Mean Square Successive Difference Research Articles

Elevated correlations in cardiac–neural dynamics: An impact of mantra meditation on stress alleviation

Mantra meditation is a widely practiced technique with a demonstrated ability to promote relaxation and alleviate stress. This study aims to evaluate the impact of regular mantra meditation practice on electroencephalogram (EEG) patterns and heart rate variability (HRV) in young adults grappling with increased stress levels. Furthermore, the study explored possible correlations between these two physiological markers. Thirty-eight participants practiced mantra meditation for eight weeks, and their EEG and HRV were recorded before and after. The pre-post analysis evaluated brain activity and autonomic nervous system regulation alterations by examining EEG and HRV in the time, frequency, and nonlinear domains. Data analysis revealed significant correlations between EEG patterns and HRV indices following mantra meditation, suggesting a potential interconnection between neural and cardiovascular regulation. A notable increase in Root Mean Square of Successive Differences (RMSSD) and Standard Deviation of NN intervals (SDNN) within HRV, along with a decrease in Heart Rate (HR) and Stress Index (SI) and an increase in EEG alpha and theta power, accompanied by a reduction in their ratio, was observed. Three pivotal correlations consistently increased during eight weeks: Alpha/Theta Ratio (ATR) with Low-Frequency/High-Frequency Ratio (LHR), ATR with SD2/SD1 Ratio (SDR), and Relaxation Index (RI) with Stress Index (SI). After eight weeks, these correlations attained statistical significance, optimizing the balance between calmness and vigilance, boosting parasympathetic activity, and reducing chaos between the parasympathetic and sympathetic systems. The study elucidates the scientific mechanisms of mantra meditation, enriching research on its stress-reducing effects and emphasizing mental and physical well-being.

Breathing variability during running in athletes: The role of sex, exercise intensity and breathing reserve

Highly trained aerobic athletes progressively use most of their breathing reserve with increased exercise intensity during whole-body exercise. Additionally, females typically present proportionally smaller lungs than males. Therefore, sex, exercise intensity, and breathing reserve use likely influence the volume and time in which respiratory parameters vary between consecutive breaths during whole-body exercise. However, breath-by-breath variability has been scarcely investigated during exercise. Accordingly, we sought to investigate breath-by-breath pulmonary ventilation (V̇E), tidal volume (VT), and respiratory frequency (fR) variability during a maximal treadmill incremental exercise test in 17 females and 18 males highly trained professional endurance runners. The breath-by-breath variability was analyzed by root mean square of successive differences (RMSSD) within 1-minute windows. Females had lower absolute and percent predicted forced expiratory volume in one second (FEV1) and forced vital capacity (FVC) than males, as well as lower height-adjusted absolute FVC than males. V̇E and VT reserve use were similar between the sexes at peak exercise. While RMSSDV̇E and RMSSDfR did not change over exercise (P > 0.05), RMSSDVT progressively decreased (P < 0.001). RMSSDVT was negatively correlated with VT reserve use only in males. Females showed lower RMSSDV̇E than males during the entire exercise test (P < 0.001). At iso-V̇E reserve use, between-sex differences in RMSSDV̇E persisted (P = 0.003). Our findings indicate that exercise intensity decreases VT variability in professional runners, which is linked to VT reserve use in males but not females. Additionally, the female sex lowers V̇E variability regardless of exercise intensity and V̇E reserve use.

A Comparative Analysis of Heart Rate Variability Indices in Patients with Liver Cirrhosis.

