Ln HF Research Articles

Association of heart rate variability and C-reactive protein in patients with depression.

Depression has been shown to be correlated with cardiovascular (CV) morbidity and mortality. Inflammation and autonomic nervous system (ANS) dysfunction are possible causes. Numerous clinical studies have found an association between inflammatory pathways and the ANS. The aim of this study was to investigate the relationship between different heart rate variability (HRV) parameters and C-reactive protein (CRP) levels in depressed patients without concomitant diseases. Sixty-five depressed patients who were not taking medication participated in this cross-sectional study. The Tenth Revision of the International Classification of Diseases and Related Health Problems (ICD-10) categorization of mental and behavioral disorders served as the basis for the diagnosis of depression. HRV processing and analysis were performed using ADInstrument's Pro LabChart (PowerLab 8Pro) data analysis software. HRV was recorded for 5 min in an upright sitting position using a lead II electrocardiogram (ECG) (short-term HRV). CRP levels were measured using an ELISA (enzyme-linked immunosorbent assay) test. None of the measures of HRV showed a significant relationship with pulse rate, systolic blood pressure, diastolic blood pressure, or body mass index (BMI). Weight and BMI were strongly positively related (r = 0.420, P = 0.003) to pRR50 (percentage of successive RR intervals differing by more than 50 ms). Very low frequency (VLF), low frequency (LF), and the LF/HF (high frequency) ratio were all strongly positively correlated with CRP (r = 0.595, P = 0.001), whereas HF was also significantly negatively correlated (r = 0.383, P = 0.007). CRP had a significant negative correlation with the logarithm (ln) HF and a significant positive correlation with lnVLF, lnLF, and lnLF/HF. Measurement of resting HRV and CRP may be helpful in detecting CV disease in depressed patients. Low HRV and elevated serum CRP should prompt physicians to begin treatment for risk CV as soon as possible.

Sex Differences in Heart Rate Variability and Vascular Function Following High-Intensity Interval Training in Young Adults.

High-intensityintervaltraining (HIIT) issuperiortoothertrainingstrategies in both male andfemalehealthyindividuals. Understanding sex-specificdifferences in cardiac auto-regulation maycontributetothe optimal trainingstrategiesfor HIIT. The presentstudyaimedtoidentifysexdifferences in heart rate variability (HRV) andvascularfunctionfollowing HIIT in youngadults. Twenty-fourphysicallyactiveyoung male andfemaleadults (M: 12, F: 12, age: 19.5 yr, BMI: 22.1 kg·m-2) volunteeredtoparticipate in thestudy. Participantsperformed 10 boutsof HIIT including 20 s of high-intensitycycling at 115-130% Wmaxfollowedby 100 s ofrecovery. The cardiac auto-regulationsincluding HRV andvascularfunctionweremeasured at five different time points. The R-R interval, rMSSD, and SDNN wererecoveredfaster in malesthan in females after 15 min of HIIT. Thereweresexdifferences in theautonomicnervoussystemwhereln LF andln HF activitiesalongwithsympathovagalbalance (ln LF/HF) weregreater in femalescomparedwithmalesimmediatelyand 15 min after HIIT. However, nosignificantdifferences in bloodpressureand brachial-ankle pulse wavevelocitywereobservedbetween male andfemaleparticipants. Overall, HRV was moreactivated in femalesthan in malesfollowing HIIT, but theacuteresponse in vascularfunction was not different betweensexes. In futurestudies, sex-specificadaptationsofcardiacautoregulationfollowingrepeated HIIT mayneedtobeperformed.

The Cardiac Comeback-Beating Stronger: Exploring the Remarkable Resilience of the Heart in COVID-19 Recovery through Cardiac Autonomic Analysis.

