Root Mean Square Of Successive Differences Research Articles

Exploring physiological stress response evoked by passive translational acceleration in healthy adults: a pilot study utilizing electrodermal activity and heart rate variability measurements.

Passive translational acceleration (PTA) has been demonstrated to induce the stress response and regulation of autonomic balance in healthy individuals. Electrodermal activity (EDA) and heart rate variability (HRV) measurements are reliable indicators of the autonomic nervous system (ANS) and can be used to assess stress levels. The objective of this study was to investigate the potential of combining EDA and HRV measurements in assessing the physiological stress response induced by PTA. Fourteen healthy subjects were randomly assigned to two groups of equal size. The experimental group underwent five trials of elevator rides, while the control group received a sham treatment. EDA and HRV indices were obtained via ultra-short-term analysis and compared between the two groups to track changes in the ANS. In addition, the complexity of the EDA time series was compared between the 4s before and the 2-6s after the onset of PTA to assess changes in the subjects' stress levels in the experimental group. The results revealed a significant increase in the skin conductance response (SCR) frequency and a decrease in the root mean square of successive differences (RMSSD) and high frequency (HF) components of HRV. In terms of stress assessment, the results showed an increase in the complexity of the EDA time series 2-6s after the onset of PTA. These results indicate an elevation in sympathetic tone when healthy subjects were exposed to a translational transport scenario. Furthermore, evidence was provided for the ability of EDA complexity to differentiate stress states in individual trials of translational acceleration.

Ventilatory Variability Is Increased at Rest in Pulmonary Arterial Hypertension

Ventilatory instability is associated with adverse outcomes in left heart failure, with periodic breathing during awake, rest, sleep and exercise (exercise oscillatory ventilation) associated with increased mortality. Increased peripheral and central chemoreflex sensitivities and impairment of cardiac output have been implicated as causative mechanisms of ventilatory instability in heart failure. As these factors are also present in pulmonary arterial hypertension (PAH), we tested the hypothesis that variability of breath-by-breath ventilation at rest would be increased in PAH compared with healthy controls. In fourteen patients with PAH (9 female, age 48.4±12.8 years, mean ± SD) and 14 healthy participants (9 female, age 49.4±14.2 years) breath-by-breath measurement of tidal volume and breathing frequency was undertaken with a pneumotachometer connected via a mouthpiece with nose-clip for 10 minutes while they rested awake and supine. Ventilatory (V̇E) variability was assessed using root mean square of successive differences (RMSSD), standard deviation (SD), average real variability (ARV, i.e., sum of absolute differences in successive observations), coeffcient of variation (CoV), as well as Poincaré analysis and compared between PAH and healthy controls (Student’s t-test). Correlations between measures of ventilatory variability and pulmonary hemodynamic characteristics, exercise capacity and function were assessed with Pearson’s correlation coeffcient. Resting V̇E was higher in PAH compared to healthy controls (14.3±1.1 and 12.1±0.5 L·min−1 respectively; p=0.009). Measures of variability for V̇E were increased in PAH compared to healthy controls. More specifically, RMSSD (3.59±1.36 vs. 2.48±0.87 L·min−1, p=0.017), SD (2.92±1.14 vs. 1.98±0.53 L·min−1, p=0.012), ARV (2.47±0.97 vs. 1.67±0.60 L·min−1, p=0.016), Poincaré SD1 (short-term variability, p=0.020) and SD2 (long-term variability, p=0.028) were increased in PAH compared to healthy controls, respectively. No correlations were found between measures of ventilatory variability and pulmonary hemodynamics (mean pulmonary artery pressure, pulmonary vascular resistance, and cardiac output), six-minute walk distance or WHO functional class. In summary, resting ventilatory variability is increased in PAH and not associated with haemodynamic factors and exercise capacity. Whether such raised ventilatory variability in PAH is related to increased chemoreflex sensitivity requires exploration. This study received funding support from the Greenlane Research and Educational Fund (21/01/4153), Health Research Council of New Zealand (19/687), and the Sidney Taylor Trust. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Does cardiovascular autonomic modulation correspond to the increase in dim-light onset of melatonin? A preliminary analysis