Cardiac autonomic dysfunction (AD) in reference to chronic liver disease (CLD) has become widely accepted as a symptomatic burden. This study will be undertaken to measure heart rate variability (HRV) indices and detect the severity of cardiac autonomic dysfunction in CLD patients. This study was conducted on 150 patients with liver cirrhosis and compared with 110 healthy controls. Information concerning medical history, radiological and laboratory findings was extracted for interpretation and association among both groups. The HRV was assessed by recording with a polygraph (RMS Polyrite D, version 1.0), which was based on the principle of electrocardiography. Heart rate variability indices like standard deviation of each interval normal-to-normal (SDNN), percentage of successive RR intervals that differ by >50 ms (pNN50%), high frequency (HF), low frequency (LF), and the LF/HF ratio were found to be remarkably low in cases with CLD in comparison to the healthy control group (p < 0.05). The Child-Pugh (CP) score was class C (10-15) in 52%, class B (7-9) in 30%, and class A (5-6) in 18% of patients. The CP score in CLD patients had a statistically significant negative correlation with SDNN (r = -0.5429, p < 0.001), root mean square of successive differences (RMSSD) (r = -0.375, p < 0.001), pNN50% (r = -0.6037, p < 0.001), HF (r = -0.2033, p = 0.0125), and LF (r = -0.3674, p < 0.001). SDNN, pNN50%, and LF parameters were lowest in alcohol-related CLD, highest in hepatitis C virus (HCV)-related CLD, and intermediate in hepatitis B virus (HBV)-related CLD. Our study concluded that liver cirrhosis patients have reduced HRV compared to healthy individuals. A decrease in HRV highlights people at risk of death. This is a variable that can be used to track patients over time and aid in transplant selection.

The level of partial pressure of carbon dioxide affects organ perfusion in respiratory failure patients undergoing pressure support ventilation with venovenous extracorporeal membrane oxygenation: a prospective study

BackgroundWe evaluated the influence of different partial carbon dioxide pressure (PaCO2) levels on organ perfusion in patients with respiratory failure receiving pressure-support ventilation with veno-venous extracorporeal membrane oxygenation (V-V ECMO).MethodsIn this twelve patients prospective study, ECMO gas-flow was decreased from baseline (PaCO2 < 40 mmHg) until PaCO2 increased by 5–10 mmHg (High-CO2 phase). Resistance indices of gut, spleen, and snuffbox artery, the peripheral perfusion index (PPI), and heart rate variability were measured at baseline and High-CO2 phase.ResultsWhen PaCO2 increased from 36 (36–37) mmHg at baseline to 42 (41–43) mmHg in the High-CO2 phase (p < 0.001), PPI decreased significantly (p = 0.026). The snuffbox artery (p = 0.022), superior mesenteric artery (p = 0.042), and spleen (p = 0.012) resistance indices increased significantly. The root mean square of successive differences (RMSSD) decreased from 19.5(18.1–22.7) to 15.9(14.4–18.6) ms (p = 0.034), and the ratio of low-frequency to high-frequency components(LF/HF) increased from 0.47 ± 0.23 to 0.70 ± 0.38 (p = 0.013).ConclusionsHigh PaCO2 might cause decreased peripheral tissue and visceral organ perfusion through autonomic nervous system in patients with respiratory failure undergoing PSV with V-V ECMO.

Menstrual Cycle Variations in Wearable-Detected Finger Temperature and Heart Rate, But Not in Sleep Metrics, in Young and Midlife Individuals.

Most studies about the menstrual cycle are laboratory-based, in small samples, with infrequent sampling, and limited to young individuals. Here, we use wearable and diary-based data to investigate menstrual phase and age effects on finger temperature, sleep, heart rate (HR), physical activity, physical symptoms, and mood. A total of 116 healthy females, without menstrual disorders, were enrolled: 67 young (18-35 years, reproductive stage) and 53 midlife (42-55 years, late reproductive to menopause transition). Over one menstrual cycle, participants wore Oura ring Gen2 to detect finger temperature, HR, heart rate variability (root mean square of successive differences between normal heartbeats [RMSSD]), steps, and sleep. They used luteinizing hormone (LH) kits and daily rated sleep, mood, and physical symptoms. A cosinor rhythm analysis was applied to detect menstrual oscillations in temperature. The effect of menstrual cycle phase and group on all other variables was assessed using hierarchical linear models. Finger temperature followed an oscillatory trend indicative of ovulatory cycles in 96 participants. In the midlife group, the temperature rhythm's mesor was higher, but period, amplitude, and number of days between menses and acrophase were similar in both groups. In those with oscillatory temperatures, HR was lowest during menses in both groups. In the young group only, RMSSD was lower in the late-luteal phase than during menses. Overall, RMSSD was lower, and number of daily steps was higher, in the midlife group. No significant menstrual cycle changes were detected in wearable-derived or self-reported measures of sleep efficiency, duration, wake-after-sleep onset, sleep onset latency, or sleep quality. Mood positivity was higher around ovulation, and physical symptoms manifested during menses. Temperature and HR changed across the menstrual cycle; however, sleep measures remained stable in these healthy young and midlife individuals. Further work should investigate over longer periods whether individual- or cluster-specific sleep changes exist, and if a buffering mechanism protects sleep from physiological changes across the menstrual cycle.

