Remote Short Sessions of Heart Rate Variability Biofeedback Monitored With Wearable Technology: Open-Label Prospective Feasibility Study.

BACKGROUND: Heart rate variability (HRV) biofeedback is often performed with structured education, laboratory-based assessments, and practice sessions. It has been shown to improve psychological and physiological function across populations. However, a means to remotely use and monitor this approach would allow for wider use of this technique. Advancements in wearable and digital technology present an opportunity for the widespread application of this approach. OBJECTIVE: The primary aim of the study was to determine the feasibility of fully remote, self-administered short sessions of HRV-directed biofeedback in a diverse population of health care workers (HCWs). The secondary aim was to determine whether a fully remote, HRV-directed biofeedback intervention significantly alters longitudinal HRV over the intervention period, as monitored by wearable devices. The tertiary aim was to estimate the impact of this intervention on metrics of psychological well-being. METHODS: To determine whether remotely implemented short sessions of HRV biofeedback can improve autonomic metrics and psychological well-being, we enrolled HCWs across 7 hospitals in New York City in the United States. They downloaded our study app, watched brief educational videos about HRV biofeedback, and used a well-studied HRV biofeedback program remotely through their smartphone. HRV biofeedback sessions were used for 5 minutes per day for 5 weeks. HCWs were then followed for 12 weeks after the intervention period. Psychological measures were obtained over the study period, and they wore an Apple Watch for at least 7 weeks to monitor the circadian features of HRV. RESULTS: In total, 127 HCWs were enrolled in the study. Overall, only 21 (16.5%) were at least 50% compliant with the HRV biofeedback intervention, representing a small portion of the total sample. This demonstrates that this study design does not feasibly result in adequate rates of compliance with the intervention. Numerical improvement in psychological metrics was observed over the 17-week study period, although it did not reach statistical significance (all P>.05). Using a mixed effect cosinor model, the mean midline-estimating statistic of rhythm (MESOR) of the circadian pattern of the SD of the interbeat interval of normal sinus beats (SDNN), an HRV metric, was observed to increase over the first 4 weeks of the biofeedback intervention in HCWs who were at least 50% compliant. CONCLUSIONS: In conclusion, we found that using brief remote HRV biofeedback sessions and monitoring its physiological effect using wearable devices, in the manner that the study was conducted, was not feasible. This is considering the low compliance rates with the study intervention. We found that remote short sessions of HRV biofeedback demonstrate potential promise in improving autonomic nervous function and warrant further study. Wearable devices can monitor the physiological effects of psychological interventions.

Effects of stress management interventions on heart rate variability in adults with cardiovascular disease: a systematic review and meta-analysis.

Meta-analysis was used to investigate the potential benefits of stress management interventions (SMIs) on vagally-mediated heart rate variability (HRV) in adults with cardiovascular disease. Electronic bibliographic databases were searched through August 2022. Randomized controlled trials and quasi-experimental studies assessing effects of SMIs on HRV were included. Methodological quality was assessed with a standardized checklist. A pooled effect size was calculated for vagally-mediated HRV indices (standard deviation of normal-to-normal intervals, root mean square of the successive differences, and high frequency power) using random effects models. Fourteen studies (1202 participants, Mage: 59 ± 6.25 years; 25% ± 16% women; 61% ± 22% White) were included. Ten studies (11 effects) reported short-term HRV assessment; a small between-group difference emerged for vagally-mediated HRV (d+ = .27, 95% confidence interval [CI] 0.01-0.52, k = 11). Most interventions examined biofeedback; these studies yielded a small between-group difference on vagally-mediated HRV (d+ = 0.31, 95% CI 0.09-0.53, k = 7, Q [6] = 3.82, p = .70, I2 = 11%). This is the first systematic examination of the effect of SMIs on HRV in adults with CVD. Findings suggest a small effect of SMIs on vagally-mediated HRV, with biofeedback likely driving the effect. More research is required to fully understand whether this benefit on vagally-mediated HRV applies to other SMIs.

Heart rate and breathing effects on attention and memory (HeartBEAM): study protocol for a randomized controlled trial in older adults.

