.019) indicating a shift in sympathovagal balance towards greater vagal modulation.There was a significant increase in delta heart rate ( P = 0.019) and expiratory:inspiratory ratio ( P = 0.011) in the intervention group at 6 weeks when compared with baseline values, indicating improved parasympathetic reactivity to DBT.

CONCLUSION

"365 breathing" technique can reduce IOP and serum cortisol, and improve autonomic dysfunction in patients with glaucoma.

Interactive pregnancy education on stress, cortisol, and epinephrine level in primigravida of trimester III pregnant: a quasi-experimental

Infant mortality is caused by various health problems, especially since the gestation period, even starting before the gestation period. Stress during pregnancy affects the motor, cognitive, and emotional development of the baby. This study aims to determine the effect of interactive pregnancy education (IPE) on decreasing levels of cortisol, epinephrine, and its relationship with stress levels in third-trimester primigravida pregnant women. This research is a quasi-experimental study using a nonequivalent control group design, which has two groups, namely the experimental group and the control group. The authors compared the experimental group that was given the intervention with the control group that was not given any treatment. This research was conducted in the three Community Health Centers in Indonesia from June 2022 until December 2022. The samples were 30 third-trimester primigravida pregnant women for the intervention and control groups. Data were analyzed using the Mann-Whitney and Wilcoxon tests with SPSS 22 software. The results of this study indicate that IPE has a good impact on pregnant women, where there is a significant relationship in the post-test cortisol and epinephrine levels in the intervention group. This indicates that IPE contributed to the difference in post-test scores in the intervention group. The IPE method is effective in reducing stress levels and cortisol levels in pregnant women, especially in pregnant women with high levels of stress.

Deep Diaphragmatic Breathing-Anatomical and Biomechanical Consideration

Background: Deep diaphragmatic breathing (DDB) involves slow and fully contraction of the diaphragm with expansion of the belly during inhalation, and slow and fully contraction of the abdominal muscles with reduction of the belly during exhalation. It is the key component of the holistic mind-body exercises commonly used for patients with multimorbidity. Purpose: The purpose of this study was to re-visit and address the fundamental anatomical and biomechanical consideration of the DDB with the relevant literature. Method: Peer-reviewed publications from last the 15 years were retrieved, reviewed, and analyzed. Findings: In this article, we described the updated morphological and anatomical characteristics of the diaphragm. Then, we elucidated in a biomechanical approach how and why the DDB can work on the gastrointestinal, cardiopulmonary, and nervous systems as well as on regulating the intra-abdominopelvic pressure and mind-body interaction to coordinate the diaphragm-pelvic floor-abdominal complex for a variety of physical and physiological activities. Conclusion: Understanding of this updated DDB knowledge may help holistic healthcare professionals including holistic nurses provide better patient education and care management during the DDB or DDB-based mind-body intervention time.

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

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

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 than 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 tachypnea-related anxiety, highlighting the role of the forebrain in affective and motor responses during breathing.

Highlights

Impaired human respiratory regulation is associated with cortical/subcortical brain lesionsFrontolimbic/temporal regions contribute to rhythmic breathing and hand motor controlFrontolimbic/temporal damage is associated with anxiety during tachypnea/irregular breathingThe human forebrain is vital for affective and interoceptive experiences during breathing.

Acute effects of the 4-4-8 breathing technique on arterial stiffness in healthy young men

BACKGROUND

Increased arterial stiffness is a risk factor for cardiovascular disease. Slow, deep breathing decreases blood pressure related to arterial stiffness. The objective of the present study was to determine the acute effects of a single session of slow breathing on arterial stiffness, blood pressure, and cardiac autonomic function.

METHODS

Fifteen healthy men (20 ± 0 years) were administered (a) a slow breathing condition (12 consecutive breaths of 4 s of inhalation, 4 s of pause, and 8 s of exhalation through the nose, approximately 5 min per breath) and (b) a control, two-condition crossover design. Carotid-femoral artery pulse wave velocity (cfPWV), brachial-ankle PWV (baPWV), brachial blood pressure, high frequency (HF) and low frequency (LF) were measured at baseline, 30 min, 60 min and 24 h after respiratory control.

