Root Mean Square Of Successive Differences Research Articles

Flexible Electrodes-Based Smart Mattress for Monitoring Physiological Signals of Heart and Autonomic Nerves in a Non-Contact Way

Heart rate variability (HRV) reflects the regulating effect of autonomic nerve on cardiovascular functions and is strongly influenced by respiratory rhythm. For more convenient monitoring physiological or pathological information about heart and autonomic nerves during sleep than conventional systems, a smart mattress that could measure electrocardiogram (ECG) and respiratory signals through clothes was designed. The system mainly consists of three electrodes that are made of flexible silver fiber conductive fabric, a signal preprocessing module and a user interface. To reduce the effect of surrounding electromagnetic radiation on the electrodes, two equipotential shielding layers are placed under the two active electrodes, respectively. To verify the proposed system, experiments in four sleeping postures (supine, left lateral, right lateral, and prone) were carried out. The results showed that the proposed system could successfully measure ECG signals and extract respiratory signals from them in all sleeping postures. Finally, to study respiratory sinus arrhythmia during sleep, an experiment was conducted to measure ECG and respiratory signals of 7 subjects under unconstrained sleep over night. Then, root mean square of successive differences (RMSSD) and peak-valley respiratory sinus arrhythmia (pvRSA) that can reflect the vagus nerve tension were calculated. The results showed that all subjects had varying degrees of respiratory sinus arrhythmia, with the mean and standard deviation of $176 \pm 80\textit {ms}$ and $288 \pm 126\textit {ms}$ , for the RMSSD and the pvRSA respectively. The RMSSD and the pvRSA of the subject with most obvious arrhythmia were $346\textit {ms}$ and $552\textit {ms}$ respectively. The results also indicate the potential application of the proposed system in detecting sleep diseases such as sleep apnea.

Adiposity and physical activity are related to heart rate variability: the African-PREDICT study.

Physical inactivity contributes significantly to the development of obesity-related cardiovascular disease. Adiposity may lead to reduced heart rate variability (HRV), whereas increased physical activity (PA) has the potential to improve autonomic activity. These associations remain largely unexplored in healthy individuals. We therefore investigated whether adiposity and physical activity (PA) are associated with reduced heart rate variability (HRV) in young adults. We examined 403 black and 461 white healthy adults (aged 20-30years) for HRV, including standard deviation of normal RR intervals (SDNN) and root mean square of successive differences (RMSSD). We measured adiposity, PA levels and blood pressure (BP). Body mass index (BMI) of≥30kg/m2 indicated obesity. Participants with obesity had lower mean HRV than normal weight (SDNN [95% CI]; 138 [131-145]s vs 161 [158-165]ms), where those with the highest PA had higher SDNN (164 [160-169]ms) and RMSSD (51 [49-53]ms) than the least active individuals (150 [146-155]s) and 46 [44-48]ms)(all P<.01). BMI, waist circumference and body fat associated with lower SDNN (P<.001). With each unit increase of vigorous PA, a favourable higher RMSSD was found (P<.05). One unit increase in diastolic BP was associated with decreased SDNN and RMSSD (P<.001). These findings remained significant in multivariable-adjusted analyses. Adiposity and low PA associated independently with depressed autonomic activity in young healthy adults. Sympathovagal imbalance seems to already contribute to elevated diastolic BP at young ages. Our study supports population-based prevention programmes in young adults, improving PA and healthy diet, to curb the development of cardiovascular disease.

Associations Between Sedentary Behavior And Steps With Heart Rate Variability In Desk Workers

