Two-week test-retest reliability of the Polar® RS800CX™ to record heart rate variability

From lab to life: Evaluating the reliability and validity of psychophysiological data from wearable devices in laboratory and ambulatory settings

Despite the increasing popularity of ambulatory assessment, the reliability and validity of psychophysiological signals from wearable devices is unproven in daily life settings. We evaluated the reliability and validity of physiological signals (electrocardiogram, ECG; photoplethysmography, PPG; electrodermal activity, EDA) collected from two wearable devices (Movisens EcgMove4 and Empatica E4) in the lab (N = 67) and daily life (N = 20) among adults aged 18-64 with Mindware as the laboratory gold standard. Results revealed that both wearable devices' valid data rates in daily life were lower than in the laboratory (Movisens ECG 82.94 vs. 93.10%, Empatica PPG 8.79 vs. 26.14%, and Empatica EDA 41.16 vs. 42.67%, respectively). The poor valid data rates of Empatica PPG signals in the laboratory could be partially attributed to participants' hand movements (r = - .27, p = .03). In laboratory settings, heart rate (HR) derived from both wearable devices exhibited higher concurrent validity than heart rate variability (HRV) metrics (ICCs 0.98-1.00 vs. 0.75-0.97). The number of skin conductance responses (SCRs) derived from Empatica showed higher concurrent validity than skin conductance level (SCL, ICCs 0.38 vs. 0.09). Movisens EcgMove4 provided more reliable and valid HRV measurements than Empatica E4 in both laboratory (split-half reliability: 0.95-0.99 vs. 0.85-0.98; concurrent validity: 0.95-1.00 vs. 0.75-0.98; valid data rate: 93.10 vs. 26.14%) and ambulatory settings (split-half reliability: 0.99-1.00 vs. 0.89-0.98; valid data rate: 82.94 vs. 8.79%). Although the reliability and validity of wearable devices are improving, findings suggest researchers should select devices that yield consistently robust and valid data for their measures of interest.

Heart Rate and Its Variability Are Associated With Resting Metabolic Rate and Substrate Oxidation in Young Women but Not in Men

BACKGROUND

This study aims to examine the relationship between resting vagal-related heart rate variability (HRV) parameters and heart rate (HR) with resting metabolic rate (RMR) and respiratory exchange ratio (RER) in young adults.

METHODS

A total of 74 young adults (22 ± 2 years old, 51 women) were included in this cross-sectional study. HRV was assessed using a HR monitor, whereas RMR and RER were determined by indirect calorimetry.

RESULTS

Linear regression analyses showed a positive association between HR and RER in women (standardized β = 0.384, p = 0.008), while negative associations were observed between vagal-related HRV parameters and RER in women (β ranged from -0.262 to -0.254, all p ≤ 0.042). No significant association was found between the abovementioned physiological parameters in men.

CONCLUSION

Here, we show that HR is positively associated with RER in young women but not in men, while vagal-related HRV parameters are inversely related to RMR, therefore suggesting a potential sexual dimorphism between cardiac rhythm and its relationship with markers of cardiometabolic health status.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT02365129.

Test-retest reliability and validity of vagally-mediated heart rate variability to monitor internal training load in older adults: a within-subjects (repeated-measures) randomized study

BACKGROUND

Vagally-mediated heart rate variability (vm-HRV) shows promise as a biomarker of internal training load (ITL) during exergame-based training or motor-cognitive training in general. This study evaluated the test-retest reliability of vm-HRV during exergaming in healthy older adults (HOA) and its validity to monitor ITL.

METHODS

A within-subjects (repeated-measures) randomized study was conducted that included baseline assessments and 4 measurement sessions. Participants played 5 exergames at 3 standardized levels of external task demands (i.e., "easy", "challenging", and "excessive") in random order for 90 s. Test-retest reliability was assessed on the basis of repeated-measures analyses of variance (ANOVA), intraclass correlation coefficients (ICC3,1), standard errors of measurement (SEM), and smallest detectable differences (SDD). Validity was determined by examining the effect of game level on vm-HRV in the ANOVA.

RESULTS

Fourty-three HOA (67.0 ± 7.0 years; 58.1% females (25 females, 18 males); body mass index = 23.7 ± 3.0 kg·m-2) were included. Mean R-R time intervals (mRR) and parasympathetic nervous system tone index (PNS-Index) exhibited mostly good to excellent relative test-retest reliability with no systematic error. Mean SEM% and SDD% were 36.4% and 100.7% for mRR, and 44.6% and 123.7% for PNS-Index, respectively. Significant differences in mRR and PNS-Index were observed between standardized levels of external task demands, with mostly large effect sizes (mean r = 0.847). These results persisted irrespective of the type of neurocognitive domain trained and when only motoric and cognitive demands were manipulated while physical intensity was kept constant. The remaining vm-HRV parameters showed inconsistent or poor reliability and validity.

CONCLUSION

Only mRR and PNS-Index demonstrated reliable measurement and served as valid biomarkers for ITL during exergaming at a group level. Nonetheless, the presence of large SEMs hampers the detection of individual changes over time and suggests insufficient precision of these measurements at the individual level. Future research should further investigate the reliability and validity of vm-HRV with a specific focus on comparing different measurement methodologies and exercise conditions, particularly focusing on ultra-short-term HRV measurements, and investigate the potential implications (i.e., superiority to other markers of ITL or monitoring strategies?) of using vm-HRV as a biomarker of ITL.

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.

Effects of Aerobic Exercise Combined With Attentional Bias Modification in the Care of Male Patients With a Methamphetamine Use Disorder

OBJECTIVE

It remains unclear which individual or combined strategies are most beneficial for methamphetamine use disorders (MUDs). We compared the effects of aerobic exercise, attentional bias modification, and combined intervention on male patients with MUD.

METHOD

One hundred male patients with MUD were randomly assigned to combined intervention, aerobic exercise, attentional bias modification, or control groups (25 patients per group). The 8-week intervention protocol included three 60-minute sessions of aerobic exercises per week. Primary outcomes included high- and low-frequency heart rate variability, executive function, and cardiorespiratory fitness measured by customized software, computerized tests, and the Harvard step test, respectively. Secondary outcomes included psychiatric symptoms, drug craving, training acceptability, and persistence.

RESULTS

Participant characteristics were matched between groups at baseline. Executive function, heart rate variability, cardiorespiratory fitness, drug craving, and most psychiatric symptoms had significant time-group interactions at posttest (p < .05, η2 = .08-.28). Compared with the attentional bias modification and control groups, the combined intervention and aerobic exercise groups improved significantly in executive function, heart rate variability, cardiorespiratory fitness, and most secondary outcomes. In addition, high-frequency heart rate variability and cardiorespiratory fitness in the aerobic exercise group were significantly higher than those in the combined intervention group.

CONCLUSIONS

Combination strategies showed comparable efficacy to aerobic exercise alone in improving executive function, psychiatric symptoms, and drug craving and significantly exceeded other conditions. For heart rate variability and cardiorespiratory fitness, aerobic exercise alone was the most effective. For acceptability and persistence, combination strategies were preferred over single-domain training and health education intervention.

