Acute Heart Rate Variability Research Articles

Acute effects of fast, slow, and graded Suryanamaskar on cardiorespiratory and cardiac autonomic functions

BackgroundSuryanamaskar (SN) is a popular yogic practice due to its health benefits and fitness promises. This study aims to assess the acute effects of different paces of SN on cardiorespiratory responses and heart rate variability (HRV). MethodsIn this self-as-control comparative study, seventeen male yoga practitioners performed three rounds of SN at fast (FSN), slow (SSN), and graded (GSN) pace in a randomly allocated sequence. Cardiorespiratory responses and HRV kinetics were continuously monitored using a metabolic gas analyzer and heart rate sensor, respectively, and were analyzed by repeated-measures ANOVA and paired t-test. ResultsFSN involved the highest VO2, followed by GSN and SSN. Average HR (AHR) was significantly greater during FSN compared to SSN (p < 0.01; d = 0.81) and GSN (p < 0.05; d = 0.39). GSN demanded significantly higher (p < 0.05; d = 0.41) stroke volume compared to FSN. VO2, AHR, and energy expenditure (EE) showed a gradual increase across rounds in FSN and SSN, whereas in GSN those significantly reduced. SSN showed significantly lesser EE, fat% utilization, and METS as compared to FSN (p < 0.001) and GSN (p < 0.01). SSN also showed significantly reduced LF power (p < 0.01; d = 0.67), LF/HF ratio, and higher HF power than GSN and FSN. ConclusionFSN is more metabolically demanding compared to the other two paces. SSN is more effective in bringing a state of parasympathetic dominance and GSN brings progressive relaxation. The results provide insights into the acute HRV and cardio-metabolic responses to different SN paces suggesting its potential as a complementary therapy and to promote holistic health and well-being.

Maternal Serotonin Reuptake Inhibitor Antidepressants Have Acute Effects on Fetal Heart Rate Variability in Late Gestation.

Background: Prenatal exposure to serotonin reuptake inhibitor (SRI) antidepressants increases risk for adverse neurodevelopmental outcomes, yet little is known about whether effects are present before birth. In relation to maternal SRI pharmacokinetics, this study investigated chronic and acute effects of prenatal SRI exposure on third-trimester fetal heart rate variability (HRV), while evaluating confounding effects of maternal depressed mood.Methods: At 36-weeks' gestation, cardiotocograph measures of fetal HR and HRV were obtained from 148 pregnant women [four groups: SRI-Depressed (n = 31), SRI-Non-Depressed (n = 18), Depressed (unmedicated; n = 42), and Control (n = 57)] before, and ~5-h after, typical SRI dose. Maternal plasma drug concentrations were quantified at baseline (pre-dose) and four time-points post-dose. Mixed effects modeling investigated group differences between baseline/pre-dose and post-dose fetal HR outcomes. Post hoc analyses investigated sex differences and dose-dependent SRI effects.Results: Maternal SRI plasma concentrations were lowest during the baseline/pre-dose fetal assessment (trough) and increased to a peak at the post-dose assessment; concentration-time curves varied widely between individuals. No group differences in fetal HR or HRV were observed at baseline/pre-dose; however, following maternal SRI dose, short-term HRV decreased in both SRI-exposed fetal groups. In the SRI-Depressed group, these post-dose decreases were displayed by male fetuses, but not females. Further, episodes of high HRV decreased post-dose relative to baseline, but only among SRI-Non-Depressed group fetuses. Higher maternal SRI doses also predicted a greater number of fetal HR decelerations. Fetuses exposed to unmedicated maternal depressed mood did not differ from Controls.Conclusions: Prenatal SRI exposure had acute post-dose effects on fetal HRV in late gestation, which differed depending on maternal mood response to SRI pharmacotherapy. Importantly, fetal SRI effects were sex-specific among mothers with persistent depressive symptoms, as only male fetuses displayed acute HRV decreases. At trough (pre-dose), chronic fetal SRI effects were not identified; however, concurrent changes in maternal SRI plasma levels suggest that fetal drug exposure is inconsistent. Acute SRI-related changes in fetal HRV may reflect a pharmacologic mechanism, a transient impairment in autonomic functioning, or an early adaption to altered serotonergic signaling, which may differ between males and females. Replication is needed to determine significance with postnatal development.

Heart rate variability is enhanced during mindfulness practice: A randomized controlled trial involving a 10-day online-based mindfulness intervention.