Background and Objectives: Analyzing the cardiac autonomic function in COVID-19 patients can provide insights into the impact of the virus on the heart's regulatory mechanisms and its recovery. The autonomic nervous system plays a crucial role in regulating the heart's functions, such as heart rate, blood pressure, and cardiac output. This study aimed to investigate the impact of COVID-19 on heart rate variability (HRV) during a 6-min walk test (6MWT). Materials and Methods: The study included 74 participants, consisting of 37 individuals who had recovered from mild to moderate COVID-19 and 37 healthy controls. The study assessed heart rate variability (HRV) and blood pressure both before and after a 6-min walk test (6MWT). Results: The study found significant differences in a few time domains (SDNN and pNN50) and all frequency domain measures, whereas there were no significant differences in demographic characteristics or blood pressure between COVID-19-recovered individuals and healthy controls at rest. There were significant 6MWT effects on average HR, time-domain (SDNN and pNN50) measures of HRV, and all frequency domain measures of HRV. A significant group × 6MWT interaction was found for SDNN, pNN50, total power, Ln total power, LF, HF, Ln LF, Ln HF, and LF nu. Conclusions: Cardiac Autonomic analysis through HRV is essential to ensure the continued health and well-being of COVID-19 survivors and to minimize the potential long-term impacts of the disease on their cardiovascular system. This suggests that HRV analysis during the recovery phase following exercise could serve as a valuable tool for evaluating the physiological effects of COVID-19 and monitoring the recovery process.

Diagnostic Efficacy of Ultra-Short Term HRV Analysis in Obstructive Sleep Apnea.

Heart rate variability (HRV) is the standard method for assessing autonomic nervous system (ANS) activity and is considered a surrogate marker for sympathetic overactivity in obstructive sleep apnea (OSA). Although HRV features are usually obtained from the short-term segment method, it is impossible to evaluate rapid dynamic changes in ANS activity. Herein, we propose the ultra-short-term analysis to detect the balance of ANS activity in patients with OSA. In 1021 OSA patients, 10 min HRV target datasets were extracted from polysomnographic data and analyzed by shifting the 2 min (ultra-short-term) and 5 min (short-term) segments. We detected frequency-domain parameters, including total power (Ln TP), very low frequency (Ln VLF), low frequency (Ln LF), and high frequency (Ln HF). We found that overall HRV feature alterations indicated sympathetic overactivity dependent on OSA severity, and that this was more pronounced in the ultra-short-term methodology. The apnea-hypopnea index, oxygen desaturation index, and Epworth sleepiness scale correlated with increased sympathetic activity and decreased parasympathetic activity, regardless of the methodology. The Bland-Altman plot analyses also showed a higher agreement of HRV features between the two methodologies. This study suggests that ultra-short-term HRV analysis may be a useful method for detecting alterations in ANS function in OSA patients.

Effect of Visually Induced Motion Sickness from Head-Mounted Display on Cardiac Activity.

Head-mounted display (HMD) virtual reality devices can facilitate positive experiences such as co-presence and deep immersion; however, motion sickness (MS) due to these experiences hinders the development of the VR industry. This paper proposes a method for assessing MS caused by watching VR content on an HMD using cardiac features. Twenty-eight undergraduate volunteers participated in the experiment by watching VR content on a 2D screen and HMD for 12 min each, and their electrocardiogram signals were measured. Cardiac features were statistically analyzed using analysis of covariance (ANCOVA). The proposed model for classifying MS was implemented in various classifiers using significant cardiac features. The results of ANCOVA reveal a significant difference between 2D and VR viewing conditions, and the correlation coefficients between the subjective ratings and cardiac features have significant results in the range of −0.377 to −0.711 (for SDNN, pNN50, and ln HF) and 0.653 to 0.677 (for ln VLF and ln VLF/ln HF ratio). Among the MS classification models, the linear support vector machine achieves the highest average accuracy of 91.1% (10-fold cross validation) and has a significant permutation test outcome. The proposed method can contribute to quantifying MS and establishing viewer-friendly VR by determining its qualities.

Cardiac Autonomic Function Following Bilateral and Unilateral Upper Body Acute Resistance Exercise.

The purpose of this study was to compare cardiac autonomic responses following bilateral and unilateral upper-body (UB) acute resistance exercise (ARE). In total, 14 individuals were assessed for markers of cardiac autonomic responses via heart rate variability (HRV) and baroreflex sensitivity (BRS) at rest and at 10- and 30-min following ARE. Logarithmically transformed (ln) HRV measures included: total power (ln TP), high-frequency power (ln HF power), low-frequency power (ln LF power), sympathovagal balance (ln LF: HF), and the square root of the mean squared differences of successive R-R intervals (ln RMSSD). BRS was assessed using the sequence method. Two-way repeated measures ANOVAs were used to analyze effects of UB ARE (bilateral, unilateral) across time (Rest, 10, and 30 min). There were no significant (p > 0.05) interactions. However, there were significant (p ≤ 0.05) main effects of time such that ln TP, ln HF power, ln RMSSD, and BRS decreased and did not recover within 30 min compared to Rest for both conditions. Collectively, this study suggests that bilateral and unilateral UB ARE yielded similar reductions, for at least 30 min, in respect to vagal measures of HRV and BRS.

