Influence Heart Rate Variability Research Articles

An Acute Bout of Endurance Exercise Does Not Prevent the Inhibitory Effect of Caffeine on Glucose Tolerance the following Morning.

Caffeine reduces glucose tolerance, whereas exercise training improves glucose homeostasis. The aim of the present study was to investigate the effect of caffeine on glucose tolerance the morning after an acute bout of aerobic exercise. Methods: The study had a 2 × 2 factorial design. Oral glucose tolerance tests (OGTT) were performed after overnight fasting with/without caffeine and with/without exercise the evening before. Eight healthy young active males were included (Age 25.5 ± 1.5 years; 83.9 ± 9.0 kg; VO2max: 54.3 ± 7.0 mL·kg-1·min-1). The exercise session consisted of 30 min cycling at 71% of VO2max followed by four 5 min intervals at 84% with 3 min of cycling at 40% of VO2max between intervals. The exercise was performed at 17:00 h. Energy expenditure at each session was ~976 kcal. Lactate increased to ~8 mM during the exercise sessions. Participants arrived at the laboratory the following morning at 7.00 AM after an overnight fast. Resting blood samples were taken before blood pressure and heart rate variability (HRV) were measured. Caffeine (3 mg/kg bodyweight) or placebo (similar taste/flavor) was ingested, and blood samples, blood pressure and HRV were measured after 30 min. Next, the OGTTs were initiated (75 g glucose dissolved in 3 dL water) and blood was sampled. Blood pressure and HRV were measured during the OGTT. Caffeine increased the area under curve (AUC) for glucose independently of whether exercise was done the evening before (p = 0.03; Two-way ANOVA; Interaction: p = 0.835). Caffeine did not significantly increase AUC for C-peptides compared to placebo (p = 0.096), and C-peptide response was not influenced by exercise. The acute bout of exercise did not significantly improve glucose tolerance the following morning. Diastolic blood pressure during the OGTT was slightly higher after intake of caffeine, independent of whether exercise was performed the evening before or not. Neither caffeine nor exercise the evening before significantly influenced HRV. In conclusion, caffeine reduced glucose tolerance independently of whether endurance exercise was performed the evening before. The low dose of caffeine did not influence heart rate variability but increased diastolic blood pressure slightly.

Mathematical model presenting to assess variations in heart rate of ‎different age groups.

Recently, older people's cardiovascular systems have been affected by aging-related changes. An electrocardiogram (ECG) provides information about cardiac health. Analyzing ECG signals can help doctors and researchers diagnose many deaths. ‎Besides direct ECG analysis, some measurements can be extracted from the ECG signals, and ‎one of the most important measurements is heart rate variability (HRV). Research and clinical domains can benefit from HRV measurement and analysis as a potential noninvasive tool for assessing autonomic nervous system activity. The HRV describes the variation between an ECG signal's RR intervals over time and the change in that interval over time. An individual's heart rate (HR) is a non-stationary signal, and its variation can indicate a medical condition or impending cardiac disease. Many factors, such as stress, gender, disease, and age, influence HRV. The data for this study is taken from a standard database, the Fantasia Database, which contains 40 subjects, including two groups of 20 young subjects (21‒34 years old) and 20 older subjects (68‒85 years old). We used two non-linear methods, Poincare and Recurrence Quantification Analysis (RQA), to determine how different age groups affect HRV using Matlab and Kubios software. By analyzing some features extracted from this non-linear method based on a mathematical model and making a comparison, the results indicate that the SD1, SD2, SD1/SD2, and area of an ellipse (S) in Poincare will be lower in old people than in young people, but %REC, %DET, Lmean and Lmax will recur more often in older people than in younger ones. Poincare Plot and RQA show opposite correlations with aging. In addition, Poincaré's plot showed that young people have a greater range of changes than the elderly. According to the result of this study, heart rate changes can be reduced by aging, and ignoring this issue could lead to cardiovascular disease in the future (Tab. 3, Fig. 7, Ref. 55).

Pulsed Laser Acupuncture in the Treatment of Pain and Heart Rate Variability in Fibromyalgia Patients: A Pilot Randomized Clinical Trial.

