Caesarean delivery accounts for more than 21% of all births worldwide, with rates exceeding 30% in several countries, yet objective physiological markers for monitoring postoperative maternal recovery remain scarce. Heart rate variability (HRV), a non-invasive index of autonomic nervous system integrity, has demonstrated prognostic value in general surgical populations. This scoping review will map the extent, range and nature of evidence on HRV monitoring in caesarean populations within a recovery-assessment framework. The review follows a Population-Concept-Context framework. The primary population comprises women undergoing elective caesarean delivery, with emergency procedures analysed as a distinct subgroup. The concept covers any validated measurement of HRV parameters (time-domain, frequency-domain and non-linear indices). The context spans the perioperative-to-postpartum continuum, from preoperative baseline through 6 weeks after delivery. Adhering to the Joanna Briggs Institute methodology, we will employ a three-step search strategy across PubMed, Embase, CINAHL, Cochrane Central Register of Controlled Trials and Web of Science. Two independent reviewers will screen records and extract data. Findings will be synthesised narratively and presented via temporal evidence mapping, an evidence gap map, and structured summary tables. Formal ethics approval is not required because this review exclusively analyses published data. We will disseminate our findings through publication in a peer-reviewed journal and presentations at relevant academic conferences.

Biologger-based monitoring of body temperature, heart rate, and heart rate variability in Lidia cattle: relationships with environmental conditions.

Rugby union is characterized by intermittent efforts combining high and lowintensity actions. In European Under-18 Rugby XV Championship, matches are played every 72 hours, which may hinder adequate recovery. Heart rate variability (HRV) is a noninvasive method that assesses the autonomic nervous system activity, yet its role to measure the rugby players recovery remains underexplored. The purpose of this study was to evaluate HRV responses in elite under-18 rugby players during an European Championship with matches every 72 hours. This prospective study was conducted with 27 players from the Spanish under-18 national rugby team. HRV data were collected daily for 12 days, including pretournament preparation and 3 matches. Measurements were taken in a supine resting position using a Bluetooth chest-strap. Time-domain, frequency-domain, and nonlinear HRV metrics were analyzed. Statistical comparisons were made using Friedman and Wilcoxon tests (p < 0.05). HRV metrics showed no significant differences between pretournament values and the first match day (first MD). However, time-domain, frequency-domain, and nonlinear variables significantly decreased after the first MD compared with the second (second MD) and third match days (third MD) (p < 0.0001). No significant differences were observed between the second MD and third MD. These findings suggest persistent autonomic imbalance and insufficient recovery between matches. Playing matches every 72 hours does not allow for adequate recovery in under-18 rugby players. Daily HRV monitoring provides a valuable tool for assessing fatigue, guiding training load management, and reducing injury risk during competitive tournaments.

Heart rate variability (HRV) and cerebral autoregulation (CAR) reflect physiologic processes that may influence neurological injury in children supported with extracorporeal membrane oxygenation (ECMO). Although abnormalities in both have been associated with adverse neurological outcomes, their physiologic relationship during ECMO remains unclear. This retrospective single-center study evaluated the association between HRV and CAR during the first 24 h of ECMO support and assessed their independent relationships with neurological outcome. Patients with at least two hours of simultaneous HRV and CAR monitoring within 24 h of ECMO initiation were included. HRV metrics were derived from artifact-free NN intervals across time, frequency, and nonlinear domains, while CAR was quantified using the cerebral oximetry index (COx), with impaired CAR defined as COx > 0.3. Associations between HRV indices and COx were examined using Spearman correlations at hourly and 24 h resolutions. Unfavorable outcome was defined as death or a Pediatric Cerebral Performance Category (PCPC) score ≥3 at discharge with deterioration from baseline. Eighty-nine patients met inclusion criteria, and 16% demonstrated impaired CAR. HRV measures were reduced relative to age-adjusted norms in both CAR groups without significant differences between groups. Correlations between HRV indices and COx were consistently weak. Overall, 50% experienced unfavorable neurological outcomes. In adjusted logistic regression models, NN skewness and COx were independently associated with outcome, although only NN skewness remained significant in interaction analyses. HRV and CAR exhibited limited physiological coupling during early ECMO support, while each measure provided independent prognostic information with respect to neurological outcome.