Introduction: The endogenous circadian system promotes the rise in melatonin approximately every 24 hours. In the laboratory, dim light melatonin onset (DLMO) is used as the gold standard method to assess circadian phase. Exogenous melatonin affects cardiac sympathovagal balance and vasomotor sympathetic modulation. Whether or not the endogenous increase in melatonin corresponds to changes in cardiovascular autonomic modulation is unclear. Objective: To evaluate if the timing of DLMO corresponds to the timing of changes in cardiovascular autonomic indices. Methods: Five healthy adults (3 females, age 23.8±SD1.8 y) completed a minimum of four nights of sleep regularization by maintaining a self-selected 8h in bed each night before the experiment. The day after regularization, they reported to the laboratory ~8 hours before bedtime. Measurements for melatonin and cardiovascular autonomic modulation started 6 hours before bedtime and continued 1 hour after. Saliva samples were collected every 30 minutes. At the end of every hour, 10 minutes of continuous R-R intervals (R-R) and systolic blood pressure (SBP) were recorded via electrocardiogram and beat-to-beat finger photoplethysmography, respectively. As currently established, DLMO was defined as the interpolated time for melatonin increase over 3pg/ml. Cardiovascular autonomic indexes were run through CardioSeries v.2 to create a temporal series for R-R interval and systolic blood pressure. Cardiac autonomic modulation was assessed by applying the spectral analysis using the fast Fourier transformation method and time domain analysis of heart rate variability (HRV) and spectral analysis of blood pressure variability (BPV). For each autonomic index, data were plotted and fitted with a segmental linear regression to reveal the intercept of the two segments to define the autonomic onset (AO). A paired t-test compared the difference between DLMO and AO times. Bland-Altman plots with a 95% limit of agreement (LOA) identified the distribution of differences between the methods. Additionally, a one-sample t-test compared the differences between methods to a fixed time clock range. Data are shown as mean ± SD and significance was set as p<0.05. Results: AO time calculated for all indexes from HRV and BPV were not statistically different compared to DLMO time (R-R: +16±86 mins, P=0.70; root mean square of successive differences (RMSSD): -20±91 mins, P=0.67; low frequency (LF) nu: +29±52 mins, P=0.74; high frequency (HF) nu: -43±91 mins, P=0.23; LFHF: -26±73 mins, P=0.47; SBP: -14±104 mins, P=0.78; LFSBP: -6±107 mins, P=0.90). The Bland Altman plots did not identify any systematic difference between AO and DLMO times. The smallest difference was LFnu with a LOA 95% from -73 to +131 minutes, while the largest difference was LFSBP with LOA 95% from -217 to +204 minutes. Additionally, the difference between DLMO and AO LFnu times (LFnu: +29±52) was statistically similar from -36 to +95 minutes. Conclusion: In young healthy adults, our preliminary data shows that AO times of cardiovascular autonomic indexes correspond to salivary DLMO. A larger dataset with more frequent simultaneous measurements of melatonin and cardiovascular autonomic modulation are essential to confirm our preliminary findings. Medical Research Foundation of Oregon, OHSU OFDIR, R01HL163232. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

The Influence of Perceived Discrimination on Heart Rate Variability in Young Black Adults

Introduction: Cardiovascular disease (CVD) is the leading cause of death in the United States, with a disproportional precedence in Black adults. Heart rate variability (HRV) is used to help predict future CVD, with lower HRV indicative of a compromised cardiovascular system. Prior evidence has suggested that experienced racial discrimination is associated with CVD risk. However, there is limited information regarding experienced racial discrimination on HRV in young Black adults. Purpose/hypothesis: The purpose of this study was to determine whether personal-level and group-level racial discrimination was associated with worse HRV in young Black adults. Methods: Black adults aged 18-25 (n=18, 44.45% female) volunteered to participate in this study, arriving at the lab at 7am in a fasted state. Following 30 minutes of rest, HRV measures were assessed using a SphygmoCor 3-lead ECG in a supine position. The HRV measure included the standard deviation of all R-R intervals (SDNN), the mean number of times an hour successive NN intervals exceeds 50ms (pNN50), the root mean square of successive differences (RMSSD), the low-frequency (LF) power domain, high-frequency (HF) power domain, and their ratio (LF:HF). Participants were given a perceived racial discrimination questionnaire that assessed personal-level and group-level discrimination. Pearson correlations were used to analyze the association between perceived racial discrimination measures and HRV measures. Results: In Black males, perceived personal-level racial discrimination was negatively associated with sympathetic activity (LF, R2 = -0.704, p = 0.023) and sympathovagal balance (LF:HF, R2 = -0.749, p = 0.013), and positively associated with parasympathetic activity (HF, R2 = 0.704, p = 0.023). Perceived group-level racial discrimination was not associated with HRV measures. Furthermore, perceived racial discrimination was not associated with HRV in Black females. Conclusion: Although decreased HRV has been associated with increased risk for CVD, higher HRV has been shown to be associated with left ventricular mass in Black adults. Therefore, HRV implications may be dependent on social determinants of health and other covariates that are associated with race/ethnicity. In the current study, higher HRV was observed in Black males who reported higher personal-level discrimination, which may be an important factor in sympathetic and parasympathetic cardiac control and CVD risk. Given our preliminary findings, more research is warranted that investigates the impact of racial identity, resiliency, coping, and healthy lifestyle behaviors on mitigating the detrimental impact of perceived racial discrimination on the cardiovascular health of young Black adults. Summer Undergraduate Research Fellowship Recipient from the American Physiological Society. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Activation of cardiac parasympathetic and sympathetic activity occurs at different skin temperatures during face cooling.