Cardiac autonomic responses to different tasks in office workers with access to a sit-stand table – a study in real work setting

The aim of this study was to characterise the cardiac autonomic modulation of different office tasks performed by office workers with access to a sit-stand table. Heart rate variability (HRV) of 24 office workers was measured for two hours during three days in the last week of sit-stand table use. HRV indexes and the percentage of heart rate reserve (%HRR) were calculated during computer and non-computer work tasks while sitting or standing, non-computer tasks away from the work desk, and informal work breaks. All cardiac autonomic responses demonstrated a statistically significant interaction effect between the tasks (all p < 0.05) except for the logarithmically-transformed high frequency power (ln HF ms2; p = 0.14). Tasks performed while standing and away from the desk had higher sympathetic modulation; in addition, the observed higher %HRR demonstrated that these tasks were more physically demanding in comparison to other tasks. Practitioner Summary: Prior reports indicated benefits based on alternated body postures using sit-stand table. Nevertheless, the cardiac autonomic responses of different tasks performed by office workers are unknown. This cross-sectional study showed that different tasks stimulate the cardiac autonomic nervous system in different ways, which could bring positive effects to the cardiovascular system.

Effect of Motion Artifact on Variation in Heart Rate Variability Parameters

The heart rate variability (HRV) is a noninvasive way properly for investigating the activity of the autonomic nervous system (ANS) as well as to predict cardiovascular diseases. To guarantee an accurate HRV analysis, a motion artifact-free HRV recording must be obtained. However, complete removal of a motion artifact is impossible when measuring heartbeats for 5 min, and the motion artifact due to sudden ANS activity must be taken into consideration for the HRV parameters. And, the ANS balance has thus far been evaluated by each individual HRV parameter calculated for a single 5 min HRV segment, leading to the dynamic activity of the ANS within the same period being ignored. Therefore, to resolve this problem, HRV parameters for ultra-short-term segments that are short enough to reflect a sudden motion artifact must be analyzed. The aim of the present study was to evaluate the effects of a motion artifact on the variation in HRV parameters to provide detailed information on ANS activity. The 121 ultra-short-term HRV segments were created by moving a 1-min window forward by a time shift interval of 2 s for the entire 5 min HRV segment. The ratios of Ln LF to Ln HF in these ultra-short-term segments and a single 5 min segment with a motion artifact were 0.89 and 1.06, respectively, while those in a motion artifact-free HRV segment were 0.75 and 0.93, respectively. This variation test for a short-term motion artifact and motion artifact-free HRV dataset was found to affect the SDNN (7.73 and 2.68), SD2 (11.44 and 4.42), TINN (40.33 and 9.92), and Ln HF (0.37 and 0.13) the most in terms of the standard deviation, respectively. Taken together, the mean HRV parameters of many ultra-short-term segments might play an important role in evaluating dynamic ANS activities within a short-term segment, avoiding the false conclusions made by the traditional HRV analysis.

Sex Differences in Autonomic Cardiac Control and Oxygen Saturation Response to Short-Term Normobaric Hypoxia and Following Recovery: Effect of Aerobic Fitness.