RESULTS

Brachial-ankle PWV and brachial systolic pressure on the 4-4-8 breathing trial decreased after 30 min of respiratory control compared to baseline (p < 0.05), but did not change on the CON trial. Carotid-femoral PWV on both trials was unchanged; HF on the 4-4-8 breathing trial increased (p < 0.05) and LF decreased (p < 0.05) after 30 min of respiratory control compared to baseline, but was unchanged on the CON trial.

CONCLUSIONS

These results suggest that slow breathing techniques may be effective in modulating autonomic function and improving arterial stiffness in healthy young adults.

Neuroimaging-based evidence for sympathetic correlation between brain activity and peripheral vasomotion during pain anticipation

Anticipation of pain engenders anxiety and fear, potentially shaping pain perception and governing bodily responses such as peripheral vasomotion through the sympathetic nervous system (SNS). Sympathetic innervation of vascular tone during pain perception has been quantified using a peripheral arterial stiffness index; however, its innervation role during pain anticipation remains unclear. This paper reports on a neuroimaging-based study designed to investigate the responsivity and attribution of the index at different levels of anticipatory anxiety and pain perception. The index was measured in a functional magnetic resonance imaging experiment that randomly combined three visual anticipation cues and painful stimuli of two intensities. The peripheral and cerebral responses to pain anticipation and perception were quantified to corroborate bodily responsivity, and their temporal correlation was also assessed to identify the response attribution of the index. Contrasting with the high responsivity across levels of pain sensation, a low responsivity of the index across levels of anticipatory anxiety revealed its specificity across pain experiences. Discrepancies between the effects of perception and anticipation were validated across regions and levels of brain activity, providing a brain basis for peripheral response specificity. The index was also characterized by a 1-s lag in both anticipation and perception of pain, implying top-down innervation of the periphery. Our findings suggest that the SNS responds to pain in an emotion-specific and sensation-unbiased manner, thus enabling an early assessment of individual pain perception using this index. This study integrates peripheral and cerebral hemodynamic responses toward a comprehensive understanding of bodily responses to pain.

Feasibility of a breath robot intervention to reduce sleep problems in posttraumatic stress disorder: protocol for a randomized controlled study

BACKGROUND

Many patients with posttraumatic stress disorder (PTSD) suffer from sleep problems. Robot-based interventions might be an innovative approach to reduce sleep problems and hyperarousal in PTSD. However, the feasibility and effectiveness of a breath robot in patients with PTSD have never been empirically tested. The aim of this study is to investigate the feasibility of a breath robot to reduce sleep problems and hyperarousal in patients with PTSD.

METHODS

This randomized controlled feasibility study will include N = 30 adult patients with at least subsyndromal PTSD (PTSD Symptom Scale - Interview-5 (PSSI-5)) according to the Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) and impaired sleep quality (Pittsburgh Sleep Quality Index (PSQI) > 5). Patients with organic sleep disorders or currently in psychotherapeutic treatment are excluded. Study participants are randomized to receive either a 4-week Somnox 2 robot intervention including simulation of human breath or a 4-week Somnox 2 robot intervention without human breath simulation. The primary outcome will be the proportion of randomized participants providing outcome data at post-treatment. We consider a proportion of > 50% to indicate feasibility. Additional feasibility outcomes include eligibility rate, recruitment speed, uptake, retention, treatment adherence, and dropout. Potential outcomes of effectiveness (sleep quality, PSQI; severity of PTSD symptoms, PSSI-5) will be assessed at two time points, before (T0) and after (T1) the intervention. Sleep characteristics (Consensus Sleep Diary (CSD)) are measured daily.

DISCUSSION

This study is the first to investigate the feasibility of a novel breath robot intervention for reducing sleep problems and hyperarousal in PTSD patients, with effectiveness considered as a secondary outcome. If feasible and effective, the use of a breath robot could be a nonintrusive and flexible intervention to supplement psychotherapy or to bridge treatment gaps.

TRIAL REGISTRATION

DRKS, DRKS00031063. Registered on 10/012023.

