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Background: Metabolic syndrome (MetS) is associated with an increased risk of cardiovascular diseases. Compelling evidence supports the key role of dysfunction in the autonomic nervous system (ANS) in that association, as well as mutual correlation among the components of MetS. The autonomic nervous system index (ANSI) is a percentile-ranked unitary proxy of cardiac autonomic regulation (CAR) that is designed to be free of age and sex bias, with higher values indicating better autonomic control. This study investigates CAR using the ANSI in patients with MetS. Methods: A total of 133 patients referred to the Exercise Medicine Clinic of Istituto Auxologico Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) underwent CAR assessment using the ANSI and answered lifestyle questions in ad hoc questionnaires. The participants were retrospectively subdivided into two groups according to the presence or absence of MetS criteria. Results: Of the subjects, 58 were diagnosed with MetS, and 75 were not (no MetS). The ANSI was significantly impaired (32.9 vs. 44.8, P<0.01) in the MetS group, and ANSI scores showed a decreasing trend (P=0.004) as the number of MetS components increased. No significant lifestyle differences were found between the groups. Conclusion: The ANSI was significantly reduced in subjects with MetS, and CAR impairment became progressively more apparent as the number of MetS components increased.

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Orthostatic testing, involving the transition from different body positions (e.g., from lying or sitting position to an upright or standing position), offers valuable insights into the autonomic nervous system (ANS) functioning and cardiovascular regulation reflected through complex adjustments in, e.g., measures of heart rate (HR) and heart rate variability (HRV). This narrative review explores the intricate physiological mechanisms underlying orthostatic stress responses and evaluates its significance for exercise science and sports practice. Into this matter, active orthostatic testing (e.g., active standing up) challenges the cardiovascular autonomic function in a different way than a passive tilt test. It is well documented that there is a transient reduction in blood pressure while standing up, leading to a reflex increase in HR and peripheral vasoconstriction. After that acute response systolic and diastolic blood pressures are usually slightly increased compared to supine lying body position. The ANS response to standing is initiated by instantaneous cardiac vagal withdrawal, followed by sympathetic activation and vagal reactivation over the first 25-30 heartbeats. Thus, HR increases immediately upon standing, peaking after 15-20 beats, and is less marked during passive tilting due to the lack of muscular activity. Standing also decreases vagally related HRV indices compared to the supine position. In overtrained endurance athletes, both parasympathetic and sympathetic activity are attenuated in supine and standing positions. Their response to standing is lower than in non-overtrained athletes, with a tendency for further decreased HRV as a sign of pronounced vagal withdrawal and, in some cases, decreased sympathetic excitability, indicating a potential overtraining state. However, as a significant main characteristic, it could be noted that additional pathophysiological conditions consist in a reduced responsiveness or counter-regulation of neural drive in ANS according to an excitatory stimulus, such as an orthostatic challenge. Hence, especially active orthostatic testing could provide additional information about HR(V) reactivity and recovery giving valuable insights into athletes' training status, fatigue levels, and adaptability to workload. Measuring while standing might also counteract the issue of parasympathetic saturation as a common phenomenon especially in well-trained endurance athletes. Data interpretation should be made within intra-individual data history in trend analysis accounting for inter-individual variations in acute responses during testing due to life and physical training stressors. Therefore, additional measures (e.g., psychometrical scales) are required to provide context for HR and HRV analysis interpretation. However, incidence of orthostatic intolerance should be evaluated on an individual level and must be taken into account when considering to implement orthostatic testing in specific subpopulations. Recommendations for standardized testing procedures and interpretation guidelines are developed with the overall aim of enhancing training and recovery strategies. Despite promising study findings in the above-mentioned applied fields, further research, thorough method comparison studies, and systematic reviews are needed to assess the overall perspective of orthostatic testing for training monitoring and fine-tuning of different populations in exercise science and training.