Introduction: The main aims of this study were to investigate autonomic nervous system (ANS) and arterial oxygen saturation (SpO2) responses to simulated altitude in males and females, and to determine the association between maximal oxygen uptake (VO2max) and these responses.Materials and Methods: Heart rate variability (HRV) and SpO2 were monitored in a resting supine position during Preliminary (6 min normoxia), Hypoxia (10 min, fraction of inspired oxygen (FiO2) of 9.6%, simulated altitude ~6,200 m) and Recovery (6 min normoxia) phases in 28 males (age 23.7 ± 1.7 years, normoxic VO2max 59.0 ± 7.8 ml.kg−1.min−1, body mass index (BMI) 24.2 ± 2.1 kg.m−2) and 30 females (age 23.8 ± 1.8 years, VO2max 45.1 ± 8.7 ml.kg−1.min−1, BMI 21.8 ± 3.0 kg.m−2). Spectral analysis of HRV quantified the ANS activity by means of low frequency (LF, 0.05–0.15 Hz) and high frequency (HF, 0.15–0.50 Hz) power, transformed by natural logarithm (Ln). Time domain analysis incorporated the square root of the mean of the squares of the successive differences (rMSSD).Results: There were no significant differences in SpO2 level during hypoxia between the males (71.9 ± 7.5%) and females (70.8 ± 7.1%). Vagally-related HRV variables (Ln HF and Ln rMSSD) exhibited no significant differences between sexes across each phase. However, while the sexes demonstrated similar Ln LF/HF values during the Preliminary phase, the males (0.5 ± 1.3) had a relatively higher (p = 0.001) sympathetic activity compared to females (−0.6 ± 1.4) during the Hypoxia phase. Oxygen desaturation during resting hypoxia was significantly correlated with VO2max in males (r = −0.45, p = 0.017) but not in females (r = 0.01, p = 0.952) and difference between regression lines were significant (p = 0.024).Conclusions: Despite similar oxygen desaturation levels, males exhibited a relatively higher sympathetic responses to hypoxia exposure compared with females. In addition, the SpO2 response to resting hypoxia exposure was related to maximal aerobic capacity in males but not females.

Heart rate variability recovery after a skyrunning marathon and correlates of performance

Background: It is well known that vigorous physical activity induces functional changes in cardiac autonomic nervous system (ANS) activity that is sustained several hours after exercise. However, data related to ANS recovery after more extreme endurance events, such as skyrunning marathons, are still lacking. Objective: The aims of this prospective cohort study were firstly, to determine the ANS response to a SkyMarathon, and secondly, to examine correlates of run performance. Methods: Ten male skyrunners aged 37.2 ± 9.2 years were recruited. The race was performed at a mean intensity 85.4 ± 3.7% of heart rate reserve, and lasted for 338 ± 38 min. Morning supine heart rate variability was measured at 10, 2 and 1 days before race, on the race day, at 5 min intervals for 30 min immediately post-race and then at 5 h and 30 h post. High-frequency power (HF, 0.15-0.50 Hz), low-frequency power (LF, 0.05-0.15 Hz), and square root of the mean of the squares of the successive differences (RMSSD) were calculated and transformed by natural logarithm (Ln). Results: Sympathovagal balance (Ln LF/HF) was most likely increased above baseline during the 30 min post-race and returned to baseline by 5 h. Vagal activity (Ln RMSSD and Ln HF) was most likely decreased below baseline during the 30 min post-race and 5 h of post-race, and recovered to baseline by 30 h. Race time correlated with resting heart rate (r = .81), body mass index (r = .73), maximal power output (r = -.70), and maximal oxygen uptake (r = -.61). Conclusions: The SkyMarathon elicited disturbances in ANS activity, with relative sympathetic activity increased up to 5 h post-race and vagal activity recovering by 30 h. Resting heart rate, body mass index, maximal power output, and maximal oxygen uptake were associated with SkyMarathon performance prediction.

Observación automatizada: la variabilidad de la frecuencia cardíaca y su relación con las variables psicológicas determinantes del rendimiento en nadadores jóvenes

&lt;p style="margin: 0cm 0cm 0pt; line-height: 150%;"&gt;&lt;span style="font-size: medium;"&gt;&lt;span style="font-family: 'Times New Roman',serif; mso-ansi-language: EN-US;" lang="EN-US"&gt;Correct interpretation of performance markers from&lt;/span&gt;&lt;span style="font-family: 'Times New Roman',serif; mso-ansi-language: EN-US; mso-ascii-theme-font: minor-bidi; mso-hansi-theme-font: minor-bidi; mso-bidi-font-family: 'Times New Roman'; mso-bidi-theme-font: minor-bidi;" lang="EN-US"&gt; a psychophysiological perspective is important in young developing athletes. This study had two objectives. The first was to analyze the relationship between heart rate variability (HRV) and the psychological variables sleep quality, self-esteem, and mood states in young swimmers from a professional swimming club. The second was to study the relationship between performance and HRV and psychological determinants. The sample was composed of nine swimmers (11.7&lt;span style="color: #1c1c1c;"&gt;±1.4 years) base on purposive sampling method. Data were collected once a week during training sessions for 3 weeks. The statistical analysis showed that anxiety was negatively correlated with the high frequency component of HRV (Ln HF) and positively correlated with the very low frequency component (Ln LVF). No significant correlations were observed for self-esteem or sleep quality. Performance in a 200-m freestyle event was negatively correlated with the parasympathetic HRV indices. Our results suggest that HRV could be a valid tool for predicting performance and improving interpretation of psychometric tests. &lt;/span&gt;&lt;/span&gt;&lt;/span&gt;&lt;/p&gt;