Introduction: Laser acupuncture (LA) is a medically approved treatment for chronic pain, especially fibromyalgia. It is widely known that all pain is related to autonomic modulation, which may influence heart rate variability (HRV). There are robust studies in the literature on the effect of LA with continuous frequency on musculoskeletal pain and autonomic modulation. However, little is known about the effect of pulsed frequency on fibromyalgia. Therefore, this study aimed to evaluate whether an individualized intervention protocol applying pulsed LA would provide benefits related to pain symptoms and cardiac autonomic modulation in patients with fibromyalgia. Methods: In this pilot randomized clinical controlled trial, the sample consisted of women with fibromyalgia between the ages of 40 and 80, randomized into two groups: a control group (CG; n=10) and an experimental group (EG; n=10). EG received the intervention twice per week for 3 weeks. Statistical analysis was conducted by delta (difference between post-intervention and pre-intervention) and the Shapiro-Wilk test (normality). For comparison between the groups, the Mann-Whitney test was used. Results: The results showed a significant reduction in pain intensity as reported via the pain numerical scale (PNS; P=0.00), generalized pain index (GPI; P=0.00), and symptom severity scale (SSS; P=0.00). There was no significant difference in any HRV variable (P>0.05). Conclusion: Pulsed LA, when applied in an individualized protocol, can reduce pain intensity, as reported on the PNS, GPI, and SSS. However, no therapeutic effect was observed for HRV.

Influence of Geopathic Stress Zone on Heart Rate variability Parameters

Background and Aim: Geopathic stress (GS)is the effect of detrimental earth radiation and electro-magnetic radiation on the health of human body. The aim of this study is to evaluate the effect of the geopathic stress on heart rate variability(HRV) parameters in healthy human subjects. Methods: The time and frequency  domain HRV analyses were performed to assess the changes in sympathovagal  balance in group of 60 healthy volunteers with normal electrocardiogram(ECG).Sixty volunteers we-re selected for the study with  no history of illness(40 healthy men volunteers, 20 healthy women vo-lunteers). By using the apparatus Rayocomp PS-10(German, Rayonex), Geopathic stress zone were measured. The time and frequency domain HRV analyses were performed befor and after 60 minutes stay of volunteers in Geopathic stress zone.  Results: During 60 minutes stay on the GS zone, the time domain parameters such as standard  deviation(SD, ms) of all normal sinus RR intervals were significantly decreased. Then frequency domain parameters such as very low frequency (VLF, ms2), low frequency (LF, ms), and the LF/HF ratio were significantly increased. Conclusion: The study indicated  that the stay of healthy human in the GS zone may influence heart rate variability and change the sympathovagal balance.

Exposures to low-levels of fine particulate matter are associated with acute changes in heart rate variability, cardiac repolarization, and circulating blood lipids in coronary artery disease patients

Exposure to air pollution is a major risk factor for cardiovascular disease, disease risk factors, and mortality. Specifically, particulate matter (PM), and to some extent ozone, are contributors to these effects. In addition, exposures to these pollutants may be especially dangerous for susceptible populations. In this repeated-visit panel study, cardiovascular markers were collected from thirteen male participants with stable coronary artery disease. For 0–4 days prior to the health measurement collections, daily concentrations of fine PM (PM2.5) and ozone were obtained from local central monitoring stations located near the participant's homes. Then, single (PM2.5) and two-pollutant (PM2.5 and ozone) models were used to assess whether there were short-term changes in cardiovascular health markers. Per interquartile range increase in PM2.5, there were decrements in several heart rate variability metrics, including the standard deviation of the normal-to-normal intervals (lag 3, -5.8%, 95% confidence interval (CI) = −11.5, 0.3) and root-mean squared of successive differences (five day moving average, −8.1%, 95% CI = −15.0, −0.7). In addition, increases in PM2.5 were also associated with changes in P complexity (lag 1, 4.4%, 95% CI = 0.5, 8.5), QRS complexity (lag 1, 4.9%, 95% CI = 1.4, 8.5), total cholesterol (five day moving average, −2.1%, 95% CI = −4.1, −0.1), and high-density lipoprotein cholesterol (lag 2, -1.6%, 95% CI = −3.1, −0.1). Comparisons to our previously published work on ozone were conducted. We found that ozone affected inflammation and endothelial function, whereas PM2.5 influenced heart rate variability, repolarization, and lipids. All the health changes from these two studies were found at concentrations below the United States Environmental Protection Agency's National Ambient Air Quality Standards. Our results imply clear differences in the cardiovascular outcomes observed with exposure to the two ubiquitous air pollutants PM2.5 and ozone; this observation suggests different mechanisms of toxicity for these exposures.

