Autonomic control of heart rate during physical exercise and fractal dimension of heart rate variability

1993 ◽  
Vol 74 (2) ◽  
pp. 875-881 ◽  
Author(s):  
Y. Nakamura ◽  
Y. Yamamoto ◽  
I. Muraoka
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Nervous System ◽  
Fractal Dimension ◽  
Physical Exercise ◽  
High Frequency ◽  
Harmonic Component ◽  
Low Frequency ◽  
Total Power ◽  
Plasma Norepinephrine

The objectives of the present study were to investigate autonomic nervous system influence on heart rate during physical exercise and to examine the relationship between the fractal component in heart rate variability (HRV) and the system's response. Ten subjects performed incremental exercise on a cycle ergometer, consisting of a 5-min warm-up period followed by a ramp protocol, with work rate increasing at a rate of 2.0 W/min until exhaustion. During exercise, alveolar gas exchange, plasma norepinephrine (NE) and epinephrine (E) responses, and beat-to-beat HRV were monitored. HRV data were analyzed by "coarse-graining spectral analysis" (Y. Yamamoto and R. L. Hughson. J. Appl. Physiol. 71: 1143–1150, 1991) to break down their total power (Pt) into harmonic and nonharmonic (fractal) components. The harmonic component was further divided into low-frequency (0.0–0.15 Hz) and high-frequency (0.15–0.8 Hz) components, from which low-frequency and high-frequency power (Pl and Ph, respectively) were calculated. Parasympathetic (PNS) and sympathetic (SNS) nervous system activity indicators were evaluated by Ph/Pt and Pl/Ph, respectively. From the fractal component, the fractal dimension (DF) and the spectral exponent (beta) were calculated. The PNS indicator decreased significantly (P < 0.05) when exercise intensity exceeded 50% of peak oxygen uptake (VO2 peak). Conversely, the SNS indicator initially increased at 50–60% VO2peak (P < 0.05) and further increased significantly (P < 0.05) at > 60% VO2peak when there were also more pronounced increases in NE and E.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals The Influence ofNrf2on Cardiac Responses to Environmental Stressors

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Reuben Howden ◽  
Eva Gougian ◽  
Marcus Lawrence ◽  
Samantha Cividanes ◽  
Wesley Gladwell ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
High Frequency ◽  
Low Frequency ◽  
Therapeutic Strategies ◽  
Environmental Stressors ◽  
Total Power ◽  
Airborne Pollutants ◽  
Cardiac Responses

Nrf2protects the lung from adverse responses to oxidants, including 100% oxygen (hyperoxia) and airborne pollutants like particulate matter (PM) exposure, but the role ofNrf2on heart rate (HR) and heart rate variability (HRV) responses is not known. We hypothesized that genetic disruption ofNrf2would exacerbate murine HR and HRV responses to severe hyperoxia or moderate PM exposures.Nrf2-/-andNrf2+/+mice were instrumented for continuous ECG recording to calculate HR and HRV (low frequency (LF), high frequency (HF), and total power (TP)). Mice were then either exposed to hyperoxia for up to 72 hrs or aspirated with ultrafine PM (UF-PM). Compared to respective controls, UF-PM induced significantly greater effects on HR (P<0.001) and HF HRV (P<0.001) inNrf2-/-mice compared toNrf2+/+mice.Nrf2-/-mice tolerated hyperoxia significantly less thanNrf2+/+mice (~22 hrs;P<0.001). Reductions in HR, LF, HF, and TP HRV were also significantly greater inNrf2-/-compared toNrf2+/+mice (P<0.01). Results demonstrate thatNrf2deletion increases susceptibility to change in HR and HRV responses to environmental stressors and suggest potential therapeutic strategies to prevent cardiovascular alterations.

Elevated heart rate variability in physically active postmenopausal women: a cardioprotective effect?

