Impact of Using Different Levels of Threshold-Based Artefact Correction on the Quantification of Heart Rate Variability in Three Independent Human Cohorts

The clinical effectiveness of sivelestat in treating sepsis patients with both acute respiratory distress syndrome and septic cardiomyopathy

BACKGROUND

We aimed to assess the efficacy of the neutrophil elastase inhibitor, sivelestat, in the treatment of sepsis-induced acute respiratory distress syndrome (ARDS) and septic cardiomyopathy (SCM).

METHODS

Between January 2019 and December 2021, we conducted a randomized trial on patients who had been diagnosed with sepsis-induced acute respiratory distress syndrome (ARDS) and septic cardiomyopathy (SCM) at Wuhan Union Hospital. The patients were divided into two groups by random envelop method, the Sivelestat group and the Control group. We measured the serum concentrations of Interleukin (IL)-6, IL-8, Tumor necrosis factor-α (TNF-α), and High-mobility group box 1 (HMGB1) at five time points, which were the baseline, 12 h, 24 h, 48 h, and 72 h after admission to the ICU. We evaluated the cardiac function by sonography and the heart rate variability (HRV) with 24-hour Holter recording between the time of admission to the intensive care unit (ICU) and 72 h after Sivelestat treatment.

RESULTS

From January 2019 to December 2021, a total of 70 patients were included in this study. The levels of IL-6, IL-8, and TNF-α were significantly lower in the Sivelestat group at different time points (12 h, 24 h, 48 h, and 72 h). HMGB1 levels were significantly lower at 72 h after Sivelestat treatment (19.46 ± 2.63pg/mL vs. 21.20 ± 2.03pg/mL, P = 0.003). The stroke volume (SV), tricuspid annular plane systolic excursion (TAPSE), early to late diastolic transmitral flow velocity (E/A), early (e') and late (a') diastoles were significantly low in the Control group compared with the Sivelestat group. Tei index was high in the Control group compared with the Sivelestat group (0.60 ± 0.08 vs. 0.56 ± 0.07, P = 0.029). The result of HRV showed significant differences in standard deviation of normal-to-normal intervals (SDNN), low frequency (LF), and LF/HF (high frequency) between the two groups.

CONCLUSIONS

Sivelestat can significantly reduce the levels of serum inflammatory factors, improve cardiac function, and reduce heart rate variability in patients with Sepsis-induced ARDS and SCM.

Publication guidelines for human heart rate and heart rate variability studies in psychophysiology-Part 1: Physiological underpinnings and foundations of measurement

This Committee Report provides methodological, interpretive, and reporting guidance for researchers who use measures of heart rate (HR) and heart rate variability (HRV) in psychophysiological research. We provide brief summaries of best practices in measuring HR and HRV via electrocardiographic and photoplethysmographic signals in laboratory, field (ambulatory), and brain-imaging contexts to address research questions incorporating measures of HR and HRV. The Report emphasizes evidence for the strengths and weaknesses of different recording and derivation methods for measures of HR and HRV. Along with this guidance, the Report reviews what is known about the origin of the heartbeat and its neural control, including factors that produce and influence HRV metrics. The Report concludes with checklists to guide authors in study design and analysis considerations, as well as guidance on the reporting of key methodological details and characteristics of the samples under study. It is expected that rigorous and transparent recording and reporting of HR and HRV measures will strengthen inferences across the many applications of these metrics in psychophysiology. The prior Committee Reports on HR and HRV are several decades old. Since their appearance, technologies for human cardiac and vascular monitoring in laboratory and daily life (i.e., ambulatory) contexts have greatly expanded. This Committee Report was prepared for the Society for Psychophysiological Research to provide updated methodological and interpretive guidance, as well as to summarize best practices for reporting HR and HRV studies in humans.

Targeted proteomics involved in cardiovascular health and heart rate variability in children with overweight/obesity

BACKGROUND

Children with overweight/obesity often exhibit alterations in their plasma protein profiles and reduced heart rate variability (HRV). Plasma proteomics is at the forefront of identifying biomarkers for various clinical conditions. We aimed to examine the association between plasma-targeted proteomics involved in cardiovascular health and resting vagal-related HRV parameters in children with overweight/obesity.

METHODS

Forty-four children with overweight/obesity (10.2 ± 1.1 years old; 52% boys) participated in the study. Olink's technology was used to quantify 92 proteins involved in cardiovascular health. HRV was measured using a heart rate monitor (Polar RS800CX). Four resting vagal-related HRV parameters were derived in time- and frequency-domain.

RESULTS

Eight proteins (KIM1, IgG Fc receptor II-b, IDUA, BOC, IL1RL2, TNFRSF11A, VSIG2, and TF) were associated with at least one out of the four vagal-related HRV parameters (β values ranging from -0.188 to 0.288; all p < .05), while KIM1, IDUA, and BOC associated with ≥ three vagal-related HRV parameters. Multiple hypothesis testing corrections did not reach statistical significance (false discovery rate [FDR >0.05]).

CONCLUSION

Plasma-targeted proteomics suggested novel biomarkers for resting vagal-related HRV parameters in children with overweight/obesity. Future studies using larger cohorts and longitudinal designs should confirm our findings and their potential clinical implications.

The relationship between heart rate variability and glucose clearance in healthy men and women

Heart rate variability (HRV) is a non-invasive indicator of the activity of the autonomic nervous system, which regulates many physiological functions including metabolism. The purpose of this study was to quantify the relationship between resting markers of HRV and oral glucose tolerance test (OGTT) response. Eighteen healthy individuals (10 males, 8 females, (23.8±2.9 years) underwent a 10-minute resting HRV recording. The final five minutes were evaluated via Kubios HRV Standard for: root mean square of successive differences (RMSSD), standard deviation of normal-to-normal sinus beats (SDNN), high frequency (HF), and low frequency (LF). A standard 2-hour OGTT was then administered. Glucose was measured via finger stick before, 30-minutes post, 1-hour post, and 2-hours post OGTT. Pearson correlations demonstrated that RMSSD, SDNN, HF and LF were strongly correlated to fasting blood glucose (FBG) for the group (p<0.05) but not for glucose area under the curve (AUC). When analyzed by sex, only males demonstrated significant correlations between AUC and RMSSD, SDNN, and LF (p<0.05). An independent samples t-test revealed no sex differences for FBG, AUC, RMSSD, SDNN, HF and LF. These findings provide new and interesting insights into the relationship of autonomic activity and glucose uptake, highlighting sex-based relationships.