BACKGROUND: In healthy people, the "fight-or-flight" sympathetic system is counterbalanced by the "rest-and-digest" parasympathetic system. As we grow older, the parasympathetic system declines as the sympathetic system becomes hyperactive. In our prior heart rate variability biofeedback and emotion regulation (HRV-ER) clinical trial, we found that increasing parasympathetic activity through daily practice of slow-paced breathing significantly decreased plasma amyloid-ß (Aß) in healthy younger and older adults. In healthy adults, higher plasma Aß is associated with greater risk of Alzheimer's disease (AD). Our primary goal of this trial is to reproduce and extend our initial findings regarding effects of slow-paced breathing on Aß. Our secondary objectives are to examine the effects of daily slow-paced breathing on brain structure and the rate of learning. METHODS: Adults aged 50-70 have been randomized to practice one of two breathing protocols twice daily for 9 weeks: (1) "slow-paced breathing condition" involving daily cognitive training followed by slow-paced breathing designed to maximize heart rate oscillations or (2) "random-paced breathing condition" involving daily cognitive training followed by random-paced breathing to avoid increasing heart rate oscillations. The primary outcomes are plasma Aß40 and Aß42 levels and plasma Aß42/40 ratio. The secondary outcomes are brain perivascular space volume, hippocampal volume, and learning rates measured by cognitive training performance. Other pre-registered outcomes include plasma pTau-181/tTau ratio and urine Aß42. Recruitment began in January 2023. Interventions are ongoing and will be completed by the end of 2023. DISCUSSION: Our HRV-ER trial was groundbreaking in demonstrating that a behavioral intervention can reduce plasma Aß levels relative to a randomized control group. We aim to reproduce these findings while testing effects on brain clearance pathways and cognition. TRIAL REGISTRATION: ClinicalTrials.gov NCT05602220. Registered on January 12, 2023.

A framework for the interpretation of heart rate variability applied to transcutaneous auricular vagus nerve stimulation and osteopathic manipulation.

Reports on autonomic responses to transcutaneous auricular vagus nerve stimulation (taVNS) and osteopathic manipulative techniques have been equivocal, partly due to inconsistent interpretation of heart rate variability (HRV). We developed a mechanistic framework for the interpretation of HRV based on a model of sinus node automaticity that considers autonomic effects on Phase 3 repolarization and Phase 4 depolarization of the sinoatrial action potential. The model was applied to HRV parameters calculated from ECG recordings (healthy adult humans, both genders) before (30 min), during (15 min), and after (30 min) a time control intervention (rest, n = 23), taVNS (10 Hz, 300 µs, 1-2 mA, cymba concha, left ear, n = 12), or occipitoatlantal decompression (OA-D, n = 14). The experimental protocol was repeated on 3 consecutive days. The model simulation revealed that low frequency (LF) HRV best predicts sympathetic tone when calculated from heart rate time series, while high frequency (HF) HRV best predicts parasympathetic tone when calculated from heart period time series. Applying our model to the HRV responses to taVNS and OA-D, revealed that taVNS increases cardiac parasympathetic tone, while OA-D elicits a mild decrease in cardiac sympathetic tone.

Effect of Prenatal Yoga versus Moderate-Intensity Walking on Cardiorespiratory Adaptation to Acute Psychological Stress: Insights from Non-Invasive Beat-to-Beat Monitoring.

We recently reported enhanced parasympathetic activation at rest throughout pregnancy associated with regular yoga practice. The present study presents a secondary analysis of data collected within a prospective cohort study of 33 pregnant women practicing yoga once weekly throughout pregnancy and 36 controls not involved in formal pregnancy exercise programs. The objective was to assess the impact of prenatal yoga on the autonomic nervous system stress response. Healthy pregnant women with singleton pregnancies were recruited in the first trimester. There was no significant difference in the maternal body mass index (BMI) between the yoga group and the controls (24.06 ± 3.55 vs. 23.74 ± 3.43 kg/m2, p = 0.693). Women practicing yoga were older (28.6 ± 3.9 vs. 31.3 ± 3.5 years, p = 0.005) and more often nulliparous (26 (79%) vs. 18 (50%), p = 0.001). We studied heart rate variability (HRV) parameters in the time domain (SDNN, standard deviation of regular R-R intervals, and RMSSD, square root of mean squared differences of successive R-R intervals) and frequency domain (ln(LF/HF), natural logarithm of low-frequency to high-frequency power), as well as synchronization indices of heart rate, blood pressure and respiration during and immediately following acute psychological stress of a standardized mental challenge test. Measurements were performed once per trimester before and after yoga or a 30 min moderate-intensity walk. Statistical comparison was performed using three-way analyses of variance (p < 0.05 significant). Time domain HRV parameters during and following mental challenge in the yoga group were significantly higher compared to the controls regardless of the trimester (F = 7.22, p = 0.009 for SDNN and F = 9.57, p = 0.003 for RMSSD, respectively). We observed no significant differences in the yoga group vs. the controls in terms of ln(LF/HF) and synchronization indices. Regular prenatal yoga practice was associated with a significantly reduced sympathetic response to mental challenge and quicker recovery after acute psychological stress. These effects persisted throughout pregnancy with regular practice.