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The main genetic risk factors for Parkinson's disease (PD) are presently represented by variants in GBA1 gene encoding for the ß-glucocerebrosidase (GCase). Searching for a peripheral biomarker that can be used for selecting and monitoring patients in clinical trials targeting GBA1-associated PD (GBA1-PD) is a current challenge. We previously demonstrated that α-synuclein oligomers expressed as proximity ligation assay (PLA) score in synaptic terminals of skin biopsy are a reliable biomarker for distinguishing idiopathic PD (iPD) from healthy controls (HC). This cross-sectional study investigates an unexplored cohort of GBA1-PD (n = 27) compared to 28 HC, and 36 iPD cases to (i) analyze α-synuclein oligomers and quantify them throughout PLA score, (ii) investigate GCase expression in brain and synaptic terminals targeting the sweat gland, (iii) unravel indicators that could differentiate patients with specific GBA1 mutations. PLA score discriminates GBA1-PD from HC with sensitivity = 88.9% (95% CI 70.84-97.65), specificity = 88.5% (95% CI 69.85-97.55), and PPV = 88.9% (95% CI 73.24-95.90), AUC value = 0.927 (95% CI 0.859-0.996). No difference was found between GBA1-PD patients and iPD, suggesting a common pathological pathway based on α-synuclein oligomers. GCase score did not differ in GBA1-PD, iPD, and HC in the synaptic terminals, whereas a positive correlation was found between PLA score and GCase score. Moreover, a significant increase in synaptic density was observed in GBA1-PD compared to iPD and HC (P < 0.0001). Employing ROC curve to discriminate GBA1-PD from iPD, we found an AUC value for synaptic density = 0.855 (95% CI 0.749-0.961) with sensitivity = 85.2% (95% CI 66.27%-95.81%), specificity = 77.1% (95% CI 59.86%-89.58%), and PPV = 74.19% (60.53%-84.35%). The highest synaptic density values were observed in p.N409S patients. This work points out to the value of both PLA score and synaptic density in distinguishing GBA1-PD from iPD and to their potential to stratify and monitor patients in the context of new pathway-specific therapeutic options.

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Autonomic nervous system dysfunction is increasingly recognized as a common sequela of traumatic brain injury (TBI). Heart rate variability (HRV) is a specific measure of autonomic nervous system functioning that can be used to measure beat-to-beat changes in heart rate following TBI. The objective of this systematic review was to determine the state of the literature on HRV dysfunction following TBI, assess the level of support for HRV dysfunction following TBI, and determine if HRV dysfunction predicts mortality and the severity and subsequent recovery of TBI symptoms. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Two raters coded each article and provided quality ratings with discrepancies resolved by consensus. Eighty-nine papers met the inclusion criteria. Findings indicated that TBI of any severity is associated with decreased (i.e., worse) HRV; the severity of TBI appears to moderate the relationship between HRV and recovery; decreased HRV following TBI predicts mortality beyond age; HRV disturbances may persist beyond return-to-play and symptom resolution following mild TBI. Overall, current literature suggests HRV is decreased following TBI and may be a good indicator of physiological change and predictor of important outcomes including mortality and symptom improvement following TBI.

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Nearly all geriatric surgical complications are studied in the context of a single organ system, e.g., cardiac complications and the heart; delirium and the brain; infections and the immune system. Yet, we know that advanced age, physiological stress, and infection all increase sympathetic and decrease parasympathetic nervous system function. Parasympathetic function is mediated through the vagus nerve, which connects the heart, brain, and immune system to form, what we have termed, the brain-heart-immune axis. We hypothesize that this brain-heart-immune axis plays a critical role in surgical recovery among older adults. In particular, we hypothesize that the brain-heart-immune axis plays a critical role in the most common surgical complication among older adults: postoperative delirium. Further, we present heart rate variability as a measure that may eventually become a multi-system vital sign evaluating brain-heart-immune axis function. Finally, we suggest the brain-heart-immune axis as a potential interventional target for bio-electronic neuro-immune modulation to enhance resilient surgical recovery among older adults.