Active force generation contributes to the complexity of spontaneous activity and to the response to stretch of murine cardiomyocyte cultures.

Cardiomyocyte cultures exhibit spontaneous electrical and contractile activity, as in a natural cardiac pacemaker. In such preparations, beat rate variability exhibits features similar to those of heart rate variability in vivo. Mechanical deformations and forces feed back on the electrical properties of cardiomyocytes, but it is not fully elucidated how this mechano‐electrical interplay affects beating variability in such preparations. Using stretchable microelectrode arrays, we assessed the effects of the myosin inhibitor blebbistatin and the non‐selective stretch‐activated channel blocker streptomycin on beating variability and on the response of neonatal or fetal murine ventricular cell cultures against deformation. Spontaneous electrical activity was recorded without stretch and upon predefined deformation protocols (5% uniaxial and 2% equibiaxial strain, applied repeatedly for 1 min every 3 min). Without stretch, spontaneous activity originated from the edge of the preparations, and its site of origin switched frequently in a complex manner across the cultures. Blebbistatin did not change mean beat rate, but it decreased the spatial complexity of spontaneous activity. In contrast, streptomycin did not exert any manifest effects. During the deformation protocols, beat rate increased transiently upon stretch but, paradoxically, also upon release. Blebbistatin attenuated the response to stretch, whereas this response was not affected by streptomycin. Therefore, our data support the notion that in a spontaneously firing network of cardiomyocytes, active force generation, rather than stretch‐activated channels, is involved mechanistically in the complexity of the spatiotemporal patterns of spontaneous activity and in the stretch‐induced acceleration of beating. Key points Monolayer cultures of cardiac cells exhibit spontaneous electrical and contractile activity, as in a natural cardiac pacemaker. Beating variability in these preparations recapitulates the power‐law behaviour of heart rate variability in vivo. However, the effects of mechano‐electrical feedback on beating variability are not yet fully understood.Using stretchable microelectrode arrays, we examined the effects of the contraction uncoupler blebbistatin and the non‐specific stretch‐activated channel blocker streptomycin on beating variability and on stretch‐induced changes of beat rate.Without stretch, blebbistatin decreased the spatial complexity of beating variability, whereas streptomycin had no effects.Both stretch and release increased beat rate transiently; blebbistatin attenuated the increase of beat rate upon stretch, whereas streptomycin had no effects.Active force generation contributes to the complexity of spatiotemporal patterns of beating variability and to the increase of beat rate upon mechanical deformation. Our study contributes to the understanding of how mechano‐electrical feedback influences heart rate variability.

Ischemic Preconditioning with High and Low Pressure Enhances Maximum Strength and Modulates Heart Rate Variability.

Background: The application of ischemic preconditioning (IPC) to resistance exercise has attracted some attention, owing to increases in muscle performance. However, there is still no consensus on the optimal occlusion pressure for this procedure. This study compared the acute effects of IPC with high and low pressure of occlusion on upper and lower limb maximal strength and heart rate variability in recreationally trained individuals. Methods: Sixteen recreationally trained men (25.3 ± 1.7 years; 78.4 ± 6.2 kg; 176.9 ± 5.4 cm; 25.1 ± 1.5 m2 kg−1) were thoroughly familiarized with one repetition maximum (1 RM) testing in the following exercises: bench press (BP), front latissimus pull-down (FLPD), and shoulder press (SP) for upper limbs, and leg press 45º (LP45), hack machine (HM), and Smith Squat (SS) for lower limbs. The 1 RM exercises were then randomly performed on three separate days: after a high pressure (220 mmHg, IPChigh) and a low pressure (20 mmHg, IPClow) IPC protocol and after no intervention (control, CON). Heart rate variability was also measured at rest, during and after the entire IPC protocol, and after the exercises. Results: Maximal strength was significantly (p < 0.05) higher in both IPChigh and IPClow compared with CON in all upper- and lower-limb exercises. There was no difference between the two experimental conditions. No significant differences were found in the comparison across the different experimental conditions for LFnu, HFnu, LF/HF ratio, and RMSSDms. Conclusions: IPC performed with both high and low pressures influenced heart rate variability, which may partly explain the maximal strength enhancement.