Heart Rate Variability Biofeedback Training Reduces Early Maternal Stress, Anxiety, and Depression in Women Undergoing Cesarean Delivery: A Randomized Controlled Trial.

Women who undergo cesarean delivery have reported experiencing mood distress related to the surgery and postoperative pain. Heart rate variability biofeedback (HRVB) training is known to have positive effects on mental health, but its effects on women undergoing cesarean delivery have not yet been determined. This study evaluated the effects of an HRVB training intervention on stress, anxiety, and depression in women undergoing cesarean delivery. We hypothesized that 10 sessions of HRVB training could cumulatively improve emotion regulation in participants. This study was designed as a double-blinded randomized controlled trial involving a total of 86 enrolled women who were then divided into two groups: intervention and control. During their hospitalization, the intervention group underwent HRVB training daily, while both groups received standard perinatal care. Heart rate variability (HRV) was assessed using root mean square of successive differences (RMSSD), standard deviation of normal-to-normal intervals (SDNN), high-frequency power (HF) and low-frequency power (LF). HRV parameters, stress, anxiety, and depression were evaluated at baseline and on the fifth day after childbirth. Intention-to-treat (ITT) analyses examined change over time between groups. Although no significant effects were found for the RMSSD and HF, a significant increase was observed in SDNN (F = 13.43, p = < 0.001, ƞ2 = 0.14), and LF at post-assessment (F = 4.26, p = .04, ƞ2 = 0.05) compared to the control group. Except for the depression variable, stress (F = 6.11, p = .02, ƞ2 = 0.07) and anxiety (F = 8.78, p = .004, ƞ2 = 0.10) significantly decreased compared to the control group on the fifth postpartum day. Furthermore, post-hoc analysis showed that HRVB was more effective in decreasing mild to severe depressive symptoms (F = 7.60, p = .001, ƞ2 = 0.27). The intervention program successfully decreased self-perceived stress and anxiety in the postpartum period and relieved symptoms in more severely depressed participants. Our findings suggest that this program is suitable and beneficial for application in women during the early postpartum period following cesarean delivery.

The Impact on Autonomic Nervous System Activity during and Following Exercise in Adults: A Meta-Regression Study and Trial Sequential Analysis.

Background and Objectives: Exercise enhances cardiovascular health through various mechanisms, including the modulation of autonomic nervous system activity. This study aimed to systematically examine the impact of exercise on heart rate variability (HRV) in adults during and within one hour after exercise (WHAE). Materials and Methods: A comprehensive literature review was conducted using the MEDLINE, Embase, Cochrane Library, Scopus, and PubMed databases to identify published studies that reported the impact of exercise on autonomic nervous system activity in adults. The studies measured the absolute power of the low-frequency band (0.04-0.15 Hz) to the absolute power of the high-frequency band (0.015-0.4 Hz) (LF/HF ratio) to assess sympathetic activity and the root mean square of successive differences between normal heartbeats (RMSSD) to assess parasympathetic activity. Results: A total of 3329 studies were screened for relevance, and finally, 10 articles that utilized methods for measuring autonomic nervous system activity, such as the LF/HF ratio and RMSSD, covering 292 adult patients, were included for meta-analysis. In the current meta-analysis, we observed a significant decrease in parasympathetic activity during and after exercise, as indicated by RMSSD, compared to pre-exercise levels (mean difference [MD] = -4.96, 95% confidence interval [CI]: -8.00 to -1.91, p = 0.003). However, sympathetic activity after exercise, represented by the LF/HF ratio, showed a borderline significant increase compared to pre-exercise levels (MD = 1.06, 95% CI: -0.01 to 2.12, p = 0.052). The meta-regression model found that factors associated with RMSSD included mean age, male gender, and duration post-exercise. Additionally, the factor associated with the LF/HF ratio was the healthy condition of participants. The trial sequential analysis provided robust evidence of a decrease in RMSSD and an increase in the LF/HF ratio during and WHAE. Conclusions: Given the limitations of the current study, the findings suggest that a significant decrease in parasympathetic activity and a borderline significant increase in sympathetic activity in adults during and WHAE, as confirmed by trial sequential analysis. Meta-regression analysis indicated that parasympathetic activity was negatively associated with participant age and male gender, but positively associated with duration post-exercise. Additionally, increased sympathetic activity was linked to the healthy conditions of participants. This study suggests that exercise might differentially affect autonomic balance in individuals with chronic conditions compared to healthy individuals. This highlights the potential need for tailored exercise interventions to improve autonomic function across different populations.