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The neurocardiac axis constitutes the neuronal circuits between the arteries, heart, brain, and immune organs (including thymus, spleen, lymph nodes, and mucosal associated lymphoid tissue) that together form the cardiovascular brain circuit. This network allows the individual to maintain homeostasis in a variety of environmental situations. However, in dysfunctional states, such as exposure to environments with chronic stressors and sympathetic activation, this axis can also contribute to the development of atherosclerotic vascular disease as well as other cardiovascular pathologies and it is increasingly being recognized as an integral part of the pathogenesis of cardiovascular disease. This review article focuses on 1) the normal functioning of the neurocardiac axis; 2) pathophysiology of the neurocardiac axis; 3) clinical implications of this axis in hypertension, atherosclerotic disease, and heart failure with an update on treatments under investigation; and 4) quantification methods in research and clinical practice to measure components of the axis and future research areas.

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The brain is essential for processing and integrating sensory signals coming from peripheral tissues. Conversely, the autonomic nervous system regulated by brain centres modulates the immune responses involved in the genesis and progression of cardiovascular diseases. Understanding the pathophysiological bases of this relationship established between the brain and immune system is relevant for advancing therapies. An additional mechanism involved in the regulation of cardiovascular function is provided by the brain-mediated control of the renin-angiotensin system. In both cases, the communication is typically bidirectional and established by afferent and sensory signals collected at the level of peripheral tissues, efferent circuits, as well as of hormones. Understanding how the brain mediates the bidirectional communication and how the immune system participates in this process is object of intense investigation. This review examines key findings that support a role for these interactions in the pathogenesis of major vascular diseases that are characterized by a consistent alteration of the immune response, such as hypertension and atherosclerosis. In addition, we provide a critical appraisal of the translational implications that these discoveries have in the clinical setting where an effective management of neuroimmune and/or neuroinflammatory state might be beneficial.

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BACKGROUND: One of the most commonly experienced symptoms of premenstrual disorder (PMD) is anxiety, and there is a notable rise in sympathomimetic activity in this patient group. Studies have linked fluctuations in systemic autonomic tone to electrocardiography (ECG) changes. This study aims to investigate the relationship between anxiety, a common symptom of PMD, and alterations in QT dispersion (QTd) and P-wave dispersion (Pd) in adolescent females. METHODS: This cross-sectional study included female adolescents aged 12-18 with regular menstruation for at least 3 months. Participants completed the premenstrual syndrome scale (PMSS) and were divided into two groups, PMD and control, according to the PMSS score. A standard 12-lead body surface ECG was performed and QTd and Pd values were determined in each participant. RESULTS: Of the 43 participants, 27 were categorized into the PMD group, with a mean age of 15.15 ± 1.43 years. Age at menarche and menstrual cycle patterns were comparable between the PMD and control groups. Statistical analysis revealed significantly higher Pmin (p = 0.010) and Pd values (p < 0.001) in the PMD group compared to controls. A positive correlation between PMSS scores and Pd (p = 0.049) was also observed. CONCLUSIONS: Changes in atrial conduction and ventricular repolarization due to the pathophysiology of PMD may increase the risk of developing atrial and ventricular tachyarrhythmias over time. Screening patients with PMD using an ECG may be useful in identifying potentially at-risk adolescents.

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Patients with chronic obstructive pulmonary disease (COPD) exhibit reduced cardiac autonomic activity, linked to poor prognosis and exercise intolerance. While heart rate variability biofeedback (HRVB) can enhance cardiac autonomic activity in various diseases, its use in patients with COPD is limited. This study explored the impact of the HRVB on cardiac autonomic activity and pulmonary indicators in patients with COPD. Fifty-three patients with COPD were assigned to either the HRVB (n = 26) or the control group (n = 27), with both groups receiving standard medical care. The HRVB group also underwent one-hour HRVB sessions weekly for six weeks. All participants had pre- and post-test measurements, including the Six-Minute Walking Test (6MWT), lead II electrocardiogram (ECG) recording, Modified Medical Research Council Dyspnea Scale (mMRC), body mass index, airflow obstruction, dyspnea, and exercise capacity (BODE) index. ECG data were analyzed for heart rate variability (HRV) as an index of cardiac autonomic activity. A two-way mixed analysis of variances demonstrated significant interaction effects of Group × Time in pulmonary indicators and HRV indices. The HRVB group exhibited significant post-test improvements, with decreased mMRC and BODE scores and increased 6MWT distance and HRV indices, compared to pre-test results. The 6MWT distance significantly increased and mMRC significantly decreased at post-test in the HRVB group compared with the control group. This study confirmed the efficacy of HRVB as an adjunct therapy in patients with COPD, showing improvements in exercise capacity, breathing difficulties, and cardiac autonomic activity.