1996 ◽  
Vol 271 (2) ◽  
pp. H455-H460 ◽  
Author(s):  
K. P. Davy ◽  
N. L. Miniclier ◽  
J. A. Taylor ◽  
E. T. Stevenson ◽  
D. R. Seals
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Postmenopausal Women ◽  
High Frequency ◽  
Low Frequency ◽  
Total Power ◽  
High Frequency Power ◽  
Fat Percentage ◽  
Physically Active ◽  
Frequency Power

Coronary heart disease (CHD) and cardiac sudden death (CSD) incidence accelerates after menopause, but the incidence is lower in physically active versus less active women. Low heart rate variability (HRV) is a risk factor for CHD and CSD. The purpose of the present investigation was to test the hypothesis that HRV at rest is greater in physically active compared with less active postmenopausal women. If true, we further hypothesized that the greater HRV in the physically active women would be closely associated with an elevated spontaneous cardiac baroreflex sensitivity (SBRS). HRV (both time and frequency domain measures) and SBRS (sequence method) were measured during 5-min periods of controlled frequency breathing (15 breaths/min) in the supine, sitting, and standing postures in 9 physically active postmenopausal women (age = 53 +/- 1 yr) and 11 age-matched controls (age = 56 +/- 2 yr). Body weight, body mass index, and body fat percentage were lower (P < 0.01) and maximal oxygen uptake was higher (P < 0.01) in the physically active group. The standard deviation of the R-R intervals (time domain measure) was higher in all postures in the active women (P < 0.05) as were the high-frequency, low-frequency, and total power of HRV. SBRS also was higher (P < 0.05) in the physically active women in all postures and accounted for approximately 70% of the variance in the high-frequency power of HRV (P < 0.05). The results of the present investigation indicate that physically active postmenopausal women demonstrate higher levels of HRV compared with age-matched, less active women. Furthermore, SBRS accounted for the majority of the variance in the high-frequency power of HRV, suggesting the possibility of a mechanistic link with cardiac vagal modulation of heart rate. Our findings may provide insight into a possible cardioprotective mechanism in physically active postmenopausal women.

Sympathetic Stimulations by Exercise-Stress Testing and by Dobutamine Infusion Induce Similar Changes in Heart Rate Variability in Patients with Chronic Heart Failure

1995 ◽  
Vol 89 (2) ◽  
pp. 155-164 ◽  
Author(s):  
Massimo Piepoli ◽  
Stamatis Adamopoulos ◽  
Luciano Bernardi ◽  
Peter Sleight ◽  
Andrew J. S. Coats
Keyword(s):  
Heart Failure ◽  
Heart Rate ◽  
Heart Rate Variability ◽  
Chronic Heart Failure ◽  
Physical Exercise ◽  
High Frequency ◽  
Low Frequency ◽  
Frequency Component ◽  
Dobutamine Infusion ◽  
Inotropic Therapy

1. Heart rate variability can be used to evaluate autonomic balance, but it is unclear how inotropic therapy may affect the findings. The aim of the study was to assess whether heart rate variability can differentiate between sympathetic stimulation induced by inotrope infusion or by physical exercise. 2. Ten patients with chronic heart failure (64.3 ± 5.4 years of age) underwent four dobutamine infusions (8-min steps of 5 μg min−1 kg−1) and four supine bicycle exercise tests (5-min steps of 25 W). Plasma noradrenaline was evaluated, as well as the SD of R—R intervals, together with low-frequency (0.03–0.14 Hz) and high-frequency (0.15–0.4 Hz) components of heart rate variability using autoregressive spectral analysis. 3. Exercise and inotrope infusion produced similar changes in heart rate variability. An exercise load of 50 W and a dobutamine infusion of 15 μg min−1 kg−1 gave the following results respectively: heart rate, 120.3 ± 3.0 beats/min versus 110.2 ± 3.0 beats/min; SD, 16.0 ± 1.1 ms versus 16.3 ± 2.5 ms; low-frequency component, 4.3 ± 0.3 ln-ms2 versus 4.4 ± 0.3 ln-ms2 and high-frequency component, 2.6 ± 0.3 ln-ms2 versus 2.2 ± 0.3 ln-ms2. All comparisons were non-significant. The variables of heart rate variability showed high reproducibility in the same subject during different conditions. Noradrenaline was elevated by exercise from 326.0 ± 35.2 pg/ml to 860.1 ± 180.4 pg/ml (P < 0.05), but was unchanged by dobutamine infusion. 4. Heart rate variability changes cannot differentiate between dobutamine infusions and physical exercise, indicating that we should be cautious in evaluating patients undergoing inotropic therapy. The degree of receptor stimulations, rather than the level of sympathetic drive, would appear to determine the changes in heart rate variability.