Resting heart rate but not heart rate variability is associated with the normal-weight obesity phenotype

OBJECTIVE

To determine differences in resting heart rate variability (HRV) and heart rate (HR) between young adults with normal-weight obesity (NWO) and normal-weight lean (NWL).

METHODS

A total of 65 normal-weight individuals (18-25 years old, 50 women, body mass index 18.5 to 24.9 kg/m2) were included in this cross-sectional study. Body fat percentage was determined using a whole-body dual energy x-ray absorptiometry scanner. Resting HRV and HR were assessed with the Polar RS800CX. Forty-one participants were classified as NWO and 24 NWL using cutoff points for body fat percentage (33.3% for women and 23.1% for men).

RESULTS

There were no differences in HRV between NWO and NWL groups (all p > .05). HR was higher in NWO (mean 70 beats per minute [bpm], standard deviation [SD] 8) than in NWL adults (mean 65 bpm, SD 10), the adjusted mean difference 5 bpm (95% CI, 0 to 10 bpm).

CONCLUSION

HR is a noninvasive biomarker and relatively cheap, fast, and easy to measure that could detect "apparently healthy" young individuals with an adverse cardiovascular disease risk profile despite presenting a normal body weight.

The impact of soccer-specific psychophysiological stress on inhibition and cognitive flexibility in elite youth players

While researchers and practitioners attribute an essential role to executive functions (EFs) for soccer performance, the usefulness of respective diagnostics and the predictive value remain unclear. One limitation restricting the translation and relevance of study results to improve actual game performance is the insufficient consideration of competitive conditions. Thus, this study aimed to conduct soccer-specific cognitive diagnostics under a soccer-specific psychophysiological stress condition, mimicing the demands of a competitive game. A total of 92 (Mage = 15.17, SDage = 1.45) youth elite players performed tests for inhibition (flanker task) or cognitive flexibility (number-letter task) with a soccer-specific motor response (i.e., pass into goals). After a pre-test in a neutral condition, players were randomly assigned to a neutral (moderate soccer-specific exercise) or a stress condition (physical stress and competitive instructions and filming for psychological stress). Objective (i.e., cortisol, heart rate variability) and subjective stress-related measures (i.e., SAM, VAS) were assessed six times throughout experimental procedure. Analyses revealed significant interaction effects between time and condition for all objective and subjective variables indicating a successful experimental stress induction. For cognitive performance, results revealed significant main effects of time, but no significant interaction effects between time and condition. However, descriptive statistics suggested improved performance under stress, with decreased flanker effect and switch costs. Additionally, response time variability in the flanker task significantly decreased in the stress condition. These findings offer insights into individual stress perception and processing under game-related psychophysiological demands, expanding previous research on situational EF alterations that also hold relevance for applied practitioners.

Exercise-induced changes in plasma S-Klotho levels are associated with the obtained enhancements of heart rate variability in sedentary middle-aged adults: the FIT-AGEING study

The shed form of the Klotho protein (S-Klotho) is considered a biomarker of longevity, but it is still unknown whether the levels are related to heart rate (HR) and heart rate variability (HRV); both of them greatly influenced by the ageing process, physical fitness, exercise, and health status. This study aimed (i) to investigate the association between S-Klotho plasma levels with HR and HRV parameters and (ii) to examine the association of exercise-induced changes in S-Klotho and those obtained in HR and HRV parameters after a 12-week exercise intervention in sedentary middle-aged adults. Sixty-six sedentary middle-aged adults participated in this study (50% women; 45-65 years old). Participants were randomized into 4 groups: (a) a control group (no exercise), (b) a physical activity recommendation from the World Health Organization group, (c) a high-intensity interval training group, and (d) a high-intensity interval training group adding whole-body electromyostimulation. S-Klotho plasma levels, HR, and HRV parameters (SDNN, RMSSD, high frequency, stress score, and sympathetic/parasympathetic ratio) were measured. At baseline, S-Klotho plasma levels were not related to HR and HRV parameters. After the intervention, exercise-induced changes in S-Klotho plasma levels were positively associated with changes in SDNN (β=0.261; R2=0.102; p=0.014) and negatively related to changes in stress score and sympathetic/parasympathetic ratio (all β=-0.257; R2 ranges between 0.092 and 0.131; all p<0.020). Our study suggests that higher S-Klotho plasma levels are related to increased vagal influence and reduced sympathetic tone in the autonomic nervous system in sedentary middle-aged adults after different training programs. ClinicalTrials.gov identifier: CT03334357.

Physiological, anthropometric and athletic performance adaptations from completing a 1-month pre-season period. A two-year longitudinal study in female collegiate soccer players

Introduction

Collegiate coaches and integrative support staff often utilize pre-season as a brief and intense training period to prepare athletes technically, tactically, and physiologically, to meet the demands of competition during a soccer season. This study sought to examine the dose-response from performing on-field soccer activities during a four-week pre-season period in female collegiate soccer players, and if the magnitude in response was associated with accumulated exercise stress.

Methods

A total of twenty-seven healthy female soccer players training as part of a collegiate soccer program volunteered to participate in this two-year longitudinal study. Data collection commenced prior to the start of each pre-season period, at the beginning of August, and was completed at the beginning of September, when pre-season ended. Data collection periods were separated by a 31-day period. Indices of cardiovascular function, anthropometry, and athletic performance were examined during each data collection period. Internal and external measures of accumulated exercise stress were recorded using the Polar Team Pro® system.

Results

When comparing the beginning to the end of pre-season, significant improvements were observed in body fat (%) [24.2 ± 6.0 "vs." 23.3 ± 5.6, p = 0.001], heart rate variability (rMSSD) [51.8 ± 25.1 "vs." 67.9 ± 34.6 ms, p = 0.002], resting heart (bpm) [73.8 ± 12.1 "vs." 64.3 ± 8.8, p = 0.001] and cardiorespiratory performance (YoYo IRTL-1) [925.8 ± 272.8 "vs." 1,062.6 ± 223.3 m, p = 0.001]. Significant reductions in musculoskeletal performance were observed through vertical jump height (cm) [24.9 ± 23.7, p = 0.04]. Change in the end of pre-season body weight (kg) was significantly associated with accumulated accelerations and decelerations [r ≥ 0.49, p = 0.01]. End of pre-season change in cardiorespiratory performance was significantly associated with both accumulated training load (au) and TRIMP (au) [r ≥ 0.63, p = 0.01].