Low heart rate variability (HRV) has been associated with increased risk of morbidity and mortality. While HRV measurements from Holter monitoring have been available for over 3 decades, pediatric reference limits have not been adequately defined. We sought to determine these limits using meta-analysis. Multiple databases were searched through 2024 for relevant studies. Data extraction with meta-analysis and estimation of 95% reference ranges were performed. Linear time- and frequency-domain HRV variables were grouped by the following age ranges: infants (birth-11 months), younger children (1–6 years), older children (7–12 years), and adolescents (13–18 years). Forty-nine studies including 2993 participants were analyzed. SDNN (standard deviation of all sinus NN intervals), SDANN (standard deviation of averages of NN intervals in all 5 min segments), SDNNi (mean of standard deviations of NN intervals for all 5 min segments), rMSSD (root mean square of differences between adjacent NN intervals), and pNN50 (percentage of adjacent NN intervals that varied by more than 50ms) all demonstrated a progressive increase in younger children that required subdivision of that reference range. SDNN and SDANN exhibited further milder increases into adolescence, while SDNNi, rMSSD, and pNN50 remained relatively stable after age 4 years. LF (low frequency) and HF (high frequency) parameters increased abruptly from infancy to early childhood with minimal change thereafter. Remarkably, pediatric age-group lower limits for rMSSD, pNN50, and LF/HF were frequently at or near zero, limiting their utility for detecting decreased HRV. Age-stratified Holter monitor reference limits for HRV parameters in infants, children and adolescents are proposed.

The transition of bioelectronic medicine to clinical use is currently limited by a lack of non-invasive sensors capable of measuring autonomic tone during active neuromodulation. Conventional monitoring modalities, such as mean arterial pressure (MAP) and Ag/AgCl chest electrodes, are often invasive, cumbersome, or susceptible to motion artifacts. Here, we present a novel framework employing an in-ear sensor (AURIS) to continuously monitor heart rate variability (HRV) during therapeutic neuromodulation. These sensors utilize a polydimethylsiloxane (PDMS) substrate to ensure biocompatibility and superior conformability. Experiments in a rodent model ( n = 3 ) demonstrate that the AURIS platform achieves gold-standard fidelity, with mean heart rate differences of 6.03 BPM and mean RR interval deltas of 3.18 ms compared to chest electrodes. Sensor agreement was statistically validated using independent t-tests, showing no significant difference between modalities (all p > 0.46 ). While time-domain shifts trended toward significance, complexity metrics showed robust sequential responses with large effect sizes, including the SD1/SD2 ratio ( d = 1.474 ) and the DFA α ratio ( d = 1.091 ). These findings validate a sensor architecture that is durable, accessible, and provides the necessary technical foundation for closed-loop feedback and non-invasive clinical trials.

To objectively evaluate intraoperative stress responses in ophthalmology residents by assessing heart rate (HR) and heart rate variability (HRV) during distinct steps of cataract surgery using Holter monitoring. In this prospective study, 26 ophthalmology residents performed standard, uncomplicated phacoemulsification surgery while continuously monitored with a 3-channel digital Holter device. Each surgery was divided into four steps: (1) incision and viscoelastic injection, (2) capsulorhexis, (3) nucleus removal, and (4) cortical aspiration with intraocular lens implantation. Time-domain HR parameters including maximum HR, minimum HR, and mean HR values were recorded and analyzed at baseline and during each surgical step. HRV metrics including mean NN intervals, SDNN, SDANN, SDNN index, and RMSSD were also analyzed. All surgical steps showed significantly elevated mean HR compared to baseline (p < 0.001). The highest mean HR was observed during the capsulorhexis step (108.9 ± 7.2 bpm), followed by nucleus removal (102.7 ± 14.0 bpm). HR remained elevated throughout the procedure without returning to baseline, suggesting sustained sympathetic activation. HRV indices revealed moderate autonomic variability, with SDNN (66.5 ± 24.2 ms) and RMSSD (34.9 ± 19.6 ms) indicating heightened arousal with preserved vagal tone. No significant correlation was found between HR/HRV parameters and residency duration or surgical time (p > 0.05 for all). Ophthalmology residents experience sustained autonomic stress throughout all steps of cataract surgery, with the highest sympathetic activation occurring during capsulorhexis step. These findings can underscore the utility of HRV monitoring in surgical training and support the integration of stress management and simulation strategies into ophthalmology residency curricula.