Sufficiently cold-water temperatures (<7°C) are needed to elicit the sympathetic response to the cold pressor test using the hand. However, it is not known if stimulating the trigeminal nerve via face cooling, which increases both sympathetic and cardiac parasympathetic activity, also has a threshold temperature. We tested the hypothesis that peak autonomic activation during a progressive face cooling challenge would be achieved when the stimulus temperature is ≤7°C. Twelve healthy participants (age: 25 ± 3 yr, four women) completed our study. Six pliable bags, each containing water or an ice slurry (34°C, 28°C, 21°C, 14°C, 7°C, and 0°C) were applied sequentially to participants' forehead, eyes, and cheeks for 5 min each. Mean arterial pressure (photoplethysmography; index of sympathetic activity) and heart rhythm (3-lead ECG) were averaged in 1-min increments at the end of baseline and throughout each temperature condition. Heart rate variability in the time [(root mean square of successive differences (RMSSD)] and frequency [high-frequency (HF) power] domains was used to estimate cardiac parasympathetic activity. Data are presented as the increase from baseline ± SD. Mean arterial pressure only increased from baseline in the 7°C (13.1 ± 10.3 mmHg; P = 0.018) and 0°C (25.2 ± 7.8 mmHg; P < 0.001) conditions. Only the 0°C condition increased RMSSD (160.6 ± 208.9 ms; P = 0.009) and HF power (11,450 ± 14,555 ms2; P = 0.014) from baseline. Our data indicate that peak increases in sympathetic activity during face cooling are initiated at a higher forehead skin temperature than peak increases in cardiac parasympathetic activity.

Exercise-induced central and peripheral sympathetic activity in a community-based group of epilepsy patients differ from healthy controls

Ictal and interictal activity within the autonomic nervous system is characterized by a sympathetic overshoot in people with epilepsy. This autonomic dysfunction is assumed to be driven by alterations in the central autonomic network. In this study, exercise-induced changes of the interrelation of central and peripheral autonomic activity in patients with epilepsy was assessed. 21 patients with epilepsy (16 seizure-free), and 21 healthy matched controls performed an exhaustive bicycle ergometer test. Immediately before and after the exercise test, resting state electroencephalography measurements (Brain Products GmbH, 128-channel actiCHamp) of 5 min were carried out to investigate functional connectivity assessed by phase locking value in source space for whole brain, central autonomic network and visual network. Additionally, 1-lead ECG (Brain products GmbH) was performed to analyze parasympathetic (root mean square of successive differences (RMSSD) of the heart rate variability) and sympathetic activity (electrodermal activity (meanEDA)). MeanEDA increased (p < 0.001) and RMSSD decreased (p < 0.001) from pre to post-exercise in both groups. Correlation coefficients of meanEDA and central autonomic network functional connectivity differed significantly between the groups (p = 0.004) after exercise. Both patients with epilepsy and normal control subjects revealed the expected physiological peripheral autonomic responses to acute exhaustive exercise, but alterations of the correlation between central autonomic and peripheral sympathetic activity may indicate a different sympathetic reactivity after exercise in patients with epilepsy. The clinical relevance of this finding and its modulators (seizures, anti-seizure medication, etc.) still needs to be elucidated.

Heart rate and heart rate variability in obsessive-compulsive disorder: Evidence from patients and unaffected first-degree relatives

Altered heart rate (HR) and heart rate variability (HRV) are common observations in psychiatric disorders. Yet, few studies have examined these cardiac measures in obsessive-compulsive disorder (OCD). The current study aimed to investigate HR and HRV, indexed by the root mean square of successive differences (RMSSD) and further time domain indices, as putative biological characteristics of OCD. Electrocardiogram was recorded during a five-minute resting state. Group differences between patients with OCD (n = 96), healthy participants (n = 112), and unaffected first-degree relatives of patients with OCD (n = 47) were analyzed. As potential moderators of group differences, we examined the influence of age and medication, respectively. As results indicated, patients with OCD showed higher HR and lower HRV compared to healthy participants. These group differences were not moderated by age. Importantly, subgroup analyses showed that only medicated patients displayed lower HRV compared to healthy individuals, while HR alterations were evident in unmedicated patients. Regarding unaffected first-degree relatives, group differences in HRV remained at trend level. Further, an age-moderated group differentiation showed that higher HRV distinguished relatives from healthy individuals in young adulthood, whereas at higher age lower HRV was indicative of relatives. Both the role of familial risk and medication in HRV alterations need further elucidation. Pending future studies, alterations in HR and potentially HRV might serve as useful indices to characterize the pathophysiology of OCD.