PURPOSE: More sedentary behavior (SB) has been associated with reduced heart rate variability (HRV) in blue-collar workers; however, this association has not yet been examined in desk workers who engage in high levels of SB. This study explored associations between SB and steps/day with HRV in desk workers. METHODS: This analysis of baseline data of a subsample of participants from an ongoing clinical trial included thirty-three insufficiently active adults (age: 43.7 ± 11.6 yr; BMI: 30.0 ± 6.3 kg/m2) with desk jobs and elevated blood pressure. An activPAL3 micro device was placed on the anterior midpoint of the thigh for one week to measure SB and steps. Total and prolonged (≥30 continuous minutes) SB and total steps/day were averaged across valid days for participants with ≥10 hr/day on ≥4 days. For HRV, beat-to-beat intervals were collected during a 10-min supine rest using a Polar V800 monitor, with the last 5 min analyzed using Kubios software to measure parasympathetic-related HRV parameters including: mean R-R intervals, root mean square of successive differences (RMSSD), standard deviation of normal R-R intervals (SDNN) and high frequency (HF). Natural-log (ln) transformation was applied for skewed HRV variables. Simple and partial Pearson’s correlations between SB, steps/day and HRV parameters were calculated before and after controlling for age. RESULTS: Correlations were not statistically significant between total or prolonged SB with any of the HRV parameters (Table 1.). Steps/day were correlated with mean R-R intervals (r = .371; p = .034), with the correlation attenuated when controlling for age (r = .320; p = .075). No other significant correlations were detected between steps/day and other HRV parameters. CONCLUSION: While SB was not correlated to HRV, more steps/day were related to greater parasympathetic-related HRV in adults with desk jobs. These results may suggest that movement rather than SB should be the focus of approaches to enhance HRV.

Evaluation of infrared thermography as a non-invasive method of measuring the autonomic nervous response in sheep.

Eye temperature measured using infrared thermography (IRT) can be used as a non-invasive measure of autonomic nervous system (ANS) activity in cattle. The objective of this study was to evaluate if changes in eye temperature (measured using IRT) can be used to non-invasively measure ANS activity in sheep. Twenty, 2 to 4-year-old, Romney ewes were randomly assigned to receive either epinephrine (EPI) or physiological saline (SAL) for 5 min administered via jugular catheter (n = 10 ewes/treatment). Eye temperature (°C) was recorded continuously using IRT for approximately 25 min before and 20 min after the start of infusion. Heart rate and heart rate variability, measured using the root mean square of successive differences (RMSSD) and the standard deviation of all inter-beat intervals (SDNN), were recorded for 5 min before and up to 10 min after the start of infusion. Blood samples were taken before and after the infusion period to measure plasma epinephrine, norepinephrine, cortisol and packed cell volume (PCV) concentrations. During the infusion period, maximum eye temperature was on average higher (P<0.05) in sheep that received epinephrine than those that received saline. On average, heart rate was higher (SAL: 87.5 beats/min, EPI: 123.2 beats/min, SED = 7.07 beats/min; P<0.05), and RMSSD (SAL: 55.3 ms, EPI: 17.3 ms, SED = 14.18 ms) and SDNN (SAL: 54.3 ms, EPI: 21.5 ms, SED = 10.00 ms) lower (P<0.05) in ewes during the 5 min post-infusion period compared with ewes that received saline. An infusion of epinephrine resulted in higher geometric mean epinephrine (P<0.05) and cortisol (P<0.05) but not norepinephrine (P>0.05) concentrations in ewes compared to an infusion of saline. PCV concentrations were higher (P<0.001) by 7 ± 1.0% (mean±SED) in ewes after an epinephrine infusion. These results suggest that heart rate variability is a sensitive, non-invasive method that can be used to measure ANS activity in sheep, whereas change in eye temperature measured using IRT is a less sensitive method.

1088 Heart Rate Variability During Sleep in Adults With and Without a History of Depression and the Influence of Antidepressant Use

Abstract Introduction Individuals with depression have an increased risk for cardiovascular disease. While lower daytime HRV may be one mechanism of this association, it is less clear whether HRV during sleep (sHRV) differs between adults with and without depression. Examining sHRV is an important measure to test given evidence that nocturnal differences in physiology are strong predictors of cardiovascular disease. Methods 118 adults who completed psychiatric interviews between the ages of 21-60 y (T1) returned 18.7 ± 4.5 years later for a re-evaluation of their mental health and assessment of sleep (T2). 71 participants were diagnosed with Major Depressive Disorder (MDD) at either T1 or T2, while 47 participants were free from depression at both time points. At T2, participants underwent an overnight polysomnogram with concurrent assessment of electrocardiography. The primary measures of sHRV were root mean square of successive differences (RMSSD) values during rapid eye movement (REM) sleep and non-REM (NREM) sleep stages N2 and N3. Lower values of RMSSD suggest lower parasympathetic activity. RMSSD values were natural log-transformed prior to analysis. Differences in RMSSD between depressive groups were examined using analysis of covariance (ANCOVA), adjusting for age, body mass index, gender, race, and antihypertensive medication use. Additional ANCOVA models adjusted for antidepressant use. Results Participants with current or a history of MDD had lower RMSSD values during REM sleep (P=.01) and a trend toward lower values during NREM (P=.06) compared to those without MDD. Antidepressant use was significantly associated with lower RMSSD during both REM (P=.002) and NREM sleep (P&amp;lt;.001). Depression history was no longer associated with RMSSD during NREM or REM sleep following adjustment for antidepressant use (P&amp;gt;.40). Conclusion These data indicate that adults with MDD exhibit lower parasympathetic activity during sleep compared to those without MDD. These associations were modified by antidepressant use, suggesting that antidepressants may partially explain the association between depression and sHRV. Future studies investigating the influence of specific antidepressants for modifying nocturnal physiology may help to better understand the link between depression and cardiovascular disease risk. Support This study was funded by National Institutes of Health (NIH) grants R01 HL104607 and K23 HL118318.