Looking for the Key to Winning: Psychophysiological Predicting Factors in Healthy University Students

Performance in competitive situations has been linked to various psychobiological factors such as personality traits (e.g., competitiveness), situational appraisal (e.g., motivation), and cardiovascular response (e.g., heart rate). However, it remains unclear whether these factors can predict competitive success. This paper aims to assess, through discriminant analysis, the predictive capacity of these psychobiological variables regarding the likelihood of winning, ultimately delineating a psychophysiological profile associated with success. Across three distinct studies, a total of 154 participants (66 men) engaged in a face-to-face laboratory competition. Prior to the competition, assessments of competitiveness traits, anxiety, self-efficacy, and motivation were conducted, and heart rate reactivity during the competition was measured. These variables collectively formed the basis for constructing the predictive model. The results of the initial study demonstrated that our model accurately classified 68.8% of the cases. Specifically, high levels of competitiveness, self-efficacy, motivation, and heart rate reactivity, coupled with low anxiety, were predictive of winning. These findings were subsequently replicated in two independent validation samples involving both men and women (studies 2 and 3), thereby reinforcing the robustness of the earlier results. In conclusion, our findings suggest that the psychological state preceding competition, along with cardiovascular reactivity, may serve as predictors for the probability of winning.

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.

Exhaustion and cardiovascular risk factors: the role of vagally-mediated heart rate variability

PURPOSE

Exhaustion symptoms are known to be associated with cardiovascular disease (CVD) risk; however, the underlying mechanisms remain unclear. Autonomic imbalance, as indicated by reductions in vagally-mediated heart rate variability (vmHRV), appears to be a valid candidate for such a biological link, as it has been associated with both exhaustion symptoms and CVD risk and mortality.

METHODS

The present study examined a potential mediation of vmHRV on the association between exhaustion symptoms and self-reported CVD risk factors as well as the age dependency of this mediation in a large, heterogeneous sample of the Dresden Burnout Study (N = 388; 72.9% females; Mage = 42.61, SD = 11.67).

RESULTS

Results indicate that exhaustion symptoms were indirectly associated with CVD risk factors through vmHRV even after adjusting for well-known confounders (i.e., sex, body mass index, depressive symptoms). Moreover, this pattern was significant only among middle-aged (i.e., 54.27 years) and older individuals.

CONCLUSIONS

Our findings add to growing evidence that autonomic imbalance may be a key biological link between exhaustion symptoms and CVD risk in middle-aged and older individuals. Implications for public health are discussed.

Motor Skills, Heart Rate Variability, and Arterial Stiffness in Children with Autism Spectrum Disorder

The prevalence of autism spectrum disorder (ASD) among children has been recently increasing. The severity of symptoms greatly varies between individuals with ASD, ranging from relatively mild to extremely severe. It is important to have a clearer understanding of the possible adverse consequences resulting from this disorder, such as delayed motor development, autonomic dysregulation, and arterial stiffness. Thus, the objective of this study was to investigate differences in motor skills, heart rate variability (HRV), and arterial stiffness between children with ASD and typically developing children. In this study, the school-aged children with mild symptoms of ASD (n = 17, 11.1 ± 1.0 years old) and typically developing peers (n = 15, 11.0 ± 0.5 years old) were recruited. Motor skills, HRV, and arterial stiffness were measured in these two groups. Motor skills were evaluated by the Bruininks-Oseretsky Test of Motor Proficiency-Second Edition. Moreover, HRV was measured through a short-term recording using the Polar heart rate monitor, and arterial stiffness was assessed by non-invasive computerized oscillometry. Compared with the typically developing group, children with ASD displayed significant deficits in some areas of motor skills, including manual coordination, strength and agility, and total motor composite. Moreover, children with ASD exhibited significantly reduced HRV, including time- and frequency-domain measures. However, the results did not demonstrate any statistically significant differences in arterial stiffness between the groups. Our findings demonstrated the presence of motor skill deficits and autonomic dysregulation in children with ASD.

Effectiveness of an Individualized Exergame-Based Motor-Cognitive Training Concept Targeted to Improve Cognitive Functioning in Older Adults With Mild Neurocognitive Disorder: Study Protocol for a Randomized Controlled Trial

BACKGROUND

Simultaneous motor-cognitive training is considered promising for preventing the decline in cognitive functioning in older adults with mild neurocognitive disorder (mNCD) and can be highly motivating when applied in the form of exergaming. The literature points to opportunities for improvement in the application of exergames in individuals with mNCD by developing novel exergames and exergame-based training concepts that are specifically tailored to patients with mNCD and ensuring the implementation of effective training components.

OBJECTIVE

This study systematically explores the effectiveness of a newly developed exergame-based motor-cognitive training concept (called "Brain-IT") targeted to improve cognitive functioning in older adults with mNCD.

METHODS

A 2-arm, parallel-group, single-blinded randomized controlled trial with a 1:1 allocation ratio (ie, intervention: control), including 34 to 40 older adults with mNCD will be conducted between May 2022 and December 2023. The control group will proceed with the usual care provided by the (memory) clinics where the patients are recruited. The intervention group will perform a 12-week training intervention according to the "Brain-IT" training concept, in addition to usual care. Global cognitive functioning will be assessed as the primary outcome. As secondary outcomes, domain-specific cognitive functioning, brain structure and function, spatiotemporal parameters of gait, instrumental activities of daily living, psychosocial factors, and resting cardiac vagal modulation will be assessed. Pre- and postintervention measurements will take place within 2 weeks before starting and after completing the intervention. A 2-way analysis of covariance or the Quade nonparametric analysis of covariance will be computed for all primary and secondary outcomes, with the premeasurement value as a covariate for the predicting group factor and the postmeasurement value as the outcome variable. To determine whether the effects are substantive, partial eta-squared (η²_p) effect sizes will be calculated for all primary and secondary outcomes.

RESULTS

Upon the initial submission of this study protocol, 13 patients were contacted by the study team. Four patients were included in the study, 2 were excluded because they were not eligible, and 7 were being informed about the study in detail. Of the 4 included patients, 2 already completed all premeasurements and were in week 2 of the intervention period. Data collection is expected to be completed by December 2023. A manuscript of the results will be submitted for publication in a peer-reviewed open-access journal in 2024.

CONCLUSIONS

This study contributes to the evidence base in the highly relevant area of preventing disability because of cognitive impairment, which has been declared a public health priority by the World Health Organization.

TRIAL REGISTRATION

ClinicalTrials.gov NCT05387057; https://clinicaltrials.gov/ct2/show/NCT05387057.

INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID)

DERR1-10.2196/41173.

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.

Physiological reactions to acute stressors and subjective stress during daily life: A systematic review on ecological momentary assessment (EMA) studies

OBJECTIVE

This review aims to provide an overview of ecological momentary assessment (EMA) studies analyzing stress reactivity during daily life in terms of direct and moderated influence of acute stress on physiological responses.

MATERIALS AND METHODS

A systematic literature search was performed on November 29, 2021 using Web of Science, MEDLINE and PsycINFO to identify prospective EMA studies targeting acute stressors or stress under naturalistic conditions, without restrictions of publication date or population. Study quality was assessed for multiple EMA-specific sources of bias.

RESULTS

Out of 4285 non-duplicate records, 107 publications involving 104 unique studies were included. The majority of studies assessed acute physiological stress responses primarily through salivary cortisol (n = 59) and cardiovascular outcomes (n = 32). Most studies performed at least three measurements per day (n = 59), and had a moderate risk of recall bias (n = 68) and confounding (n = 85). Fifty-four studies reported a compliance of ≥80%. Direct, non-moderated positive associations were observed between acute stress exposure and concurrent cortisol levels (44%, n = 11/25), systolic (44%, 8/18) and diastolic blood pressure (53%, 8/15) and heart rate (53%, 9/17). Several inter- and intra-individual moderators were identified, such as age, gender, health status, chronic stress, work-related resources, physical activity and stress coping indicators.