Effects of Different Inspiratory Muscle Training Protocols on Exercise Capacity, Respiratory Muscle Strength, and Health-Related Quality of Life in Patients with Hypertension

Aim

This study aimed to explore how varying inspiratory muscle training workloads affect exercise capacity, health-related quality of life (HrQoL), depression, peripheral and respiratory muscle strength, pulmonary function, dyspnea, fatigue, and physical activity levels in hypertension (HT) patients.

Methods

A randomized, controlled three-arm study. Forty-five patients (58.37 ± 8.53 y, 7F/38M) with HT received IMT (7 days/8 weeks) by POWERbreathe® Classic LR device and were randomized to control group (CG, 10% maximal inspiratory pressure (MIP), n: 15), low-load group (LLG, 30% MIP), and high-load group (HLG, %50 MIP). Exercise capacity, HrQoL, depression, peripheral and respiratory muscle strength, pulmonary function, fatigue, physical activity level, dyspnea, and sleep quality were evaluated before and after the training.

Results

Exercise capacity, physical functioning, peripheral muscle strength, and resting dyspnea were statistically significantly improved in HLG and LLG after the training compared to CG (p < 0.05). Similar improvements in perception of depression, fatigue, and sleep quality were seen within and between the groups (p > 0.05). Statistically significant differences were found within all the groups in terms of MIP and PEF values of respiratory functions (p < 0.05). The superior improvement in the physical activity level was found in the HLG (p < 0.05). Discussion. High-load IMT was particularly effective in increasing physical activity level, peripheral muscle strength, exercise capacity, and improved HrQoL. Low-load IMT was effective in reducing dyspnea and improving respiratory function. Device-guided breathing exercises decreased blood pressure, improved sleep quality, and strengthened respiratory muscles. IMT, an efficient method, is suggested for inclusion in rehabilitation programs due to its capacity to increase physical activity, exercise capacity, and peripheral muscle strength, enhance HrQoL and respiratory function, and alleviate dyspnea. Also, the efficacy of IMT should be investigated with different training protocols such as endurance IMT or functional IMT in HT patients.

Psychophysiological Effects of Slow-Paced Breathing on Adolescent Swimmers' Subjective Performance, Recovery States, and Control Perception

This study examined the effect of a Slow-Paced Breath (i.e., 6 breaths per minute) without Biofeedback (SPB-NoHRVB) protocol on semi-elite adolescent swimmers' psychological and physiological states during a seven-week ecological training period. A linear mixed-effects multilevel regression analysis approach was used with 13 adolescent national-level swimmers. Athletes were randomly assigned to an intervention group (n = 7) and a control group (n = 6). Seven waves of assessments were completed weekly during a seven-week training preparation in ecological conditions. During the protocol, swimmers completed subjective quantitative measures (RESTQ-36-R-Sport; cognitive perceived stress and control states about the training process, training subjective performance, and subjective internal training load) and physiological heart rate (HR) (HR of exercise, absolute and normalized HR recovery during the first 60 s of recovery; HRR60 and nHRR60) and heart rate variability (HRV) (MeanRR, RMSSD, LFnu and HFnu, LF/HF ration) tests (through a submaximal heart rate (5'-5' test) once a week. Results revealed that the SPB-NoHRVB protocol significantly predicts biopsychosocial recovery states, cognitive perception of control, and training subjective performance (i.e., a significant effect of the SPB-NoHRVB protocol with the dependent variables simple time trajectories). However, no significant effects were found for biopsychosocial stress scales, cognitively perceived stress, HR, or HRV markers. Our results suggest that SPB-NoHRVB induces simple evolutions over time for crucial variables in athletes' adaptation to the training process (i.e., cognitive appraisals and biopsychosocial states). In contrast, it highlights that SPB-NoHRVB does not induce better stress states. This specific effect on the resource component is an exciting result that will be discussed in the manuscript.