Heart rate variability and cold-induced vascular dilation after stimulation of two different areas of the ear: a prospective, single-blinded, randomized crossover study.

BACKGROUND: Both noninvasive transauricular vagus nerve stimulation (taVNS) and traditional medical practice (TMP), such as auriculotherapy, use the auricle as a starting point for stimulation, but with two different conceptual frameworks: taVNS depends on vagal afferences to account for its effects, whereas TMP requires stimulation of the ear with high topographical accuracy regardless of the afferent nerves. The aim of this study was to measure heart rate variability (HRV) and cold water-induced vasodilation (CIVD) after puncturing two different ear points with the same afference but that should have opposite effects according to TMP. METHODS: Ten healthy subjects were investigated in this single-blinded crossover study over three sessions. In the first session, sympathetic activation was performed via cold water immersion of the right hand, with recordings taken from multiple fingers. HRV was assessed in the time domain (square root of the mean squared differences of NN intervals (RMSSD)) and frequency domain (low (LF) and high frequencies (HF)). In the second and third sessions, the same skin immersion test was performed, and mechanical stimulation was applied to the ear at two different points on the internal surface of the antitragus, one with alleged parasympathetic activity and the other with alleged sympathetic activity. The stimulation was done with semipermanent needles. RESULTS: Stimulation of the point with alleged parasympathetic activity immediately resulted in a significant decrease in RMSSD in 75% of the subjects and in LF in 50% of the subjects, while stimulation of the point with alleged sympathetic activity resulted in an increase in HF and RMSSD in 50% of the subjects. Stimulation of these points did not affect the CIVD reflex. The 20 min cold water immersion induced an immediate decrease in LF and the LF/HF ratio and an increase in HF. The skin temperature of the nonimmersed medius significantly decreased when the contralateral hand was immersed, from 34.4 °C to 31.8 °C. CONCLUSIONS: Stimulation of two different ear points innervated by the same afferent nerves elicited different HRV responses, suggesting somatotopy and a vagal effect beyond vagal afferences. These results are not in accordance with the claims of TMP. TRIAL REGISTRATION: NCT04130893 (18/10/2019) clinicaltrials.com.

Dorsomedial hypothalamus-raphe pallidus-cardiac sympathetic pathway mediates electroacupuncture intervention of stress-induced tachycardia.

Electroacupuncture at Neiguan point (PC6) effectively ameliorates tachycardia. However, very little is known about the neural pathway mechanism underlying the effect of electroacupuncture at PC6 in stress-induced tachycardia. Here, we investigate whether there exists a dorsomedial hypothalamus (DMH)-raphe pallidus (RP)-heart pathway to mediate the effect of electroacupuncture at PC6. The virus tracing results show that the heart is innervated by the neurons in DMH and RP, and the neurons of DMH project to RP. Chemogenetic inhibition of RP projecting DMH neurons reverses the cardiac autonomic imbalance and tachycardia induced by stress. Of note, immunofluorescence results show that the neural activity of DMH and RP is inhibited by electroacupuncture at PC6 accompanied with improved cardiac autonomic imbalance and tachycardia under stress. Moreover, chemogenetic inhibition of RP projecting DMH neurons cannot affect autonomic nervous activity and heart rate of stress rats after administrating electroacupuncture at PC6.NEW & NOTEWORTHY Our study suggests that this dorsomedial hypothalamus (DMH)-raphe pallidus (RP)-cardiac sympathetic pathway involves in the improvement of cardiac dysfunction associated with stress by administrating electroacupuncture at PC6, thus providing beneficial information for the development of therapeutic strategies to prevent stress-induced cardiovascular diseases, and insight into neural pathway basis for electroacupuncture at PC6 intervention of cardiac dysfunction.