Heart rate variability (HRV) is the variation in the time interval between consecutive heartbeats, is variable for each individual and higher or lower HRV is not always better. Despite the importance of HRV to cancer care, HRV monitoring and analysis are not standard clinical practice. In this article, we present the clinical utility of widely known recommendations for improving HRV, highlight their benefits and outline how these can provide an efficient, non-invasive and cost-effective method for identifying autonomic dysfunction through HRV. Considered together, this article can inform policy on the importance of HRV measurements and evaluation as a standard of care in supportive care guidelines.

The purpose of the study is to evaluate the effectiveness of training process adjustments based on the analysis of heart rate variability dynamics. Research methods and organization. The method of heart rate variability (HRV) assessment and statistical data analysis was applied. The study was conducted with a group of female athletes of the national curling team aged 18 to 25 years. Research results and conclusions. The results obtained demonstrate the importance of HRV monitoring as a tool for the timely detection of signs of overtraining and the optimization of training loads in the course of athletic preparation. The significance of using HRV indicators for the objective assessment of athletes' functional state and the planning of individualized training programs has been confirmed.

Background: Heart rate variability (HRV) is increasingly used in sports science as a non-invasive marker of autonomic nervous system function and training adaptation. In soccer, where players engage in mixed high-intensity efforts, HRV may provide insight into both aerobic and anaerobic capacities. This study aimed to evaluate the relationship between resting HRV and key physiological performance parameters in professional soccer players. Methods: Seventeen professional male soccer players (age: 24.554.71 years) from the Turkish second league participated. HRV data were collected using the Omegawave system alongside measures of aerobic and anaerobic power, sprinting, jumping, reaction time, lactate levels, and GPS-based match performance. Assessments were conducted over four visits, and standard time- and frequency-domain HRV indices were analyzed. Results: Velocity at anaerobic threshold was positively correlated with several time-domain and frequency-domain HRV parameters, and negatively with LF:HF and LFnu ratios. VO2max was positively associated with HFnu and negatively with LF-related parameters. GPS-derived performance metrics and lactate tolerance were also linked to HRV indicators, suggesting vagal activity reflects multiple aspects of performance. Conclusions: Resting HRV parameters, particularly those reflecting parasympathetic activity, are associated with both aerobic and anaerobic performance indicators in professional soccer players. Suggesting that HRV monitoring can serve as a practical, non-invasive tool for tracking aerobic power and for planning and adjusting daily training loads.

Abstract Background The civil engineering construction industry has long faced high accident rates and severe occupational psychological challenges. Research has shown that over 40% of construction workers report experiencing psychological distress such as anxiety and depression, and their level of psychological resilience is significantly negatively correlated with the incidence of safety accidents. Traditional mental health intervention models, such as lectures or group counseling, have limited effectiveness due to low participation and unrealistic scenarios. Therefore, exploring an immersive, quantifiable, and realistic high-pressure training method has become a key requirement for improving the psychological safety and operational efficiency of practitioners. Virtual reality (VR) technology provides an innovative path for this. Methods A targeted VR psychological resilience training system has been designed and developed, consisting of three progressive modules: a high-risk environment adaptation module (such as high-altitude and enclosed spaces), a sudden crisis stress module (such as simulating material slippage and equipment abnormalities), and an emotion regulation and cognitive reconstruction module. The study used a randomized controlled trial to randomly divide 162 frontline construction workers into an experimental group (n = 81, receiving standardized VR training twice a week for 6 weeks) and a control group (n = 81, receiving routine safety training of equal duration). Using the Psychological Resilience Scale, State Trait Anxiety Scale, Physiological Multichannel Instrument (to monitor Heart Rate Variability (HRV) and skin electrical response), and simulated task performance indicators, data collection was conducted three times before intervention, after intervention, and one month after intervention. The data analysis used repeated measures analysis of variance, independent sample t-test, and effect size calculation (Cohen's d). Results The data results indicate that the VR training system has a significant and sustained effect on improving psychological resilience. After intervention, the experimental group showed an average improvement of 38.4% in the total score of the psychological resilience scale compared to the control group (F = 25.73, p&amp;lt;.001, η2 = 0.14), with the most significant improvement in the dimension of "resilience" (d = 1.21). Physiological data shows that the experimental group showed an average increase of 52.7% in high-frequency power of HRV (reflecting parasympathetic nervous system activity and recovery ability) and a reduction of about 45% in stress recovery time (p&amp;lt;.01) when responding to sudden simulated emergencies. In simulating high-risk tasks, the experimental group's operational error rate decreased by 31.2% compared to the control group, and the decision response time was shortened by 22.5% (p&amp;lt;.01). Tracking tests show that the positive effects mentioned above remain stable after one month (with a decay rate of&amp;lt;8% for each indicator). Discussion The VR psychological training system effectively enhances the psychological resilience and stress management ability of construction workers through situational immersion, and data confirms its superiority in short-term interventions. The high interactivity of the system and the degree of scene simulation may be key driving factors. In the future, it is necessary to expand the sample and conduct long-term tracking to verify the sustainability of the effect; At the same time, it can integrate biofeedback and multi-user collaboration modules to further optimize system universality.