Mindful breathing as an effective technique in the management of hypertension

Introduction: Hypertension is one of the most important, modifiable risk factors for cardiovascular disease. The popularity of wearable devices provides an opportunity to test whether device guided slow mindful breathing may serve as a non-pharmacological treatment in the management of hypertension. Methods: Fitbit Versa-3 and Sense devices were used for this study. In addition, participants were required to own an FDA or Health Canada approved blood pressure measuring device. Advertisements were shown to 655,910 Fitbit users, of which 7,365 individuals expressed interest and filled out the initial survey. A total of 1,918 participants entered their blood pressure readings on at least 1 day and were considered enrolled in the study. Participants were instructed to download a guided mindful breathing app on their smartwatch device, and to engage with the app once a day prior to sleep. Participants measured their systolic and diastolic blood pressure prior to starting each mindful breathing session, and again after completion. All measurements were self reported. Participants were located in the United States or Canada. Results: Values of systolic and diastolic blood pressure were reduced following mindful breathing. There was also a decrease in resting systolic and diastolic measurements when measured over several days. For participants with a systolic pressure ≥ 130 mmHg, there was a decrease of 9.7 mmHg following 15 min of mindful breathing at 6 breaths per minute. When measured over several days, the resting systolic pressure decreased by an average of 4.3 mmHg. Discussion: Mindful breathing for 15 min a day, at a rate of 6 breaths per minute is effective in lowering blood pressure, and has both an immediate, and a short term effect (over several days). This large scale study demonstrates that device guided mindful breathing with a consumer wearable for 15 min a day is effective in lowering blood pressure, and a helpful complement to the standard of care.

Respiratory patterns and physical fitness in healthy adults: a cross-sectional study

BACKGROUND

The altered respiratory patterns have a significant impact on our health. However, the links between respiration patterns during spontaneous breathing and physical fitness remain unknown. Therefore, we sought to examine how the respiratory pattern during spontaneous breathing interacts with physical fitness.

METHODS

A total of 610 participants (aged 20-59 years) were enrolled; 163 men (age = 41 ± 11) and 401 women (age = 42 ± 9) were included for analysis. The parameters of the respiration pattern were respiration rate (RR) and inhalation/exhalation (I/E) ratio. The physical fitness components were body size, visuomotor reaction time, balance, flexibility, hand grip strength, back extension strength, vertical jump height, number of push-ups, number of sit-ups, and the maximum rate of oxygen consumption. The data were analyzed separately for two gender groups. Participants within each gender group were further divided into two age categories (young: 20-39 years, middle-aged: 40-59 years) for the analysis, and both correlational and comparative tests were used to solidify the results.

RESULTS

Neither RRs nor the I/E ratios were substantially correlated with physical fitness in women. In addition, the I/E ratios showed no significant correlation with physical fitness in young men, while the results from correlational and comparative tests were inconsistent in middle-aged men. Consistently, men with lower RRs exhibited significantly shorter visuomotor reaction times in two age groups, and demonstrated significantly higher vertical jump heights in the middle-aged group.

CONCLUSIONS

In women, respiratory patterns were not correlated with physical fitness. The relationship between middle-aged men's I/E ratios and their physical fitness warrants further investigation. Men with lower RRs may have better visual-motor coordination and/or sustained attention, while middle-aged men with lower RRs may also have greater leg explosive power and neuromuscular coordination, which should be considered for physical assessment and health improvement.

Efficacy of diaphragmatic breathing exercise on respiratory, cognitive, and motor function outcomes in patients with stroke: a systematic review and meta-analysis

Background

Stroke disrupts the functions carried out by the brain such as the control of movement, sensation, and cognition. Disruption of movement control results in hemiparesis that affects the function of the diaphragm. Impaired function of the diaphragm can in turn affect many outcomes such as respiratory, cognitive, and motor function. The aim of this study is to carry out a systematic review and meta-analysis to determine the efficacy of diaphragmatic breathing exercise on respiratory, cognitive, and motor outcomes after stroke.