Abstract P196: The Effects of Initiating a 24-hour Fast With a Low versus a High Carbohydrate Protein Shake on Heart Rate Variability in the Elderly

Introduction: While multiple studies demonstrate the potential cardiovascular benefits of fasting, the effects of the fast-initiating meal have not been evaluated. The aim of this secondary analysis was to examine the effects of the macronutrient composition of a fast-initiating meal on the autonomic nervous system through measurements of heart rate variability (HRV) in older, sedentary adults with abdominal obesity. Methods: Using a crossover design, each of the 24 participants (13 male, 11 female) completed two 24-hour fasts (8:00 am to 8:00 am) separated by 6-10 days. Participants were 59.54 ± 6.67 years old and had a body mass index of 31.59 ± 5.59 kg/m 2 . Each fast was initiated with either a low carbohydrate protein shake or an isocaloric and isovolumetric high carbohydrate protein shake (592.13 ± 104.57 kcal). Heart rate variability was measured for 10 minutes immediately prior to, one hour after, and then 24 hours after shake consumption. Results: A mixed effects model with repeated measures was used to assess the effects of the fasting conditions on various HRV outcomes. The sympathetic (SNS) index increased significantly over the time of each fast (p = 0.0033), but was not different between conditions (p = 0.7229). The parasympathetic PNS index experienced no change over time (p = 0.1521) and no change between conditions (p = 0.8961). The stress index increased over time (p = 0.0021), but was not different between conditions (p = 0.7308). There was no difference in standard deviation of the normal-to-normal interval (SDNN) or root mean square of successive difference (RMSSD) over time (p = 0.2022 and p = 0.2770, respectively) or between condition (p = 0.9054 and p = 0.9857, respectively). The High Frequency (HF) reading was elevated in the high-carbohydrate condition compared to the low-carbohydrate condition (p &lt; 0.0001), and the low frequency to high frequency (LF/HF) ratio showed no difference between conditions (p = 0.3460), but increased over time (p = 0.0044) and demonstrated a time by condition interaction (p = 0.0089). Conclusions: Acute fasting places strain on the cardiometabolic systems as evident by the increased SNS index and stress index as well as the increase in LF/HF ratio over the course of both fasts. A low carbohydrate shake reduced HF readings, indicating more anxiety or panic in this condition. These results agree with previous works and are unique in demonstrating that most HRV parameters are neither strengthened nor weakened by the composition of the pre-fast meal.

(072) Effect of Diafragmatic Breathing Exercises on Individual with Premature Ejaculation

Abstract Introduction Premature ejaculation (PE) is defined as an intravaginal ejaculation latency time (IELT) of less than 60 seconds and the most common sexual dysfunction among men. There is no published study researching the effect of diafragmatic breathing exercises (DBE) on PE and also no optimal training protocol has been identified. Objective Investigate the effect of DBE on PE and to create a new treatment protocol. Methods Sixty two men with PE aged between 20–45 years were included in the study and randomly divided into Group I or Group II (n=1:1). Both groups underwent the treatment protocol includes behavioral therapy (BT) and pelvic floor rehabilitation (PFR) in 4 steps: 1) awareness of the pelvic floor muscles (PFM), 2) PFM specific contraction, 3) using the BT for learning the timing of pre-orgasmic sensation and maintenance of PFM contraction during sensation of the pre-orgasm, 4) PFM strengthening exercises. PFM strengthening exercises were given 3 days/week, 2 times/day for 8 weeks. Group I also underwent DBE that were given as 3 s inspiration-7 s expiration, at least 10 times/session for each day, 2 sessions/day, for 8 weeks. For awareness and specific contraction of PFM, patient was asked to contract his PFM with the cue to stop to urine while performing a digital rectal examination in supine. In order to learn the timing of pre-orgasmic sensation, masturbation exercises were given to the patient with start-stop tecnique. During the cycle of the pre-orgasmic sensation contraction of PFM was requested. After 4 or 5 cycles the patient can let himself reach ejaculation. Result of this training discussed with the patient once a month by phone-call. PFM strengthening exercises comprised sustained for slow (10 s submax. contraction-10 s relaxation x15 times) and fast twitch muscle fibers (1 s contraction-10 s relaxation x10 times). Outcome measurements were made by a blinded assessor at pre-treatment and at the end of the 8 week (post-treatment). Stop watch was used to calculate IELT, Ultrasound was used to measure PFM strength (US-S) and PFM endurance (US-E) and Elite-HRV device was used to measure autonomic nervous system parameters (Root mean square of successive differences (RMSSD), proportion of NN50 (PNN50), Low frequency power (LF-Power), High frequency power (HF-power), Low frequency/high frequency ratio (LF/HF-ratio)). Results Twenty nine (mean age=31.4±6.5) in Group I and 30 (mean age=31.3±7.6) in Group II (total 59) completed the study. There was no significant difference between the groups in terms of demographic characteristics and pre-treatment IELT. Both groups showed significant improvement in all measurement parameters (all p&amp;lt;0.001), except LF/HF at post-treatment. When the differences between pre-treatment and posttreatment were compared, IELT (p=0.016), RMSDD (p&amp;lt;0.001), PNN50 (p=0.001), LF Power (p=0.001), HF Power (p=0.006), US-S (p&amp;lt;0.001), US-E (p&amp;lt;0.001) were significant in favor of Group I. Conclusions BT and PFR combined protocol, showed increase in IELT, PFM strentgh and endurance and improvements at autonomic nervous system parameters. Adding DBE to this protocol showed better improvements in all parameters. Disclosure No.