scholarly journals Is the algorithm used to process heart rate variability data clinically relevant? Analysis in male adolescents

2016 ◽  
Vol 14 (2) ◽  
pp. 196-201 ◽  
Author(s):  
Antonio Henrique Germano Soares ◽  
Breno Quintella Farah ◽  
Gabriel Grizzo Cucato ◽  
Carmelo José Albanez Bastos-Filho ◽  
Diego Giulliano Destro Christofaro ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Fourier Transform ◽  
Fast Fourier Transform ◽  
High Frequency ◽  
Low Frequency ◽  
Total Power ◽  
Cross Sectional ◽  
Negatively Associated ◽  
Male Adolescents

ABSTRACT Objective To analyze whether the algorithm used for the heart rate variability assessment (fast Fourier transform versus autoregressive methods) influenced its association with cardiovascular risk factors in male adolescents. Methods This cross-sectional study included 1,152 male adolescents (aged 14 to 19 years). The low frequency, high frequency components (absolute numbers and normalized units), low frequency/high frequency ratio, and total power of heart rate variability parameters were obtained using the fast Fourier transform and autoregressive methods, while the adolescents were resting in a supine position. Results All heart rate variability parameters calculated from both methods were different (p<0.05). However, a low effect size (<0.1) was found for all parameters. The intra-class correlation between methods ranged from 0.96 to 0.99, whereas the variation coefficient ranged from 7.4 to 14.8%. Furthermore, waist circumference was negatively associated with high frequency, and positively associated with low frequency and sympatovagal balance (p<0.001 for both fast Fourier transform and autoregressive methods in all associations). Systolic blood pressure was negatively associated with total power and high frequency, whereas it was positively associated with low frequency and sympatovagal balance (p<0.001 for both fast Fourier transform and autoregressive methods in all associations). Body mass index was negatively associated with high frequency, while it was positively associated with low frequency and sympatovagal balance (p values ranged from <0.001 to 0.007). Conclusion There are significant differences in heart rate variability parameters obtained with the fast Fourier transform and autoregressive methods in male adolescent; however, these differences are not clinically significant.

Effects of acute exposure to simulated altitude on heart rate variability during exercise

1996 ◽  
Vol 81 (3) ◽  
pp. 1223-1229 ◽  
Author(s):  
Y. Yamamoto ◽  
Y. Hoshikawa ◽  
M. Miyashita
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Nervous System ◽  
Harmonic Component ◽  
Acute Exposure ◽  
Total Power ◽  
Intensity Increase ◽  
Moderate Altitude ◽  
Simulated Altitude ◽  
Cardiac Autonomic Nervous System

It has been shown that fluctuation of human heartbeat intervals [heart rate variability (HRV)] reflects variations in cardiac autonomic nervous system activity. The present study was designed to investigate whether the acute exposure to moderate levels of simulated altitude and the resultant hypoxia could modify HRV during exercise. Seven healthy men completed one resting measurement in the upright sitting position and two submaximal steady-state cycle ergometer exercises at intensities equivalent to 25 and 50% of their estimated maximal work rate. Experiments were conducted in random order at altitude equivalents of 500, 1,500, 2,500, and 3,500 m within 2 h of exposure to that altitude. Beat-to-beat HRV was measured continuously during the tests. HRV data were analyzed by "coarse-graining spectral analysis" (Y. Yamamoto and R.L. Hughson, Physica 68D: 250-264, 1993) to break down their total power (PT) into harmonic and nonharmonic (fractal) components. The harmonic component was further divided into low (0.0- to 0.15-Hz; PL)- and high (> 0.15-Hz; PH)-frequency components, and the indicators of relative sympathetic (SNS) and parasympathetic (PNS) nervous system activities were calculated by PL/PH and PH/PT, respectively. The fractal component was used to calculate the spectral exponent (beta) to evaluate the overall "irregularity" of HRV. The effects of exercise intensity (increase in heart rate, SNS indicator, and beta and decrease in PNS indicator) were significant (P < 0.05) at all altitude levels. The altitude effects (increase in heart rate and SNS indicator and decrease in PNS indicator) were found only during exercise at 3,500 m (P < 0.05). There was no significant effect of altitude on beta (P > 0.05). These data indicate that acute effects of altitude exposure on HRV were found 1) during exercise at moderate altitude (> 2,500 m) and 2) mainly for the harmonic components of HRV.