Effects of blebbistatin and streptomycin on beat rate variability and mechano-electric feedback in spontaneously active cardiomyocyte cultures

Monolayer cultures of cardiac cells exhibit spontaneous electrical and contractile activity and represent an in vitro model of a natural cardiac pacemaker. In such preparations, it was shown previously that beat rate variability (BRV) exhibits features similar to those of heart rate variability in vivo. However, tissue deformation and mechanical forces feedback on the electrical properties of cardiomyocytes (mechano-electrical feedback) e.g., through stretch-activated channels (SACs), and it is not known how mechano-electrical feedback affects BRV in such preparations. Our objective was to assess the contribution of active force generation and SACs on BRV and on the response of neonatal or fetal murine ventricular cell cultures to mechanical deformation. Monolayer cultures were grown on stretchable microelectrode arrays. Spontaneous electrical activity was recorded without deformation and upon predefined deformation protocols (5% uniaxial and 2% biaxial strain, applied repeatedly for 1 min every 3 min), before and after the application of the myosin inhibitor blebbistatin (10 μmol/L) or the SAC blocker streptomycin (20 μmol/L). Without deformation, spontaneous activity originated from the edge of the preparations and the site of origin switched frequently in a complex manner. Blebbistatin did not change mean beat rate, but it decreased the spatial complexity of beating variability. In contrast, streptomycin did not exert any manifest effects on spontaneous activity. During the deformation protocols, beat rate transiently increased upon stretch, but paradoxically also upon release. Blebbistatin attenuated the response to stretch, while this response was not manifestly affected by streptomycin. These results indicate that any change of shape transiently increases beat rate. Importantly, active force generation, rather than SACs, appears to be mechanistically involved in this response as well as in the complexity of spatiotemporal BRV patterns. Our study thus contributes to understand how mechano-electric feedback may influence heart rate variability.

Physical activity influences heart rate variability in young adults, regardless of dextrose ingestion.

Cardiac autonomic modulation can be altered by carbohydrate ingestion. On the other hand, some of the protective effects of physical activity may be due to its impact on the autonomic nervous system. This cross-sectional study was conducted to evaluate whether physical activity level influences heart rate variability (HRV) under fasting and mainly, after dextrose ingestion. Healthy adults aged 18-40 years ( n = 92; 54.35 % women) were separated into nonactive ( n = 47) and active groups ( n = 45), based on the physical activity level determined by International Physical Activity Questionnaire (IPAQ) and then compared. There were no significant differences ( P > 0.05) for age, body mass, BMI, abdominal circumference, blood pressure, fasting glucose and blood glucose at 60 min after dextrose ingestion between groups. Body fat (%) was lower in the active group ( P = 0.02). The time-domain indices (RMSSD, SDNN and pNN50) were higher in the physically active group compared to the nonactive group (main effect of group, P < 0.01). The SDNN index was higher at 60 min after dextrose ingestion compared to fasting (main effect of time, P ≤ 0.01). However, no HRV indices showed significantly interaction effect (group x time; P > 0.05). The magnitude of HRV responses to glucose was not influenced by physical activity status. Young adults who met at least the minimum physical activity recommendations showed a higher cardiac autonomic modulation, regardless of dextrose ingestion.

Influence of Chronic Exposure to Exercise on Heart Rate Variability in Children and Adolescents Affected by Obesity: A Systematic Review and Meta-Analysis.

Background: Sedentary lifestyles are increasingly common amongst children, and insufficient physical activity is a global epidemic estimated to contribute to future incapacities and potential deaths. Objective: We aimed to increase the amount of evidence concerning the effect of chronic exposure to exercise on heart rate variability in children and adolescents affected by obesity. Methods: A systematic review commenced following the PRISMA guidelines developed by Web of Science, Virtual Health Library, PubMed, Cochrane Library, Embase, Ovid, Medline Complete, and Scopus using keywords obtained from the Descriptors in Health Sciences and Medical Subject Headlines (MeSH) terms. We considered (1) Population: Pediatric individuals affected by obesity; (2) Intervention: Exercise; (3) Control: Pre-intervention and sedentary; (4) Outcomes: Clearly presented primary parameters; and (5) Studies: Clinical trials, case controls, case reports, and case series. Results: 11 articles were involved and predominantly included procedures observed during approximately 12 weeks with a distribution of three sessions per week, each session being 30–60 min of aerobic exercise; additionally, the exercise grades were typically completed at a percentage of subjects’ maximum heart rates. The meta-analyses displayed a significant effect on the domains of time (R-R interval, SDNN, rMSSD), frequency (HF ms2, HF (n.u.), LF/HF), and the non-linear index (SD1). Conclusions: Chronic exposure to exercise influences heart rate variability in children and adolescents affected by obesity by elevating the variability and parasympathetic activity and improving the sympathetic-vagal balance. Exercises should be recommended for the improvement of cardiac autonomic modulation to prevent the likelihood of further chronic diseases.