Pulse rate variability and health-related quality of life assessment with the Short Form-8 Japanese version in the general Japanese population

We aimed to investigate the association between pulse rate variability (PRV) and health-related quality of life (HRQOL) in the general population. A cross-sectional study was conducted with 5908 Japanese men and women aged 30–79 years. PRV was assessed at rest using 5-min recordings of pulse waves with a photoplethysmographic signal from a fingertip sensor, and the time and frequency domains of PRV were determined. HRQOL was assessed with the Short Form-8 (SF-8) Japanese version, and poor HRQOL was defined as an SF-8 sub-scale score < 50. A test for nonlinear trends was performed with the generalized additive model with a smoothing spline adjusted for confounders. The lowest multivariable-adjusted odds ratios for poor physical component score were found in those who had second or third quartile levels of standard deviation of normal-to-normal intervals (SDNN) and root mean square of successive difference (RMSSD), and high-frequency (HF) power and trended slightly upward in the higher levels. PRV-derived parameters were nonlinearly associated with poor physical component scores. In conclusion, reduced PRV-derived SDNN, RMSSD and HF power were associated with poor HRQOL in the domain of physical function. Higher levels of these parameters did not necessarily translate into better HRQOL.

Changepoint Detection in Heart Rate Variability Indices in Older Patients Without Cancer at End of Life Using Ballistocardiography Signals: Preliminary Retrospective Study.

In an aging society such as Japan, where the number of older people continues to increase, providing in-hospital end-of-life care for all deaths, and end-of-life care outside of hospitals, such as at home or in nursing homes, will be difficult. In end-of-life care, monitoring patients is important to understand their condition and predict survival time; this information gives family members and caregivers time to prepare for the end of life. However, with no clear indicators, health care providers must subjectively decide if an older patient is in the end-of-life stage, considering factors such as condition changes and decreased food intake. This complicates decisions for family members, especially during home-based care. The purpose of this preliminary retrospective study was to determine whether and how changes in heart rate variability (HRV) indices estimated from ballistocardiography (BCG) occur before the date of death in terminally ill older patients, and ultimately to predict the date of death from the changepoint. This retrospective pilot study assessed the medical records of 15 older patients admitted to a special nursing home between August 2019 and December 2021. Patient characteristics and time-domain HRV indices such as the average normal-to-normal (ANN) interval, SD of the normal-to-normal (SDNN) interval, and root mean square of successive differences (RMSSD) from at least 2 months before the date of death were collected. Overall trends of indices were examined by drawing a restricted cubic spline curve. A repeated measures ANOVA was performed to evaluate changes in the indices over the observation period. To explore more detailed changes in HRV, a piecewise regression analysis was conducted to estimate the changepoint of HRV indices. The 15 patients included 8 men and 7 women with a median age of 93 (IQR 91-96) years. The cubic spline curve showed a gradual decline of indices from approximately 30 days before the patients' deaths. The repeated measures ANOVA showed that when compared with 8 weeks before death, the ratio of the geometric mean of ANN (0.90, 95% CI 0.84-0.98; P=.005) and RMSSD (0.83, 95% CI 0.70-0.99; P=.03) began to decrease 3 weeks before death. The piecewise regression analysis estimated the changepoints for ANN, SDNN, and RMSSD at -34.5 (95% CI -42.5 to -26.5; P<.001), -33.0 (95% CI -40.9 to -25.1; P<.001), and -35.0 (95% CI -42.3 to -27.7; P<.001) days, respectively, before death. This preliminary study identified the changepoint of HRV indices before death in older patients at end of life. Although few data were examined, our findings indicated that HRV indices from BCG can be useful for monitoring and predicting survival time in older patients at end of life. The study and results suggest the potential for more objective and accurate prognostic tools in predicting end-of-life outcomes.

Cold stimulation of the oral cavity redistributes blood towards the brain in healthy volunteers.

The aim of this study was to analyze cold stimulation-induced changes in cerebral and cardiac hemodynamics. Upon ingestion of an ice cube, the changes in resistance index, mean flow velocity and flow index of the middle cerebral arteries (MCA) were assessed using transcranial Doppler sonography. Extracranial duplex sonography was used to measure the mean flow velocity and resistance index of the right internal carotid artery (ICA). The change in mean arterial pressure, heart rate, root mean square of successive differences (RMSSD) and end-tidal carbon dioxide pressure were analyzed additionally. These changes were compared to sham stimulation. Compared with sham stimulation, cooling of the oral cavity resulted in significant changes in cerebral and cardiac hemodynamics. The cold stimulation decreased the resistance index in the MCA (-4.5% ± 5.4%, p < 0.0001) and right ICA (-6.3% ± 15.6%, p = 0.001). This was accompanied by an increase in mean flow velocity (4.1% ± 8.0%, p < 0.0001) and flow index (10.1% ± 43.6%, p = 0.008) in the MCA. The cardiac effects caused an increase in mean arterial pressure (1.8% ± 11.2%, p = 0.017) and RMSSD (55% ± 112%, p = 0.048), while simultaneously decreasing the heart rate (-4.3% ± 9.6%, p = 0.0001). Cooling of the oral cavity resulted in substantial changes in cerebral and cardiac hemodynamics resulting in a blood flow diversion to the brain.