Regulatory Fit

Sport behavior may be regulated through a desire to win (promotion) or a desire to avoid losing (prevention), which differentially impacts cognitive tasks. Performance facilitation may also stem from a match between an individual’s self-regulatory focus and her chronic regulatory strategy, possibly due to “feeling right”. This notion of regulatory fit may impact pre-performance anxiety and arousal which may impact sport performance. PURPOSE: To determine the impact of regulatory fit on anxiety, arousal, and performance of college soccer players. METHODS: Twenty-five female soccer players were randomly assigned to a regulatory match (M) or mismatch (MM) condition. Participants received a task-framing phrase in which their performance goal either matched (M) or mismatched (MM) their chronic regulatory strategy. Anxiety, measured by the Competitive State Anxiety Inventory-2 Revised (CSAI-2R) and arousal, measured by pre-ejection period (PEP), heart rate (HR), and heart rate variability (e.g. high frequency variability (HF), and the square root of the mean squared differences of successive NN intervals (RMSSD)) were determined pre- and post-manipulation. Performance, the number of successful penalty kicks out of 10, was measured post-manipulation. The impact of regulatory fit on performance and on anxiety and arousal variables were determined by ANOVA and RM ANOVA, respectively. RESULTS: There was no difference between M (3.0 + .95) and MM (2.5 + 1.8) on performance (p>0.05). Pre (32.6 + 4.8) to post (34.5 + 5.4) CSAI-2R for M was not different than MM pre (35.0 + 4.6) to post (35.4 + 6.3) (p>0.05). Arousal variables ln HF, HR, and ln RMSSD in M were not significantly different pre (6.2 + .99; 76.4 + 15.0 bpm; 3.6 + .54) to post (6.3 + .99; 75.1 + 17.5 bpm; 3.6 + .53) compared to MM pre (6.6 + 1.0; 75.3 + 12.3; 3.8 + .49) to post (6.9 + .85; 74.6 + 10.5; 4.0 + .36), respectively (p>0.05). There was an interaction effect for PEP (p<0.05). Post-hoc testing indicated M post (0.14 + 0.01 msec) was greater than pre (0.13 + 0.01 msec) (p<0.05) but MM did not change pre (0.15 + 0.02 msec) to post (0.15 + 0.02 msec) (p<0.05). CONCLUSION: PEP is an indicator of the sympathetic nervous system (SNS), thus regulatory fit may impact pre-performance arousal through SNS activation. Supported by a Hollis Grant, ASPiRE program, Ball State University.

Autonomic cardiac regulation, blood pressure and cardiorespiratory fitness responses to different training doses over a 12 week group program in the elderly

AimThe study assessed the effects of different weekly training frequencies performed over a 12 week exercise programme (strength, endurance, balance) on autonomic cardiac activity, blood pressure and cardiorespiratory fitness (CRF) in elderly individuals. MethodsFifty-eight individuals participated in the study: 2TG (N=24, 71.1±6.4 yrs; 19 females, 5 males) performing two, 60min sessions/week; and 3TG (N=34, 72.3±7.9 yrs; 25 females, 9 males) performing three, 60min sessions/week. Time domain and spectral analysis of heart rate variability (HRV) quantified autonomic cardiac regulation. ResultsNatural logarithm (Ln) transformation was applied to all HRV parameters. There were significant reductions in total power (Ln TP) (p=0.006), low frequency (Ln LF) (p=0.013), high frequency (Ln HF) (p=0.013) and root mean square of successive differences (Ln rMSSD) (p=0.014) post training in 3TG after intervention. Diastolic BP (DBP) decreased significantly in both groups (2TG: P<0.001; 3TG: P<0.001). Both groups showed significant improvements in six-minute walk distance (2TG: P=0.003, 3TG: P=0.001). However, there were significant HRV differences between 2TG and 3TG for Ln TP (P=0.018), Ln LF (P=0.049), Ln HF (P=0.039) and Ln rMSSD (P=0.049). ConclusionsA combined exercise programme resulted in improved DBP and CRF irrespective of training two or three 60min sessions/week. However, training three, sessions/week induced negative health-related changes in autonomic cardiac activity through reducing HRV parasympathetic function, while HRV was maintained in the group training twice a week.