CONCLUSIONS

About half of the reviewed EMA studies demonstrated direct associations between everyday acute stress exposure and physiological responses, including increased cortisol levels, blood pressure and heart rate. Results further suggested various moderator variables that could help develop tailored prevention strategies and identify groups at higher risk for dysfunctional stress responses.

REGISTRATION

PROSPERO-Reg.-No.: PROSPERO 2020 CRD42020163178.

Determining the direction of prediction of the association between parasympathetic dysregulation and exhaustion symptoms

Stress-related exhaustion symptoms have a high prevalence which is only likely to increase further in the near future. Understanding the physiological underpinnings of exhaustion has important implications for accurate diagnosis and the development of effective prevention and intervention programs. Given its integrative role in stress-regulation, the parasympathetic branch of the autonomic nervous systems has been a valid starting point in the exploration of the physiological mechanisms behind exhaustion. The aim of the present study was to examine the directionality and specificity of the association between exhaustion symptoms and vagally-mediated heart rate variability (vmHRV), a relatively pure measure of parasympathetic tone. Exhaustion symptoms and vmHRV were measured at four annually assessment waves (2015-2018) of the Dresden Burnout Study. A total sample of N = 378 participants who attended at least two of the four annual biomarker measurements were included in the present analyses. Cross-lagged multi-level panel modelling adjusting for various covariates (e.g., age, sex, BMI) revealed that vmHRV was meaningfully predictive of exhaustion symptoms and not vice versa. In addition, these effects were specific for exhaustion symptoms as no effect was shown for the other burnout sub-dimensions, or for depressive symptoms. Our findings indicate a clear link between exhaustion symptoms and vmHRV which may hold great potential for both enhancing the diagnosis and treatment of exhaustion symptoms.

Self-compassion, Stress, and Eating Behaviour: Exploring the Effects of Self-compassion on Dietary Choice and Food Craving After Laboratory-Induced Stress

BACKGROUND

Stress has been linked to high-fat and high-sugar food consumption. Self-compassion is associated with better emotional and physiological responses to stress. The current study explored whether trait self-compassion or induced state self-compassion could improve dietary choice and food craving after a stress induction.

METHOD

Fifty-three university students completed an online survey assessing self-compassion, eating restraint, and general perceived stress before attending a laboratory visit. In the laboratory, participants were randomised to a neutral writing control or a self-compassion letter writing condition before a stress induction. Measures of heart rate, heart rate variability, state self-compassion, dietary choice, and state food cravings were taken.

RESULTS

The brief self-compassion intervention did not sufficiently increase state self-compassion in the intervention group compared to the neutral writing condition. There was no effect of the written self-compassion intervention on heart rate, heart rate variability, dietary choice, or food craving. However, higher trait self-compassion was associated with healthier dietary choices (F(1, 49) = 5.35, p = .025, R² = .098).

CONCLUSION

Results suggest that higher trait self-compassion improved dietary choice after stress in a controlled environment in a university population. Further research is warranted to explore whether brief self-compassion interventions can improve state self-compassion and thereby influence dietary choices and food cravings after a stress induction.

Evaluation of short-term effects of three passive aquatic interventions on chronic non-specific low back pain: Study protocol for a randomized cross-over clinical trial

Background

Low back pain (LBP) is among the most common physical ailments and its chronic manifestation is a leading cause for disability worldwide. LBP is not attributable to a known diagnosis in 85% of the cases and therefore called chronic non-specific LBP (cnLBP). Passive immersion in warm water is commonly claimed to reduce muscular tension and pain, but not yet sufficiently investigated with regard to cnLBP. The current study compares three passive aquatic interventions regarding their effects on cnLBP: floating (resting in a supine immersed position on flotation devices), WATSU (a passive hands-on treatment, in which a practitioner stands in warm water, gently moving and massaging the client), and a Spa session.

Methods

In this randomized cross-over clinical trial, all 24 adult participants with cnLBP will undergo the three interventions in balanced order with a washout-period of at least two weeks in between. Assessments will take place at baseline and follow-up of study and immediately before and after each intervention. Assessments cover the primary outcome self-reported current pain (Visual Analog Scale, range: 0–100 mm), other self-report questionnaires (addressing, e.g., personality traits or -states), and physiological parameters (e.g., measurement of spinal range of motion).

Discussion

The study adds estimates of intervention-specific effect-sizes of widespread passive aquatic interventions to cnLBP. The study also points to potential underlying pain-reducing mechanisms.

Trial registration

The protocol was approved by the Ethics Committee of the Canton Bern (ProjectID: 2018–00461). Trial registration is intended at ClinicalTrials.gov.

Effect of aerobic exercise on executive function in individuals with methamphetamine use disorder: Modulation by the autonomic nervous system

This study assessed the effects of aerobic exercise on cardiac autonomic nervous system function (based on heart rate variability [HRV]) and executive function among individuals with methamphetamine use disorder (MUD). We further examine the role of autonomic nervous system control in aerobic exercise (assessed via cardiopulmonary fitness) and executive function. A total of 330 individuals with MUD were randomly divided into exercise (n = 165) and control (n = 165) groups, who underwent eight-week aerobic exercise/health education program consisting of five 60 min sessions a week. The outcome measures included cardiopulmonary fitness, HRV time-domain and frequency-domain parameters, and executive function. Our statistical analyses comprised repeated-measures analyses of variance, correlation analyses, and mediation and moderation effect tests. The results indicated that aerobic exercise could simultaneously improve autonomic nervous system function and executive function among individuals with MUD. Moreover, the changes in cardiopulmonary fitness, high frequency HRV, and executive function were positively correlated. HRV did not significantly mediate the relationship between aerobic exercise and executive function; however, it did have a moderating effect, which was eliminated after adjusting for demographic and drug-use covariates. Among the covariates, age was the greatest confounder and was inversely proportional to cardiopulmonary function, HRV, and executive function. Cardiac autonomic nervous system function exerted a moderating, rather than a mediating, effect on the relationship between aerobic exercise and executive function. However, this potential effect was largely influenced by covariates, particularly age.

The interplay of self-critical rumination and resting heart rate variability on subjective well-being and somatic symptom distress: A prospective study

OBJECTIVE

The aim of this prospective study was to investigate the association of self-critical rumination, autonomic function (indexed by a time domain metric of resting heart rate variability-RMSSD), subjective well-being and somatic symptom distress.

METHOD

84 healthy participants (73 females; mean age = 23.56, SD = 3.35 years) completed the Somatic Symptom Severity Scale of the Patient Health Questionnaire and Mental Health Continuum Short Form at two timepoints (at baseline and six months later). Resting heart rate variability (HRV) was assessed at baseline, along with content specific rumination using the Self-Critical Rumination Scale. Four moderation analyses were performed to test these associations.

RESULTS

The interaction between resting HRV and self-critical rumination significantly explained somatic symptom distress at baseline. For those participants who had high resting HRV, somatic symptom distress was basically independent from the level of self-critical rumination. At the same time, lower resting HRV was associated with higher somatic symptom distress, especially in the presence of more ruminative thoughts. Prospectively, however, the interaction between rumination and resting HRV was not a significant predictor of somatic symptom distress. The association between resting HRV and self-critical rumination did not explain the variance on subjective well-being, but subjective well-being was negatively related to self-critical rumination.