Influence of shift work on sleep quality and circadian patterns of heart rate variability among nurses.

Shift work implementation is essential for providing continuous patient care in hospitals. However, working in shifts on a routine basis may disrupt the circadian pattern and alter the sleep-wakefulness cycle in nurses. Stress due to shift work can influence the adaptability of the cardiovascular system, produce psychophysiological strain and deteriorate work performance in female nurses. This study investigated the effect of morning and night shift work on sleep quality and circadian patterns governing heart rate variability (HRV) in female nurses working in a tertiary care hospital. Thirty-eight healthy female nurses were recruited. Frequency and time domain parameters of HRV were recorded as markers of cardiac autonomic function. A student t-test was used to investigate differences in HRV between morning and night shift workers. Mann-Whitney non-parametric test was applied for the difference between Pittsburgh Sleep Quality Index (PSQI) scores in the two groups. Standard deviation of the normal-to-normal interval (SDNN) (msec), total power (ms2) and high-frequency (HF) band power (ms2) were significantly reduced in night shift nurses than in morning shift nurses. The low-frequency (LF)/HF ratio was significantly increased in night shift nurses. The differences in standard deviation of the averages of NN intervals (SDaNN) (msec), root mean square of successive differences between adjacent NN intervals (RMSSD), mean NN, very low-frequency (VLF) band power (ms2) and LF band power (ms2) were not statistically significant. The global PSQI score was significantly higher among night shift workers than in morning shifts. Inadequate sleep can disrupt the body's ability to regulate heart rhythm and increase the risk of cardiovascular diseases and mortality. The research suggests a propensity for autonomic imbalance in night shift workers when compared to their counterparts on morning shifts.

Multimodal analysis of temporal affective variability within treatment for depression.

Affective flexibility, the capacity to respond to life's varying environmental changes in a dynamic and adaptive manner, is considered a central aspect of psychological health in many psychotherapeutic approaches. The present study examined whether affective two-dimensional (i.e., arousal and valence) temporal variability extracted from voice and facial expressions would be associated with positive changes over the course of psychotherapy, at the session, client, and treatment levels. A total of 22,741 mean vocal arousal and facial expression valence observations were extracted from 137 therapy sessions in a sample of 30 clients treated for major depressive disorder by nine therapists. Before and after each session, the clients self-reported their level of well-being on the outcome rating scale. Session-level affective temporal variability was assessed as the mean square of successive differences between consecutive two-dimensional affective measures. Session outcome was positively associated with temporal variability at the session level (i.e., within clients, between sessions) and at the client level (i.e., between clients). Importantly, these associations held when controlling for average session- and client-level valence scores. In addition, the expansion of temporal variability throughout treatment was associated with steeper positive session outcome trajectories over the course of treatment. The continuous assessment of both vocal and facial affective expressions and the ability to extract measures of affective temporal variability from within-session data may enable therapists to better respond and modulate clients' affective flexibility; however, further research is necessary to determine whether there is a causal link between affective temporal variability and psychotherapy outcomes. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

An emotional distress biomarker in pregnant women: Ultra-short-term heart rate variability