Arterial Stiffness and Autonomic Modulation After Free-Weight Resistance Exercises in Resistance Trained Individuals.

Kingsley, JD, Mayo, X, Tai, YL, and Fennell, C. Arterial stiffness and autonomic modulation after free-weight resistance exercises in resistance trained individuals. J Strength Cond Res 30(12): 3373-3380, 2016-We investigated the effects of an acute bout of free-weight, whole-body resistance exercise consisting of the squat, bench press, and deadlift on arterial stiffness and cardiac autonomic modulation in 16 (aged 23 ± 3 years; mean ± SD) resistance-trained individuals. Arterial stiffness, autonomic modulation, and baroreflex sensitivity (BRS) were assessed at rest and after 3 sets of 10 repetitions at 75% 1-repetition maximum on each exercise with 2 minutes of rest between sets and exercises. Arterial stiffness was analyzed using carotid-femoral pulse wave velocity (cf-PWV). Linear heart rate variability (log transformed [ln] absolute and normalized units [nu] of low-frequency [LF] and high-frequency [HF] power) and nonlinear heart rate complexity (Sample Entropy [SampEn], Lempel-Ziv Entropy [LZEn]) were measured to determine autonomic modulation. BRS was measured by the sequence method. A 2 × 2 repeated measures analysis of variance (ANOVA) was used to analyze time (rest, recovery) across condition (acute resistance exercise, control). There were significant increases in cf-PWV (p = 0.05), heart rate (p = 0.0001), normalized LF (LFnu; p = 0.001), and the LF/HF ratio (p = 0.0001). Interactions were also noted for ln HF (p = 0.006), HFnu (p = 0.0001), SampEn (p = 0.001), LZEn (p = 0.005), and BRS (p = 0.0001) such that they significantly decreased during recovery from the resistance exercise compared with rest and the control. There was no effect on ln total power, or ln LF. These data suggest that a bout of resistance exercise using free-weights increases arterial stiffness and reduces vagal activity and BRS in comparison with a control session. Vagal tone may not be fully recovered up to 30 minutes after a resistance exercise bout.

Somatic, Endurance Performance and Heart Rate Variability Profiles of Professional Soccer Players Grouped According to Age

This cross-sectional study compared somatic, endurance performance determinants and heart rate variability (HRV) profiles of professional soccer players divided into different age groups: GI (17–19.9 years; n = 23), GII (20–24.9 years; n = 45), GIII (25–29.9 years; n = 30), and GIV (30–39 years; n = 26). Players underwent somatic and HRV assessment and maximal exercise testing. HRV was analyzed by spectral analysis of HRV, and high (HF) and low (LF) frequency power was transformed by a natural logarithm (Ln). Players in GIV (83 ± 7 kg) were heavier (p < 0.05) compared to both GI (73 ± 6 kg), and GII (78 ± 6 kg). Significantly lower maximal oxygen uptake (VO2max, ml•kg-1•min-1) was observed for GIV (56.6 ± 3.8) compared to GI (59.6 ± 3.9), GII (59.4 ± 4.2) and GIV (59.7 ± 4.1). All agegroups, except for GII, demonstrated comparable relative maximal power output (Pmax). For supine HRV, significantly lower Ln HF (ms2) was identified in both GIII (7.1 ± 0.8) and GIV (6.9 ± 1.0) compared to GI (7.9 ± 0.6) and GII (7.7 ± 0.9). In conclusion, soccer players aged >25 years showed negligible differences in Pmax unlike the age group differences demonstrated in VO2max. A shift towards relative sympathetic dominance, particularly due to reduced vagal activity, was apparent after approximately 8 years of competing at the professional level.