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Surgical aortic valve replacement (SAVR) and transcatheter aortic valve implantation (TAVI) are options in severe aortic valve stenosis (AVS). Cardiovascular (CV) and cerebrovascular (CBV) control markers, derived from variability of heart period, systolic arterial pressure, mean cerebral blood velocity and mean arterial pressure, were acquired in 19 AVS patients (age: 76.8 ± 3.1 yrs, eight males) scheduled for SAVR and in 19 AVS patients (age: 79.9 + 6.5 yrs, 11 males) scheduled for TAVI before (PRE) and after intervention (POST, <7 days). Left ventricular function was preserved in both groups. Patients were studied at supine resting (REST) and during active standing (STAND). We found that: (i) both SAVR and TAVI groups featured a weak pre-procedure CV control; (ii) TAVI ensured better CV control; (iii) cerebral autoregulation was working in PRE in both SAVR and TAVI groups; (iv) SAVR and TAVI had no impact on the CBV control; (v) regardless of group, CV and CBV control markers were not influenced by STAND in POST. Even though the post-procedure preservation of both CV and CBV controls in TAVI group might lead to privilege this procedure in patients at higher risk, the missing response to STAND suggests that this advantage could be insignificant.

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BACKGROUND: Sex differences in the symptomatology of adults with attention-deficit/hyperactivity disorder (ADHD) have often been overlooked when studying behavioral abnormalities. However, it is known that women exhibit considerably more stronger symptoms related to emotional competence than men. Since affective functions significantly influence the processing of risky decision-making and risk-engagement, we assume that risky behavior in ADHD is affected by sex differences. Therefore, we specifically investigated sex-specific effects on the interaction between emotionally induced changes in physiology and behavioral performance on a decision-making task. METHODS: Skin conductance responses of twenty-nine adults with ADHD (n = 16 male; n = 13 female) and thirty-three adults in the control group (n = 14 male; n = 19 female) were recorded during the performance in a modified version of the Balloon Analogue Risk Task (BART). Additional questionnaires were used to reveal insights in the self-assessment of emotional competence, risk perception, and feedback sensitivity. Emotional arousal and decision-making behavior were analyzed using linear mixed-effects models. RESULTS: Results showed different effects of sex on risk behaviors in controls and ADHD. In contrast to healthy controls, female adults with ADHD showed a significantly greater risk engagement in the BART compared to males with ADHD. This contrary sex relation was not observed in skin conductance responses and revealed a significantly different sex-dependent correlation of body response and behavioral task performance in ADHD. Comparisons with results from self-assessments furthermore indicate a reduced behavioral self-perception in women with ADHD, but not in men. CONCLUSION: In summary, we found an altered interaction between physiological activity and risky behavior in women with ADHD. Thus, the present study indicates a reduced sensitivity towards the own bodily responses in women with ADHD, which could consequently cause increased risky DM behavior in daily life. The current results suggest that more consideration needs to be given to sex-specific effects on physiological processes and behavior in adults with ADHD.