EFFECTS OF A SINGLE EVENING VINYASA YOGA SESSION ON SLEEP IN ADULTS WITH INSOMNIA SYMPTOMS

BACKGROUND Vinyasa yoga (VY), a form of yoga that links breath with movement and has higher energy expenditure perhaps than most other types of yoga, has been sparsely studied for its effects on sleep among adults with insomnia. It remains unknown whether and how an acute bout of VY performed in the evening impacts sleep and autonomic function. The purpose of this study it to examine the effects of an acute session of VY performed in the evening on sleep and nocturnal heart rate variability (HRV) in adults with insomnia symptoms. METHODS 33 insufficiently active adults (84.8% female; 78.8% White; age=34.9±10.6 y; body mass index=28.9 kg/m2) with at least mild insomnia symptoms (Insomnia Severity Index ≥ 10) were randomized to either a single 60-min session of VY (n=17) or a quiet rest control condition (CON: n=16) occurring between 15:00 and 20:00 h. VY followed a pre-recorded practice and CON watched a nature documentary. On one night before and after the experimental session, participants wore a wrist accelerometer and a chest heart rate (HR) monitor overnight and completed a sleep diary. HRV was derived from the entire HR recording across the nocturnal period and standardized for sleep duration, with root mean square of successive differences (RMSSD) as the primary outcome. Analyses compared the changes from pre- to post-session between groups using linear mixed models and Cohen’s d effect sizes. RESULTS The change in actigraphy-assessed sleep efficiency (SE) and total sleep time (TST) did not differ from pre- to post-session for VY (SE: 88.9±1.4 to 88.9±1.5%; TST: 454.7±15.8 to 445.8±17.4 min) or CON (SE: 89.4±1.4 to 88.7±1.6%; TST: 401.3±16.3 vs. 407.3±17.3 min); group x time interactions were not statistically significant (each p &amp;gt; 0.48). The change in nocturnal RMSSD did not differ from pre- to post-session for either VY (39.5±6.8 to 38.7±6.0 ms) or CON (37.6±7.0 to 35.8±6.2 ms) and the group x time interaction was not statistically significant (p=0.94). CONCLUSION An acute bout of VY performed in the early evening did not significantly change accelerometer- or diary-assessed sleep or impact parasympathetic tone during sleep. VY in the early evening is unlikely to benefit or impair sleep in adults with insomnia symptoms.

Sampling rate requirement for accurate calculation of heart rate and its variability based on the electrocardiogram.

Objective. To develop analytical formulas which can serve as quantitative guidelines for the selection of the sampling rate for the electrocardiogram (ECG) required to calculate heart rate (HR) and heart rate variability (HRV) with a desired level of accuracy.Approach. We developed analytical formulas which relate the ECG sampling rate to conservative bounds on HR and HRV errors: (i) one relating HR and sampling rate to a HR error bound and (ii) the others relating sampling rate to HRV error bounds (in terms of root-mean-square of successive differences (RMSSD) and standard deviation of normal sinus beats (SDNN)). We validated the formulas using experimental data collected from 58 young healthy volunteers which encompass a wide HR and HRV ranges through strenuous exercise.Main results. The results strongly supported the validity of the analytical formulas as well as their tightness. The formulas can be used to (i) predict an upper bound of inaccuracy in HR and HRV for a given sampling rate in conjunction with HR and HRV as well as to (ii) determine a sampling rate to achieve a desired accuracy requirement at a given HR or HRV (or its range).Significance. HR and its variability (HRV) derived from the ECG have been widely utilized in a wide range of research in physiology and psychophysiology. However, there is no established guideline for the selection of the sampling rate for the ECG required to calculate HR and HRV with a desired level of accuracy. Hence, the analytical formulas may guide in selecting sampling rates for the ECG tailored to various applications of HR and HRV.

Heart Rate Variability-Based Prediction of Autonomic Dysreflexia After Spinal Cord Injury.