Autonomic outcome is better after endarterectomy than after stenting in patients with asymptomatic carotid stenosis

Carotid endarterectomy and stenting have comparable efficacy in stroke prevention in asymptomatic carotid stenosis. In patients with carotid stenosis, cardiac events have a more than threefold higher incidence than cerebrovascular events. Autonomic dysfunction predicts cardiovascular morbidity and mortality, and carotid stenosis interferes with baroreceptor and chemoreceptor function. We assessed the effect of elective carotid revascularization (endarterectomy vs stenting) on autonomic function as a major prognostic factor of cardiovascular health. In 42 patients with ≥70% asymptomatic extracranial carotid stenosis, autonomic function was determined by analysis of heart rate variability (total band power [TP], high frequency band power [HF], low-frequency band power [LF], very low frequency band power [VLF]), baroreflex sensitivity (αHF, αLF), respiratory chemoreflex sensitivity (central apnea-hypopnea index), and cardiac chemoreflex sensitivity (hyperoxic TP, HF, LF, and VLF ratios) before and 30days after revascularization. Patients with endarterectomy were older than patients with stenting (69± 7 vs 62± 7years; P ≤ .008) but did not differ in gender distribution and preintervention autonomic function. Compared with stenting, postintervention heart rate variability was higher (ln TP, 6.7 [95% confidence interval (CI), 6.3-7.0] vs 6.1 [95% CI, 5.8-6.5; P ≤ .009]; ln HF, 4.5 [95% CI, 4.1-5.0] vs 4.0 [95% CI, 3.4-4.5; P ≤ .05]; ln VLF, 6.0 [95% CI, 5.7-6.4] vs 5.5 [95% CI, 5.2-5.9; P≤.02]); respiratory chemoreflex sensitivity (central apnea-hypopnea index, 5.5 [95% CI, 2.8-8.2] vs 10.0 [95% CI, 6.9-13.1; P ≤. 01]) and cardiac chemoreflex sensitivity (TP ratio, 1.2 [95% CI, 1.1-1.3] vs 1.0 [95% CI, 0.9-1.0; P ≤ .0001]; HF ratio, 1.4 [95% CI, 1.2-1.5] vs 0.9 [95% CI, 0.8-1.1; P ≤ .001]; LF ratio, 1.5 [95% CI, 1.3-1.6] vs 1.0 [95% CI, 0.8-1.1; P ≤ .0001]; VLF ratio, 1.2 [95% CI, 1.1-1.3) vs 1.0 [95% CI, 0.9-1.1; P ≤ .002]) were lower after endarterectomy. Postintervention baroreflex sensitivity did not differ after endarterectomy and stenting. Autonomic function was better after endarterectomy than after stenting. Better autonomic function after endarterectomy was based on restoration of chemoreceptor but not baroreceptor function and may improve cardiovascular long-term outcome.

Heart rate variability and DNA methylation levels are altered after short-term metal fume exposure among occupational welders: a repeated-measures panel study.

BackgroundIn occupational settings, boilermakers are exposed to high levels of metallic fine particulate matter (PM2.5) generated during the welding process. The effect of welding PM2.5 on heart rate variability (HRV) has been described, but the relationship between PM2.5, DNA methylation, and HRV is not known.MethodsIn this repeated-measures panel study, we recorded resting HRV and measured DNA methylation levels in transposable elements Alu and long interspersed nuclear element-1 (LINE-1) in peripheral blood leukocytes under ambient conditions (pre-shift) and right after a welding task (post-shift) among 66 welders. We also monitored personal PM2.5 level in the ambient environment and during the welding procedure.ResultsThe concentration of welding PM2.5 was significantly higher than background levels in the union hall (0.43 mg/m3 vs. 0.11 mg/m3, p < 0.0001). The natural log of transformed power in the high frequency range (ln HF) had a significantly negative association with PM2.5 exposure (β = -0.76, p = 0.035). pNN10 and pNN20 also had a negative association with PM2.5 exposure (β = -0.16%, p = 0.006 and β = -0.13%, p = 0.030, respectively). PM2.5 was positively associated with LINE-1 methylation [β = 0.79%, 5-methylcytosince (%mC), p = 0.013]; adjusted for covariates. LINE-1 methylation did not show an independent association with HRV.ConclusionsAcute decline of HRV was observed following exposure to welding PM2.5 and evidence for an epigenetic response of transposable elements to short-term exposure to high-level metal-rich particulates was reported.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2458-14-1279) contains supplementary material, which is available to authorized users.