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BACKGROUND: Equine asthma in severe form (severe equine asthma [sEA]) shares remarkable similarities with human asthma. Human studies detected changes in the autonomic nervous system function in asthmatic patients based on heart rate variability (HRV) analysis. STUDY DESIGN: Observational study. OBJECTIVES: To investigate the relationship between sEA and HRV in horses. METHODS: Twenty horses diagnosed with sEA and 20 asymptomatic (non-sEA) horses were investigated. SEA horses showed clinical signs. The RR intervals of the ECG were recorded for 1 h at rest between 9 AM and 11 AM using a heart rate (HR) monitor. HRV data were calculated using Kubios software. Parameters recorded for the sEA and non-sEA groups were compared using one-way MANOVA model. The significance level was set at α = 0.05. RESULTS: SD2 (mean 99.6 ± SD 25.3 vs. 42.5 ± 17.1), SDNN (82.7 ± 20.7 vs. 41.3 ± 14.3), TINN (398.1 ± 104.9 vs. 209.3 ± 71.9), SD2/SD1 ratio (1.7 ± 0.2 vs. 1.1 ± 0.3), Total power (4740.2 ± 1977.9 vs. 1503.0 ± 1179.3), LF (2415.3 ± 1072.4 vs. 707.4 ± 649.9), SD1 (60.9 ± 15.9 vs. 39.2 ± 14.1), RMSSD (86.0 ± 22.6 vs. 55.3 ± 19.8) and HF (1575.8 ± 902.5 vs. 578.1 ± 491.1) were lower in sEA horses compared with the non-sEA horses (p < 0.01 for each variable). SD2, SDNN, TNN, the SD2/SD1 ratio and Total power showed the greatest discriminatory power in differentiating the sEA and non-sEA groups. MAIN LIMITATIONS: Small sample size. CONCLUSION: Our findings indicate that like humans, asthmatic horses show an overall reduction in autonomic control. A relative increase of the parasympathetic modulation of the heart was also observed. After further investigations, HRV measurement might be a non-invasive approach to monitor autonomic nervous system responses of sEA horses.

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Heart rate variability biofeedback (HRVBF) is a non-invasive therapeutic technique that aims to regulate variability in heart rate. This intervention has promise in mitigating perioperative stress, a critical factor for surgical patient outcomes. This comprehensive review aimed to explore the current evidence on the perioperative role of HRV biofeedback in improving patient outcomes, reducing perioperative stress, enhancing recovery, and optimizing anaesthesia management. A review of the PubMed and Google Scholar databases was conducted to identify articles focused on HRVBF in relation to the perioperative period. Studies were selected using appropriate keywords in English (MeSH). Ample potential applications of HRVBF in clinical anaesthesia have been identified and proven feasible. It is a non-invasive and an easy method an anaesthesiologists has at its disposal with potential utility in reducing perioperative stress, as a tool of optimization of comorbidities, analgesia supplementation and in predicting catastrophic complications. Although HRVBF has the potential to enhance anaesthesia management and improve patient outcomes, several limitations and challenges must be addressed to maximize its clinical utility. Overcoming these obstacles through research and technological advancements will be crucial for realizing the full benefits of HRVBF in perioperative care.

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INTRODUCTION: Postural orthostatic tachycardia syndrome is a debilitating disorder. We compared paediatric patients with this dysautonomia presenting with and without peak upright heart rate > 100 beats per minute. MATERIALS AND METHODS: Subjects were drawn from the Postural Orthostatic Tachycardia Syndrome Program database of the Children's Hospital of Philadelphia diagnosed between 2007 and 2018. Subjects were aged 12-18 years at diagnosis with demographic data, supine and peak heart rate from 10-minute stand, symptoms, and family history. Patients were divided into "low heart rate" (peak less than 100 beats/minute) and "high heart rate" (peak at least 100 beats/minute) groups. RESULTS: In total, 729 subjects were included (low heart rate group: 131 patients, high heart rate group: 598 patients). The low heart rate group had later age at diagnosis (16.1 versus 15.7, p = 0.0027). Median heart rate increase was 32 beats/minute in the low heart rate group versus 40 beats/minute in the high heart rate group (p < 0.00001). Excluding palpitations and tachypalpitations, there were no differences in symptom type or frequency between groups. DISCUSSION: Paediatric patients meeting heart rate criteria for postural orthostatic tachycardia syndrome but without peak heart rate > 100 demonstrate no difference in symptom type or frequency versus those who meet both criteria. Differences observed reached statistical significance due to population size but are not clinically meaningful. This suggests that increased heart rate, but not necessarily tachycardia, is seen in these patients, supporting previous findings suggesting maximal heart rate is not a major determinant of symptom prevalence in paediatric postural orthostatic tachycardia syndrome.