Effects of Traditional Chinese Medicine "Fuzheng Qingdu Decoction" on Autonomic Function and Cancer-Related Symptoms in Patients with Advanced Gastric Cancer undergoing Chemotherapy: A Controlled Trial.

OBJECTIVE: To evaluate the effects of Fuzheng Qingdu Decoction (FZQDD) on the autonomic function and cancer-related symptoms of patients with advanced gastric cancer undergoing chemotherapy to verify its clinical efficacy. METHODS: Sixty-two patients with stage III or IV gastric cancer were included in this study. The patients were divided into 2 groups: the chemotherapy (33 patients) and chemotherapy with FZQDD (29 patients) groups. The primary outcome was the autonomic function of the patients before and after the interventions. The parameters that were used to assess autonomic function were deceleration capacity (DC) and acceleration capacity (AC) of heart rate and heart rate variability (HRV), which comprised standard deviation of the normal-normal interval (SDNN), root mean square of successive interval differences (RMSSD), low-frequency power (LF), high-frequency power (HF), total power (TP), and LF-HF ratio. The secondary outcomes were cancer-related symptoms and the quality of life. RESULTS: DC and HRV parameters (ie, SDNN, RMSSD, LF, HF, and TP) were significantly decreased in the chemotherapy group; however, AC significantly increased after the interventions. No significant differences were observed in the DC, AC, and HRV parameters before and after the interventions in the chemotherapy with FZQDD group. Nevertheless, the changes in DC, AC, and HRV parameters (SDNN, RMSSD, HF, and TP) before and after the interventions were statistically significant between both the groups. FZQDD significantly improved the cancer-related symptoms and the quality of life of the patients. CONCLUSIONS: Oxaliplatin combined with S-1 (tegafur, gimeracil, and oteracil potassium) can impair autonomic modulation in patients with advanced gastric cancer. FZQDD can alleviate autonomic dysfunction by increasing the parasympathetic activity and decreasing the sympathetic tone, helping patients restore the dynamic sympathovagal balance, and significantly improving the cancer-related symptoms and the quality of life of patients.

Transcutaneous auricular vagus nerve stimulation modulates the processing of interoceptive prediction error signals and their role in allostatic regulation.

It has recently been suggested that predictive processing principles may apply to interoception, defined as the processing of hormonal, autonomic, visceral, and immunological signals. In the current study, we aimed at providing empirical evidence for the role of cardiac interoceptive prediction errors signals on allostatic adjustments, using transcutaneous auricular vagus nerve stimulation (taVNS) as a tool to modulate the processing of interoceptive afferents. In a within-subject design, participants performed a cardiac-related interoceptive task (heartbeat counting task) under taVNS and sham stimulation, spaced 1-week apart. We observed that taVNS, in contrast to sham stimulation, facilitated the maintenance of interoceptive accuracy levels over time (from the initial, stimulation-free, baseline block to subsequent stimulation blocks), suggesting that vagus nerve stimulation may have helped to maintain engagement to cardiac afferent signals. During the interoceptive task, taVNS compared to sham, produced higher heart-evoked potentials (HEP) amplitudes, a potential readout measure of cardiac-related prediction error processing. Further analyses revealed that the positive relation between interoceptive accuracy and allostatic adjustments-as measured by heart rate variability (HRV)-was mediated by HEP amplitudes. Providing initial support for predictive processing accounts of interoception, our results suggest that the stimulation of the vagus nerve may increase the precision with which interoceptive signals are processed, favoring their influence on allostatic adjustments.

Heart rate variability profile changes associated with specialist police selection activities: A case study.