Prenatal emotional distress is common in pregnant women. Altered emotional distress can occur from the very beginning to the end of pregnancy. Heart rate variability (HRV) has recently become considered to be a potentially reliable psychophysiological stress biomarker in adults. In the current study, we evaluated ultra-short-term HRV (1-minute measurement) as a psychophysiological biomarker by examining the association between HRV parameters and self-reported prenatal emotional distress among pregnant women (N = 230) across three trimesters of pregnancy. ResultsPrenatal emotional distress was associated with a lower root mean square of successive differences between normal heartbeats (RMSSD), NN50, and SDNN Index among pregnant women who are in the second trimester. For women in the first and third trimester of pregnancy, prenatal emotional distress was not significantly correlated with any HRV indicators. LimitationsThe cross-sectional nature of our results limits the directional expression and assessment of the relationships, and longitudinal studies that target the recruitment of more pregnant women with subtypes of emotional distress issues are also needed. ConclusionsTime-domain parameters of low HRV (associated with reduced parasympathetic activity) can potentially serve as an efficient psychophysiological biomarker for prenatal emotional distress in the second trimester of pregnancy. However, the time-domain HRV indicators in pregnant women in the first and third trimesters may be affected by other physiological and psychological fluctuations, thus decreasing the HRV biomarker’s efficiency in predicting their prenatal emotional distress.

Effects of voluntary exercise and electrical muscle stimulation on reaction time in the Go/No-Go task.

Acute exercise improves cognitive performance. However, it remains unclear what triggers cognitive improvement. Electrical muscle stimulation (EMS) facilitates the examination of physiological changes derived from peripheral muscle contraction during exercise. Thus, we compared the effects of EMS and voluntary exercise at low- or moderate-intensity on reaction time (RT) in a cognitive task to understand the contribution of central and peripheral physiological factors to RT improvement. Twenty-four young, healthy male participants performed a Go/No-Go task before and after EMS/exercise. In the EMS condition, EMS was applied to the lower limb muscles. In the low-intensity exercise condition, the participants cycled an ergometer while maintaining their heart rate (HR) at the similar level during EMS. In the moderate-intensity exercise condition, exercise intensity corresponded to ratings of perceived exertion of 13/20. The natural log-transformed root mean square of successive differences between adjacent inter-beat (R-R) intervals (LnRMSSD), which predominantly reflects parasympathetic HR modulation, was calculated before and during EMS/exercise. RT improved following moderate-intensity exercise (p = 0.002, Cohen' d = 0.694), but not following EMS (p = 0.107, Cohen' d = 0.342) and low-intensity exercise (p = 0.076, Cohen' d = 0.380). Repeated measures correlation analysis revealed that RT was correlated with LnRMSSD (Rrm(23) = 0.599, p = 0.002) in the moderate-intensity exercise condition. These findings suggest that the amount of central neural activity and exercise pressor reflex may be crucial for RT improvement. RT improvement following moderate-intensity exercise may, at least partly, be associated with enhanced sympathetic nervous system activity.

The Effects of Caffeine on Heart Rate and Heart Rate Variability at Rest and During Submaximal Cycling Exercise

ABSTRACT The aim of this study was to investigate the effects of caffeine on heart rate and heart rate variability (HRV) at rest and during submaximal exercise. Using a balanced, double-blind, randomized, crossover design, 16 male cyclists (age: 37 ± 9 years; V ˙ O2max: 4.44 ± 0.67 L·min−1) completed three trials in an air-conditioned laboratory. In Trial 1, cyclists completed two incremental cycling tests to establish the V ˙ O2-power output relationship and V ˙ O2max. In trials 2 and 3, cyclists were evaluated for heart rate and HRV at rest, after which they ingested a capsule containing 5 mg·kg−1 of caffeine or placebo. Thirty-five minutes post-supplementation, additional resting heart rate and HRV readings were taken after which cyclists completed a submaximal incremental cycling test (6 min stages) at 40–80% of V ˙ O2max; with HR and HRV measurements taken in the last 5 min of each increment. HRV was determined from the root mean square of successive differences between R–R intervals. There were significant supplement × exercise intensity interactions on heart rate (p = .019) and HRV (p = .023), with post hoc tests on the latter showing that caffeine increased HRV at 40%, 50%, and 60% of V ˙ O2max by 3.6 ± 4.9, 2.6 ± 2.8, and 0.6 ± 1.7 ms, respectively. There was a supplement × time interaction effect on resting HRV (p < .001), but not on heart rate (p = .351). The results of this study support the suggestion that caffeine increases the parasympathetic modulation of heart rate.Clinical trial registration number: NCT05521386.