Rumination syndrome: Assessment of vagal tone during and after meals and during diaphragmatic breathing.

Pathophysiology of rumination syndrome (RS) is not well understood. Treatment with diaphragmatic breathing improves rumination syndrome. The aim of the study was to characterize vagal tone in patients with rumination syndrome during and after meals and during diaphragmatic breathing. We prospectively recruited 10 healthy volunteers (HV) and 10 patients with RS. Subjects underwent measurement of vagal tone using heart rate variability. Vagal tone was measured during baseline, test meal and intervention (diaphragmatic (DiaB), slow deep (SlowDB), and normal breathing). Vagal tone was assessed using mean values of root mean square of successive differences (RMSSD), and area under curves (AUC) were calculated for each period. We compared baseline RMSSD, the AUC and meal-induced discomfort scores between HV and RS. Furthermore, we assessed the effect of respiratory exercises on symptom scores, and number of rumination episodes. There was no significant difference in baseline vagal tone between HV and RS. During the postprandial period, there was a trend to higher vagal tone in RS, but not significantly (P>.2 for all). RS had the higher total symptom scores than HV (P<.011). In RS, only DiaB decreased the number of rumination episodes during the intervention period (P=.028), while both DiaB and SlowDB increased vagal tone (P<.05 for both). The symptom scores with the 3 breathing exercises showed very similar trends. Patients with RS do not have decreased vagal tone related to meals. DiaB reduced number of rumination events by a mechanism not related to changes in vagal tone.

Lacrosse Athletes Load and Recovery Monitoring: Comparison between Objective and Subjective Methods.

Both objective (OM) and subjective (SM) methods are used in athletic studies, regardless of sport type, to identify and analyze load and recovery status of athletes. As little information exists about the comparison of these two methodologies, the aim of this study is to compare and contrast information that defines the relationship between both methods. Twelve international male lacrosse athletes participated in this study over the course of which participants heart-rate-variability and questionnaire-data were collected. Statistical analysis was performed to evaluate changes over time and correlations between used methods. Comparison between baseline values and competition showed a reduction in root-mean-square of successive differences (RMSSD) (p < 0.01) and the proportion of beat-intervals (NN) that differ by more than 50 ms divided by total number of NNs (pNN50) (p < 0.01). Further, RMSSD values showed differences during competition with large effects (p = 0.02; η2 = 0.24). SM (p < 0.01) showed different progression during competition. Correlation was found for used SM and OM, when considered separately. No evidence for a reliable prediction of OM values using SM could be found. According to these findings, we recommend using a combination of SM and OM data to quantify the physiological stress of training and competition, respectively.

RMSSD-Based Variability Measures for Suicidal Ideation From EMA Data

Ecological Momentary Assessment (EMA) records individuals’ ratings of emotions, thoughts, behaviors, and stressors in real-time, during daily life. EMA provides important information about moment-to-moment variation in mental state, but computing variability metrics is not straightforward. One candidate statistic is Root-Mean-Square-of-Successive-Differences (RMSSD). However, RMSSD of EMA Suicidal Ideation (SI) is dependent on mean SI severity and shows greater spread with higher SI severity.

Heart Rate Variability in College Football Players throughout Preseason Camp in the Heat.