Effect of 8-week exercise-based cardiac rehabilitation on cardiac autonomic function: A randomized controlled trial in myocardial infarction patients

The purpose of this study is to evaluate the effects of an 8-week exercise-based cardiac rehabilitation program on traditional and nonlinear heart rate variability (HRV) indexes, assessing the potential confounding influences of habitual physical activity (PA) and dietary intake. In this parallel-group trial, 96 patients (56 ± 10 years old) were randomized to the exercise group (EG) or to the control group (CG) 4 weeks after an acute myocardial infarction. Exercise-based cardiac rehabilitation program consisted of aerobic exercise at 70% to 85% of maximal heart rate for 3 sessions per week plus usual care. The CG received only usual care. The baseline and final assessments comprised resting short-term HRV (primary outcome) by a Polar R-R recorder under controlled breathing (12 breaths per minute), habitual PA by accelerometers, and dietary intake by a 4-day food diary. Two patients in each group dropped out and were not included in the intention-to-treat analysis. In the remaining 92 patients (EG = 47 and CG = 45), at baseline, only a difference in the proportion of nitrate medication use was significant between groups. After 8 weeks, no significant changes were found between groups on traditional and nonlinear HRV indexes (eg, ln HF, EG from 5.7 ± 1.5 to 5.9 ± 1.3 and CG from 5.5 ± 1.6 to 5.5 ± 1.5), habitual PA, and dietary intake. Eight weeks of exercise-based cardiac rehabilitation program is an insufficient stimulus to improve cardiac autonomic function in post-myocardial infarction patients under optimal medication and with high levels of traditional and nonlinear HRV indexes at baseline.

Mindfulness meditation, well-being, and heart rate variability: A preliminary investigation into the impact of intensive Vipassana meditation

Mindfulness meditation has beneficial effects on brain and body, yet the impact of Vipassana, a type of mindfulness meditation, on heart rate variability (HRV) – a psychophysiological marker of mental and physical health – is unknown. We hypothesised increases in measures of well-being and HRV, and decreases in ill-being after training in Vipassana compared to before (time effects), during the meditation task compared to resting baseline (task effects), and a time by task interaction with more pronounced differences between tasks after Vipassana training. HRV (5-minute resting baseline vs. 5-minute meditation) was collected from 36 participants before and after they completed a 10-day intensive Vipassana retreat. Changes in three frequency-domain measures of HRV were analysed using 2 (Time; pre- vs. post-Vipassana)×2 (Task; resting baseline vs. meditation) within subjects ANOVA. These measures were: normalised high-frequency power (HF n.u.), a widely used biomarker of parasympathetic activity; log-transformed high frequency power (ln HF), a measure of RSA and required to interpret normalised HF; and Traube–Hering–Mayer waves (THM), a component of the low frequency spectrum linked to baroreflex outflow. As expected, participants showed significantly increased well-being, and decreased ill-being. ln HF increased overall during meditation compared to resting baseline, while there was a time∗task interaction for THM. Further testing revealed that pre-Vipassana only ln HF increased during meditation (vs. resting baseline), consistent with a change in respiration. Post-Vipassana, the meditation task increased HF n.u. and decreased THM compared to resting baseline, suggesting post-Vipassana task-related changes are characterised by a decrease in absolute LF power, not parasympathetic-mediated increases in HF power. Such baroreflex changes are classically associated with attentional load, and our results are interpreted in light of the concept of ‘flow’ — a state of positive and full immersion in an activity. These results are also consistent with changes in normalised HRV reported in other meditation studies.

온천이 소아의 체성분과 자율 신경 기능에 미치는 영향에 관한 연구

Objectives: This study was performed to investigate the effect of hot spring therapy on children weight, body composition and heart rate variability. Methods: The study was carried out from 30 children who visited the spa from August 1, 2011 to August 31, 2011. We measured the change of weight, body composition, and heart rate variability after hot spring therapy for an hour per day. Results: The subject was consisted of 13 boys and 17 girls. This study revealed that their weight got lost from a hot spring therapy, which was statistically significant. Their body mass index(BMI) was decreased in from a hot spring therapy, which was not statistically significant. Total body water, muscle, protein, and mineral were decreased from a hot spring therapy, which was statistically significant. We measured HRV(heart rate variability) before and after the hot spring therapy. The mean HRT was increased, which was statistically insignificant. SDNN(standard deviation of the NN interval) and RMSSD(square root of the mean of the sum of the square of differences) were not different before and after the hot spring therapy. ln TP was decreased insignificantly. ln VLF was not affected before and after hot spring therapy. ln LF and ln HF was decreased, LF norm was increased, and HF norm was decreased, which were not statistically significant. Also, LF/HF ratio was increased insignificantly. Conclusions: From these results, we concluded that the weight, total body water, muscle, protein, and mineral got lost from the hot spring therapy. However, the HRV was not affected from the hot spring therapy.