Non-Contact Measurement of Heart Rate Variability in Frail Geriatric Patients: Response to Early Geriatric Rehabilitation and Comparison with Healthy Old Community-Dwelling Individuals – A Pilot Study

Introduction: Frailty is a central geriatric syndrome characterized by a state of increased physiological vulnerability. As the key components of frailty are difficult to capture in their entirety, easily measurable and reliable surrogate parameters are desirable. Since frailty influences heart rate variability (HRV), HRV may be such a surrogate parameter. HRV is typically acquired by an ECG, which, however, may not be tolerated by all patients; in some, it may even trigger delirium. Therefore, we sought to measure HRV in a non-contact and unobtrusive way through photoplethysmography imaging (PPGI). Using our previously presented HRV estimation algorithm for PPGI, we investigated whether PPGI could reveal (1) HRV differences between frail and non-frail individuals and (2) the influences of early geriatric rehabilitation on HRV. Methods: The study involved 10 frail geriatric inpatients undergoing early geriatric rehabilitation and 10 healthy community-dwelling older adults. All participants underwent a comprehensive geriatric assessment. HRV measurements using a PPGI system and a reference ECG were made at the beginning and the end of the rehabilitation. HRV in terms of LF/HF ratio was analysed for both intra-individual changes during the geriatric rehabilitation and differences between frail geriatric patients and healthy community-dwelling individuals. Results: Across all geriatric patients, the median LF/HF ratio obtained with PPGI was found to be reduced by 0.178 (24.8%) during early geriatric rehabilitation. The assessment at the end of the rehabilitation revealed a simultaneous improvement of the functional state. Moreover, frail geriatric patients had a higher LF/HF ratio than their community-dwelling counterparts. Both observations in PPGI-based HRV were confirmed by the reference. The capability of PPGI to track intra-individual HRV changes was also analysed; a Spearman correlation of ρ = 1.0 between PPGI-based HRV and reference was achieved for 58.8% of the participants. Conclusion: Early geriatric rehabilitation improves the functional state, which is associated with an increased HRV. PPGI is capable of detecting HRV changes/trends in that age group. While the tracking of intra-individual HRV changes is also possible, its reliability needs improvement. Nevertheless, the capabilities demonstrated in our study and the non-contact measurement principle of PPGI emphasize its potential for application in geriatric medicine.

N2 event-related potential component is associated with cardiac autonomic tone regulation during mental fatigue

Mental fatigue alters cognitive performance and autonomic regulation. The neurovisceral model proposes that forebrain structures associated to cognitive control abilities influences heart rate variability. Parasympathetic mediated heart rate variability indices reduction during mental fatigue experience is well-described in previous studies, but the contribution of heart-brain axis to cardiac autonomic adaptation remains unknown. This study investigates the association between root mean square of successive differences between RR intervals (rMSSD) and N2 event-related potential component during visual prolonged odd/ball task (≅ 60min.). The comparison between task blocks shows that rMSSD (p = 0.004) and N2 (p = 0.04) decreased with time on task. Pearson correlation shows that ΔrMSSD is associated with ΔN2 (p = 0.007). Our results support the neurovisceral integration model showing that cognitive control contributes to cardiac autonomic tone adaptation during mental fatigue experience.

The Effects of an Artificial Garden on Heart Rate Variability among Healthy Young Japanese Adults.