scholarly journals Heart rate variability in women with essential hypertension under exposure of regular moderate physical training

2019 ◽  
Vol 16 (4) ◽  
pp. 61-64 ◽  
Author(s):  
Yuriy N Smolyakov ◽  
Boris I Kuznik ◽  
Ekaterina S Guseva ◽  
Sergey O Davydov
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Essential Hypertension ◽  
High Frequency ◽  
Low Frequency ◽  
Total Power ◽  
Vagal Activity ◽  
Frequency Range ◽  
Pronounced Increase ◽  
Respiratory Movements

The task of the study was to elucidate the effect of moderate exercise on heart rate variability (HRV) in women who regularly take kinesitherapy courses. Materials and methods. Studies were conducted on 72 women with essential hypertension (EH), divided into 2 subgroups: first (EH-1) included 37 women suffering from stage II EH and under medical therapy, the second (EH-2) consisted of patients who underwent along with medication treatment, regular courses of kinesitherapy. To evaluate the characteristics of HRV, a photoplethysmography method was used. The following indicators were used: SDRR is the standard deviation of all cardiointervals, RMSSD is the square root of the average sum of squares of cardiointerval differences, LF - is the oscillation power in the low frequency range, due to the activity of the sympathetic section, HF - is the power in the high frequency range, associated with respiratory movements and caused by vagal activity, LF/HF - is the power ratio, reflecting sympathetic balance, CVI - nonlinear parasympathetic index, CSI - nonlinear sympathetic index. Results. It was established that the average heart rate in women of both groups is approximately the same, while all other indicators (with the exception of LF/HF and CSI) were significantly higher in patients EH-2 group. In patients EH-2 group, there is a significantly larger value of SDRR, RMSSD, LF, HF. In the frequency analysis, no increase in the total power of cardiointerval oscillations and autonomic balance (LF/HF) was detected. A pronounced increase in the nonlinear parasympathetic index (CVI) has been shown, while the sympathetic index (CSI) remained unchanged. Conclusion. Regular use of kinesitherapy courses helps to increase the tone of the parasympathetic division of the autonomic nervous system, which is significantly depressed in EH.

scholarly journals Effects of exercise on heart rate variability by time-domain, frequency-domain and non-linear analyses in equine athletes

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 147 ◽  
Author(s):  
Ka Hou Christien Li ◽  
Rachel Wing Chuen Lai ◽  
Yimei Du ◽  
Vivian Ly ◽  
David Chun Yin Li ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Frequency Domain ◽  
Time Domain ◽  
High Frequency ◽  
Low Frequency ◽  
Total Power ◽  
Series Data ◽  
Non Linear ◽  
Term Fluctuation