Discussion

In conclusion, performing a four-week pre-season period, involving only on-field training, can promote positive and significant adaptations in anthropometry, cardiovascular function, and athletic performance measures in female collegiate soccer players. The magnitudes of these adaptations were associated with both internal and external measures of accumulated exercise stress.

How to properly evaluate cardiac vagal tone in oncology studies: a state-of-the-art review

Heart rate variability (HRV) analysis provides an assessment of cardiac vagal tone and consequently global cardiac health as well as systemic condition. In systemic diseases such as cancer and during treatments that affect the whole body, like chemotherapy, the vagus nerve activity is low and deregulated. Some studies focus on using HRV to predict mortality in oncology. However, in cancer patients, systemic alterations substantially increase artifacts during HRV measurement, especially atrial ectopic beats. Moreover, HRV may be altered by various factors (duration and time of measurement, breathing, drugs, and other confounding factors) that alter each metric in different ways. The Standard Deviation of all Normal to Normal intervals (SDNN) is the most commonly used metric to evaluate HRV in oncology, but it does not appear to be specific to the cardiac vagal tone. Thus, cardiac vagal activity diagnosis and vital prognosis of cancer patients can be biased. Our review presents the main HRV metrics that can be currently used in oncology studies and their links with vagus nerve and cancer. We present the influence of external factors and the required duration and time of measurement. Considering all these parameters, this review proposes seven key points for an assessment of HRV and cardiac vagal tone in patients with cancer.

Fit-Fat Index is better associated with heart rate variability compared to fitness and fatness alone as indicators of cardiometabolic human health

OBJECTIVES

Cardiorespiratory fitness and fatness indicators have been related to heart rate variability (HRV) parameters. The Fit-Fat Index (FFI) is a single index combining cardiorespiratory fitness and fatness indicators. To the best of our knowledge, no studies have previously analyzed whether FFI are related to cardiac autonomic nervous system activity assessed through HRV parameters. This study aimed (i) to examine the association of cardiorespiratory fitness, fatness indicators, and FFI with HRV parameters; and (ii) to report what of the different fatness indicators included in FFI is better associated with HRV parameters in sedentary adults.

METHODS

One hundred and fifty healthy adults (74 women; 76 men), aged between 18 and 65 years old, participated in this cross-sectional study. We measured cardiorespiratory fitness (maximal oxygen consumption) and fatness indicators (waist-to-height ratio [WHR], fat mass percentage [FM%] and visceral adipose tissue [VAT]). Three FFIs were calculated as the quotient between cardiorespiratory fitness and one out of three possible fatness indicators: Fit-Fat Index calculated waist-to-height ratio (FFIWHR ), Fit-Fat Index calculated with FM% (FFIFM% ), and Fit-Fat Index calculated with VAT (FFIVAT ). HRV parameters were measured in resting conditions using a Polar RS800CX.

RESULTS

FFIWTHR , FFIFM% and FFIVAT were related to different HRV parameters (β ranges between -0.507 and 0.529; R2 ranges between 0.096 and 0.275; all p < .001) and the association was stronger with HRV parameters than the isolated fitness or fatness indicators (β ranges between -0.483 and 0.518; R2 ranges between 0.071 and 0.263; all p < .001). FFIVAT was the index more consistently associated with HRV parameters (β ranges between -0.507 and 0.529; R2 ranges between 0.235 and 0.275; all p < .001).

CONCLUSION

Our study suggests that compound FFIs are better predictors of HRV parameters than either cardiorespiratory fitness or fatness indicators alone. The FFIVAT was the best index in terms of its association to HRV.

Short-term heart rate variability at rest in individuals with temporomandibular disorder: a comparative analysis

OBJECTIVE

Compare heart rate variability (HRV) indices in participants with and without myogenic temporomandibular disorder (TMD). Secondarily, we correlated HRV indices with pain and quality of life variables.

METHODS

This is a comparative observational cross-sectional study. Individuals of both genders with and without a history of TMD were included. Short-term heart rate variability was assessed using a Polar V800. Central sensitization was assessed using the Central Sensitization Inventory. Pain through the numeric pain scale and the impact of oral health on quality of life using the OHIP-14 questionnaire.

RESULTS

A total of 80 participants were enrolled in the study: most individuals included in both groups were young adults, women and slightly overweight. We observed a decrease in HRV in the TMD group (p < 0.01) when compared to the control group. In addition, we observed a greater impact of oral health on quality of life, central sensitization in addition to high resting pain scores (p < 0.01). We observed significant correlation between the LF index of HRV and the FAI score (r = 0.311; p = 0.05). The NPS, CSI and OHIP-14 scores did not correlate with any of the HRV indices (p > 0.05).

CONCLUSION

The short-term HRV in individuals with TMD is significantly lower when compared to a control group. Furthermore, there seems to be a relationship between the severity of the dysfunction and the HRV variables.

CLINICAL RELEVANCE

Using portable and low-cost devices, the HRV can be easily collected and analyzed, without the need for an arsenal of equipment such as the conventional electrocardiogram. This measure can contribute to the therapy adopted and identify individuals prone to unfavorable outcomes involving ANS modulation.

Inter- and intrarater reliability of short-term measurement of heart rate variability on rest in chronic obstructive pulmonary disease (COPD)

BACKGROUND

Individuals with COPD have an imbalance of cardiac autonomic control. In this context, HRV is considered an important tool for assessing cardiac sympathetic and parasympathetic balance, however it is a dependent evaluator measure and subject to methodological biases that may compromise the interpretation of results.

OBJECTIVE

This study examines the inter- and intrarater reliability of HRV parameters derived from short-term recordings in individuals with COPD.

METHODOLOGY

Fifty-one individuals of both genders with COPD clinical diagnosis confirmed by the pulmonary function test and aged ≥50 years were included. The RR interval (RRi) were recorded during a 10 min period on supine position using a portable heart rate monitor (Polar® H10 model). The data were transferred into Kubios® HRV Standard analysis software and analyzed within the stable sessions containing 256 sequential RRi.