Spending time in nature might positively influence mental health by inducing a relaxed state. Recently, gardens have been created on hospital rooftops in Japan to help inpatients recover from various physical and mental aliments. However, there is little evidence regarding any positive physiological effects of artificial gardens designed for health. The purpose of this study was to assess the psychological and cardiovascular responses incited by artificial natural environments. Japanese university students (n = 38) participated in a one-group pretest post-test experiment conducted at the Yamaguchi Flower Expo in Japan in October 2018, designed to assess whether exposure to four environments (forest, flowers, ocean, and artificial garden for health) influenced heart rate variability measures. After pretesting to determine baseline measurements, participants completed a circuit through the four natural environments. Following circuit completion, post-testing determined that the low frequency/high frequency ratio was significantly lower in the overall sample and the four areas had similar influences on heart rate variability. Findings suggest that exposure to nature by walking through natural areas and in rooftop artificial gardens might enhance the balance between the sympathetic and parasympathetic nervous systems.

How Do Amusement, Anger and Fear Influence Heart Rate and Heart Rate Variability?

Emotions involve subjective experiences, behavioral performances, and physiological responses. Research concerning autonomic states corresponding to different emotions has prevailed for several decades. The present study was designed to investigate how specific emotions influence cardiac activities that reflect autonomic responses. Affective videos selected from a standardized Chinese database were used to induce amused, fearful, angry, and neutral emotions, while electrocardiogram and self-rated emotional experiences were recorded. Heart rate was significantly lower in the amused condition than in the angry, fearful and neutral condition. There were no significant differences among the latter three conditions. The root mean square of successive differences, an index of heart rate variability (HRV), was significantly larger in the amused condition than in the fearful, neutral, and angry conditions. It was also significantly larger in the angry condition than in the fearful condition. There were no significant differences between the fearful and neutral, or angry and neutral conditions. These results revealed that: (1) amusement activates the parasympathetic nervous system, and (2) compared with fear, anger is more likely to be linked with parasympathetic activation. We suggest that HRV, rather than the valence dimension (i.e., positive or negative) be regarded as a potential index to discriminate emotions related to approach or avoidance motivation.

Abstract P099: Heart Rate Variability Differences Between Green and Suburban Walking: A Pilot Crossover Study

Introduction: Heart rate variability (HRV) assesses the sympathetic and parasympathetic innervation of the heart. Lower HRV indicates greater sympathetic tone and is associated with adverse cardiovascular outcomes. During exercise, factors like activity intensity influence HRV. Yet, an environment’s inherent anxiety-/stress-promoting characteristics may also affect HRV. Hypothesis: Given nature’s calming characteristics, we hypothesized green (i.e., nature-based) walking would promote higher HRV and less HRV reduction than suburban walking. Methods: Twenty-four middle-aged adults (20 female; 49.3 ± 6.7 yrs; BMI: 30.7 ± 7.9 kg/m 2 ) participated in this nine-week crossover study comprised of once-weekly 50-minute moderate-intensity walking sessions. Participants walked for three weeks in each of two treatment conditions: (1) green walking: nature-based walking on trails of local arboretum; and (2) suburban walking: walking on sidewalks of a local suburb’s downtown area. Half were assigned to suburban walking in the first treatment period, and half completed green walking first. A two-week washout separated treatments. The Zephyr BioHarness 3 assessed HRV—reported as standard deviations of normal-to-normal RR intervals in milliseconds (ms) while also tracking activity intensity. For analysis, walks were split into 15-minute intra-walk phases with the first, second, and third phases representing each walk’s beginning, middle, and end. Five-minute pre- and post-walk sitting phases for HRV were also created. Linear mixed models with repeated measures evaluated HRV phase differences between treatments and HRV change between phases by treatment. Results: Lower HRV was observed during the pre-walk sitting phase in the green (56.5 ms) vs. the suburban walking treatment (62.4 ms; p = 0.04); however, a sequence effect was present ( p = 0.02). Due to lower walking intensity during green walking (0.31 g vs. 0.27 g; p &lt; 0.01), activity intensity was a covariate in all intra-walk analyses. Intra-walk phase analyses revealed higher green vs. suburban walking HRV during the second (29.1 ms vs. 24.2 ms, respectively; p &lt; 0.01) and third (33.9 ms vs. 23.8 ms, respectively; p = 0.03) phases. Further, less HRV reduction was seen between the first and second intra-walk phases during green (-7.6 ms) vs. suburban walking (-12.4 ms; p = 0.05). Between-treatment HRV differences were not found for the post-walk sitting phase. No sequence effects were observed for the intra-walk or post-walk phases. Finally, no carryover effects were observed—suggesting adequate washout between treatments. Conclusions: Green walking elicits higher HRV and less HRV reduction vs. suburban walking. Activity intensity did not explain these observations. Fully powered longer-term trials should rigorously evaluate green walking’s potential anxiety-/stress-reducing characteristics.