Autonomic dysreflexia (AD) is a common autonomic complication of spinal cord injury (SCI) characterized by a sudden increase is blood pressure triggered by peripheral stimulation, such as bladder distention. Iatrogenic AD events often occur during various medical procedures including urodynamic assessments (UDSs) used to evaluate lower urinary tract (LUT) function in individuals with SCI. To date, there are no established clinical practices that would allow early detection of the development of episodes of AD. Heart rate variability (HRV) is a reliable and non-invasive metric for evaluating autonomic regulation of the cardiovascular system, with demonstrated utility in people with SCI during UDSs. We aim to provide a comprehensive evaluation of cardiovascular function during UDS-induced AD using ultra-short-term HRV analysis and identify changes in cardiovascular dynamics to predict the onset of AD. We assessed cardiovascular data in a total of 24 participants with sensorimotor complete SCI above T6 (17 males, 7 females, median age = 43 [36-50] years) who experienced AD during UDS. We used continuous electrocardiographic recordings to evaluate HRV in 60 sec overlapping windows during filling cystometry. The mean of "normal-to-normal" heartbeats (meanNN), its standard deviation (SDNN), and the root mean square of successive differences (RMSSD) were calculated and used in all subsequent analyses. We found that SDNN and RMSSD diminished during the early phase of bladder filling and sharply increased during AD. Using the lowest point of statistical variability in heart rate (i.e., SDNN), we were able to predict AD events within 240 sec (percentile 25-percentile 75: 172-339 sec) before the first systolic blood pressure peak after AD onset (sensitivity = 0.667; specificity = 0.875). Our results indicated a temporary increase in sympathetic activity during the early phase of bladder filling, which is followed by an increase in parasympathetic outflow to the heart when AD occurs. These findings have significant clinical implications that extend beyond the context of UDS and demonstrate the importance of identifying early changes in HRV in order to accurately predict AD episodes in people living with SCI.

Naturalistic assessment of reaction time variability in older adults at risk for Alzheimer's disease.

Maintaining attention underlies many aspects of cognition and becomes compromised early in neurodegenerative diseases like Alzheimer's disease (AD). The consistency of maintaining attention can be measured with reaction time (RT) variability. Previous work has focused on measuring such fluctuations during in-clinic testing, but recent developments in remote, smartphone-based cognitive assessments can allow one to test if these fluctuations in attention are evident in naturalistic settings and if they are sensitive to traditional clinical and cognitive markers of AD. Three hundred and seventy older adults (aged 75.8 +/- 5.8 years) completed a week of remote daily testing on the Ambulatory Research in Cognition (ARC) smartphone platform and also completed clinical, genetic, and conventional in-clinic cognitive assessments. RT variability was assessed in a brief (20-40 seconds) processing speed task using two different measures of variability, the Coefficient of Variation (CoV) and the Root Mean Squared Successive Difference (RMSSD) of RTs on correct trials. Symptomatic participants showed greater variability compared to cognitively normal participants. When restricted to cognitively normal participants, APOE ε4 carriers exhibited greater variability than noncarriers. Both CoV and RMSSD showed significant, and similar, correlations with several in-clinic cognitive composites. Finally, both RT variability measures significantly mediated the relationship between APOE ε4 status and several in-clinic cognition composites. Attentional fluctuations over 20-40 seconds assessed in daily life, are sensitive to clinical status and genetic risk for AD. RT variability appears to be an important predictor of cognitive deficits during the preclinical disease stage.

The effectiveness of an osteopathic manual technique compared with a breathing exercise on vagal tone as indicated by heart rate variability, a crossover study

IntroductionParasympathetic nervous system (PSNS) function can be inferred by heart rate variability (HRV) providing indications about an individual's health. Manual therapy may influence PSNS function, however the research outcomes in this regard are equivocal. This study explored the PSNS effect of a measured breathing technique with suboccipital balanced ligamentous tension, an osteopathic manipulative therapy technique. Methods: Healthy adult participants in this crossover study (n = 18) were randomly allocated into two groups with differing order of interventions. A 1:1 breathing rate of 6 breaths per minute maintained for 5 min was compared to the osteopathic intervention. HRV was measured for 5 min before and after each intervention and analysed using the root mean square of successive differences (RMSSD) between normal heartbeats and high frequency normalised units (HFnu). Results: The RMSSD data demonstrated no significant difference between groups or within groups (p > 0.05) over time. HFnu results showed a significant between-group difference over the four time points (p = 0.004) with a medium effect size (ηp2 = 0.240), and no significant within-group difference (p > 0.05). Discussion: The osteopathic intervention raised HRV to a small extent, however measured breathing lowered HRV. In the group that received the osteopathic technique first, HFnu values continued to rise post-osteopathic treatment possibly indicating an increasing parasympathetic effect over time. Recommendations for future studies include changing the breathing ratio to ensure parasympathetic response, take into account potential delayed effects of interventions, consider outcome measures less variable than HRV, and longer follow up times. Conclusion: This study suggests parasympathetic stimulation may occur with the application of suboccipital balanced ligamentous tension and sympathetic stimulation from measured breathing.