Background: Heart rate variability (HRV) is an intrinsic property that reflects autonomic balance and has been shown to be predictive of all-cause and cardiovascular mortality. It can be altered by physiological states such as exercise or pathological conditions. However, there are only a handful of studies on HRV in horses. The aim of this study is to compare HRV parameters before and during exercise in horses. Methods: Time-domain, frequency-domain and non-linear analyses were applied to quantify time series data on RR intervals before and during exercise in horses (n=7). Results: Exercise increased heart rate from 44±8 to 113±17 bpm (ANOVA, P<0.05) and decreased standard deviation (SD) from 7±2 to 4±2 bpm, coefficient of variation (CoV) from 16±4% to 3±2% and root mean square of successive RR interval differences (RMSSD) from 89.4±91.5 to 6.5±3.7 ms. Contrastingly, no difference in low-frequency (0.10±0.03 vs. 0.09±0.03 Hz) and high-frequency (0.19±0.03 vs. 0.18±0.03 Hz) peaks, nor in their percentage powers (2±1 vs. 4±5%; 59±9 vs. 64±20%; 39±10 vs. 32±19%) were observed but very low-frequency, low-frequency, and high-frequency powers (ms2) were reduced from 29±17 to 2±5, 1138±372 to 22±22 and 860±564 to 9±6, respectively, as was total power (in logarithms) (7.52±0.52 to 3.25±0.73). Poincaré plots of RRn+1 against RRn revealed similar ellipsoid shapes before and after exercise. The SD along the line-of-identity (SD2) and SD perpendicular to the line-of-identity (SD1) were decreased by exercise (62±17 vs. 9±5 and 63±65 vs. 5±3), corresponding to increased SD2/SD1 ratio from 1.33±0.45 to 2.19±0.72. No change in approximate and sample entropy was detected (0.97±0.23 vs. 0.82±0.22 and 1.14±0.43 vs. 1.37±0.49). Detrended fluctuation analysis revealed unaltered short-term fluctuation slopes (0.76±0.27 vs. 1.18±0.55) but increased long-term fluctuation slopes (0.16±0.11 vs. 0.50±0.16) after exercise. Conclusion: Exercise leads to a decrease in HRV but did not affect signal entropy in horses.

Effect of adenosine on heart rate variability in humans

1999 ◽  
Vol 96 (6) ◽  
pp. 597-604 ◽  
Author(s):  
Gerard A. RONGEN ◽  
Steven C. BROOKS ◽  
Michael J. POLLARD ◽  
Shin-ichi ANDO ◽  
Hilmi R. DAJANI ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Intravenous Infusion ◽  
High Frequency ◽  
Stress Testing ◽  
Low Frequency ◽  
Total Power ◽  
Afferent Nerve Endings ◽  
Adenosine Stress Testing ◽  
Modest Effect

By stimulating afferent nerve endings in skeletal muscle, heart, kidney and the carotid body, adenosine infusion evokes a receptor-specific sympatho-excitatory reflex in humans that overrides its direct negative chronotropic effect. We tested the hypothesis that adenosine increases heart rate by suppressing parasympathetic and augmenting sympathetic components of heart rate variability. High-frequency (PH; 0.15-0.50 Hz) and low-frequency (PL; 0.05-0.15 Hz) components of heart rate variability total power (PT) were determined by spectral analysis. The ratios PH/PT and PL/PH respectively were used to estimate parasympathetic and sympathetic input to the sino-atrial node. Heart rate was recorded before and during a 5 min intravenous infusion of adenosine (140 μg·min-1·kg-1) in seven healthy men. Adenosine did not affect blood pressure, but increased heart rate by 33±6 beats/min, and reduced PT, PH, PL and PH/PT. In contrast, there was an increase in PL/PH. In a second experiment in nine men, brachial artery infusion of adenosine (15 μg·min-1·100 ml-1 forearm tissue) increased heart rate by 3 beats/min, had no effect on PT, PH, PL or PH/PT, yet increased PL/PH. Intra-arterial adenosine exerts a modest effect on heart rate by modulating cardiac sympathetic indices, without affecting parasympathetic indices, of heart rate variability, whereas intravenous infusion of adenosine reduces heart rate variability and raises heart rate by decreasing parasympathetic and increasing cardiac sympathetic tone. These reflex effects may become clinically relevant during adenosine stress testing, or when endogenous adenosine is increased, such as during ischaemia, exercise or vasodepressor reactions, or in heart failure.