We aimed to characterize cardiac-autonomic responses to a 13-day preseason camp in the heat among an American college football team. Players were categorized as linemen (n=10) and non-linemen (n=18). RHR, natural logarithm of the root-mean square of successive differences multiplied by twenty (LnRMSSD), and subjective wellbeing (LnWellness) were acquired daily. Effect sizes±90% confidence interval showed that for linemen, LnRMSSD decreased (moderate) on day 2 (71.2±10.4) and increased (moderate) on day 12 (87.1±11.2) relative to day 1 (77.9±11.2) while RHR decreased (small-moderate) on days 6, 7, and 12 (67.7±9.3-70.4±5.5 b∙min-1) relative to day 1 (77.1±10.1 b∙min-1). For non-linemen, LnRMSSD increased (small-large) on days 3-5, 7, 12, and 13 (83.4±6.8-87.6±8.5) relative to day 1 (80.0±6.5) while RHR decreased (small-large) on days 3-9, 12, and 13 (62.1±5.2-67.9±8.1 b∙min-1) relative to day 1 (70.8±6.2 b∙min-1). Decrements in LnWellness were observed on days 4-10 and 13 for linemen (moderate) and on days 6-9, 12, and 13 for non-linemen (small-moderate). Despite reductions in LnWellness, cardiac-autonomic parameters demonstrated responses consistent with heat-acclimation, which possibly attenuated fatigue-related decrements.

Autonomic Modulation Improves in Response to Harder Performances While Playing Wind Instruments

Background: Despite inducing autonomic benefits similar to exercise, playing wind instruments is a physical, and cognitive task of high attentional requirements, which demands musicians maximal efforts, leading to sympathetic hyperarousal and autonomic worsening. In this context of controversy, it remains unknown the autonomic response to playing highly demanding music performances, as compared to an easier one, which might be of interest in wind musicians' cardiovascular health. Objectives: This study aimed to investigate differences in the autonomic control of the heart with regard to task demands (TD), avoiding emotional influences (rehearsal performance). Methods: Eight healthy male professionals (29.13 ± 7.33 years) ranked a list of well-known musical scores according to their perception of the task demands. Later on, in 2 two normal rehearsals with no audience, musicians performed one mild performance (M), and another one ranked as hardest (H) on two alternative days. After 10 minutes of warm-up, they performed two laps of 20 minutes interspersed with 5 minutes of rest. Heart rate variability (HRV) was recorded in both laps, 20 minutes at baseline (before warming-up), and 20 minutes after cessation. Owing to non-stationarity of the cardiac signal, the root mean square of successive differences (RMSSD) and Poincare-Plot indexes (SD1, SD2) were analyzed in the last 500 beats of each 20 minutes (Kubios software V. 2.1). Results: Musicians showed larger parasympathetic responses in H (lnRMSSD, lnSD1, SD2), mostly after 30 minutes playing, without RRi differences. Vagal control diminished in the first lap, where musicians might be coupling heart rate to changes in breathing. Later on, this initial discomfort disappeared, followed by autonomic reactivation in H. Sympathetic arousal due to neuromuscular and cognitive demands while playing demanding music seems to be vagally counteracted, suggesting that the more the difficulty, the more coupled the respiratory sinus arrhythmia (i.e., cardiovascular adjustments). Conclusions: Playing wind instruments seems healthy in terms of autonomic modulation, and the psychophysiological wellness of wind musicians might benefit from HRV monitoring in the long-term.

Affect fluctuations examined with ecological momentary assessment in patients with current or remitted depression and anxiety disorders.

There is increasing interest in day-to-day affect fluctuations of patients with depressive and anxiety disorders. Few studies have compared repeated assessments of positive affect (PA) and negative affect (NA) across diagnostic groups, and fluctuation patterns were not uniformly defined. The aim of this study is to compare affect fluctuations in patients with a current episode of depressive or anxiety disorder, in remitted patients and in controls, using affect instability as a core concept but also describing other measures of variability and adjusting for possible confounders. Ecological momentary assessment (EMA) data were obtained from 365 participants of the Netherlands Study of Depression and Anxiety with current (n = 95), remitted (n = 178) or no (n = 92) DSM-IV defined depression/anxiety disorder. For 2 weeks, five times per day, participants filled-out items on PA and NA. Affect instability was calculated as the root mean square of successive differences (RMSSD). Tests on group differences in RMSSD, within-person variance, and autocorrelation were performed, controlling for mean affect levels. Current depression/anxiety patients had the highest affect instability in both PA and NA, followed by remitters and then controls. Instability differences between groups remained significant when controlling for mean affect levels, but differences between current and remitted were no longer significant. Patients with a current disorder have higher instability of NA and PA than remitted patients and controls. Especially with regard to NA, this could be interpreted as patients with a current disorder being more sensitive to internal and external stressors and having suboptimal affect regulation.