Method

The study was registered in PROSPERO (CRD42023422293). PubMED, Embase, Web of Science (WoS), PEDro, Scopus, and CENTRAL databases were searched until September 2023. Only randomized controlled trials comparing diaphragmatic breathing exercise with a control were included. Information on the study authors, time since stroke, mean age, height, weight, sex, and the protocols of the experimental and control interventions including intensity, mean scores on the outcomes such as respiratory, cognitive, and motor functions were extracted. Cochrane risks of bias assessment tool and PEDro scale were used to assess the risks of bias and methodological quality of the studies. Narrative synthesis and meta-analysis were used to summarize the results, which were then presented in tables, risk-of-bias graph, and forest plots. The meta-analysis was carried out on respiratory function [forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), FEV1/FVC, peak expiratory flow (PEF)] and motor function (trunk impairment, and internal and external oblique muscles activity).

Results

Six studies consisting of 151 participants were included. The results of the meta-analyses showed that diaphragmatic breathing exercise is only superior to the control at improving respiratory function, FVC (MD = 0.90, 95% CI = 0.76 to 1.04, P < 0.00001), FEV1 (MD = 0.32, 95% CI = 0.11 to 0.52, P = 0.002), and PEF (MD = 1.48, 95% CI = 1.15 to 1.81, P < 0.00001).

Conclusion

There is limited evidence suggesting that diaphragmatic breathing exercise may help enhance respiratory function, which may help enhance recovery of function post stroke.

Systematic Review Registration

PROSPERO, identifier CRD42023422293.

Noninvasive characterization of peripheral sympathetic activation across sensory stimuli using a peripheral arterial stiffness index

Introduction: The peripheral arterial stiffness index has been proposed and validated as a noninvasive measure quantifying stimulus intensity based on amplitude changes induced by sympathetic innervation of vascular tone. However, its temporal response characteristics remain unclear, thus hindering continuous and accurate monitoring of the dynamic process of sympathetic activation. This paper presents a study aimed at modeling the transient response of the index across sensory stimuli to characterize the corresponding peripheral sympathetic activation. Methods: The index was measured using a continuous arterial pressure monitor and a pulse oximeter during experiments with local pain and local cooling stimuli designed to elicit different patterns of sympathetic activation. The corresponding response of the index was modeled to clarify its transient response characteristics across stimuli. Results: The constructed transfer function accurately depicted the transient response of the index to local pain and local cooling stimuli (Fit percentage: 78.4% ± 11.00% and 79.92% ± 8.79%). Differences in dead time (1.17 ± 0.67 and 0.99 ± 0.56 s, p = 0.082), peak time (2.89 ± 0.81 and 2.64 ± 0.68 s, p = 0.006), and rise time (1.81 ± 0.50 and 1.65 ± 0.48 s, p = 0.020) revealed different response patterns of the index across stimuli. The index also accurately characterized similar vasomotor velocities at different normalized peak amplitudes (0.19 ± 0.16 and 0.16 ± 0.19 a.u., p = 0.007). Discussion: Our findings flesh out the characterization of peripheral arterial stiffness index responses to different sensory stimuli and demonstrate its validity in characterizing peripheral sympathetic activation. This study valorizes a noninvasive method to characterize peripheral sympathetic activation, with the potential to use this index to continuously and accurately track sympathetic activators.

Similar Patterns of Dysautonomia in Myalgic Encephalomyelitis/Chronic Fatigue and Post-COVID-19 Syndromes

BACKGROUND

There is a considerable overlap between the clinical presentation of post-COVID-19 condition (PCC) and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Many of their common symptoms can be linked to dysregulation of the autonomic nervous system (dysautonomia). This study aimed to objectively assess autonomic function in a general group of patients with PCC and in a group of patients with ME/CFS whose disease was not related to COVID-19. We hypothesize that the similarity in the chronic symptoms of patients with PCC and ME/CFS extends to objective autonomic nervous system abnormalities.

METHODS

Synchronous recordings of an electrocardiogram and continuous dynamics of blood pressure in the digital artery using the Penaz method were obtained using the spiroarteriocardiorhythmography method in 34 patients diagnosed with ME/CFS, in whom the onset of the disease was not associated with COVID-19, 29 patients meeting the PCC definition and 32 healthy controls. Heart rate variability (HRV) and systolic and diastolic blood pressure variability (BPV) were assessed at rest and in tests with fixed respiratory rates. Indicators of baroreflex regulation (baroreflex effectiveness index and baroreflex sensitivity) were additionally determined at rest.