CONCLUSION

Our findings potentially indicate that self-critical rumination could have a long-term negative impact on psychological functioning, even in a non-clinical sample, and highlight that a lower level of parasympathetic activation, assessed with RMSSD, might be an important factor in the relationship of self-critical rumination and somatic symptom distress.

Acute cardiovascular stress induced by shoulder vibratory exercise of different amplitudes

BACKGROUND

Vibration exercise has been investigated to enhance muscle activation, however, the effect of different amplitude vibratory exercises on cardiovascular stress is less understood.

OBJECTIVE

Our study aims to explore the acute effect of shoulder vibratory exercises with different postures and amplitudes on the cardiovascular response in healthy adults.

METHODS

Using a repeated measures randomized design, 36 subjects performed three different sessions with FLEXI-BAR exercise (FBE): (1) zero-amplitude, (2) small-amplitude, (3) large-amplitude. Each session included three different shoulder positions: 45-, 90- and 180-degree flexion. Heart rate variability (HRV), heart rate (HR) and rating of perceived exertion (RPE) were monitored continuously, while systolic blood pressure (SBP), diastolic blood pressure (DBP) and rate-pressure product (RPP) were measured before and after each exercise session.

RESULTS

Compared with zero-amplitude, both small- and large-amplitude FBE protocols induced higher SBP. By contrast, DBP decreased with small- and large-amplitude. The RPP immediately after the exercise session were higher than at baseline. For high frequency, low frequency of HRV and HR there was a main effect of amplitude.

CONCLUSION

Small- and large-amplitude FBE increased significantly SBP, RPE, HRV, HR and induced lower DBP, but the changes were modest, suggesting that FBE impose no extra threats to cardiovascular stress.

Alternative Devices for Heart Rate Variability Measures: A Comparative Test-Retest Reliability Study

Using healthy adult participants, seven measures of heart rate variability were obtained simultaneously from four devices in five behavioral conditions. Two devices were ECG-based and two utilized photoplethysmography. The 140 numerical values (measure, condition, device) are presented. The comparative operational reliability of the four devices was assessed, and it was found that the two ECG-base devices were more reliable than the photoplethysmographic devices. The interchangeability of devices was assessed by determining the between-device Limits of Agreement. Intraclass correlation coefficients were determined and used to calculate the standard error of measurement and the Minimal Detectable Difference. The Minimal Detectable Difference, MDD, quantifies the smallest statistically significant change in a measure and is therefore critical when HRV measures are used longitudinally to assess treatment response or disease progression.

Physiological Changes, Activity, and Stress During a 100-km-24-h Walking-March

Background

Long-endurance exercises like ultramarathons are known to elicit various metabolic and physiological changes in the human body. However, little is known about very long-duration exercise at low intensities regarding healthy human subjects.

Aim

The purpose of this study was to evaluate changes in body composition and metabolism in long-endurance but low-intensity events.

Methods

Twenty-five male and 18 female healthy recreational athletes (age 34.6 ± 8.8 years; BMI: 22.4 ± 2.0 kg/m²) of the "100 km Mammutmarsch" were recruited for participation during the events in 2014-2016. Other than classical ultramarathons, the "Mammutmarsch" is a hiking event, in which participants were required to walk but not run or jog. It was expected to complete the 100-km distance within 24 h, resulting in a calculated mean speed of 4.17 km/h, which fits to the mean speed observed (4.12 ± 0.76 km/h). As not all participants reached the finish line, comparison of finishers (FIN, n = 11) and non-finishers (NON, n = 21) allowed differential assessment of performance. Body composition measured through bioelectrical impedance analysis (BIA) was determined pre- and post-event, and serum samples were taken pre-event, at 30, 70, and 100 km to determine NT-pro-BNP, troponin T, C-reactive protein (CRP), cortisol, low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglycerides, total cholesterol, total creatine kinase (CK), CK-MB, aminotransferase (AST), ALT, and sodium levels. Nineteen participants wore actimeter armbands (SenseWear^®) to gain information about body activity and exercise intensity [metabolic equivalent of task (MET)]. Sixteen participants wore mobile heart rate monitors to assess mean heart rate during the race. Serum parameter alterations over the course of the race were analyzed with mixed-effects ANOVA and additional t-tests. All serum parameters were analyzed for correlation concerning different MET levels, speed, age, BMI, baseline NT-pro-BNP, mean heart rate during the race, and sex with linear regression analysis.

Results

We found significant elevations for muscle and cardiac stress markers (CRP, CK, CK-MB, AST, ALT, cortisol, and NT-pro-BNP) as well as decreasing markers of lipid metabolism (cholesterol, triglycerides, LDL). Although the intensity level demanded from our participants was low compared with other studies on (ultra-) marathons, the alteration of tested parameters was similar to those of high-intensity exercise, e.g., NT-pro-BNP showed a fourfold increase (p < 0.01) and LDL decreased by 20% (p = 0.05). Besides the duration of exercise, age, BMI, training status, and sex are relevant parameters that influence the elevation of stress factors. Notably, our data indicate that NT-pro-BNP might be a marker for cardiovascular fitness also in healthy adults.

Conclusion

This low-intensity long-endurance walk evoked a strong systemic reaction and large cell stress and shifted to a favorable lipid profile, comparable to higher intensity events. Despite increasing cardiac stress parameters, there were no indications of cardiac cell damage. Remarkably, the duration seems to have a greater influence on stress markers and metabolism than intensity.

Cardiovascular Acute Effects of Traditional vs. Paired Set Resistance Training in Patients With Liver Cirrhosis

Purpose: This study compared the acute effects of two different resistance training methods on heart rate variability, blood pressure, and rating of perceived exertion in patients with liver cirrhosis. Methods: Ten patients with Child-Pugh A (seven women and three men) participated in two experimental sessions, in random order: The traditional set condition consisted of three sets of six exercises performed in a sequential manner, while the paired set condition consisted of alternating sets between two exercises (three pairs of exercises). Ten repetitions were performed for each set with 70% of a 10 repetition maximum load and with 2 min rest between sets. Blood pressure and heart rate variability were assessed pre-workout and for 60 min post-workout. The rating of perceived exertion was assessed at the end of the third set for each exercise. Results: Significant alterations in heart rate variability were observed when considering the lowest value obtained during recovery, in which the SDNN was reduced in both the traditional set and paired set conditions, as well as the root mean square of standard deviation for the traditional set condition (p < .05). Additionally, for the paired set condition, there was a significant reduction in the HFnu band and a significant increase in the LFnu band (p < .05). Effect size showed reductions in diastolic and mean blood pressure until 30 min in a small magnitude for traditional sets. Conclusion: Similar cardiovascular responses were observed between methods eliciting normal physiological responses within safe limits for patients with liver cirrhosis.

Using bodily postures in the treatment of anorexia nervosa: Effects of power posing on interoception and affective states

OBJECTIVE

Power posing involves the adoption of an expansive bodily posture. This study examined whether power posing could benefit individuals with anorexia nervosa (AN) and women with normal weight in regards to interoceptive ability and affective states.

METHOD

Participants included 50 inpatients and outpatients with AN as well as 51 normal-weight women. Interoceptive accuracy (IAcc), measured by the heartbeat tracking task and interoceptive sensibility (IS), measured by confidence ratings, were assessed at baseline, after a single power posing session and after 1 week of daily training. Also, the short-term effects of power posing on subjective feelings of dominance, pleasantness, and arousal were investigated.