RESULTS

The intraclass correlation coefficient (ICC) ranged from 0.942 to 1.000 according to the intrarater analysis by Researcher 01 and 0.915 to 0.998 to the intrarater by Researcher 02. The interrater ICC ranged from 0.921 to 0.998. The coefficient of variation was up to 8.28 for Researcher 01 intrarater analysis, 9.06 for Researcher 02 intrarater analysis and 13.07 for interrater analysis.

CONCLUSION

The measurement of HRV using a portable heart rate device in individuals with COPD present acceptable values of intra- and interrater reliability, supporting the use of HRV in the clinical and scientific scenario. Furthermore, it is important that the data analysis be performed by the same experienced evaluator.

Use of immersive virtual reality for stress reduction during botulinum toxin injection for spasticity (RVTOX): a study protocol of a randomised control trial

INTRODUCTION

Botulinum toxin injection is a common way to help reduce spasticity in the body caused by central neurological damage such as cerebral stroke, multiple sclerosis or traumatic brain injury. The pain felt during the injection causes most patients to experience significant stress for further injections, the level of which is variable between patients.Immersive virtual reality is a digital technique that simulates the three-dimensional spatial and sound environment around a person said to be immersed in this virtualised world. The effectiveness of virtual reality comes from the intensity of this multisensory immersion, known as the feeling of presence (ie, subjective experience of being in one place or one environment, even when you are physically in another one).Only one research article in paediatrics has shown that immersive reality technique has a positive impact on the level of pain and agitation suffered during botulinum toxin injections. The purpose of this study is therefore to evaluate with sufficient assurance the following research hypothesis: virtual reality can help adults cope with the stress and pain of botulinum toxin treatment injection.

METHODS AND ANALYSIS

The research hypothesis will be tested using a randomised stepped-wedge method versus a non-invasive technique (headset with virtual reality session) to its control (headset with no image nor audio).The design leads to considering the injection as a statistical unit as all participants will undergo the standard condition, the control technique and virtual reality technique.

ETHICS AND DISSEMINATION

Patients will be fully and fairly informed in terms of their understanding of the objectives and constraints of the study and the possible risks involved. They will also be entitled to refuse the study and/or withdraw, and this refusal will have no impact on their follow-up as part of their pathology. Dissemination of the results of this study will be through peer-reviewed publications, and national and international conferences.Ethics were approved by the Comité de Protection des Personnes Nord-Ouest in January 2022.

TRIAL REGISTRATION NUMBER

NCT05364203.

Detraining Effect on Cardiac Autonomic Response to an All-Out Sprint Exercise in Trained Adolescent Swimmers

PURPOSE

This study aimed to investigate the effects of a 5-week training cessation on the cardiac autonomic response after a 50-m swimming time-trial test.

METHODS

Twenty trained and highly trained adolescent swimmers (17.1 [2.7] y) performed a 50-m front-crawl all-out test before (visit 1) and after a 5-week training cessation (visit 2). After the warm-up, heart-rate variability (HRV) was recorded in a seated position using a Polar RS800CX heart-rate monitor during the 10 minutes before (preexercise) and immediately after the 50-m front-crawl all-out test (postexercise). Two-way analysis of variance (time × visit) and analysis of covariance were conducted to compute the effect of the 50-m all-out test on vagal-related HRV parameters (mean R-R, standard deviation of R-R intervals [SDNN], square root of the mean squared differences between successive R-R intervals [RMSSD], the percentage number of pairs of adjacent normal R-R intervals differing by more than 50 milliseconds in the entire recording [pNN50], and power in the high frequency [HF]) with Bonferroni post hoc test.

RESULTS

All the HRV parameters had a time main effect (P < .05), showing a reduction after the 50 m in both visits (P < .05). All the variables exhibited a visit main effect (P < .05); the preexercise and postexercise mean R-R, natural logarithm SDNN, natural logarithm RMSSD, and natural logarithm HF values declined after the training cessation (P < .05). Natural logarithm pNN50 preexercise values were reduced in visit 2 compared with visit 1 (P < .05). Only mean R-R was further reduced in response to the test in visit 2 compared with visit 1 (P < .05).

CONCLUSIONS

After 5 weeks of training cessation, all the preexercise and postexercise vagal-related HRV parameters evidenced a reduction, suggesting an impairment in swimmers' physical status. Coaches should be cautious with training loads at the start of the season.

Cardiac autonomic and cortisol stress responses to real operations in surgeons: relationship with individual psychobiological characteristics and experience

BACKGROUND

Surgeons are exposed to high levels of intraoperative stress, which could compromise their psychological well-being in the long term. This study aimed at exploring the effects of real operations on the activity of stress response systems (i.e., cardiac autonomic function and hypothalamic-pituitary-adrenal axis) during and in the aftermath of surgery, and the moderating role of individual psychobiological characteristics and different levels of experience (senior vs expert surgeons).

METHODS

Heart rate, heart rate variability, and salivary cortisol measures (as indexes of cardiac autonomic and hypothalamic-pituitary-adrenal axis activity, respectively) were assessed during real operations and in the perioperative period in a sample of surgeons (n = 16). Surgeons' psychometric characteristics were collected using questionnaires.

RESULTS

Real operations triggered both cardiac autonomic and cortisol stress responses which were independent from surgeons' level of experience. Intraoperative stress responses did not affect cardiac autonomic activity during the following night but were associated with a blunted cortisol awakening response. Moreover, senior surgeons reported higher levels of negative affectivity and depressive symptoms than expert surgeons prior to the surgery. Lastly, the magnitude of heart rate responses to surgery positively correlated with scores on negative affectivity, depression, perceived stress, and trait anxiety scales.

CONCLUSION

This exploratory study allows to put forward the hypotheses that in surgeons cardiac autonomic and cortisol stress responses to real operations (i) may be associated with specific individual psychological characteristics regardless of the level of experience, (ii) and may have a longer lasting impact on hypothalamic-pituitary-adrenal axis function with potential implications for surgeons' physical and psychological well-being.