Assessment of heart rate variability among healthy 1st year medical students in a Government Medical College of Kolkata: A cross-sectional observational study

Background: Heart rate variability (HRV) means the beat-to-beat variations of cardiac rhythm which is influenced by the interplay of sympathetic and parasympathetic nerves. At present, cardiovascular morbidity and mortality have become a matter of great concern in the young population. Such complications may arise from cardiac dysautonomia. HRV analysis may be considered an efficient tool to detect this derangement as early as possible. Moreover, normative data on HRV should be established among the young population of India considering other demographic parameters such as gender, height, weight, and BMI. Aim and Objective: Our study intends to establish normative data for short-term HRV parameters among medical students of a tertiary care hospital in West Bengal. Materials and Methods: After obtaining approval from the Institutional Ethics Committee, 250 apparently healthy medical students were assessed and HRV parameters such as mean RR, mean HR, SDNN, NN50, pNN50, root mean square of successive differences (RMSSD), high frequency (HF), low frequency (LF), and LF/HF ratio were recorded. Results: In time domain parameters, values were significantly higher in males for mean HR and significantly higher in females for mean RR, NN50, and pNN50. In frequency domain parameters, significantly higher values were found for LF and LF/HF ratio in males and HF in females. Conclusion: We have established gender-based normative values of HRV parameters in the young population.

Relationship between dust allergen sensitization and cardiac autonomic function in patients with chronic obstructive pulmonary disease.

Cardiac autonomic function predicts cardiovascular disease risk. The aim of this study was to investigate the relationship between sensitization to dust allergens and cardiac autonomic dysfunction in patients with chronic obstructive pulmonary disease (COPD), and to provide new ideas for the prevention of cardiovascular complications in these patients. Immunoassays for sensitization to cats/dogs, cockroaches and dust mites were performed in 840 patients with COPD. Indicators of heart rate variability in these patients were used to assess cardiac autonomic function, including standard deviation of normal-to-normal intervals (SDNN), root-mean square of successive differences between normal-to-normal intervals (RMSSD), low-frequency power (LF), high-frequency power (HF), and LF/HF ratios, which were obtained based on ambulatory electrocardiographic monitoring data. The relationship between sensitization to these dust allergens and heart rate variability was explored using multivariate logistic regression. The multivariate analyses showed that sensitization to total allergens was associated with reduced levels of SDNN, RMSSD, LF and HF and with increased levels of the LF/HF ratio in the patients with COPD (p < .05). Dust allergen sensitization may be associated with cardiac autonomic dysfunction in patients with COPD. Whether desensitization can prevent cardiovascular complications in these patients should be further explored.

Pilot Randomized Controlled Trial of Multi-Disciplinary Community-Based Biofeedback Vs Health Promotion Programs on Mental Health And Drug Use Among People Experiencing Homelessness

Background: PEH are most vulnerable to COVID-19 due to high levels of chronic disease and social isolation. However, in Skid Row Los Angeles, there are limited resources for mental health and drug treatment services. Biofeedback (BF) has been found to decrease depression and substance use among drug users; however, no studies have assessed the impact of BF on PEH during the COVID-19 pandemic.&#x0D; Aim: Our multi-disciplinary team designed and pilot tested an 8-week Heart Rate Variability-Biofeedback (HRV-BF) intervention, utilizing a nurse-led, Community Health Worker model of care with 50 people experiencing homelessness (PEH) as compared with a Health Promotion (HP) program. Our goal was to establish feasibility of the program, and to assess effects HRV-BF on measures of HRV, mental health and drug use as compared to HP.&#x0D; Methods: Utilizing Community Based Participatory Research (CBPR) principles, a community advisory board was established to refine the HRV-BF intervention and assess acceptability and feasibility. We enrolled 40 PEH and randomized into HRV-BF vs HP program and assessed a) impact on anxiety and depression; b) HRV and cortisol indices; and c) drug and alcohol use among all participants.&#x0D; Results: In total, 40 PEH were enrolled with 36 completing the intervention; 17 HRV-BF and 19 HP. Majority were male (80%) and were equally Black (37.5%) or Hispanic (35%). The mean age of PEH was 49 (SD 16.7), median age 53. The HRV measure RMSSD (root mean square of successive differences between normal heart beats, a time-based variable reflecting vagally mediated HRV), assessed during the resting 5-minute period, showed significant increases in 71% of participants (75% among HRV-BF and 68% among HP), using paired t-tests with natural log transformed variables, p=0.004, and by non-parametric tests, p= 0.006 (p values one-sided). Across the sample, PHQ-9 (depressive symptoms) showed marginally significant improvement (p= 0.09). Anxiety and Mental Health Inventory scores showed improvement, though not significant. Between-group analysis showed the HRV-BF group had better GAD-7 and MHI scores at 8 weeks (post-intervention), though not statistically significant. Chronic disease was found to be high in both groups (67% among HRV-BF and 82% among HP). No significant differences were found in terms of substance use.&#x0D; Conclusions: As the first known study to date examining the role of a biofeedback self-regulation training on biomarkers of stress/mental health measures among PEH, our study shows feasibility and acceptability among the study population and positive initial results for both arms of the study. We plan to extend the follow-up period beyond the intervention period of 8 weeks to establish the sustainability of the intervention.&#x0D; Funding: Susan Samueli Integrative Health Institute Pilot Studies Award&#x0D;