Effects of parathyroidectomy on blood bone markers and heart rate variability in patients with stage 5 chronic kidney disease.

Decreased heart rate variability (HRV) is closely related to abnormal cardiac autonomic nervous function, especially sympathetic hyperactivity, which intensifies the risk of cardiovascular events and sudden death. HRV parameters are lower in chronic kidney disease (CKD) and parathyroidectomy (PTX) can improve these abnormalities in severe secondary hyperparathyroidism (SHPT) patients. However, few studies have evaluated correlations between circulating bone markers and HRV in CKD patients. We conducted a cross-sectional study including 134 stage 5 CKD patients with 100 controls and a prospective study of 29 PTX patients with follow-up. Circulating bone biomarkers included: (1) intact parathyroid hormone (iPTH) as bone remodeling regulator; (2) bone-specific alkaline phosphatase (BAP), representing bone formation; (3) tartrate-resistant acid phosphatase 5b (TRACP-5b), indicating bone resorption; and (4) bone-derived hormone, fibroblast growth factor 23 (FGF23). Stage 5 CKD patients had higher circulating iPTH, BAP, TRACP-5b, and FGF23 than controls and these bone markers were significantly elevated in SHPT patients. Baseline iPTH, BAP, and lnFGF23 were independently associated with HRV in CKD patients. After PTX with a follow-up (median interval: 6.7months), high blood iPTH, BAP, TRACP-5b, FGF23, and attenuated HRV were ameliorated. Furthermore, improved HRV indices were associated with reduced iPTH, BAP, TRACP-5b, and FGF23. Circulating bone markers are correlated with HRV in CKD 5 patients and PTX can improve decreased HRV, which are associated with corrected bone markers in severe SHPT patients. Thus, we propose that PTH increases sympathetic tone and both high circulating PTH levels and sympathetic hyperactivity increase bone turnover, and that the products of bone turnover influence HRV.

Sex and family history of cardiovascular disease influence heart rate variability during stress among healthy adults

ObjectiveStudies of sex differences in heart rate variability (HRV) typically have not accounted for the influence of family history (FH) of cardiovascular disease (CVD). This study evaluated sex differences in HRV response to speech stress among men and women (age range 30–49 years) with and without a documented FH of CVD. MethodsParticipants were 77 adults (mean age = 39.8 ± 6.2 years; range: 30–49 years; 52% female) with positive FH (FH+, n = 32) and negative FH (FH−, n = 45) of CVD, verified with relatives of participants. Cardiac activity for all participants was recorded via electrocardiogram during a standardized speech stress task with three phases: 5-minute rest, 5-minute speech, and 5-minute recovery. Outcomes included time domain and frequency domain indicators of HRV and heart rate (HR) at rest and during stress. Data were analyzed with repeated measures analysis of variance, with sex and FH as between subject variables and time/phase as a within subject variable. ResultsWomen exhibited higher HR than did men and greater HR reactivity in response to the speech stress. However, women also exhibited greater HRV in both the time and frequency domains. FH+ women generally exhibited elevated HRV, despite the elevated risk of CVD associated with FH+. ConclusionsAlthough women participants exhibited higher HR at rest and during stress, women (both FH+ and FH−) also exhibited elevated HRV reactivity, reflecting greater autonomic control. Thus, enhanced autonomic function observed in prior studies of HRV among women is also evident among FH+ women during a standardized stress task.

Can Speech-Guided Breathing Influence Cardiovascular Regulation and Mood Perception in Hypertensive Patients?