Effects of Qi-Training on Heart Rate Variability

2002 ◽  
Vol 30 (04) ◽  
pp. 463-470 ◽  
Author(s):  
Myeong Soo Lee ◽  
Hwa Jeong Huh ◽  
Byung Gi Kim ◽  
Hoon Ryu ◽  
Ho-Sub Lee ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Nervous System ◽  
High Frequency ◽  
Parasympathetic Nervous System ◽  
Low Frequency ◽  
Autonomic Nervous ◽  
Nervous Function ◽  
Young Subjects

This study investigates changes in autonomic nervous function through Qi-training. The power spectrum of heart rate variability (HRV) was examined in 20 sedentary healthy subjects and 20 Qi-trainees. It was found that Qi-training in healthy young subjects during controlled respiration increases the high frequency (HF) power and decreases the low frequency / high frequency (LF/HF) power ratio of HRV. These results support the hypothesis that Qi-training increases cardiac parasympathetic tone. In addition, Qi-trainees were found to have higher parasympathetic heart modulation compared with their age-matched, sedentary counterparts. This augmented HRV in Qi-trainees provides further support for long-term Qi-training as a possible non-pharmacological cardio-protective maneuver. In conclusion, Qi-training may stabilize the autonomic nervous system by modulating the parasympathetic nervous system.

scholarly journals Assessment of autonomous nerve system through non-linear heart rate variability outcomes in sedentary healthy adults

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e10178
Author(s):  
Gines Navarro-Lomas ◽  
Alejandro De-la-O ◽  
Lucas Jurado-Fasoli ◽  
Manuel J. Castillo ◽  
Pedro Femia ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Nervous System ◽  
Autonomic Nervous System ◽  
Regression Model ◽  
High Frequency ◽  
Low Frequency ◽  
Healthy Adults ◽  
Non Linear ◽  
Stress Score

Background Heart rate variability (HRV) is a psycho-physiological phenomenon with broad health implications. Different data analysis methods have been used to assess the autonomic nervous system activity, but the validation of new indexes that accurately describe its balance through non-invasive methods (i.e., HRV analysis) is of clinical interest. This study aimed: (i) to evaluate the association of the Stress Score (SS) and the Sympathetic/Parasympathetic Ratio (S/PS) with time domain and frequency domain analysis of HRV, and (ii) to set reference values of SS and S/PS in sedentary healthy adults. Methods A total of 156 sedentary healthy adults (38.4 ± 15.57 years old, 81 women), aged were involved in this study. HRV was measured for 15 min in a supine position at rest. SS and S/PS were calculated from the non-linear HRV analyses based on Poincare Plot. Results Stress Score showed a non-linear negative power-law relationship with SDNN (β = −0.969; R2 = 0.963; P < 0.001), RMSSD (β = −0.867; R2 = 0.722; P < 0.001), high frequency (β = −0.834; R2 = 0.752; P =< 0.001), low frequency (β = −0.627; R2 = 0.330; P < 0.001), SD1 (β = −0.867; R2 = 0.722; P < 0.001) and SD2 (β = −1.000; R2 > 0.999; P < 0.001). There was observed a negative cubic relationship between SS with PNN50 (β = −1.972; R2 = 0.644; P < 0.001). A linear regression model was conducted between SS with Ratio Low/High Frequency (β = 0.026; R2 < 0.001; P = 0.750). Non-linear power-law regression models were built between S/PS and SDNN (β = −0.990; R2 = 0.981; P < 0.001), RMSSD (β = −0.973; R2 = 0.939; P < 0.001), high frequency (β = −0.928; R2 = 0.970; P < 0.001), low frequency (β = −2.344; R2 = 0.557; P < 0.001), SD1 (β = −0.973; R2 = 0.939; P < 0.001) and SD2 (β = −0.611; R2 = 0.908; P < 0.001). A non-linear negative regression model was built between S/PS and PNN50 (β = −3.412; R2 = 0.868; P < 0.001). A linear regression model was conducted between S/PS and SD2/SD1 (β = 0.075; R2 = 0.006; P < 0.001). Conclusion Our results support the use of SS as a sympathetic activity marker, and S/PS as an indicator of the sympathetic and parasympathetic activity of the autonomic nervous system in sedentary healthy adults.

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