Overnight heart rate variability responses to military combat engineer training

The study aimed to determine if overnight heart rate variability (HRV) is reflective of workload and stress during military training. Measures of cognitive load, perceived exertion, physical activity, nocturnal HRV, cognitive performance and sleep were recorded for a 15-day assessment period in 32 combat engineers. The assessment period consisted of 4 phases, PRE, FIELD, BASE and RECOVERY that exposed trainees to periods of sleep deprivation and restriction. The FIELD phase was characterised by an increase in mood disturbance, perceived exertion, physical activity, HRV and a reduction in sleep quantity (p < 0.05). Measures of HRV returned to PRE-values quicker than subjective wellbeing responses. The combination of sleep duration (β = -0.002, F = 13.42, p < 0.001) and physical activity (metabolic equivalents, β = -0.483, F = 5.95, p = 0.017), the main stressors of the exercise, provided a significant effect in the best predictive model of HRV. The different recovery rates of HRV and subjective wellbeing suggest a different physiological and psychological response.

Exploratory Investigation of the Effects of Tactile Stimulation Using Air Pressure at the Auricular Vagus Nerve on Heart Rate Variability

OBJECTIVE

To explore the effects of tactile stimulation using air pressure at the auricular branch of the vagus nerve on autonomic activity in healthy individuals.

METHODS

Three types of tactile stimulation were used in this study: continuous low-amplitude, continuous high-amplitude, and pulsed airflow. The tactile stimulations were provided to the cymba concha to investigate autonomic activity in 22 healthy participants. The mean heart rate (HR) and parameters of HR variability, including the standard deviation of R-R intervals (SDNN) and root mean square of successive R-R interval differences (RMSSD) were compared at baseline, stimulation, and recovery periods.

RESULTS

Two-way repeated measures ANOVA indicated a significant main effect of time on HR (p=0.001), SDNN (p=0.003), and RMSSD (p<0.001). These parameters showed significant differences between baseline and stimulation periods and baseline and recovery periods in the post-hoc analyses. There were no significant differences in the changes induced by stimulation type and the interaction between time and stimulation type for all parameters. One-way repeated measures ANOVA showed that HR, SDNN, and RMSSD did not differ significantly among the three time periods during sham stimulation.

CONCLUSION

Parasympathetic activity can be enhanced by auricular tactile stimulation using air pressure, targeting the cymba concha. Further studies are warranted to investigate the optimal stimulation parameters for potential clinical significance.

Heart Rate Variability in Individuals with Down Syndrome: A Scoping Review with Methodological Considerations

Individuals with Down syndrome (DS) present similar heart rate variability (HRV) parameters at rest but different responses to selected movement maneuvers in comparison to individuals without DS, which indicates reduced vagal regulation. The present study undertakes a scoping review of research on HRV in individuals with DS, with special attention paid to the compliance of the studies with standards and methodological paper guidelines for HRV assessment and interpretation. A review was performed using PubMed, Web of Science and CINAHL databases to search for English language publications from 1996 to 2020 with the MESH terms "heart rate variability" and "down syndrome", with the additional inclusion criteria of including only human participants and empirical investigations. From 74 studies, 15 were included in the review. None of the reviewed studies met the recommendations laid out by the standards and guidelines for providing the acquisition of RR intervals and necessary details on HRV analysis. Since authors publishing papers on this research topic do not adhere to the prescribed standards and guidelines when constructing the methodology, results of the research papers on the topic are not directly comparable. Authors need to design the study methodology more robustly by following the aforementioned standards, guidelines and recommendations.

Associations between Intra-Assessment Resting Metabolic Rate Variability and Health-Related Factors

In humans, the variation in resting metabolic rate (RMR) might be associated with health-related factors, as suggested by previous studies. This study explored whether the intra-assessment RMR variability (expressed as a coefficient of variation (CV; %)) is similar in men and women and if it is similarly associated with diverse health-related factors. The RMR of 107 young, and relatively healthy adults, was assessed using indirect calorimetry. Then, the CV for volumes of oxygen consumption (VO2) and carbon dioxide production (VCO2), respiratory exchange ratio (RER), and resting energy expenditure (REE) were computed as indicators of intra-assessment RMR variability. Body composition, cardiorespiratory fitness (peak VO2 uptake), circulating cardiometabolic risk factors, and heart rate and its variability (HR and HRV) were assessed. Men presented higher CVs for VO2, VCO2, and REE (all p ≤ 0.001) compared to women. Furthermore, in men, the intra-assessment RER variability was associated with vagal-related HRV parameters and with mean HR (standardized β = −0.36, −0.38, and 0.41, respectively; all p < 0.04). In contrast, no associations were observed in women. In conclusion, men exhibited higher variability (CVs for VO2, VCO2, and REE) compared to women. The CV for RER could be a potential marker of cardiometabolic risk in young men.

Associations between different heart rate variability ratios and cardiometabolic risk factors in young adults

AIMS

To study the association of two different heart rate variability (HRV) ratios with cardiovascular disease (CVD) risk factors in young adults.

METHOD

A total of 132 participants (89 women) were included in this cross-sectional study. We assessed their HRV and computed the low frequency-to-high frequency ratio (LF/HF) and, from the Poincaré plot, the ratio of the inverse of the longitudinal (SD2) to the transversal (SD1) axes ([1000/SD2]/SD1; sympathetic: parasympathetic [S:PS] ratio). From blood samples, we determined total cholesterol, high-density (HDL-C) and low-density lipoprotein-cholesterol, triglycerides, glucose, insulin, and the homeostatic model assessment of insulin resistance (HOMA) index. Multiple linear regression models were adjusted for age.

RESULTS

Both, the LF/HF and the S:PS ratios, were positively associated with glucose metabolism markers (glucose, insulin, HOMA index), and negatively associated with HDL-C in women but not in men.

CONCLUSION

We showed that the LF/HF and the S:PS are associated similarly with CVD risk factors in young women.

Associations between heart rate variability and maximal fat oxidation in two different cohorts of healthy sedentary adults

BACKGROUND AND AIMS

Resting heart rate variability (HRV) and maximal fat oxidation (MFO) during exercise are both considered as a noninvasive biomarkers for early detection of cardiovascular risk factors. Thus, this study aimed to analyze the relationship between resting HRV parameters and MFO during exercise, and the intensity of exercise that elicit MFO (Fat_max) in healthy sedentary adults.