RESULTS

Both groups increased in their IAcc after one power posing session. Also, there was a significant main effect of time on feelings of dominance and pleasantness in the short-term. Women with AN displayed lower levels of IS, dominance, and pleasantness as well as higher levels of arousal than women without AN.

DISCUSSION

These findings suggest that power posing has the potential to increase IAcc, subjective feelings of power and pleasant affect in the short-term. Further research should investigate which mechanisms foster the effectiveness of this intervention to tailor it to the needs of women with AN.

Heart Rate Variability Mainly Relates to Cognitive Executive Functions and Improves Through Exergame Training in Older Adults: A Secondary Analysis of a 6-Month Randomized Controlled Trial

Heart rate variability (HRV) mirrors autonomic nervous system activities and might serve as a parameter to monitor health status in older adults. However, it is currently unknown which functional health measures, including cognitive, physical, and gait performance parameters, are most strongly related to HRV indices. This knowledge would enable implementing HRV assessments into health monitoring routines and training planning for older adults. Simultaneous cognitive-motor and exergame training may be effective to improve HRV indices but has not been investigated yet. Eighty-nine healthy older adults (≥70 years of age) were randomized into three groups: (1) virtual reality video game dancing, i.e., exergaming (DANCE); (2) treadmill walking with simultaneous verbal memory training (MEMORY); or (3) treadmill walking only (PHYS). Strength and balance exercises complemented each program. Over 6 months, two weekly 1-h training sessions were performed. HRV indices (standard deviation of N-N intervals, SDNN; root mean square of successive R-R interval differences, RMSSD; and absolute power of high-frequency band (0.15-0.4 Hz), HF power) and various measures of cognitive, physical, and gait performance were assessed at baseline and after 3 months and 6 months. Multiple linear regression analyses with planned comparisons were calculated. At baseline, 8-12% of HRV variance was significantly explained by cognitive executive functions and leg strength (inversely related). Verbal long-term memory, aerobic and functional fitness, and gait performance did not contribute to the model (SDNN: R² = 0.082, p = 0.016; RMSSD: R² = 0.121, p = 0.013; HF power: R² = 0.119, p = 0.015). After 6 months, DANCE improved HRV indices, while MEMORY and PHYS did not (time × intervention interactions: first-contrast DANCE/MEMORY vs. PHYS: SDNN p = 0.014 one-tailed, ΔR ² = 0.020 and RMSSD p = 0.052 one-tailed (trend), ΔR ² = 0.007; second-contrast DANCE vs. MEMORY: SDNN p = 0.002 one-tailed, ΔR ² = 0.035, RMSSD p = 0.017 one-tailed, ΔR ² = 0.012, and HF power p = 0.011 one-tailed, ΔR ² = 0.013). We conclude that mainly cognitive executive functions are associated with HRV indices and that exergame training improves global and parasympathetic autonomic nervous system activities in older adults. Periodic assessments of HRV in older citizens could be particularly beneficial to monitor cognitive health and provide indications for preventative exercise measures.

Heart Rate Variability in Children and Adolescents with Cerebral Palsy-A Systematic Literature Review

Cardiac autonomic dysfunction has been reported in patients with cerebral palsy (CP). The aim of this study was to assess the existing literature on heart rate variability (HRV) in pediatric patients with CP and a special attention was paid to the compliance of the studies with the current HRV assessment and interpretation guidelines. A systematic review was performed in PubMed, Web of Science, and Cumulative Index to Nursing and Allied Health Literature (CINAHL) databases searched for English language publications from 1996 to 2019 using Medical Subject Headings (MeSH) terms “heart rate variability” and “cerebral palsy” in conjunction with additional inclusion criteria: studies limited to humans in the age range of 0–18 years and empirical investigations. Out of 47 studies, 12 were included in the review. Pediatric patients with CP presented a significantly higher resting heart rate and reduced HRV, different autonomic responses to movement stimuli compared to children with normal development, but also reduced HRV parameters in the children dependent on adult assistance for mobility compared to those generally independent. None of the included studies contained the necessary details concerning RR intervals acquisition and HRV measurements as recommended by the guidelines. Authors of HRV studies should follow the methodological guidelines and recommendations on HRV measurement, because such an approach may allow a direct comparison of their results.

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

Heart rate variability (HRV) is a non-invasive indicator of autonomic nervous system function. HRV recordings show artefacts due to technical and/or biological issues. The Kubios software is one of the most used software to process HRV recordings, offering different levels of threshold-based artefact correction (i.e., Kubios filters). The aim of the study was to analyze the impact of different Kubios filters on the quantification of HRV derived parameters from short-term recordings in three independent human cohorts. A total of 312 participants were included: 107 children with overweight/obesity (10.0 ± 1.1 years, 58% men), 132 young adults (22.2 ± 2.2 years, 33% men) and 73 middle-aged adults (53.6 ± 5.2 years, 48% men). HRV was assessed using a heart rate monitor during 10–15 min, and the Kubios software was used for HRV data processing using all the Kubios filters available (i.e., 6). Repeated-measures analysis of variance indicated significant differences in HRV derived parameters in the time-domain (all p < 0.001) across the Kubios filters in all cohorts, moreover similar results were observed in the frequency-domain. When comparing two extreme Kubios filters, these statistical differences could be clinically relevant, e.g. more than 10 ms in the standard deviation of all normal R-R intervals (SDNN). In conclusion, the results of the present study suggest that the application of different Kubios filters had a significant impact on HRV derived parameters obtained from short-term recordings in both time and frequency-domains.

Comparison of Linear and Nonlinear HRV Dynamics Across Exercise Intensities After Menopause

The authors compared the linear and nonlinear heart rate variability dynamics from rest through maximal exercise in postmenopausal women who trained at either moderate or high intensities. The outcome variables included the RR triangular index, TINN, SD1, SD2, SD1/SD2, DFA α1, DFA α2, and α1/α2. Maximal exercise reduced SD1, SD2, DFA α1, DFA α2, α1/α2, RRTri, and TINN in both groups and increased SD1/SD2 (p < .05). Two minutes of active recovery produced significant increases in SD1, SD2, DFA α1, and TINN, compared with exercise in both groups (p < .0001). There was also a significant main effect between groups for RRTri during exercise recovery, with the moderate group achieving higher levels (p < .04). The authors have shown that both moderate and vigorous exercise training can lead to a healthy response to maximal exercise and recovery, with the moderate group having a slightly improved recovery in the triangular index.

Intra-Individual Variation of HRV during Orthostatic Challenge in Elite Male Field Hockey Players

The purpose of this study was to examine the intra-individual variation of heart rate variability (HRV) and heart rate using an orthostatic challenge in elite male athletes during a training camp. Heart rate (variability) was measured upon waking. Log-transformed HRV metrics were evaluated in three segments (first min discarded for stabilization): 0-3 min supine, 3-6 min supine, and standing. Heart rate was assessed while supine, 15 s after standing and average final 30 s standing (Rusko protocol). A RM-ANOVA compared intra-individual means, standard deviations (SD) and coefficients of variation (CV%) for HRV and heart rate. The intraclass correlation coefficient (ICC) and standard error of measurement (SEmeas) were used for relative and absolute reliability, respectively. Time and frequency domain HRV metrics had low variation (CV% <8.5%; SEmeas% ≤4.0%) for 0-3 min supine which was not improved during 3-6 min. Standing HRV had lower ICC and higher SEmeas than supine values. Variability and reliability outcomes for heart rate were comparable to log-transformed HRV metrics. This study uniquely describes the intra-individual variation of HRV metrics during an orthostatic challenge and demonstrated low variability in this cohort of elite male athletes. These data can be helpful for identifying when true individual changes occur for the autonomic nervous system indices in supine and standing positions.