Higher Weekly Walking Volume Improves Cardiac Autonomic Profile and Arterial Stiffness Index in Hypertensive Elderly

BackgroundThe practice of daily aerobic exercise such as healthy walking could have an important effect on cardiovascular parameters. However, there is still little evidence of how much weekly walking volume is enough to influence cardiovascular autonomic modulation and arterial stiffness on hypertension.PurposeTo assess effects of weekly walking volume on cardiac autonomic function and arterial stiffness index in elderly hypertensive.MethodsSixty hypertensive elderly with 71.7 ± 3.4 years old were allocated in physically inactive (PI, n=30) and active (PA, n=30) groups. Hemodynamic parameters of heart rate (HR), peripheral blood pressure (SYS, DIA, MBP), cardiac autonomic modulation by the method of HR variability in both the time (root mean square of successive differences (RMSSD) and percentage of RR intervals differing by &lt;50ms (pNN50)) and frequency domains (low and high frequency (LF, HF), and LF/HF ratio), stiffness (augmentation index; AIX, pulse wave velocity; PWV) and total vascular conductance (TVC), and central blood pressure (cSYS, cDIA) were measured in baseline conditions.ResultsThe average of weekly walk in PA group was 312.4 ± 36.5 min. vs. 57.7 ± 47.9 min. in PI group (p &lt;0.001). Pronounced resting bradycardia was observed in PA group (62.1 ± 8.7 bpm) in comparison with PI group (75.7 ± 9.1; p=0.0). Brachial SYS (124.3 ± 7.6 mmHg) DIA (76.5 ± 7.4 mmHg) and MBP (92.4 ± 7.4 mmHg) were lowers in PA than PI group (133.6 ± 6.0 mmHg; p=0.003), (82.7 ± 7.6 mmHg; p=0.032) and (99.4 ± 7.0 mmHg; p&lt;0.05), respectively. The PA group showed higher cardiac parasympathetic modulation than PI group, evidenced by an increase in RMSSD (PI: 43.8 ± 23.9 vs. PA: 69.4 ± 29.4 ms; p=0.047), pNN50 (22.7 ± 3.9 vs. 40.7 ± 5.1 %; p=0.038) and in cardiac HF band (PI: 59.9 ± 5.8 vs. PA: 67.0 ± 3.7 nu; p=0.005). There were no differences in sympathetic modulation between PA and PI groups. The PI group had higher PWV (10.3 ± 1.2 m/s), AIX (36.4 ± 8.0 %) and TVC (1.4 ± 0.1 s*mmHg/ml) when compared to PA group (PWV = 9.1 ± 0.7 m/s; p = 0.005), (AIX = 23.5 ± 13.6 %; p = 0.003) and (TVC = 1.2 ± 0.1 s*mmHg/ml; p &lt;0.001). Additionally, the cSYS (119.5 ± 14.0 mmHg) and cDIA (76.2 ± 18.3 mmHg) were lower in PA than PI (135.8 ± 20.6 mmHg; p=0.045 and 91.8 ± 20.5 mmHg; p=0.034), respectively.ConclusionThese findings suggest that a higher weekly volume of walking improves baseline hemodynamic parameters and provides greater vagal modulation at rest, concomitant with attenuation of arterial stiffness evidencing that this type of intervention has important cardiovascular safety.Support or Funding InformationCAPES, CNPq, FAPEMIG, UFTM.

Association of Heart Rate Variability With Cognitive Performance: The Multi-Ethnic Study of Atherosclerosis.