ObjectivesThe goal of the present study was to probe the effects of mindfulness practice in a naturalistic setting as opposed to a lab-based environment in the presence of continuous heart rate variability (HRV) measurements. The specific experimental goals were to examine the effects of a brief 10-day online-based mindfulness intervention on both chronic and acute HRV responses.MethodWe conducted a fully randomized 10-day longitudinal trial of mindfulness practice, explicitly controlling for practice effects with an active-control group (music listening) and a non-intervention control group. To assess chronic cardiovascular effects, we asked participants in the 3 groups to complete 2-day HRV pre- and post-intervention measurement sessions. Using this experimental setup enabled us to address training effects arising from mindfulness practice to assess physiological impact on daytime as well as nighttime (i.e. assessing sleep quality) on the underlying HRV response. To assess acute cardiovascular effects, we measured HRV in the 2 active intervention groups during each of the 10 daily mindfulness or music sessions. This allowed us to track the development of purported training effects arising from mindfulness practice relative to the active-control intervention in terms of changes in the HRV slope over the 10-day time-course.ResultsFirstly, for the acute phase we found increased HRV during the daily practice sessions in both the mindfulness and active-control group indicating that both interventions were effective in decreasing acute physiological stress. Secondly, for the chronic phase we found increased HRV in both the day- and nighttime indicating increased sleep quality, specifically in the mindfulness group.ConclusionThese results suggest causal effects in both chronic and acute phases of mindfulness practice in formerly naïve subjects and provides support for the argument that brief online-based mindfulness interventions exert positive impact on HRV.

Competitive behavior, stress, and gender

This paper investigates whether physiological measures related to chronic and acute stress predict individual differences in willingness to compete. We measure individuals' autonomic nervous system activity in a resting state as well as under non-competitive and competitive incentive schemes using heart rate variability (HRV) measurement. We find that both baseline HRV and competition-induced changes in HRV predict willingness to compete. Notably, we find that women with low baseline HRV, a marker associated with chronic stress exposure, are more likely to choose piece rate incentives over competitive incentives than women with high baseline HRV. We observe that men with large acute HRV response to forced competition are more likely to choose tournament pay over piece rate pay than men with small acute HRV response to competition. Our results suggest that HRV can predict individual differences in willingness to compete, but HRV does not close the gender gap in willingness to compete at the aggregate level.

Relationship Between Heart Rate Variability Outcomes vs Firefighter Performance, Physical Activity, and Fitness Measures

PURPOSE: The purpose of this study was to determine the relationship between heart rate variability (HRV) versus firefighter (FF) occupational performance, fitness characteristics and physical activity measures. METHODS: Twelve male structural firefighters (age: 37.3±7.6 yr; height: 183.2±7.1 cm; body mass: 90.4±13.7 kg; body mass index: 26.9±2.4 kg·m-2) wore an accelerometer for 19.1±5.8 days to measure physical activity. Physical activity was also quantified by a self-reported log. HRV was determined with a portable ECG device upon waking for 20.8±4.6 days. HRV was assessed daily, upon waking, and included SDNN, RMSSD, High frequency (HF) and low frequency (LF) components. FFs completed a simulated fire ground test (SFGT) and a battery of fitness tests including estimated 1-repetition maximum shoulder press, deadlift, bench press, bent over row and kettlebell swing, and a submaximal prediction of aerobic capacity. HRV was assessed the day of the SFGT (acute) and averaged over all days during the observation period (chronic). Descriptive statistics were calculated as mean ± standard deviation and Pearson product moment correlation coefficients were calculated. The level of significance was set at p < .05. RESULTS: SDNN values recorded the same day as the SFGT were correlated with decreased SFGT time on 3 individual SFGT tasks (r=-.7 to -.745, p<.05) and overall SFGT time (r=-.735, p=.016). Chronic HF was correlated with frequency of moderate-to-vigorous physical activity (r=.728, p=.011). RMSSD and SDNN were also correlated with shoulder press strength (r=.885, p<.01; and r=.875, p<.01 respectively) and bench press strength (r=.775, p=.008; and r=.758, p=.011 respectively). CONCLUSIONS: Increased acute HRV was associated with more efficient SFGT performance, whereas chronic HRV was associated with physical activity and strength measures. These outcomes indicate that HRV parameters may reflect the physiological status of FFs and the complex interaction between HRV, physical activity and fitness outcomes. Supported by the NSCA’s Senior Investigator Research Grant

Yoga Nidra Relaxation Increases Heart Rate Variability and is Unaffected by a Prior Bout of Hatha Yoga