Validity of Ultra-Short-Term Heart Rate Variability Derived from Femoral Arterial Pulse Waveform in a British Military Cohort.

Various non-electrocardiogram (ECG) based methods are considered reliable sources of heart rate variability (HRV) measurement. However, the ultra-short recording of a femoral arterial waveform has never been validated against the gold-standard ECG-based 300s HRV and was the aim of this study.A validity study was conducted using a sample from the first follow-up of the longitudinal ADVANCE study UK. The participants were adult servicemen (n = 100); similar in age, rank, and deployment period (Afghanistan 2003-2014). The femoral arterial waveforms (14s) from the pulse wave velocity (PWV) assessment, and ECG (300s) were recorded at rest in the supine position using the Vicorder™ and Bittium Faros™ devices, respectively, in the same session. HRV analysis was performed using Kubios Premium. Resting heart rate (HR) and root mean square of successive differences (RMSSD) were reported. The Bland-Altman %plots were constructed to explore the PWV-ECG agreement in HRV measurement. A further exploratory analysis was conducted across methods and durations.The participants' mean age was 38.0 ± 5.3 years. Both PWV-derived HR (r = 0.85) and RMSSD (rs=0.84) showed strong correlations with their 300s-ECG counterparts (p < 0.001). Mean HR was significantly higher with ECG than PWV (mean bias: -12.71 ± 7.73%, 95%CI: -14.25%, -11.18%). In contrast, the difference in RMSSD between the two methods was non-significant [mean bias: -2.90 ± 37.82% (95%CI: -10.40%, 4.60%)] indicating good agreement. An exploratory analysis of 14s ECG-vs-300s ECG measurement revealed strong agreement in both RMSSD and HR.The 14s PWV-derived RMSSD strongly agrees with the gold-standard (300s-ECG-based) RMSSD at rest. Conversely, HR appears method sensitive.

Altered Heart Rate Variability During Mobile Game Playing and Watching Self-Mobile Gaming in Individuals with Problematic Mobile Game Use: Implications for Cardiac Health.

The surge in mobile gaming, fueled by smartphone and internet accessibility, lacks a comprehensive understanding of physiological changes during gameplay. This study, involving 93 participants (average age 21.75 years), categorized them into Problematic Mobile Gaming (PMG) and non-problematic Mobile Gaming (nPMG) groups based on Problematic Mobile Gaming Questionnaire (PMGQ) scores. The PMGQ is a 12-item scale developed in Taiwan to assess symptoms of problematic mobile gaming. The research delved into heart rate variability (HRV) alterations during real-time mobile gaming and self-gaming video viewing. Results showed that the PMG group significantly presents a lower root mean square of successive differences (RMSSD), and High Frequency (lnHF) than does the nPMG group (F=4.73, p=0.03; F=10.65, p=0.002, respectively) at the baseline. In addition, the PMG group significantly displayed elevated HF and low-frequency to high-frequency (LF/HF) in the mobile-gaming (F=7.59, p=0.007; F=9.31, p=0.003) condition as well as in the watching self-gaming videos (F=9.75, p=0.002; F=9.02, p=0.003) than did the nPMG. The study suggests targeted interventions to mitigate autonomic arousal, offering a potential avenue to address adverse effects associated with problematic mobile gaming behavior. The PMG group displayed increased craving scores after real-time mobile gaming and watching self-gaming video excerpts, unlike the nPMG group. Elevated LF/HF ratios in frequent gaming cases heightened autonomic arousal, presenting challenges in relaxation after mobile gaming. These findings contribute to a nuanced understanding of the complex interplay between mobile gaming activities, physiological responses, and potential intervention strategies.