BackgroundHeart rate variability (HRV) is associated with vascular risk factors for dementia, but whether HRV is associated with specific domains of cognitive performance is unclear.Methods and ResultsIn the Multi‐Ethnic Study of Atherosclerosis (N=3018; mean age 59.3±9.2 years), we assessed the relationship of 10‐second HRV to scores on tests of global cognitive performance (Cognitive Abilities Screening Instrument), processing speed (Digit Symbol Coding), and working memory (Digit Span). HRV was computed as the SD of normal‐normal intervals (SDNN) and root mean square of successive differences (RMSSD) at Exam 1 (2000–2002) and Exam 5 (2010–2012). Cognitive tests were administered at Exam 5. We report regression coefficients (β [95% CI]) representing cognitive test score change per 2‐fold increase in HRV. After adjustment for age, race/ethnicity, sex, education, apolipoprotein E genotype, and cardiovascular risk factors and incident disease, higher Exam 1 (β=0.37 [0.06, 0.67]) and Exam 5 (β=0.31 [0.04, 0.59]) SDNN were associated with better Cognitive Abilities Screening Instrument performance. Higher Exam 1 (β=0.80 [0.17, 1.43]) and Exam 5 (β=0.63 [0.06, 1.20]) SDNN, and Exam 5 RMSSD (β=0.54 [0.01, 1.08]) were associated with better Digit Symbol Coding performance. Finally, higher Exam 5 SDNN was associated with better Digit Span performance (β=0.17 [0.01, 0.33]). Associations were attenuated after adjustment for resting heart rate.ConclusionsHigher HRV is generally associated with better cognitive performance in this multi‐ethnic cohort of aging adults, and further study of the relationship of autonomic function to cognition is warranted.

Effects of Expectancy on Cognitive Performance, Mood, and Psychophysiology in Healthy Adolescents and Their Parents in an Experimental Study.

ObjectivePlacebo effects on cognitive performance and mood and their underlying mechanisms have rarely been investigated in adolescents. Therefore, the following hypotheses were investigated with an experimental paradigm: (1) placebo effects could be larger in adolescents than in adults, (2) parents’ expectations influence their adolescents’ expectations and placebo effects, and (3) a decrease in stress levels could be an underlying mechanism of placebo effects.MethodsTwenty-six healthy adolescents (13.8 ± 1.6 years, 14 girls) each with a parent (45.5 ± 4.2 years, 17 mothers) took part in an experimental within-subjects study. On two occasions, a transdermal patch was applied to their hips and they received an envelope containing either the information that it is a Ginkgo patch to improve cognitive performance and mood, or it is an inactive placebo patch, in counterbalanced order. Cognitive performance and mood were assessed with a parametric Go/No-Go task (PGNG), a modification of California Verbal Learning Test, and Profile of Mood Scales (POMS). Subjects rated their expectations about Ginkgo’s effects before patch application as well as their subjective assessment of its effects after the tests. An electrocardiogram and skin conductance levels (SCLs) were recorded and root mean square of successive differences (RMSSD), high-frequency power (HF), and the area under the curve of the SCL (AUC) were analyzed as psychophysiological stress markers.ResultsExpectations did not differ between adolescents and parents and were correlated concerning reaction times only. Overall, expectations did not influence placebo effects. There was only one significant placebo effect on the percentage of correct inhibited trials in one level of the PGNG in adolescents, but not in parents. RMSSD and HF significantly increased, and AUC decreased from pre- to post-patch application in adolescents, but not in parents.ConclusionWith this experimental paradigm, we could not induce relevant placebo effects in adolescents and parents. This could be due to aspects of the study design such as application form and substance, and that healthy subjects were employed. Nevertheless, we could show that adolescents are more sensitive to psychophysiological reactions related with interventions which could be part of the underlying mechanisms of placebo effects in adolescents.

Basal and post-exercise heart rate variability correlates with training load in endurance athletes

Objective: Heart rate variability has been proposed as a valid method to examine the individual response to training load in endurance athletes. Thanks to this tool, the relationship between basal and post-exercise Heart rate variability measurements can be analyzed during a microcycle (one week) using straight values or their coefficients of variation.&#x0D; Method: Ten amateur endurance athletes (n = 5 men, n = 5 women) were monitored during a 7-day microcycle that included three road-cycling sessions, two running sessions and two trail-running sessions. The RR series were measured for 5 minutes upon wake up and after training, in a seating position, using a chest strap.&#x0D; Results: Basal and post-exercise Heart rate variability measurements showed high correlation when weekly mean values were used, very similar to when coefficients of variation values were used. In women, the root mean square of successive differences (RMSSD) was: r= 0.73; RMSSD coefficients of variation (RMSSDcv) was: r= 0.66; natural logarithm (Ln) RMSSD: r= 0.68; LnRMSSDcv: r= 0.79; and in men it RMSSD was: r= 0.78; RMSSDcv: r= -0.62; LnRMSSD: r= 0.75; LnRMSSDcv: r= -0.73).&#x0D; Conclusion: the relationship between these two measurements could be useful to program the training loads of the following microcycle.