Bidirectional Links Between Social Rejection and Sleep

OBJECTIVE

This set of studies examines the bidirectional links between social rejection and poor sleep, a ubiquitous and increasingly problematic health behavior.

METHODS

In study 1, a multiday field experiment, 43 participants completed a neutral task just before sleep on night 1 and a social rejection task on night 2. Objective and subjective sleep, postrejection affect, and physiological responses were measured. In study 2, 338 participants reported typical sleep quality before coming to the laboratory where they received social rejection or social acceptance feedback from a stranger. Physiological and affective responses were measured throughout the session.

RESULTS

In study 1, after social rejection, participants took longer going to bed (M [SD] = 38.06 [48.56] versus 11.18 [15.52], t(42) = 3.86, p < .001) and had shorter sleep durations (6:46 [1:27] versus 7:19 [1:38], t(41) = 2.92, p = .006) compared with the baseline night. Trait rumination moderated these effects, with high ruminators taking the longest to go to bed postrejection (t(38) = 2.90, p = .006). In both studies, there was (inconsistent) evidence that sleep influences reactions to rejection: some sleep measures predicted physiological reactivity during the rejection task in study 1 and greater negative affect after social rejection in study 2.

CONCLUSIONS

These studies provide evidence that social rejection may affect sleep outcomes, particularly for trait ruminators, and poor sleep in turn may exacerbate affective responses to social rejection. Given the mixed findings, small sample size, and no active control condition, more work is needed to confirm and build on these findings.

An experiment to assess emotional and physiological arousal and personality correlates while imagining deceit

In order to examine how personality traits, emotional arousal and physiological arousal affect deception confidence, students (N = 102) completed the Eysenck Personality Questionnaire-Revised (EPQ-R) as well as stress and deception tasks while their heart rate variability was measured. Findings indicated psychoticism did not moderate how physiologically aroused participants were while viewing emotionally salient stimuli (video of a road traffic accident) or the thought of enacting deceit, although this came close to significance. However, participants (particularly males) higher in psychoticism reported less subjective distress after imagining enacting deceit than those lower on psychoticism. Extroversion had no impact on physiological arousal when viewing emotionally salient stimuli or thinking about enacting deceit. However, extroverts reported more subjective distress after thinking about enacting deceit than introverts. Also, deception confidence was not correlated to any of these variables. Future research could examine a sample higher in psychoticism and how this trait impacts deception confidence.

Endurance Running Training Individually Guided by HRV in Untrained Women

da Silva, DF, Ferraro, ZM, Adamo, KB, and Machado, FA. Endurance running training individually guided by HRV in untrained women. J Strength Cond Res 33(3): 736-746, 2019-The aim of this study was to analyze the effects of heart rate variability (HRV)-guided training compared with a standardized prescription on (a) time to complete 5-km running performance (t5km), (b) peak treadmill running speed (Vpeak) and its time limit (tlim at Vpeak), and (c) autonomic cardiac modulation (i.e., parasympathetic activity and recovery) in untrained women. Additionally, we correlated changes in t5km with changes in Vpeak, tlim at Vpeak and autonomic cardiac modulation. Thirty-six untrained women were divided into a HRV-guided training group (HRVG) and a control group (CG). The CG followed a predefined program, alternating moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT). The determination of MICT or HIIT was based on the pretraining HRV for HRVG. MICT was performed if HRV was <mean - 1 SD of previous measures. Otherwise, HIIT was prescribed. The t5km, Vpeak, tlim at Vpeak, parasympathetic activity (i.e., rMSSD) and parasympathetic reactivation (i.e., HRR) were measured before and after the training period. The t5km decreased to a greater magnitude in the HRVG (-17.5 ± 5.6% vs. -14 ± 4.7%; Effect Size (ES) between-group difference = moderate). rMSSD and tlim at Vpeak only improved in HRVG (+23.3 ± 27.8% and +23.6 ± 31.9%, respectively). The HRVG experienced greater improvements in Vpeak and HRR (Vpeak: 10 ± 7.3% vs. 8.2 ± 4.7%; HRR: 19.1 ± 28.1% vs. 12.6 ± 12.9%; ES between-group difference = small). Although HRVG performed less MICT than CG, the volume of MICT was negatively related to changes in t5km. Vpeak changes were highly correlated with t5km changes. The greater improvements in HRVG for t5km and autonomic modulation reinforce the potential application of this tool.

Evolution of gait parameters in individuals with a lower-limb amputation during a six-minute walk test

BACKGROUND

A recent amputation leads to decreased functional capacities in the lower limb amputees (LLA), especially during walking. Assessments of LLA's gait in clinical settings are used to provide feedback on their evolution without quantifying gait parameters distinctly, unlike new technologies, such as inertial sensors (IMUs), which have demonstrated their effectiveness in different environments and populations.

RESEARCH QUESTION

How do the spatial-temporal gait parameters and kinematics of the LLA evolve quantitatively over a six-minute walk test (6MWT) and is the use of inertial sensors relevant in clinical practice to quantify those parameters?

METHODS

Fifteen LLA from a study cohort performed a 6MWT post-rehabilitation, wearing inertial sensors on both feet to provide gait parameters (i.e., minimum toe clearance (minTC), speed, cadence, stance time and foot flat ratio (FFr)) over this test. A non-parametric ANOVA was conducted comparing the evolution of each parameter over the 6MWT (12 intervals of 30 s). Significance level was set at P ≤  0.05. Post-hoc Wilcoxon signed-rank tests were performed if a main effect was detected.

RESULTS

MinTC and stance phase variability along the 6MWT were significantly different over time. Cadence variability and speed variation were significantly different between both feet (amputated and non-amputated leg).

SIGNIFICANCE

The increased variability in gait parameters along the 6MWT suggests a greater risk of future mobility problems following a return in community. The data provided by the IMUs reflect the potential of the clinical rehabilitation programme and could, therefore, help clinicians to refine their interventions.

Stress and stressors of medical student near-peer tutors during courses: a psychophysiological mixed methods study

BACKGROUND

Structured peer-led tutorial courses are widespread and indispensable teaching methods that relieve teaching staff and contribute to the development of students' competencies. Nevertheless, despite high general stress levels in medical students and associated increases in psychopathology, specific knowledge of peer tutors' additional burdens is very limited.

METHODS

Sixty student near-peer tutors from two structured peer-teaching programmes volunteered to participate. On multiple occasions in three different course sessions, we assessed tutors' subjective stress, affective state, heart rate variability, and salivary cortisol. Additionally, tutors named everyday and course-specific stressors, which were evaluated by means of content analyses.

RESULTS

The study participation rate was high (63% of all active tutors). The participating tutors are socially well adapted and resilient individuals. They report a variety of stressors such as time pressure, participant characteristics, teacher role demands, and study requirements, but nevertheless display only moderate psychological and physiological stress that decreases over sessions. Tutors' negative affect in sessions is low; their positive affect is consistently high for senior as well as novice tutors. Tutors rate their courses' quality as high and quickly recover after sessions.