METHODS AND RESULTS

A total of 103 healthy young adults (22.2 ± 2.3 years old, 67% female; from the ACTIBATE cohort) and 67 healthy middle-aged adults (53.1 ± 5.0 years old, 52% female; from the FIT-AGEING cohort) were included in this cross-sectional study. HRV was assessed using a Polar RS800CX heart rate monitor, while MFO and Fat_max were determined during a graded exercise treadmill test using indirect calorimetry. No significant associations were observed for healthy young adults (standardized β coefficients ranged from -0.063 to 0.094, and all P ≥ 0.347) and for middle-aged adults (standardized β coefficients ranged from -0.234 to 0.090, and all P ≥ 0.056). Nevertheless, only a weak association was observed between one HRV parameter in time-domain (the percentage of R-R intervals that shows a difference higher than 50 ms [pNN50]) and MFO in the cohort of middle-aged adults (β coefficient = -0.279, and P = 0.033).

CONCLUSION

The results of this study suggest that resting HRV parameters are not associated with MFO and Fat_max during exercise in two independent cohorts of healthy sedentary young and middle-aged adults, respectively.

Modulation of Heart and Brain Function by Surah Al-Rehman Recitation Among Distressed Diabetic Patients in Pakistan

Distress causes psychophysiological alterations that affect autonomic function. The current study explores psychophysiological modulation in diabetic distress in response to Surah Al-Rehman recitation. A single-group experimental study with before and after intervention assessments was conducted during April 2018 to February 2019 in which participants (n = 10) listened to Surah Al-Rehman recitation. Blood pressure, blood glucose, cortisol, ECG and EEG were recorded before and after recitation. Significant reduction in systolic blood pressure, increase in low frequency and absolute alpha power at Fp2 were observed. Heartbeat evoked potentials (HEP) were also significantly modulated at Fp1, Fp2 and F4. These findings suggest that Surah Al-Rehman modulated baroreflex activity thereby reducing sympathetic activity and improved heart brain coherence as reflected by HEP.

Heart rate variability (HRV): Checklist for observational and experimental studies

Ford et al. provided (via review study) an overview of the psychiatric features associated with encephalitis mediated by autoantibodies targeting neuronal cellsurface antigens and describe indicators of potential immunopathology underlying psychiatric manifestations. In this scientific context of psychiatric manifestations, studies strongly suggest that scientists include heart rate variability assessment in these patients (because this is a way to evaluate the autonomic nervous system's sympathetic and parasympathetic components). Ford's paper has significant clinical relevance and will generate new studies (experimental and observational) on psychiatric manifestations; therefore, we have six suggestions for the authors and other scientists/researchers who will use this article to perform further research using the heart rate variability assessment. Our objective is to contribute to scientific research and help to strengthen the new studies that will emerge.

Acute Effect of a Dietary Multi-Ingredient Nootropic as a Cognitive Enhancer in Young Healthy Adults: A Randomized, Triple-Blinded, Placebo-Controlled, Crossover Trial

Aim

To study the acute effect of a dietary multi-ingredient nootropic on cognitive performance in young healthy adults. We also analyzed the influence of the dietary multi-ingredient nootropic on emotional state, heart rate (HR), and heart rate variability (HRV).

Methods

This is a randomized, triple-blinded, placebo-controlled, crossover trial. In total, 26 young healthy adults (50% women; 24.9 ± 3.3 years old) ingested 10 g of a dietary multi-ingredient nootropic [Evo-Gamers^®; Harrison Sport Nutrition (HSN), Granada, Spain] or placebo (maltodextrin) in a randomized order (clinicaltrials.gov No. NCT04790188). After 30 min of the ingestion, participants performed a battery of cognitive performance tests to measure the processing speed, inhibitory control, working memory, cognitive flexibility, creativity, and verbal fluency. The emotional status was assessed through questionnaires, and HR and HRV were measured using a heart rate monitor.

Results

In comparison with placebo, the acute ingestion of the nootropic showed a significantly better response time in several cognitive tests (i.e., processing speed, inhibitory control, spatial working memory, and cognitive flexibility, all P < 0.05 and effect size range of 0.4–0.6). It also displayed a higher accuracy in the processing speed, the inhibitory control, and cognitive flexibility tests (all P < 0.05; effect size ranged from 0.4 to 0.6). Furthermore, the nootropic showed a higher creativity and positive emotions and lower sadness-depression emotions, whereas HR and HRV remained similar between placebo vs. nootropic conditions. However, there were no differences between the nootropic and placebo in verbal fluency, motivation, or anxiety (all P > 0.05).

Conclusion

An acute ingestion of a dietary multi-ingredient nootropic enhances cognitive performance in comparison with placebo without negatively influencing HR or HRV in young healthy adults.

Monitoring Responses to Basic Military Training with Heart Rate Variability

INTRODUCTION

Heart rate variability (HRV) has shown sensitivity to the acute stressors experienced by defence personnel. This study examines the suitability of overnight HRV as a repeated measure of allostatic load in defence personnel.

METHODS

Daily measures of sleep, cognitive load and perceived exertion were reported for the 12-week duration of basic military training (BMT) in 48 recruits. Measures of physical activity, subjective wellbeing and HRV were measured weekly. The natural log of the root mean square of successive differences of inter-beat intervals (Ln RMSSD) and the Ln RMSSD to inter-beat interval ratio (Ln RMSSD:RRi ratio) during predicted slow wave sleep were used for HRV. Physical performance was assessed via the 20-m shuttle run and maximal push-up test in week two and eight of BMT with predicted V̇O2 peak values calculated.

RESULTS

Predicted V̇O2 peak increased from 42.6 ± 4.5 to 48.0 ± 2.7 mL·kg·min (p < 0.001). Ln RMSSD was elevated in week seven and ten and the Ln RMSSD:RRi ratio was elevated in week ten above all other weeks (p < 0.05). An increase in perceived exertion (F = 9.10, p = 0.003) and subjective fatigue (F = 6.97, p = 0.009), as well as a reduction in V̇O2 peak (F = 7.95, p = 0.009), individually predicted an increase in Ln RMSSD. The best predictive model of Ln RMSSD included perceived exertion (F = 8.16, p = 0.005), subjective fatigue (F = 8.49, p = 0.004), the number of awakenings during sleep (F = 7.79, p = 0.006) and the change in V̇O2 peak (F = 19.110, p < 0.001).