Purpose: This longitudinal case study examined the efficacy of systematic physiological monitoring in guiding individualized training periodization for junior cross-country skiers across three consecutive competitive seasons. Methods: Six male junior cross-country skiers (age 15.3-18.7 years) from a regional sports academy underwent quarterly laboratory testing on a cycle ergometer, including determination of anaerobic threshold (AnT) via ventilatory breakpoint, maximal alactic muscular power (MAM) via 6-second sprint, stroke volume (SV) estimation via HR-power extrapolation, and daily heart rate variability (HRV) monitoring. Training zones were individually prescribed and dynamically adjusted based on test results. Results: Over three seasons, mean AnT power increased 16.9% (225 +/- 18 to 263 +/- 22 W; Cohen's d = 1.87), MAM increased 30.8% (650 +/- 45 to 851 +/- 62 W; d = 3.70), and estimated VO2max improved 14.8% (58.2 +/- 3.1 to 66.8 +/- 2.9 mL/kg/min; d = 2.78). Ventilatory threshold showed strong agreement with blood lactate measurements (r = 0.91, mean difference = 6.2 W). A targeted SV training protocol produced measurable SV increases in four of six athletes. HRV monitoring enabled early detection of functional overreaching in two athletes, prompting training modifications that prevented progression to non-functional overreaching. Individual response patterns varied substantially, underscoring the necessity of personalized training approaches. Conclusions: Systematic physiological monitoring integrated into a coaching feedback loop can guide effective individualized training periodization in developing endurance athletes. The ventilatory threshold method provides a practical, non-invasive alternative to blood lactate testing for training zone determination.

Low preoperative heart rate variability (HRV) is associated with adverse cardiovascular outcomes and delirium after geriatric surgery, but in-person testing is burdensome and impractical. To evaluate wrist-based wearables for remotely capturing preoperative outpatient and postoperative inpatient data for HRV analysis. RR-intervals were extracted, and data missingness was assessed for systematic differences. Delirium incidence was evaluated. Preoperatively, 76.9% of participants provided high-quality outpatient data, with no systematic demographic or clinical differences. Postoperatively, 80.2% had high-quality inpatient data; however, missing data were associated with older age, lower BMI, ICU admission, and longer surgeries and hospitalizations. Postoperative HRV did not significantly differ between participants with and without delirium. Outpatient HRV capture via wrist-based wearables is broadly feasible in older surgical patients, while postoperative inpatient data are disproportionately missing in higher-risk patients. These differences highlight both the translational potential and limitations of wearable HRV measurements for perioperative outcome prediction.

This study evaluated the feasibility and acceptability of Ōura, a finger-worn sensor used to monitor heart rate variability (HRV) as a digital biomarker of stress among Korean-American home care workers caring for Korean-American individuals with dementia. This prospective, single-cohort study included 15 home care workers who wore Ōura for 21 days, with HRV data collected over a 14-day analysis period. Feasibility and acceptability were evaluated through quantitative and qualitative approaches. All participants were female, with a median age of 61 years, and each cared for a median of 1 Korean-American individual with dementia (range: 1 to 3 care recipients). We achieved an 88.24% retention rate and a 100% completion rate. Of the 210 potential daily HRV data points, 94.2% were valid. Participants reported high ease of use and comfort wearing the ring. Qualitative findings revealed themes of enhanced health awareness, variability in comfort and fit, and a need for more information about the health data provided by the ring application. The findings demonstrate the feasibility and acceptability of using a finger-worn sensor in Korean-American home care workers. Future studies should address data validity issues and explore the clinical utility of HRV monitoring via finger-worn sensors for stress management in this understudied population.