A Virtual Reality Game-Based Intervention to Enhance Stress Mindset and Performance among Firefighting Trainees from the Singapore Civil Defence Force (SCDF)

This research paper investigates the effectiveness of a virtual reality (VR) game-based intervention using real-time biofeedback for stress management and performance among fire-fighting trainees from the Singapore Civil Defence Force (SCDF). Forty-seven trainees were enrolled in this study and randomly assigned into three groups: control, placebo, and intervention. The participants’ physiological responses, psychological responses, and training performances were evaluated during specific times over the standard 22-week training regimen. Participants from the control and placebo groups showed a similar overall perceived stress profile, with an initial increase in the early stages that was subsequently maintained over the remaining training period. Participants from the intervention group had a significantly lower level of perceived stress compared to the control and placebo groups, and their stress-is-enhancing mindset was significantly increased before the game in week 12 compared to week 3. Cortisol levels remained comparable between pre-game and post-game for the placebo group at week 12, but there was a significant reduction in cortisol levels post-game in comparison to pre-game for the intervention group. The biofeedback data as a measurement of root mean square of successive differences (RMSSD) during the gameplay were also significantly increased at week 12 when compared to week 3. Notably, the intervention group had a significant improvement in the final exercise assessment when compared to the control based on the participants’ role as duty officers. In conclusion, a VR game-based intervention with real-time biofeedback shows promise as an engaging and effective way of training firefighting trainees to enhance their stress mindset and reduce their perceived stress, which may enable them to perform better in the daily emergencies that they respond to.

Loneliness dynamics and physical health symptomology among midlife adults in daily life.

The current study examined how average daily loneliness (between-persons [BPs]), intraindividual variability in loneliness across days (within-persons [WPs]), and loneliness stability informed physical health symptomatology. We utilized daily diary data from a national sample of 1,538 middle-aged adults (Mage = 51.02; 57.61% women) who completed eight end-of-day telephone interviews about daily experiences, including loneliness and physical health symptoms (e.g., headaches, nausea). Via multilevel modeling, we examined average daily loneliness (BPs), intraindividual variability in loneliness (WPs), stability in loneliness (individual mean-squared successive difference) in association with the number and average severity of daily physical health symptoms. When participants were less lonely on average, and on days when loneliness was lower than a person's average, they had fewer and less severe physical health symptoms. Additionally, participants who were more stable in loneliness across 8 days had less severe physical health symptoms. Further, there was a stronger association between instability in loneliness and more physical health symptoms for people who were lonelier on average. Finally, the increase in physical health symptom severity associated with WP loneliness was strongest for participants with low variability in loneliness. Loneliness is associated with physical health symptoms on a day-to-day basis, especially for people who are highly variable in loneliness. Considerations of multiple sources of variation in daily loneliness may be necessary to adequately address loneliness and promote health. Public health interventions addressing loneliness may be most effective if they support social connectedness in people's everyday lives in ways that promote stable, low levels of loneliness. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Are Wearable Photoplethysmogram-Based Heart Rate Variability Measures Equivalent to Electrocardiogram? A Simulation Study.

Traditional electrocardiography (ECG)-derived heart rate variability (HRV) and photoplethysmography (PPG)-derived "HRV" (termed PRV) have been reported interchangeably. Any potential dissociation between HRV and PRV could be due to the variability in pulse arrival time (PAT; time between heartbeat and peripheral pulse). This study examined if PRV is equivalent to ECG-derived HRV and if PRV's innate error makes it a high-quality measurement separate from HRV. ECG data from 1084 subjects were obtained from the PhysioNet Autonomic Aging dataset, and individual PAT dispersions for both the wrist (n = 42) and finger (n = 49) were derived from Mol et al. (Exp Gerontol. 2020; 135: 110938). A Bayesian simulation was constructed whereby the individual arrival times of the PPG wave were calculated by placing a Gaussian prior on the individual QRS-wave timings of each ECG series. The standard deviation (σ) of the prior corresponds to the PAT dispersion from Mol et al. This was simulated 10,000 times for each PAT σ. The root mean square of successive differences (RMSSD) and standard deviation of N-N intervals (SDNN) were calculated for both HRV and PRV. The Region of Practical Equivalence bounds (ROPE) were set a priori at ± 0.2% of true HRV. The highest density interval (HDI) width, encompassing 95% of the posterior distribution, was calculated for each PAT σ. The lowest PAT σ (2.0 SD) corresponded to 88.4% within ROPE for SDNN and 21.4% for RMSSD. As the σ of PAT increases, the equivalence of PRV and HRV decreases for both SDNN and RMSSD. The HDI interval width increases with increasing PAT σ, with the HDI width increasing at a higher rate for RMSSD than SDNN. For individuals with greater PAT variability, PRV is not a surrogate for HRV. When considering PRV as a unique biometric measure, SDNN may have more favorable measurement properties than RMSSD, though both exhibit a non-uniform measurement error.