CONCLUSIONS

Tutors successfully cope with teaching-associated and everyday life demands. The results corroborate the viability and success of current peer-teaching programmes from the tutors' perspective. This study is the first to comprehensively quantify tutors' stress and describe frequent stressors, thus contributing to the development of better peer teaching programmes and tutor qualification training.

Active coping moderates associations among race-related stress, rumination, and depressive symptoms in emerging adult African American women

Cross-sectional and longitudinal research has shown that race-related stress is associated with increased depressive symptoms among racial/ethnic minorities. Rumination has long been considered a maladaptive self-regulatory response to race-related stress, and growing evidence suggests that it may be an important link in the relation between race-related stress and depression. More adaptive forms of self-regulation, such as active coping, may counteract the negative impact of rumination. We examined the influence of rumination on the relation between race-related stress and depressive symptoms in a sample (N = 69) of young adult (mean age = 20 ± 1.5 years) African American women. We also considered the possible moderating effects of John Henryism, a form of persistent and determined goal striving, and vagally mediated heart rate variability, a purported biomarker of coping. Anticipatory race-related stress was indirectly associated with depressive symptoms through rumination: estimate = 0.07, 95% confidence interval [0.01, 0.16]. Both John Henryism and vagally mediated heart rate variability moderated the relationship between race-related stress and rumination; however, only John Henryism reliably influenced the indirect association between race-related stress and depression through rumination. We discuss these findings in the context of growing research examining the interplay between cultural and biological factors in the risk for poorer mental health.

Improving interoceptive ability through the practice of power posing: A pilot study

Interoception refers to the detection and perception of signals from the inner body. Deficits in this domain have been linked to psychopathologies, prompting the search for strategies to improve this ability. Preliminary studies have shown that interoception could be enhanced through the manipulation of subjective feelings of power. We tested the effects of adopting powerful postures on different facets of interoception. Firstly, we measured the impact of a single power posing session on interoceptive ability in 41 healthy females. Then, the same participants were randomly assigned to two conditions (daily power posing practice vs. no practice). After one week the conditions alternated. Interoceptive accuracy, measured by the heartbeat tracking task, interoceptive sensibility, measured by the Body Perception Questionnaire (BPQ) and confidence ratings, as well as subjective feelings of power were assessed at baseline, after a single power posing session and after one week of training. A single power posing session significantly increased individuals' interoceptive accuracy. Also, power posing reduced individuals' scores on the BPQ after one week of daily practice and increased subjective feelings of power after one session and one week of daily practice. These findings suggest that adopting powerful postures has the potential to increase interoceptive accuracy, as well as subjective feelings of power, and to reduce interoceptive sensibility, measured by questionnaire.

Impact of heart rate on reproducibility of heart rate variability analysis in the supine and standing positions in healthy men

OBJECTIVE

The reliability of heart rate variability (HRV) analysis is not yet fully understood, especially considering different body positions and the mathematical influence of heart rate. The aim of this study was to evaluate the reliability of HRV in supine and standing positions, with and without mathematical adjustment of HRV by the average R-R interval (iRR).

METHODS

We evaluated 37 young males (23.1±4 years; 25.1±3 kg/m2). A 5-min segment of the iRR was collected in the supine and standing positions on three occasions separated by 48-hour intervals. Absolute and relative reliability of temporal and spectral indices were assessed by the coefficient of variation (CV) and the intraclass correlation coefficient (ICC), respectively.

RESULTS

We did not observe differences in HRV indices in the three occasions in the supine or standing position (p>0.05). Moderate to good reproducibility was observed for temporal and spectral indices of HRV in the supine position (ICC: 0.65-0.89; CV: 0.9-19.8). In the orthostatic position, low to good reproducibility was observed (ICC: 0.35-0.89; CV: 1.1-34.8), with higher ICCs for temporal indices. After mathematical adjustment, only a small modification in HRV reliability was observed in both positions.

CONCLUSIONS

In young adult males, the mathematical adjustment of HRV by the average iRR led to a nonsignificant effect on HRV reliability. Additionally, HRV reliability is dependent on body position and the index analyzed. Promising measures in both supine and standing positions include r-MSSD and the HF band (parasympathetic indices).

Psychophysiological characterization of different capoeira performances in experienced individuals: A randomized controlled trial

The aim of this study was to characterize the psychophysiological demand in different capoeira performances. Eleven experienced capoeira practitioners underwent the following procedures in different days: 1) anamnesis and anthropometric measurements; 2) aerobic performance assessment; 3 to 5) performances of 90 seconds in three capoeira styles (Angola, Benguela and São Bento), which were performed in randomized controlled cross-over design. The psychophysiological demand was assessed through the heart rate (HR), R-R interval (RRi), blood pressure (BP), blood lactate ([Lac]), blood glucose ([Gluc]), rating perceived effort (RPE), feeling scale (FS) and perceived activation (PA). Descriptive statistics with mean and standard deviation was performed. A two-way repeated measures ANOVA with Bonferroni post-hoc test was used. The Angola demand was between 56–71% maximal HR with [Lac]_PEAK: 6.9±2.9 mM, RPE_PEAK: 10.0±2.2 pts and FS: 2.7±1.7 pts, while in the Benguela participants reached 64–85% maximal HR with [Lac]_PEAK: 9.5±3.0 mM, RPE_PEAK: 11.0±2.8 pts and FS: 2.1±1.6 pts and for São Bento between 69–102% maximal HR with [Lac]_PEAK: 15.7±2.6 mM, RPE_PEAK: 15.5±4.1 pts and FS: -0.8±3.0 pts. Interaction time*performance occurred to [Lac] (F = 42.157; p<0.001), HR (F = 12.154; p<0.001), RRi (F = 4.774; p<0.001), parasympathetic modulation-rMSSD (F = 3.189; p<0.01), [Gluc] (F = 2.152; p<0.05), RPE (F = 5.855; p<0.01), FS (F = 2.448; p<0.05) and PA (F = 3.893; p<0.05). We concluded that São Bento rhythm resulted in a greater physiological demand according to the HR, [Lac] and cardiac autonomic indicators, with the Benguela rhythm being intermediate while the Angola rhythm presented a reduced demand. The [Gluc] increased after the São Bento rhythm when compared to the other rhythms. The perceptual demand presented increased in terms of RPE and PA variables and decreased in terms of FS when the São Bento performance was analyzed in comparison to the Angola and/or Benguela in capoeira.

Good decision-making is associated with an adaptive cardiovascular response to social competitive stress

Competition elicits different psychological and cardiovascular responses depending on a person's skills. Decision-making has been considered a distal factor that influences competition, but there are no studies analyzing this relationship. Our objective was to analyze whether decision-making affects the response to competition. Specifically, we aimed to test whether good performers on a decision-making test, the Iowa Gambling Task (IGT), showed an adaptive cardiovascular response to competition. In all, 116 participants (44 women) performed the IGT and were classified into Good or Poor decision-makers. Subsequently, they were exposed to a stress task in two different conditions: a face-to-face competition (winners/losers) or a control condition, while an electrocardiogram was recorded. In the competition group, good decision-makers increased their high-frequency respect to the total heart rate variability (HF/HRV) levels during the task, compared to Poor decision-makers. Again, competition group good decision-makers, showed lower LF and higher HF/HRV reactivity than the control group, which represents lower HRV stress pattern. Moreover, in the group of losers, good decision-makers had a decline in low frequency (LF) during the task and faster recovery than poor decision-makers. In conclusion, good decision-makers have a more adaptive stress response and higher levels of mental effort, based on total HRV interpretation. Decision-making skills could be a factor in a more adaptive cardiovascular response to competition.