Heart rate variability (HRV) is a well-established, noninvasive measure of autonomic nervous system activity and is associated with clinical outcomes. Although real-time monitoring of HRV is valuable in clinical practice, its effectiveness is often compromised by major challenges: high inter-individual variability and frequent data contamination from procedural artifacts. To address these challenges, we developed and validated a computational framework for robust and personalized real-time HRV analysis oriented toward clinical application. The framework performs simultaneous analysis and visualization of both time- and frequency-domain HRV indices and incorporates an adaptive alert algorithm that personalizes alert thresholds using the interquartile range of each patient's own data. A workflow-integrated mechanism for manually annotating and excluding artifact-prone periods prevents procedural artifacts from skewing the statistical baselines, and a multi-scale visualization module provides a unified view of short-term fluctuations and long-term trends. While existing HRV tools are powerful for research or offline analysis, they often lack the integration of personalized alerting and workflow-oriented artifact management needed for bedside care. The proposed system uniquely combines personalized alerting, care-linked artifact exclusion, and multi-scale bedside visualization within a single real-time software package. The framework was validated using open-access electrocardiogram (ECG) databases and synthetic noise-contaminated signals, confirming robust R-wave detection across pediatric and adult recordings and under low signal-to-noise conditions. In addition, the framework was operationally validated at the bedside using ECG data from 24 newborn patients. By systematically addressing the core challenges of personalization and artifact management in a clinically integrated manner, this work represents a significant step toward translating real-time HRV analysis into routine vital sign management and, ultimately, improved patient outcomes.

The escalating prevalence of chronic stress necessitates development of highly personalized non-pharmacological interventions. Traditional art therapy lacks real-time adaptability to match individuals' fluctuating physiological states. This paper introduces the Bio-Aesthetic Resonator (BAR), a novel closed-loop immersive art therapy system driven by real-time physiological feedback. The BAR integrates biosensors for continuous monitoring of Heart Rate Variability (HRV) and Galvanic Skin Response (GSR), utilizing deep reinforcement learning (DRL) to dynamically generate immersive visual and auditory artscapes. We conducted a pilot randomized controlled trial (pRCT) with 60 participants with mild-moderate anxiety. The BAR intervention significantly reduced perceived stress scores (PSS-10: Cohen's d = 0.65, 95% CI [0.22, 1.08], p = 0.003) and increased high-frequency HRV (HF-HRV: Cohen's d = 0.92, 95% CI [0.48, 1.36], p &lt; 0.001) compared to a sham-adaptive control. These results support bio-aesthetic resonance as a viable framework for personalized digital therapeutics.

Heart rate variability (HRV) is a vital metric for assessing cardiovascular health, psychological stress, and sleep quality. Non-contact HRV monitoring offers advantages in safety, comfort, and hygiene, making it an increasingly attractive solution. In this study, we propose a high-precision, non-contact HRV analysis method using a 77 GHz multiple-input multiple-output (MIMO) frequency-modulated continuous wave (FMCW) radar system. The proposed method first employs an optimized Capon beamforming algorithm to accurately localize the heart and enhance intermediate frequency (IF) signals from the heart's direction. A modified differentiate and cross-multiply (MDACM) algorithm is then used to demodulate the phase sequence, yielding a raw vital sign signal that includes both respiratory and cardiac components. This signal is further processed using a six-level wavelet packet transform (WPT), from which specific wavelet coefficients (6th to 12th bands at level six) are selected to reconstruct the seismocardiogram (SCG) signal. To extract precise inter-beat interval (IBI) sequences, a robust aortic valve opening (AO) point detection algorithm is developed. Time-domain HRV indices-including the standard deviation of normal-to-normal intervals (SDNN), the root mean square of successive differences (RMSSD), and the percentage of successive normal-to-normal intervals differing by more than 50 milliseconds (ms) (pNN50)-are then computed from the IBI sequence. To validate the approach, we developed a synchronized data acquisition system combining radar and electrocardiogram (ECG) sensors and collected data from 13 participants-each person collected data for 10 min. Experimental results demonstrate the effectiveness of our method, achieving average errors of 4.11 ms in SDNN, 8.05 ms in RMSSD, and 2.15% in pNN50 compared to ECG-derived ground truth. These results outperform existing non-contact HRV monitoring techniques and highlight the method's potential for practical, continuous, and unobtrusive cardiovascular monitoring.