Immediate Increase in the Root Mean Square of Successive Differences after Three Bouts of Remote Ischemic Preconditioning: A Randomized Controlled Trial.

(1) Background: Remote ischemic preconditioning (RIPC) is an intervention involving the application of brief episodes of ischemia and reperfusion to distant tissues to activate protective pathways in the heart. There is evidence suggesting the involvement of the autonomic nervous system (ANS) in RIPC-induced cardioprotection. This study aimed to investigate the immediate effects of RIPC on the ANS using a randomized controlled trial. (2) Methods: From March 2018 to November 2018, we conducted a single-blinded randomized controlled study involving 51 healthy volunteers (29 female, 24.9 [23.8, 26.4] years). Participants were placed in a supine position and heart rate variability was measured over 260 consecutive beats before they were randomized into either the intervention or the SHAM group. The intervention group underwent an RIPC protocol (3 cycles of 5 min of 200 mmHg ischemia followed by 5 min reperfusion) at the upper thigh. The SHAM group followed the same protocol but on the right upper arm, with just 40 mmHg of pressure inflation, resulting in no ischemic stimulus. Heart rate variability measures were reassessed afterward. (3) Results: The intervention group showed a significant increase in RMSSD, the possible marker of the parasympathetic nervous system (IG: 14.5 [5.4, 27.5] ms vs. CG: 7.0 [-4.3, 23.1 ms], p = 0.027), as well as a significant improvement in Alpha 1 levels compared to the control group (IG: -0.1 [-0.2, 0.1] vs. CG: 0.0 [-0.1, 0.2], p = 0.001). (4) Conclusions: Our results hint that RIPC increases the RMSSD and Alpha 1 parameters showing possible immediate parasympathetic modulations. RIPC could be favorable in promoting cardioprotective or/and cardiovascular effects by ameliorating ANS modulations.

Thermoregulatory differences in sex and time-of-day within naturally ventilated office environments

Thermal comfort research lacks continuous data collection on thermoregulation and adaptive behavior in real-world environments. This paper presents the findings of a field study that aimed at understanding the temporal and individual differences between humans’ thermoregulation and adaptation within a dynamic thermal environment. The dataset contains a 6-week long summer field study of 2022 observing nine participants in a naturally ventilated office without a cooling system. The data collection comprises a total of 43 measurement days (22,776 data points at 60s frequency). The results indicate that the overall trend in clothing insulation deviates from standard assumptions (0.5 clo), especially above air temperatures of 26 °C. The mean clothing insulation was 0.29 clo ±0.08, overall ranging from 0.20 to 0.73 clo. The data showed significant sex differences in tonic levels of electrodermal activity, the low-frequency to high-frequency heart rate variability ratio, and clothing insulation. Other heart rate variability data, like the root mean square of successive differences and beats per minute, as well as the distal skin temperature of the wrist, show significant sex differences and time-of-day variations in morning-to-afternoon comparisons. The findings indicate a nuanced relationship between air temperature and thermoregulatory responses, highlighting the need for future research with larger, more diverse participant cohorts and enhanced environmental monitoring to strengthen the validity and generalizability of the findings.

Aerobic Exercise Improves Heart Rate Variability After an Implantable Cardioverter Defibrillator (ICD).

Clinicaltrials.gov: NCT00522340.