Anthroposophic therapeutic speech (ATS) has been shown to positively influence heart rate variability (HRV) and cardiorespiratory coordination in healthy volunteers. This prospective, exploratory, pre-post study was performed to investigate ATS effects on baroreflex sensitivity (BRS), heart rate (HR), HRV by standard deviation of beat to beat intervals (SDNN), blood pressure (BP), and mood in hypertensive patients. Patients received three ATS treatments, alternating with three sham interventions (control). During the sessions, BP and electrocardiography were continuously recorded. BRS and SDNN were analyzed from those measurements. Changes in mood score were assessed by a questionnaire. All data were compared before and after intervention (ATS and control). Thirty-one patients participated, the majority diagnosed with arterial hypertension (22 out of 31). Pre-post analysis of the data revealed immediate and significant changes in hypertensive patients during control and ATS with respect to BRS (control: 6.57 to 6.92 msec/mmHg, p = 0.0349; ATS: 6.03 to 7.27 msec/mmHg, p < 0.0001), SDNN (control: 39 to 42 msec, p = 0.0058; ATS: 38 to 43 msec, p = 0.0003), and HR (control: 74 to 71 beats per minute [bpm], p < 0.0001; ATS: 74 to 70 bpm, p < 0.0001). In normotensive patients, those changes were generally less pronounced and less significant with respect to BRS (control: 8.13 to 8.56 msec/mmHg, p = 0.1102; ATS: 8.20 to 8.98 msec/mmHg, p = 0.0273), SDNN (control: 36 to 40 msec, p = 0.0002; ATS: 35 to 38 msec, p = 0.0556), and HR (control: 80 to 77 bpm, p < 0.0001; ATS: 80 to 78 bpm, p < 0.0011). Only in hypertensive patients significant long-term changes were observed for BRS (6.6 to 7.7 msec/mmHg, p = 0.0070), SDNN (39.1 to 45.5 msec, p = 0.0074), and HR (75.8 to 67.2 bpm, p = 0.0001). No significant long-term changes were observed in normotensive patients. The mean systolic BP did not change significantly during this study. Both ATS and control also yielded improvements in the mood summary score, which again were more apparent for ATS than for sham interventions, but these were more pronounced among normotensive patients (3.5 to 4.2) than for hypertensive patients (2.9 to 3.9). The results indicate that ATS has the potential to improve cardiovascular parameters which play an important role in BP regulation capability.

Polycyclic Aromatic Hydrocarbons-Associated MicroRNAs and Heart Rate Variability in Coke Oven Workers.

We aimed to evaluate the association between polycyclic aromatic hydrocarbons (PAHs)-related microRNAs (miRNAs) and heart rate variability indices in coke oven workers. We recruited 365 male coke oven workers and measured urinary PAH metabolites by gas chromatography-mass spectrometry. Five heart rate variability indices were measured using three-channel Holter monitor. Six miRNAs were detected by TaqMan miRNA assays (Life Technologies, Foster City, CA). miR-24-3p, miR-27a-3p, miR-142-5p, and miR-320b were negatively associated with the root mean of square of successive differences between adjacent normal NN intervals (RMSSD) (P(trend) = 0.006, 0.047, 0.019, 0.011, respectively). miR-142-5p and miR-320b were also negatively associated with standard deviation of all normal to normal NN intervals (SDNN) (P(trend) = 0.01 and 0.035). miR-24-3p, miR-27a-3p, and miR-320b were significantly interacted with multiple PAH metabolites and influenced heart rate variability indices, whereas miR-24-3p also significantly interacted with smoking to influence low frequency (P(interaction) < 0.05 for all). Plasma miRNAs might act as potential biomarkers for the adverse effect of PAH exposure on the cardiovascular system.

Nocturnal snoring decreases daytime baroreceptor sensitivity

In patients with obstructive sleep apnea heart rate variability and baroreceptor sensitivity during night and daytime are impaired. Snoring without obstructive sleep apnea may already influence heart rate variability and baroreceptor sensitivity during daytime. Cardiovascular daytime testing was performed in 11 snorers and age, BMI, and gender matched controls. Sleep apnea and snoring were quantified by sleep recordings. Paced breathing was performed during daytime with ECG, non-invasive blood pressure, and respiration recorded. Heart rate variability and blood pressure variability were analyzed in the time and frequency domain. Baroreceptor sensitivity (alpha gain) was calculated. In snorers a significant increase in high frequency systolic blood pressure variability (SBPV-HF) compared to control group (0.37mmHg(2) vs. 0.11mmHg(2) for 12 breaths and 0.35mmHg(2) vs. 0.10mmHg(2) for 15 breaths) was demonstrated. Furthermore a lower baroreceptor sensitivity was found in snorers compared to controls (9.2ms/mmHg vs. 16.2ms/mmHg for 12 breaths and 8.5ms/mmHg vs. 17.4ms/mmHg for 15 breaths per minute) using the paced breathing protocol. Mean heart rate was elevated in snorers as well. Snorers may have a reduced parasympathetic tone during daytime rather than an increased sympathetic tone.