Maternal Pregnancy Diet Quality Is Directly Associated with Autonomic Nervous System Function in 6-Month-Old Offspring

Many pregnant women are consuming diets of poor overall quality. Although many studies have linked poor prenatal diet quality to an increased risk of specific diseases in offspring, it is not known if exposure to poor prenatal diet affects core neurophysiological regulatory systems in offspring known to lie upstream of multiple diseases. We aimed to examine the association between prenatal diet quality and autonomic nervous system (ANS) function in infants at 6 mo of age. Data from 400 women (aged >18 y, with uncomplicated pregnancies) and their infants participating in the Maternal-Infant Research on Environmental Chemicals-Infant Development cohort were used to investigate links between prenatal diet quality and infant ANS function at 6 mo of age. Prenatal diet quality was assessed using the Healthy Eating Index (2010), calculated from a validated FFQ completed by women during the first trimester. Infant ANS function was measured using 2 assessments of heart rate variability (HRV) including root mean square of successive differences (RMSSD) and SD of N-N intervals (SDNN). Associations were analyzed before and after adjustment for socioeconomic status, maternal depression symptoms, maternal cardiometabolic dysfunction, breastfeeding, and prenatal smoking. Poorer prenatal diet quality was associated with lower infant HRV assessed using RMSSD (B: 0.07; 95% CI: 0.01, 0.13; R2=0.013) and SDNN (B: 0.18; 95% CI: 0.02, 0.35; R2=0.011). These associations remained significant after adjustment for confounding variables [RMSSD: B: 0.09; 95% CI: 0.003, 0.18; squared semipartial correlation (sp2)=0.14 and SDNN B: 0.24; 95% CI: 0.0, 0.49; sp2=0.13]. In a large cohort study, poorer prenatal diet quality was associated with lower offspring HRV, a marker of decreased capacity of the ANS to respond adaptively to challenge. Therefore, poor prenatal diet may play a significant role in the programming of multiple organ systems and could increase general susceptibility to disease in offspring.

Ballistocardiography Can Estimate Beat-to-Beat Heart Rate Accurately at Night in Patients After Vascular Intervention.

While bed-integrated ballistocardiography (BCG) has potential clinical applications such as unobtrusive monitoring of patients staying in the general hospital ward, it has so far mainly gained interest in the wellness domain. In this article, the potential of BCG to monitor hospitalized patients after surgical intervention was assessed. Long-term BCG recordings (mean duration 17.7h) of 14 patients were performed with an EMFit QS bed sensor. In addition, ten healthy subjects were recorded during sleep (mean duration 7.8h). Using an iterative algorithm, beat-to-beat intervals (BBIs) and the ultra-short-term heart-rate-variability (HRV) parameters standard deviation of NN intervals (SDNN) and root mean square of successive differences (RMSSD) were estimated and compared to an ECG reference in terms of average estimation error and temporal coverage. While the absolute BBI estimation error was found to be higher when full-day patient data was used (16.5ms), no significant difference between healthy subjects (12.7ms) and patient nighttime data (11.0ms) was observed. Nevertheless, temporal coverage of BBI estimation was significantly lower in patients (39.3% overall, 51.7% at night) compared to the healthy sleepers (73.2%). This resulted in reduced HRV estimation coverage (9.7% vs. 37.2%) at comparable estimation error levels.