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Objective.The present study investigated how breathing stimuli affect both non-linear and linear metrics of the autonomic nervous system (ANS).Approach.The analysed dataset consisted of 70 young, healthy volunteers, in whom arterial blood pressure (ABP) was measured noninvasively during 5 min sessions of controlled breathing at three different frequencies: 6, 10 and 15 breaths min-1. CO2concentration and respiratory rate were continuously monitored throughout the controlled breathing sessions. The ANS was characterized using non-linear methods, including phase-rectified signal averaging (PRSA) for estimating heart acceleration and deceleration capacity (AC, DC), multiscale entropy, approximate entropy, sample entropy, and fuzzy entropy, as well as time and frequency-domain measures (low frequency, LF; high-frequency, HF; total power, TP) of heart rate variability (HRV).Main results.Higher breathing rates resulted in a significant decrease in end-tidal CO2concentration (p< 0.001), accompanied by increases in both ABP (p <0.001) and heart rate (HR,p <0.001). A strong, linear decline in AC and DC (p <0.001 for both) was observed with increasing breathing rate. All entropy metrics increased with breathing frequency (p <0.001). In the time-domain, HRV metrics significantly decreased with breathing frequency (p <0.01 for all). In the frequency-domain, HRV LF and HRV HF decreased (p= 0.038 andp= 0.040, respectively), although these changes were modest. There was no significant change in HRV TP with breathing frequencies.Significance.Alterations in CO2levels, a potent chemoreceptor trigger, and changes in HR most likely modulate ANS metrics. Non-linear PRSA and entropy appear to be more sensitive to breathing stimuli compared to frequency-dependent HRV metrics. Further research involving a larger cohort of healthy subjects is needed to validate our observations.

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BACKGROUND: Non-ordinary states of consciousness induced by psychedelics can be accompanied by so-called "peak experiences," characterized at the emotional level by their intensity and positive valence. These experiences are strong predictors of positive outcomes following psychedelic-assisted therapy, and it is therefore important to better understand their biology. Despite growing evidence that the autonomic nervous system (ANS) plays an important role in mediating emotional experiences, its involvement in the psychedelic experience is poorly understood. The aim of this study was to investigate to what extent changes in the relative influence of the sympathetic (SNS) and parasympathetic nervous systems (PNS) over cardiac activity may reflect the subjective experience induced by the short-acting psychedelic N,N-Dimethyltryptamine (DMT). METHODS: We derived measures of SNS and PNS activity from the electrocardiograms of 17 participants (11 males, mean age = 33.8 years, SD = 8.3) while they received either DMT or placebo. RESULTS: Results show that the joint influence of SNS and PNS ("sympathovagal coactivation") over cardiac activity was positively related to participants' ratings of "Spiritual Experience" and "Insightfulness" during the DMT experience, while also being related to improved well-being scores 2 weeks after the session. In addition, we found that the state of balance between the two ANS branches ("sympathovagal balance") before DMT injection predicted scores of "Insightfulness" during the DMT experience, as well as subsequent sympathovagal coactivation. CONCLUSION: These findings demonstrate the involvement of the ANS in psychedelic-induced peak experiences and may pave the way to the development of biofeedback-based tools to enhance psychedelic therapy.

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Cervical or upper-thoracic spinal cord injury (SCI, ≥T6) often leads to low resting blood pressure (BP) and impaired cardiovascular responses to acute exercise due to disrupted supraspinal sympathetic drive. Epidural spinal cord stimulation (invasive, ESCS) and transcutaneous spinal cord stimulation (non-invasive, TSCS) have previously been used to target dormant sympathetic circuits and modulate cardiovascular responses. This case series compared the effects of cardiovascular-optimised ESCS and TSCS versus sham ESCS and TSCS on modulating cardiovascular responses and improving submaximal upper-body exercise performance in individuals with SCI. Seven males with a chronic, motor-complete SCI between C6 and T4 underwent a mapping session to identify cardiovascular responses to spinal cord stimulation. Subsequently, four participants (two ESCS and two TSCS) completed submaximal exercise testing. Stimulation parameters (waveform, frequency, intensity, epidural electrode array configuration, and transcutaneous electrode locations in the lumbosacral region) were optimised to elevate cardiovascular responses (CV-SCS). A sham condition (SHAM-SCS) served as a comparison. Participants performed arm-crank exercise to exhaustion at a fixed workload corresponding to above ventilatory threshold, on separate days, with CV-SCS or SHAM-SCS. At rest, CV-SCS increased BP and predicted left ventricular cardiac contractility and total peripheral resistance. During exercise, CV-SCS increased time to exhaustion and peak oxygen pulse (a surrogate for stroke volume), relative to SHAM-SCS. Ratings of perceived exertion also tended to be lower with CV-SCS than SHAM-SCS. Comparable improvements in time to exhaustion with ESCS and TSCS suggest that both approaches could be promising ergogenic aids to support exercise performance or rehabilitation, along with reducing fatigue during activities of daily living in individuals with SCI.