BACKGROUND: Police Tactical Groups (PTGs) are specialist police units tasked with rigorous physical and psychosocial duties. Consequently, selection courses (SCs) for service in these units must also be rigorous. Given the intensity of SCs, holistic monitoring for potential overstress may be beneficial. Heart Rate Variability (HRV) is one holistic stress measure that can be obtained in austere environments. OBJECTIVE: The purpose of this study was to profile HRV during a PTG SC. Six (n = 6) qualified male police officers attempted a 36-hour PTG selection course held at an Australian state facility. METHODS: HRV was obtained from Equivitaltrademark EQ02 + LifeMonitor bioharnesses. The selection course consisted of physically demanding events with minimal sleep (approx. 45 mins). Only one candidate completed the full selection course; whose results are reported here. RESULTS: A visual time-series of 384 consecutive 5 min HRV analyses was generated. Contextual analysis was applied to appreciate HRV changes between SC serials. HRV decline occurred during the planning of a navigation exercise and a pack march. Increases in HRV were observed throughout the pack march exercise and rest period. CONCLUSION: This case study demonstrates the potential utility for selection personnel to obtain additional insight into candidate responses to various occupational challenges throughout an SC. Information provided by HRV monitoring may support leadership decisions when evaluating personnel holistically. For example, the ability to continue occupational task execution even while experiencing potential overstress (as measured by HRV) and after food and sleep deprivation is desirable. HRV may potentially inform stakeholders regarding overstress in PTG candidates.

Far-infrared stimulation of Neiguan acupoints improves heart rate variability and ameliorate fatigue in hemodialysis patients: A randomized trial.

BACKGROUND: In 2018, 84 615 patients in Taiwan received hemodialysis, of which about 62% to 97% suffered from fatigue. Fatigue caused by hemodialysis may be mental or physical. However, the detailed mechanism remains unclear. This study aimed to evaluate whether far-infrared stimulation of the Neiguan acupoint (P6) could effectively reduce fatigue and improve heart rate variability (HRV) in hemodialysis patients. METHODS: We conducted a two-arm, randomized trial in a hemodialysis center between March 2015 and March 2016. A total of 73 hemodialysis patients were included and were randomly assigned to an experimental group (n = 37) and a control group (n = 36). The experimental group received far-infrared radiation on Neiguan acupoint during hemodialysis for 12 weeks. The outcomes were fatigue level and HRV. RESULTS: All patients showed moderate fatigue ( M = 26.00 ± 13.01, range = 0-78) at baseline. Far-infrared stimulation on Neiguan acupoint significantly reduced overall fatigue ( ß = 24, p < 0.001) and improved HRV ( ß = 74.36, p < 0.001). Compared to the control group, the experiment group had significantly reduced fatigue levels in all aspects such as reduced energy and motivation ( ß = -2.97, p < 0.001), reduced physical strength ( ß = -1.28, p < 0.01), reduced mental capability ( ß = -2.38, p < 0.001), reduction in daily activities ( ß = -1.48, p < 0.01), depressed mood and loss of control ( ß = -1.21, p < 0.05) as well as increased autonomous nervous system activity ( ß = 14.71, p < 0.01) in the third month of stimulation. CONCLUSION: Far-infrared stimulation of the Neiguan acupoints effectively reduces fatigue and increases autonomic nervous system activity in hemodialysis patients.

Autonomic nervous system responses in the intermediate band to cranial cutaneous stimulation.

Cardiovascular rhythms representing functional states of the autonomic nervous system (ANS) are insufficiently reflected by the current physiological model based on low and high frequency bands (LF, HF, resp.). An intermediate (IM) frequency band generated by a brainstem pacemaker was included in systemic physiological ANS analyses of forehead skin perfusion (SP), ECG, and respiration. Data of 38 healthy participants at T0 and T1 (+1 week) before, during, and following osteopathic cranial vault hold (CVH) stimulation were analyzed including momentary frequencies of highest amplitude, amplitudes in low (0.05-0.12 Hz), IM (0.12-0.18 Hz), and high (0.18-0.4 Hz) frequency bands, and established heart rate variability (HRV) metrics. During CVH, LF interval durations increased, whereas IM/HF band durations decreased significantly. Amplitudes increased significantly in all frequency bands. A cluster analysis found one response pattern dominated by IM activity (47% of participants) with highly stable 0.08 Hz oscillation to CVH, and one dominated by LF activity (0.10 Hz) at T0, increasing to IM activity at T1. Showing frequency ratios at ≈3:1, respiration was not responsible for oscillations in PPG during CVH. HRV revealed no significant responses. Rhythmic patterns in SP and respiration matched previous findings on a reticular "0.15 Hz rhythm". Involvement of baroreflex pathways is discussed as alternative explanation.

Exploring the Bob Ross effect: A psychophysiological investigation.