Emergency service personnel work under substantial physical and psychological strain. Heart rate variability (HRV) reflects autonomic reactivity and may serve as a non invasive indicator of occupational load. This study assessed heart rate (HR) and ultra short term HRV responses during simulated cardiopulmonary resuscitation (CPR).A total of 110 participants were enrolled (mean age 25.7 7.9 years; BMI 23.8 3.2 kg/m): 84 emergency healthcare workers (43 women, 41 men) and 26 male firefighters, recruited from two sites (Poland n = 34; Hungary n = 76). The protocol consisted of three consecutive 120 second phases: Pre (rest), During (continuous chest compressions on a Rescue Anne QCPR manikin), and Post (rest). RR intervals were recorded using a Polar H10 sensor (1000 Hz). The primary outcome was RMSSD (ms), with mean HR (bpm) as a secondary measure. Statistical analyses included the Friedman test with Dunn–Bonferroni correction, Mann–Whitney U tests, and Spearman correlations.Mean HR increased from 92.8 23.0 bpm (Pre) to 117.8 18.7 bpm (During) (Δ = +25.0 bpm, +27%, p &lt; 0.001), then decreased to 104.7 22.3 bpm (Post). RMSSD declined from 23 ms (IQR 16–33) to 19.5 ms (12–27) (Δ = −3.5 ms, −15%, p = 0.001), with partial recovery to 20 ms (15–28) (Pre vs Post phase). HR varied by age, BMI, and sex across multiple phases (e.g., mean HR: all phases p &lt; 0.01). RMSSD differed by sex During and Post (p = 0.031 and p = 0.012), but not by age or BMI (all p ≥ 0.07). No monotonic association was found between mean HR and mean HRV within phases (|ρ| ≤ 0.056, p ≥ 0.559).Simulated CPR induced marked tachycardia and a short term reduction in RMSSD, indicating acute sympathetic activation with partial recovery afterward. Ultra short term HRV monitoring using wearable devices appears feasible in both training and operational contexts and may serve as an early marker of excessive psychophysical load. Incorporating HRV metrics into occupational health protocols could support risk stratification, targeted conditioning and recovery strategies, and enhance safety among emergency personnel.

The role of separation anxiety and autonomic dysregulation in pediatric vasovagal syncope. A cross-sectional study.

In veterinary medicine, heart rate variability (HRV) has emerged as a valuable tool for assessing welfare, comfort, stress responses, and overall physiological status. This study aimed to design and validate a harness/vest wearable system for remote HRV measurement and monitoring in dairy cows managed under rotational grazing conditions in the high tropics. The harness/vest was developed to protect and stabilize Holter-type measurement devices under field conditions, ensuring that it did not interfere with animal comfort and allowed proper HRV signal acquisition. For HRV measurements, a Polar H10® Heart Rate Sensor paired with a Polar Unite® watch was used. To evaluate the practical application of the harness/vest and its impact on animal comfort, lactating Holstein and Holstein x Jersey crossbreed dairy cows (n = 74) were monitored. The behavior of the animals was observed, and these observations were subsequently compiled into an ethogram, used as an outcome measure to verify whether the harness/vest altered natural behaviors. Behavioral and physiological responses were compared between cows wearing the harness/vest and those without it. The observed behavioral patterns, including posture, locomotion, feeding behavior, and social interactions, were similar between groups, indicating that the harness/vest did not interfere with comfort or routine activities. Comfort was assessed through: (1) comparison of frequencies and durations of key behaviors, (2) evaluation of any avoidance or agitation responses at fitting, and (3) continuous observation for signs of mechanical interference, rubbing, or restraint. Based on these evaluations, Holter-type devices can be reliably integrated into the harness/vest system developed in this study, representing an innovative and effective tool for continuous, remote, and noninvasive HRV monitoring in grazing dairy cows in the high tropics, while preserving comfort and welfare.