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Throughout our lifetime the heart executes cycles of contraction and relaxation to meet the body's ever-changing metabolic needs. This vital function is continuously regulated by the autonomic nervous system. Cardiovascular dysfunction and autonomic dysregulation are also closely associated; however, the degrees of cause and effect are not always readily discernible. Thus, to better understand cardiovascular disorders, it is crucial to develop model systems that can be used to study the neurocardiac interaction in healthy and diseased states. Human pluripotent stem cell (hiPSC) technology offers a unique human-based modelling system that allows for studies of disease effects on the cells of the heart and autonomic neurons as well as of their interaction. In this review, we summarize current understanding of the embryonic development of the autonomic, cardiac and neurocardiac systems, their regulation, as well as recent progress of in vitro modelling systems based on hiPSCs. We further discuss the advantages and limitations of hiPSC-based models in neurocardiac research.

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OBJECTIVE: Many employees, especially in voice-intensive professions, are under psychological stress at work, which is very difficult to objectify. The aim of the study was to analyze correlations between heart rate variability (HRV) parameters and objective voice function using weighted voice parameters (Dysphonia Severity Index [DSI]) in order to determine whether subjects with impaired vocal function show a predominance of sympathetic control during a vocal stress test. STUDY DESIGN: Prospective. METHODS: Fifty-three people of working age were examined. After asking for sociodemographic, occupational, and voice-related data, the objective voice function was determined using the DiVAS voice diagnostics system, and a 20-minute vocal stress test was performed. The electrocardiogram was recorded using medilog AR12plus during the vocal stress test and in a 5-minute rest phase before and a 5-minute recovery phase after the test. HRV was analyzed using the Kubios HRV Premium software. RESULTS: HRV was reduced during the vocal stress test compared to the resting and recovery phase. A Spearman correlation analysis showed significant correlations, particularly between the frequency-related HRV parameters and the DSI. The DSI correlated positively with the high frequency (HF) band (the relative power and the normalized unit). The DSI correlated negatively with the quotient between low frequency and HF and the low frequency normalized unit. CONCLUSION: During a vocal stress test, adults in working age show a correlation between parameters of objective vocal function and parameters of HRV. The more impaired the objective vocal function, the higher the predominance of sympathetic activation under vocal stress. The voice can therefore be seen as a "warning signal" for the processes in the autonomic nervous system. The use of preventive strategies for stress management and for voice health appears to be particularly beneficial in vocally stressful occupations in order to achieve a positive effect on parasympathetic activity.

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BACKGROUND: Wearable technology is increasingly used in clinical practice and research to monitor functional gastrointestinal symptoms and mental health. AIMS: This article explores the potential of wearable sensors to enhance the understanding of the autonomic nervous system (ANS), particularly its role in linking psychological and gastrointestinal function. The ANS, facilitates brain-gut communication and is responsive to psychosocial conditions. It is implicated in disorders related to psychological stress and gut-brain interaction. Wearable technology enables tracking of the ANS in daily life, offering complementary and alternative methods from traditional lab-based measures. This review places focus on autonomic metrics such as respiratory sinus arrhythmia, vagal efficiency, and electrodermal activity as well as self-reports of autonomic symptoms. DISCUSSION: Potential applications include use of wearable sensors for tracking autonomic activity in disorder of gut-brain interaction such as cyclic vomiting syndrome, in which ANS dysregulation may be triggered by psychosocial factors. Considerations for data interpretation and contextualization are addressed, acknowledging challenges such as situational confounders of ANS activity and accuracy of wearable devices.