CONCLUSIONS

HRV was predicted by subjective recruit responses to BMT workloads rather than objective measures of physical activity. Improvements in cardiorespiratory fitness depicted recruits who experienced enough stress to facilitate physiological adaptation which was reflected by a reduction in HRV during BMT. Monitoring HRV and HRV in relation to inter-beat interval length may provide a better tool for determining allostatic load than HRV alone.

Validity of Detrended Fluctuation Analysis of Heart Rate Variability to determine intensity thresholds in professional cyclists

BACKGROUND

The evaluation of performance in endurance athletes and the subsequent individualization of training is based on the determination of individual physiological thresholds during incremental tests. Gas exchange or blood lactate analysis are usually implemented for this purpose, but these methodologies are expensive and invasive. The short-term scaling exponent alpha 1 of detrended Fluctuation Analysis (DFA-α1) of the Heart Rate Variability (HRV) has been proposed as a non-invasive methodology to detect intensity thresholds.

PURPOSE

The aim of this study is to analyse the validity of DFA-α1 HRV analysis to determine the individual training thresholds in elite cyclists and to compare them against the lactate thresholds.

METHODOLOGY

38 male elite cyclists performed a graded exercise test to determine their individual thresholds. HRV and blood lactate were monitored during the test. The first (LT1 and DFA-α1-0.75, for lactate and HRV, respectively) and second (LT2 and DFA-α1-0.5, for lactate and HRV, respectively) training intensity thresholds were calculated. Then, these points were matched to their respective power output (PO) and heart rate (HR).

RESULTS

There were no significant differences (p > 0.05) between the DFA-α1-0.75 and LT1 with significant positive correlations in PO (r = 0.85) and HR (r = 0.66). The DFA-α1-0.5 was different against LT2 in PO (p = 0.04) and HR (p = 0.02), but it showed significant positive correlation in PO (r = 0.93) and HR (r = 0.71).

CONCLUSIONS

The DFA1-a-0.75 can be used to estimate LT1 non-invasively in elite cyclists. Further research should explore the validity of DFA-α1-0.5.

Efficient methods for acute stress detection using heart rate variability data from Ambient Assisted Living sensors

Background

Using Ambient Assisted Living sensors to detect acute stress could help people mitigate the harmful effects of everyday stressful situations. This would help both the healthy and those affected more by sudden stressors, e.g., people with diabetes or heart conditions. The study aimed to develop a method for providing reliable stress detection based on heart rate variability features extracted from portable devices.

Methods

Features extracted from portable electrocardiogram sensor recordings were used for training various classification algorithms for stress detection purposes. Data were recorded in a clinical trial with 7 participants and two stressors, the Trier Social Stress Test and the Stroop colour word test, both validated by standardised questionnaires. Different heart rate variability feature sets (all, time-domain and non-linear only, frequency-domain only) were tested to investigate how classification performance is affected, in addition to various time window length setups and participant-wise training sessions. The accuracy and F1 score of the trained models were compared and analysed.

Results

The best results were achieved with models using time-domain and non-linear heart rate variability features with 5-min-long overlapping time windows, yielding 96.31% accuracy and 96.26% F1 score. Shorter overlapping windows had slightly lower performance, with 91.62–94.55% accuracy and 91.77–94.55% F1 score ranges. Non-overlapping window configurations were less effective, with both accuracy and F1 score below 88%. For participant-wise learning, average F1 scores of 99.47%, 98.93% and 96.1% were achieved for feature sets using all, time-domain and non-linear, and frequency-domain features, respectively.

Conclusion

The tested stress detector models based on heart rate variability data recorded by a single electrocardiogram sensor performed just as well as those published in the literature working with multiple sensors, or even better. This suggests that once portable devices such as smartwatches provide reliable hear rate variability recordings, efficient stress detection can be achieved without the need for additional physiological measurements.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12938-021-00911-6.

Heart rate rather than heart rate variability is better associated with cardiorespiratory fitness in adults

This study aimed to examine the association of heart rate (HR) and heart rate variability (HRV) with cardiorespiratory fitness (CRF) in adults. This cross-sectional study included 204 participants: 132 young adults (67% women; 22.3 ± 2.3 years) and 72 middle-aged adults (53% women; 53.2 ± 5 years). HR and HRV were measured using a Polar RS800CX heart rate monitor. CRF was assessed using a metabolic cart during an incremental test. HR was negatively associated with CRF relative to body weight (BW) in young adults adjusting for sex, age, and physical activity (β ranged from -0.200 to -0.195; all P ≤ 0.022). These associations disappeared after including fat mass as a covariate (all P ≥ 0.106) while remained significant after adjusting for fat-free mass (FFM; all P ≤ 0.008). Neither HR nor HRV variables were associated with CRF expressed as absolute values or relative to FFM in young and middle-aged adults after adjusting for the abovementioned covariates (all P ≥ 0.074). Our results suggest that HR rather than HRV is better associated with CRF relative to BW in young adults. However, this association seems to be explained by the inclusion of fat mass in the calculation of CRF relative to BW.Highlights Heart rate and heart rate variability variables have been associated with cardiorespiratory fitness.Our present results, and previous literature, suggest that the "simple" measurement of the heart rate could be easier to obtain and interpret than the heart rate variability variables.The heart rate variable rather than the heart rate variability variables is better associated with cardiorespiratory fitness relative to body weight in healthy young adults.

Influence of Artefact Correction and Recording Device Type on the Practical Application of a Non-Linear Heart Rate Variability Biomarker for Aerobic Threshold Determination

Recent study points to the value of a non-linear heart rate variability (HRV) biomarker using detrended fluctuation analysis (DFA a1) for aerobic threshold determination (HRVT). Significance of recording artefact, correction methods and device bias on DFA a1 during exercise and HRVT is unclear. Gas exchange and HRV data were obtained from 17 participants during an incremental treadmill run using both ECG and Polar H7 as recording devices. First, artefacts were randomly placed in the ECG time series to equal 1, 3 and 6% missed beats with correction by Kubios software’s automatic and medium threshold method. Based on linear regression, Bland Altman analysis and Wilcoxon paired testing, there was bias present with increasing artefact quantity. Regardless of artefact correction method, 1 to 3% missed beat artefact introduced small but discernible bias in raw DFA a1 measurements. At 6% artefact using medium correction, proportional bias was found (maximum 19%). Despite this bias, the mean HRVT determination was within 1 bpm across all artefact levels and correction modalities. Second, the HRVT ascertained from synchronous ECG vs. Polar H7 recordings did show an average bias of minus 4 bpm. Polar H7 results suggest that device related bias is possible but in the reverse direction as artefact related bias.