RESULTS

The total power and power of low-frequency and high-frequency of RR interval variability at rest as well as baroreflex sensitivity were significantly lower both in PCC and ME/CFS patients compared to healthy controls. Several diagnostic prediction models for ME/CFS were developed based on HRV parameters. During slow breathing, the HRV parameters returned to normal in PCC but not in ME/CFS patients. The correlation analysis revealed a close relationship of HRV, BPV parameters and baroreflex sensitivity with fatigue, but not with HADS depressive/anxiety symptoms in the ME/CFS and PCC patients.

CONCLUSIONS

A similar pattern of HRV and baroreflex failure with signs of a pathological acceleration of age-dependent dysautonomia was identified in the ME/CFS and PCC patients. The clinical, diagnostic and therapeutic implications of these findings are discussed, in light of previously described relationships between inflammation, vascular pathology, atherosclerotic cardiovascular disease and autonomic dysfunction.

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

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

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.

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

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

Effect of coherent breathing on mental health and wellbeing: a randomised placebo-controlled trial

Breathwork may offer simple tools for stress resilience. We conducted the largest parallel randomised-controlled trial on breathwork to date (NCT05676658) wherein 400 participants on the research platform Prolific were randomised, in blocks of 2 via remote software, to coherent breathing at ~ 5.5 breaths/min or a matched attention-placebo at 12 breaths/min, for ~ 10 min/day over 4 weeks. Participants were blinded to their allocated interventions, both of which were paced with equal inhalation:exhalation ratios. There were no differences on credibility and expectancy of benefit between conditions. At the primary timepoint post-intervention for the primary outcome subjective stress, there was no significant group by time interaction (F(1,377) = 0.089, p = 0.765, ηp2 < 0.001) nor main effect of group (F = 0.002, p = 0.961, ηp2 < 0.001), however there was a significant main effect of time (F = 72.1, p < 0.001, ηp2 = 0.161). Similar results were found at 1-month follow-up for stress and for secondary outcomes of anxiety, depression and wellbeing. There were overall improvements on these mental health and wellbeing outcomes from baseline to post-intervention and follow-up across both groups, yet the magnitude of this improvement was not different between arms. Accordingly, we found no measurable effect of coherent breathing over and above a well-designed breathwork placebo at improving mental health and wellbeing. Methodological considerations and recommendations for robust future research are discussed. Funder: Sasakawa Young Leaders Fellowship Fund, Tokyo, Japan.

Guiding Principles for the Practice of Integrative Physical Therapy

Integrative health is an emerging specialty inside multiple disciplines within the medical community, yet the practice of integrative physical therapy remains undefined. This perspective paper suggests a set of guiding principles to support the role of physical therapy in integrative health. These guiding principles, including therapeutic partnership, whole person health, living systems, movement as an integrative experience, and salutogenesis, are described and explored in-depth as they relate to all aspects of patient care and clinician experience. These guiding principles are articulated within the context of social determinants of health and the interrelated roles that environment, trauma, stress, and lifestyle all play within an integrative physical therapy plan of care. Examples of current integrative physical therapy practices that embody these principles are described. The 5 guiding principles are designed to elicit interprofessional inquiry into how integrative health models can be applied to the art and science of physical therapy practice. The expansion of integrative health into the field of physical therapy has the potential to improve individual and population health, as integrative physical therapy can be used to address prevention, health promotion, primary care, and wellness while acknowledging the complex, dynamic, and interconnected nature of the human condition.

IMPACT

This perspective article presents 5 guiding principles to establish a framework to define and shape the growing application of an integrative health model to physical therapy practice. These integrative physical therapy guiding principles aim to improve the quality of whole-person, patient-centered care.