Autonomic response to fetal acidosis using an experimental sheep model

BackgroundThe autonomic nervous system has a major role in fetal adaptation to hypoxia. Its activity might be assessed using heart rate variability and heart rate deceleration analyses. ObjectiveTo evaluate the ability of different heart rate variability and morphological deceleration analyses to predict fetal acidosis during labor in an experimental fetal sheep model. Study DesignRepeated 1-minute total umbilical cord occlusions were performed at mild (1minute every 5 min), moderate (1 min every 3 min), and severe (1 min every 2 min) umbilical cord occlusion periodicities until arterial pH reached 7.10. Hemodynamic,blood gas analysis, morphological analysis of decelerations (magnitude, slope, and area ofdecelerations), and heart rate variability parameters were recorded throughout the experiment.Heart rate variability analysis included temporal analysis (root mean square of successivedifferences between adjacent RR intervals, standard deviation of normal to normal RR intervals, short term variability), spectral analysis (low frequencies, high frequencies,normalized high frequencies), and a new index developed by our team, the Fetal Stress Index.We defined and compared three pH groups: >7.20, 7.10–7.20, and <7.10. ResultsEleven experiments were performed. Repetitive umbilical cord occlusions resulted in progressive fetal acidosis. Fetal Stress Index was correlated with pH and lactate (p < 0.05) and increased with acidosis. There were no significant correlations between pH, lactate, and other indices (spectral analysis, temporal analysis, or morphological analysis of decelerations). ConclusionThis protocol allowed us to identify the progressive onset of fetal acidosis in an experimental model close to labor. Fetal Stress Index is a heart rate variability method that varies with acidosis and indicates an increase in parasympathetic nervous system activity in response to fetal acidosis.

Impaired heart rate recovery after sub-maximal physical exercise in people with multiple sclerosis

BackgroundHeart Rate Recovery (HRR) after a physical exercise has been poorly investigated in people with multiple sclerosis (PwMS). ObjectiveTo evaluate the kinetics of HRR and its autonomic modulation in PwMS and to elucidate the interplay between HRR and subjective fatigue. MethodsECG was digitally acquired during rest (5 min), submaximal exercise (4 min at 10 W of upper limb cycling) and recovery (3 min) in 17 PwMS (EDSS: 5.9 ± 1.2, mean±standard deviation) and 17 healthy control (HC) subjects. Short-term (first 30 s) and long-term (up to180 s) validated indices of HRR were calculated. The time course of the parasympathetic index of heart rate variability RMSSD (Root Mean Square of Successive Differences) was computed every 30 s of recovery. Subjective fatigue was evaluated by the Borg scale applied to breathing and upper limbs. ResultsIn comparison with HC, the short-term HRR indices were significantly slower (P < 0.05) in PwMS, whereas the long-term ones did not. The time course of RMSSD was significantly different in PwMS (P < 0.05). HRR and HRV indexes did not correlate with fatigue perception and baseline HRV values. ConclusionThe cardiac parasympathetic reactivation from a submaximal exercise was blunted in PwMS, thereby slowing the short-term phase of HRR. This may contribute to the higher cardiovascular risk in PwMS, but the mechanism needs further investigation. The parasympathetic impairment during post-exercise HR reactivation cannot be predicted by baseline HRV values and may therefore be revealed only by an appropriate provocative low-intensity physical test.

The short Sing-a-Song Stress Test: A practical and valid test of autonomic responses induced by social-evaluative stress.

The Sing-a-Song Stress Test (SSST) was recently developed as an alternative to the Trier Social Stress Test (TSST) to investigate autonomic nervous system responses to social-evaluative stress. In the SSST, participants are suddenly cued to sing a song in the presence of confederates. However, the SSST is still quite long (~15min) and the requirement for confederates makes it labor-intensive. The current study tested whether a shorter (~6.5min), single-experimenter, version of the SSST can still reliably elicit subjective and physiological stress reactivity. Our sample consisted of 87 healthy young adult participants (age range: 18-35years). During the short SSST and a speeded reaction time task, in which aversive loud tones were to be avoided (TA), we measured heart period (HP), sympathetic nervous system (SNS) activity using pre-ejection-period (PEP), skin conductance level (SCL), and non-specific skin conductance responses (ns.SCR), and parasympathetic nervous system (PNS) activity using respiratory-sinus-arrhythmia (RSA) and the root-mean-square of successive differences (RMSSD). The short SSST induced significant decreases in positive affect and increases in negative affect. MANOVAs on the clusters of SNS and PNS variables showed that the short SSST elicited significant HP (-118.46ms), PEP (-7.76ms), SCL (+4.85 μS), ns.SCR (+8.42 peaks/min) and RMSSD (-14.67) reactivity. Affective, SNS, and PNS reactivity to the new SSST social-evaluative stress task were of comparable magnitude to that evoked by the TA mental stressor. We conclude that the short SSST is a valid and cost-effective task for large scaled studies to induce social-evaluative stress to a sufficient degree to evoke measurable changes in PNS and SNS activity and affective state.