Cardiovascular Risk Factors and Heart Rate Variability: Impact of the Level of the Threshold-Based Artefact Correction Used to Process the Heart Rate Variability Signal

The associations between cardiovascular disease (CVD) risk factors and heart rate variability (HRV) have shown some inconsistencies. To examine the impact of the different Kubios threshold-based artefact correction levels on the associations between different CVD risk factors and a heart rate variability (HRV) score in three independent human cohorts. A total of 107 children with overweight/obesity, 132 young adults, and 73 middle-aged adults were included in the present study. Waist circumference and the HRV score were negatively associated using the medium and the strong Kubios filters in children (β = -0.22 and - 0.24, P = 0.03 and 0.02 respectively) and the very strong Kubios filter in middle-aged adults (β = -0.39, P = 0.01). HDL-C was positively associated with the HRV score across Kubios filters (β ranged from 0.21 to 0.31, all P ≤ 0.04), while triglycerides were negatively associated with the HRV score using the very strong Kubios filter in young adults (β = -0.22, P = 0.02). Glucose metabolism markers (glucose, insulin, and HOMA index) were inversely associated with the HRV score across Kubios filters in young adults (β ranged from -0.29 to -0.22; all P ≤ 0.03). Importantly, most of these associations disappeared after including HR as a covariate, especially in children and young adults. It should be mandatory to report the Kubios filter used and to include the HR (as a confounder factor) to allow the comparability of the results across different studies.

Artifact Correction in Short-Term HRV during Strenuous Physical Exercise

Heart rate variability (HRV) analysis can be a useful tool to detect underlying heart or even general health problems. Currently, such analysis is usually performed in controlled or semi-controlled conditions. Since many of the typical HRV measures are sensitive to data quality, manual artifact correction is common in literature, both as an exclusive method or in addition to various filters. With proliferation of Personal Monitoring Devices with continuous HRV analysis an opportunity opens for HRV analysis in a new setting. However, current artifact correction approaches have several limitations that hamper the analysis of real-life HRV data. To address this issue we propose an algorithm for automated artifact correction that has a minimal impact on HRV measures, but can handle more artifacts than existing solutions. We verify this algorithm based on two datasets. One collected during a recreational bicycle race and another one in a laboratory, both using a PMD in form of a GPS watch. Data include direct measurement of electrical myocardial signals using chest straps and direct measurements of power using a crank sensor (in case of race dataset), both paired with the watch. Early results suggest that the algorithm can correct more artifacts than existing solutions without a need for manual support or parameter tuning. At the same time, the error introduced to HRV measures for peak correction and shorter gaps is similar to the best existing solution (Kubios-inspired threshold-based cubic interpolation) and better than commonly used median filter. For longer gaps, cubic interpolation can in some cases result in lower error in HRV measures, but the shape of the curve it generates matches ground truth worse than our algorithm. It might suggest that further development of the proposed algorithm may also improve these results.

Alterations in Cardiac Vagal Modulation-to-Vagal Tone Ratio in response to accumulated exercise stress in intermittent team sport

Study aim: This investigation examined the cardiac vagal modulation-to-vagal tone ratio and its utility to represent the dose response to accumulated exercise stress in intermittent team sport.

Material and methods: Fourteen international calibre female field hockey players training as part of a national team were participants over a three-week period. Exercise stress was expressed through cardiovascular strain using heart rate (HR) dynamics and was quantified as a training load (AU) and time spent exercising above anaerobic threshold (min). Cardiac autonomic activity was examined using heart rate variability; R-R intervals (ms) were collected immediately upon awakening throughout each weekend. The square root of the mean squared differences of successive R–R intervals were individually calculated, and log transformed prior to being averaged (Ln rMSSD) along with the corresponding mean R-R interval length. Multiple linear regression analysis examined the association between cardiac autonomic activity and indices of accumulated exercise stress.

Results: Significant inverse associations (95% CI) between the Ln rMSSD:R-R ratio and both training load [r = –0.48 (–0.70: –0.18), p = 0.012] and time spent exercising above anaerobic threshold [r = –0.51 (–0.72 : –0.22), p = 0.006] were observed. The association between mean R-R interval length and Ln rMSSD was not significant [r = 0.05, p = 0.950].

Conclusion: The current study demonstrated high intensity exercise, as defined through time spent above anaerobic threshold, displayed a stronger association with the Ln rMSSD:R-R ratio compared to a HR-derived training load when examining the dose response to accumulated intermittent exercise.

Inter- and intra-researcher reproducibility of heart rate variability parameters in three human cohorts

Heart rate variability (HRV) is a valid and non-invasive indicator of cardiac autonomic nervous system functioning. Short-term HRV recordings (e.g., 10 min long) produce data that usually is manually processed. Researcher subjective decision-making on data processing could produce inter- or intra-researcher differences whose magnitude has not been previously quantified in three independent human cohorts. This study examines the inter- and intra-researcher reproducibility of HRV parameters (i.e., the influence of R–R interval selection by different researchers and by the same researcher in different moments on the quantification of HRV parameters, respectively) derived from short-term recordings in a cohort of children with overweight/obesity, young adults and middle-age adults. Participants were recruited from 3 different studies: 107 children (10.03 ± 1.13 years, 58% male), 132 young adults (22.22 ± 2.20 years, 33% males) and 73 middle-aged adults (53.62 ± 5.18 years, 48% males). HRV was measured using a Polar RS800CX heart rate monitor. The intraclass correlation coefficient (ICC) ranged from 0.703 to 0.989 and from 0.950 to 0.998 for inter-and intra-researcher reproducibility, respectively. Limits of agreement for HRV parameters were higher for the inter-researcher processing compared with the intra-researcher processing. On average, the intra-researcher differences were 31%, 62%, and 80% smaller than the inter-researchers differences based on Coefficient of Variation in children, young and middle-aged adults, respectively. Our study provides the quantification of the inter-researcher and intra-researcher differences in three independent human cohorts, which could elicit some clinical relevant differences for HRV parameters. Based on our findings, we recommend the HRV data signal processing to be performed always by the same trained researcher and we postulate a development of algorithms for an automatic ECG selection.