A conceptual model for managing sexual pain with somatocognitive therapy in women with provoked vestibulodynia and implications for physiotherapy practice

Somatocognitive therapy is a multimodal physiotherapy treatment developed in the early 2000s to alleviate the burden of chronic pelvic pain. In recent years, somatocognitive therapy has been further developed to treat women with provoked vestibulodynia. This prevalent gynecological pain condition is a subgroup of chronic pelvic pain and the most common form of vulvodynia. Provoked vestibulodynia is a neglected multifactorial pain condition of unknown cause, adversely affecting women's sexual life, relation to their partners and their psychological health. Pain is located at the vulvar vestibule and is provoked by touch or pressure such as sexual intercourse. In the management of sexual pain, somatocognitive therapy combines bodily exploration, pain education, cognitive coping strategies and structured homework to improve sexual function and reduce pain. To support these processes, developing a sound therapeutic alliance with the patient is essential. The aim of this article is to provide a conceptual model for managing provoked vestibulodynia with somatocognitive therapy, including a theoretical rational for this treatment. We base our conceptual model on the biopsychosocial model, i.e., considering the complex interplay of biomedical, emotional/cognitive, psychosexual and interpersonal factors in provoked vestibulodynia management. In addition, implications for practice and a detailed description of somatocognitive therapy for provoked vestibulodynia will be provided, to allow replication in clinical practice and in clinical trials.

Pain Informed Movement for people with knee osteoarthritis: Protocol for a pilot randomized controlled trial

Objective

Conservative pain management strategies for knee osteoarthritis (KOA) have limited effectiveness and do not employ a pain-mechanism informed approach. Pain Informed Movement is a novel intervention combining mind-body techniques with neuromuscular exercise and pain neuroscience education (PNE), aimed at improving endogenous pain modulation. While the feasibility and acceptability of this program has been previously established, it now requires further evaluation in comparison to standard KOA care.

Design

This protocol describes the design of a pilot two-arm randomized controlled trial (RCT) with an embedded qualitative component. The primary outcome is complete follow-up rate. With an allocation ratio of 1:1, 66 participants (33/arm) (age ≥40 years, KOA diagnosis or meeting KOA NICE criteria, and pain intensity ≥3/10), will be randomly allocated to two groups that will both receive 8 weeks of twice weekly in-person exercise sessions. Those randomized to Pain Informed Movement will receive PNE and mind-body technique instruction provided initially as videos and integrated into exercise sessions. The control arm will receive neuromuscular exercise and standard OA education. Assessment will include clinical questionnaires, physical and psychophysical tests, and blood draws at baseline and program completion. Secondary outcomes are program acceptability, burden, rate of recruitment, compliance and adherence, and adverse events. Participants will be invited to an online focus group at program completion.

Conclusion

The results of this pilot RCT will serve as the basis for a larger multi-site RCT aimed at determining the program's effectiveness with the primary outcome of assessing the mediating effects of descending modulation on changes in pain.

Daily heart rate variability biofeedback training decreases locus coeruleus MRI contrast in younger adults in a randomized clinical trial

As an arousal hub region in the brain, the locus coeruleus (LC) has bidirectional connections with the autonomic nervous system. Magnetic resonance imaging (MRI)-based measures of LC structural integrity have been linked to cognition and arousal, but less is known about factors that influence LC structure and function across time. Here, we tested the effects of heart rate variability (HRV) biofeedback, an intervention targeting the autonomic nervous system, on LC MRI contrast and sympathetic activity. Younger and older participants completed daily HRV biofeedback training for five weeks. Those assigned to an experimental condition performed biofeedback involving slow, paced breathing designed to increase heart rate oscillations, whereas those assigned to a control condition performed biofeedback to decrease heart rate oscillations. At the pre- and post-training timepoints, LC contrast was assessed using turbo spin echo MRI scans, and RNA sequencing was used to assess cAMP-responsive element binding protein (CREB)-regulated gene expression in circulating blood cells, an index of sympathetic nervous system signaling. We found that left LC contrast decreased in younger participants in the experimental group, and across younger participants, decreases in left LC contrast were related to the extent to which participants increased their heart rate oscillations during training. Furthermore, decreases in left LC contrast were associated with decreased expression of CREB-associated gene transcripts. On the contrary, there were no effects of biofeedback on LC contrast among older participants in the experimental group. These findings provide novel evidence that in younger adults, HRV biofeedback involving slow, paced breathing can decrease both LC contrast and sympathetic nervous system signaling.