Watching news broadcasts is known to elicit psychological stress. Conversely, the iconic painter Bob Ross (BR) has risen to pop culture status and amassed a following, as many find the messages and sounds of BR to be soothing and relaxing. Though, it has yet to be directly tested if such exposure can confer psychological or physiological benefit. The purpose of this study was to compare the effects of watching BR versus streaming news on markers of cardiovascular health and profile of mood states (POMS). It was hypothesized that watching BR would increase POMS scores and heart rate variability (HRV). It was also hypothesized that watching the news would increase blood pressure (BP), vascular stiffness (VS), and heart rate (HR). METHODS: In a randomized, controlled, crossover design, 18 young (21 ± 1 yrs, 9 female, 9 male) healthy participants (172.6 ± 9.9 cm, 69 ± 18 kg) were assessed for BP, VS, HR, HRV, and POMS before and after watching an episode of BR or the News matched for time (∼27 mins). RESULTS: A significant interaction effect on POMS scores were observed for, anxiety (p = 0.01), anger (p = 0.008), depression (p = 0.003), fatigue (p = 0.001), and confusion (p = 0.01) domains after watching BR. The LF/HF ratio, an HRV marker of sympathovagal balance, was significantly lower after watching BR (p = 0.04). There were no significant time, condition, or interaction effects on systolic BP, mean arterial pressure, and diastolic BP. CONCLUSION: The "Bob Ross Effect" reduces overall mood disturbance, though appears to exert little influence on the cardiovascular system in this acute paradigm.

Stress Response Pattern of Heart Rate Variability in Patients with Functional Somatic Syndromes.

Functional somatic syndromes (FSSs) represent a clinically important group of disorders that are often stress-related. Their autonomic pathophysiology, including reduced heart rate variability (HRV), has been reported. However, the response pattern to mental stress and recovery in FSSs remains unclear. Thus, we aimed to clarify the pattern of autonomic stress response and recovery to mental arithmetic stress in patients with FSS compared to that in healthy controls. This cross-sectional study included 79 patients with FSS who visited the Department of Psychosomatic Medicine at a university hospital in Japan and 39 healthy controls. Following a mood questionnaire and obtaining epidemiologic information, HRV was measured during three periods (5 min each): relaxation baseline resting, stress (mental arithmetic task), and post-stress recovery period. The HRV analysis included inter-beat interval, low frequency power, and high frequency power. Compared to healthy controls, patients with FSS exhibited significantly higher scores on the mood questionnaire, prolonged duration of illness, and decreased functionality in daily activities. While the healthy control group showed a pronounced stress response pattern with a significant decrease in vagal HRV and recovery, the FSS group showed a "flat" vagal stress response pattern, and the HRV in the FSS group was lower at relaxation baseline, remained low during the stress, and did not change post stress. Patients with severe FSS exhibit an altered stress response pattern. Our results could provide significant clues for the diagnosis and treatment of such patients, as well as useful insights into the relationship between stress and illness.

Influence of Respiratory Frequency of Slow-Paced Breathing on Vagally-Mediated Heart Rate Variability.

Breathing techniques, particularly slow-paced breathing (SPB), have gained popularity among athletes due to their potential to enhance performance by increasing cardiac vagal activity (CVA), which in turn can help manage stress and regulate emotions. However, it is still unclear whether the frequency of SPB affects its effectiveness in increasing CVA. Therefore, this study aimed to investigate the effects of a brief SPB intervention (i.e., 5 min) on CVA using heart rate variability (HRV) measurement as an index. A total of 75 athletes (22 female; Mage = 22.32; age range = 19-31) participated in the study, attending one lab session where they performed six breathing exercises, including SPB at different frequencies (5 cycles per minute (cpm), 5.5 cpm, 6 cpm, 6.5 cpm, 7 cpm), and a control condition of spontaneous breathing. The study found that CVA was significantly higher in all SPB conditions compared to the control condition, as indexed by both root mean square of the successive differences (RMSSD) and low-frequency HRV (LF-HRVms2). Interestingly, LF-HRVms2 was more sensitive in differentiating the respiratory frequencies than RMSSD. These results suggest that SPB at a range of 5 cpm to 7 cpm can be an effective method to increase CVA and potentially improve stress management and emotion regulation in athletes. This short SPB exercise can be a simple yet useful tool for athletes to use during competitive scenarios and short breaks in competitions. Overall, these findings highlight the potential benefits of incorporating SPB into athletes' training and competition routines.