Inter and Intra-Rater Reliability of Short-Term Measurement of Heart Rate Variability on Rest in Diabetic Type 2 Patients

Heart rate variability (HRV) among other methods can be used to assess diabetic cardiac autonomic neuropathy by cardiac intervals were recorded. However, the amount of error depending on this measurement methodology is unclear. To evaluate the intra- and inter-rater reliability to calculate HRV indices, comparing different times and by different trained examiners in patients with type 2 diabetes mellitus (T2DM). Thirty individuals of both genders, aged between 18 and 45 years, with T2DM. The RR interval (RRi) were recorded during a 10 min period on supine position using a portable heart rate monitor (Polar® S810i model). HRV indices were calculated by the software Kubios® HRV analysis (version 2.2). Linear (Mean RRi; STD RR; Mean HR; rMSSD; RR Tri; TINN LF; HF; total power) and non-linear (SD1; SD2; DFα1; DFα2, ApEn and, SampEn) indices were calculated by two examiners with an interval of one week between them. Substantial to excellent was found for reliability of the intra-examiner, with intraclass correlation coefficient (ICC) values ranging from 0.79 to 0.99, standard error of measurement (SEM) between 0.02 and 123.49 (in percentage: 1.83 and 16.67), and minimum detectable change (MDC) between 0.07 and 342.30. Regarding the inter-examiner reliability, substantial to excellent reliability was found, with ICC values ranging from 0.73 to 0.97, SEM between 0.04 and 178.13 (in percentage: 3.26 and 24.18), and MDC between 0.11 and 493.77. The use of the portable heart rate monitor to measure HRV showed acceptable intra and inter reliability in individuals with T2DM, supporting the use of this method of evaluation in research and clinical practice.

Heart rate variability and implication for sport concussion

Finding sensitive and specific markers for sports-related concussion is both challenging and clinically important. Such biomarkers might be helpful in the management of patients with concussion (i.e. diagnosis, monitoring and risk prediction). Among many parameters, blood flow-pressure metrics and heart rate variability (HRV) have been used to gauge concussion outcomes. Reports on the relation between HRV and both acute and prolonged concussion recovery are conflicting. While some authors report on differences in the low-frequency (LF) component of HRV during postural manipulations and postexercise conditions, others observe no significant differences in various HRV measures. Despite the early success of using the HRV LF for concussion recovery, the interpretation of the LF is debated. Recent research suggests the LF power is a net effect of several intrinsic modulatory factors from both sympathetic and parasympathetic branches of the autonomic nervous system, vagally mediated baroreflex and even some respiratory influences at lower respiratory rate. There are only a few well-controlled concussion studies that specifically examine the contribution of the autonomic nervous system branches with HRV for concussion management. This study reviews the most recent HRV- concussion literature and the underlying HRV physiology. It also highlights cerebral blood flow studies related to concussion and the importance of multimodal assessment of various biological signals. It is hoped that a better understanding of the physiology behind HRV might generate cost-effective, repeatable and reliable protocols, all of which will improve the interpretation of HRV throughout concussion recovery.

Classification of caesarean section and normal vaginal deliveries using foetal heart rate signals and advanced machine learning algorithms

BACKGROUND

Visual inspection of cardiotocography traces by obstetricians and midwives is the gold standard for monitoring the wellbeing of the foetus during antenatal care. However, inter- and intra-observer variability is high with only a 30% positive predictive value for the classification of pathological outcomes. This has a significant negative impact on the perinatal foetus and often results in cardio-pulmonary arrest, brain and vital organ damage, cerebral palsy, hearing, visual and cognitive defects and in severe cases, death. This paper shows that using machine learning and foetal heart rate signals provides direct information about the foetal state and helps to filter the subjective opinions of medical practitioners when used as a decision support tool. The primary aim is to provide a proof-of-concept that demonstrates how machine learning can be used to objectively determine when medical intervention, such as caesarean section, is required and help avoid preventable perinatal deaths.

METHODS

This is evidenced using an open dataset that comprises 506 controls (normal virginal deliveries) and 46 cases (caesarean due to pH ≤ 7.20-acidosis, n = 18; pH > 7.20 and pH < 7.25-foetal deterioration, n = 4; or clinical decision without evidence of pathological outcome measures, n = 24). Several machine-learning algorithms are trained, and validated, using binary classifier performance measures.

RESULTS

The findings show that deep learning classification achieves sensitivity = 94%, specificity = 91%, Area under the curve = 99%, F-score = 100%, and mean square error = 1%.

CONCLUSIONS

The results demonstrate that machine learning significantly improves the efficiency for the detection of caesarean section and normal vaginal deliveries using foetal heart rate signals compared with obstetrician and midwife predictions and systems reported in previous studies.

Buccal telomere length and its associations with cortisol, heart rate variability, heart rate, and blood pressure responses to an acute social evaluative stressor in college students

OBJECTIVE

Understanding the relationship between stress and telomere length (a marker of cellular aging) is of great interest for reducing aging-related disease and death. One important aspect of acute stress exposure that may underlie detrimental effects on health is physiological reactivity to the stressor.

METHODS

This study tested the relationship between buccal telomere length and physiological reactivity (salivary cortisol reactivity and total output, heart rate (HR) variability, blood pressure, and HR) to an acute psychosocial stressor in a sample of 77 (53% male) healthy young adults.

RESULTS

Consistent with predictions, greater reductions in HR variability (HRV) in response to a stressor and greater cortisol output during the study session were associated with shorter relative buccal telomere length (i.e. greater cellular aging). However, the relationship between cortisol output and buccal telomere length became non-significant when adjusting for medication use. Contrary to past findings and study hypotheses, associations between cortisol, blood pressure, and HR reactivity and relative buccal telomere length were not significant. Overall, these findings may indicate there are limited and mixed associations between stress reactivity and telomere length across physiological systems.

Autonomic cardiovascular modulation in masters and young cyclists following high-intensity interval training

PURPOSE

This study aimed at examining the autonomic cardiovascular modulation in well-trained masters and young cyclists following high-intensity interval training (HIT).

METHODS

Nine masters (age 55.6 ± 5.0 years) and eight young cyclists (age 25.9 ± 3.0 years) completed a HIT protocol of 6 x 30 sec at 175% of peak power output, with 4.5-min' rest between efforts. Immediately following HIT, heart rate and R-R intervals were monitored for 30-min during passive supine recovery. Autonomic modulation was examined by i) heart rate recovery in the first 60-sec of recovery (HRR₆₀); ii) the time constant of the 30-min heart rate recovery curve (HRRτ); iii) the time course of the root mean square for successive 30-sec R-R interval (RMSSD₃₀); and iv) time and frequency domain analyses of subsequent 5-min R-R interval segments.

RESULTS

No significant between-group differences were observed for HRR₆₀ (P = 0.096) or HRR_τ (P = 0.617). However, a significant interaction effect was found for RMSSD₃₀ (P = 0.021), with the master cyclists showing higher RMSSD₃₀ values following HIT. Similar results were observed in the time and frequency domain analyses with significant interaction effects found for the natural logarithm of the RMSSD (P = 0.008), normalised low-frequency power (P = 0.016) and natural logarithm of high-frequency power (P = 0.012).

CONCLUSION

Following high-intensity interval training, master cyclists demonstrated greater post-exercise parasympathetic reactivation compared to young cyclists, indicating that physical training at older ages has significant effects on autonomic function.