The measurement of heart rate variability (HRV) is often applied as an index of autonomic nervous system (ANS) balance and, therefore, myocardial stability. Previous studies have suggested that relaxation or mind-body exercise can influence ANS balance positively as measured by HRV but may act via different mechanisms. No studies, to the authors' knowledge, have examined the acute response in HRV to interventions combining relaxation and mind-body exercise. The objective of this study was to compare the acute HRV responses to Yoga Nidra relaxation alone versus Yoga Nidra relaxation preceded by Hatha yoga. This was a randomized counter-balanced trial. The trial was conducted in a university exercise physiology laboratory. Subjects included 20 women and men (29.15±6.98 years of age, with a range of 18-47 years). Participants completed a yoga plus relaxation (YR) session and a relaxation only (R) session. The YR condition produced significant changes from baseline in heart rate (HR; beats per minute [bpm], p<0.001) and indices of HRV: R-R (ms, p<0.001), pNN50 (%, p=0.009), low frequency (LF; %, p=0.008) and high frequency (HF; %, p=0.035). The R condition produced significant changes from baseline in heart rate (bpm, p<0.001) as well as indices of HRV: R-R (ms, p<0.001), HF (ms(2), p=0.004), LF (%, p=0.005), HF (%, p=0.008) and LF:HF ratio (%, p=0.008). There were no significant differences between conditions at baseline nor for the changes from baseline for any of the variables. These changes demonstrate a favorable shift in autonomic balance to the parasympathetic branch of the ANS for both conditions, and that Yoga Nidra relaxation produces favorable changes in measures of HRV whether alone or preceded by a bout of Hatha yoga.

Reactivity of heart rate variability after exposure to colored lights in healthy adults with symptoms of anxiety and depression

Studies on human psychological domains associated with color specific light effects have been reported. The heart rate variability (HRV) has been suggested to be a useful tool for the detection of short-term effects of light on the autonomic nervous system (ANS). The emotional state of an individual has an independent effect on the HRV. The purpose of this study was to investigate the acute HRV reactivity after illumination with colored lights and determine the possible interaction between the colored lights and emotional states. Ninety-two healthy adult volunteers underwent short-term measurement of HRV before and after exposures to blue ( λmax 420, 380–495 nm, 0.04 lux, 0.41 μW/cm 2), red ( λmax 765 nm, 620–780 nm, 0.4 lux, 1.62 μW/cm 2) and white (49.5 lux, 12.9 μW/cm 2) colored fluorescent lights for 5 min during the daytime. A depressed group and an anxious group were identified in 28 (30.4%) and 23 (25.0%) of the subjects, respectively, according to their responses to the Korean version of the hospital anxiety and depression scale (score ≥ 8). The high frequency (HF) reactivity and the root mean square successive differences (RMSSD) were significantly different in the depressed ( p < .05) and anxious groups ( p < .05) based on the colored lights. The parasympathetic activity was decreased with red light in the depressed and anxious groups; this activity was further decreased in subjects with both symptoms. However, it was unchanged in the subjects without symptoms of depression and anxiety. The results of this study showed that the emotional state of the subjects was an important modulator of the acute effects of dim colored light on the ANS.

Dose-related effects of red wine and alcohol on heart rate variability

In healthy subjects a standard drink of either red wine (RW) or ethanol (EtOH) has no effect on muscle sympathetic nerve activity or on heart rate (HR), whereas two drinks increase both. Using time- and frequency-domain indexes of HR variability (HRV), we now tested in 12 subjects (24-47 yr, 6 men) the hypotheses that 1) this HR increase reflects concurrent dose-related augmented sympathetic HR modulation and 2) RW with high-polyphenol content differs from EtOH in its acute HRV effects. RW, EtOH, and water were provided on 3 days, 2 wk apart according to a randomized, single-blind design. Eight-minute segments were analyzed. One alcoholic drink increased blood concentrations to 36 + or - 2 mg/dl (mean + or - SE), and 2 drinks to 72 + or - 4 (RW) and 80 + or - 2 mg/dl (EtOH). RW quadrupled plasma resveratrol (P < 0.001). HR fell after both water drinks. When compared with respective baselines, one alcoholic drink had no effect on HR or HRV, whereas two glasses of both increased HR (RW, +5.4 + or - 1.2; and EtOH, +5.7 + or - 1.2 min(-1); P < 0.001), decreased total HRV by 28-33% (P < 0.05) and high-frequency spectral power by 32-42% (vagal HR modulation), and increased low-frequency power by 28-34% and the ratio of low frequency to high frequency by 98-119% (sympathetic HR modulation) (all, P < or = 0.01). In summary, when compared with water, one standard drink lowered time- and frequency-domain markers of vagal HR modulation. When compared with respective baselines, two alcoholic drinks increased HR by diminished vagal and augmented sympathetic HR modulation. Thus alcohol exerts dose-dependent HRV responses, with RW and EtOH having a similar effect.