A Comparison Between Pre-Sleep Heart Rate Variability Biofeedback and Electroencephalographic Biofeedback Training on Sleep in National Level Athletes with Sleep Disturbances.

The current study compared the effects of heart rate variability biofeedback (HRV-BF) and electroencephalographic biofeedback (EEG-BF) on sleep, mood, and reaction time. Fourteen highly trained male athletes with sleep disturbances participated in this randomised crossover study. Participants took part in HRV-BF and EEG-BF training, with each condition consisting of eight sessions over 15 days. Polysomnography (PSG) and the Pittsburgh sleep quality index (PSQI) were used to assess sleep quality, the profile of mood states (POMS) questionnaire to monitor mood, and reaction time to measure performance pre and post intervention. HRV-BF training improved PSG sleep efficiency (SE) (P = 0.022, d = 0.35, 95% CI 0.01 to 0.16) and subjective sleep duration (P = 0.011, ES = 0.40) when compared to EEG-BF. Only HRV-BF reduced reaction time pre to post biofeedback training (P = 0.020, d = 0.75, 95% CI 0.006 to 0.059). The PSQI showed that both HRV-BF (P = 0.025, ES = 0.31) and EEG-BF (P = 0.003, ES = 0.32) resulted in improved global PSQI scores. Total mood disturbance was also reduced though HRV-BF (P = 0.001, ES = 0.40) and EEG-BF (P = 0.001, ES = 0.30). HRV-BF and EEG-BF enhanced some subjective parameters of sleep and mood. HRV-BF increased PSG SE and subjective sleep duration more than EEG-BF in highly trained athletes with sleep disturbances.

Effects of 3-month Qigong exercise on heart rate variability and respiration in anxious college students.

OBJECTIVE: This longitudinal study aimed to investigate the effects of Qigong on the anxiety state, heart rate variability (HRV), and breathing of anxious college students. METHODS: A total of 37 individuals (18-25 years old) were randomly allocated to the control (n = 19) and intervention (n = 18) groups. Qigong interventions were conducted five times weekly for 12 weeks, with each session lasting 60 min. Hamilton Anxiety Scale, Fatigue Scale 14, Pittsburgh Sleep Quality Index, and 36-item Short Form Survey, HRV, and respiration data were collected before and after the 3-month intervention. RESULTS: Individuals who participated in the three-month Qigong exercise intervention showed a significant reduction in anxiety, particularly mental anxiety (p < 0.05). Subjects in the intervention group presented a decrease in skin temperature (p < 0.05) and an increase in blood volume pulsation (p < 0.05). Meanwhile, HRV exhibited a significant increase in the standard deviation of interbeat interval before and after comparisons (p < 0.05) and between the two groups (p = 0.039) and a reduction in the normalized low-frequency power after the intervention. Moreover, the intervention group experienced increased abdominal breathing depth and abdominal breathing per minute (p < 0.05). CONCLUSION: These findings indicate that Qigong is an effective mind-body exercise strategy for relieving anxiety. HRV and breathing were improved accordingly among college students after the completion of the 3-month Qigong program.

Uncertainties in the Analysis of Heart Rate Variability: A Systematic Review.

Heart rate variability (HRV) is an important metric with a variety of applications in clinical situations such as cardiovascular diseases, diabetes mellitus, and mental health. HRV data can be potentially obtained from electrocardiography and photoplethysmography signals, then computational techniques such as signal filtering and data segmentation are used to process the sampled data for calculating HRV measures. However, uncertainties arising from data acquisition, computational models, and physiological factors can lead to degraded signal quality and affect HRV analysis. Therefore, it is crucial to address these uncertainties and develop advanced models for HRV analysis. Although several reviews of HRV analysis exist, they primarily focus on clinical applications, trends in HRV methods, or specific aspects of uncertainties such as measurement noise. This paper provides a comprehensive review of uncertainties in HRV analysis, quantifies their impacts, and outlines potential solutions. To the best of our knowledge, this is the first study that presents a holistic review of uncertainties in HRV methods and quantifies their impacts on HRV measures from an engineer's perspective. This review is essential for developing robust and reliable models, and could serve as a valuable future reference in the field, particularly for dealing with uncertainties in HRV analysis.