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.

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 Assessment of the impact of 10-day intermittent hypoxia on the autonomic control measured by heart rate variability

2018 ◽  
Vol 105 (4) ◽  
pp. 386-396 ◽  
Author(s):  
ZZ Taralov ◽  
KV Terziyski ◽  
PK Dimov ◽  
BI Marinov ◽  
SS Kostianev
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Nervous System ◽  
Parasympathetic Nervous System ◽  
Autonomic Control ◽  
Total Power ◽  
Hypoxic Exposure ◽  
Intermittent Hypoxic Training ◽  
Parasympathetic Nervous System Activity ◽  
The Impact

Purpose The purpose of this study is to establish the alterations in the activity of the autonomic nervous system (ANS) via heart rate variability (HRV) in subjects exposed to 1 h of exogenous hypoxia for 10 consecutive days. Methods Twelve healthy non-smoker males at mean age of 29.8 ± 7.4 (mean ± SD) breathed hypoxic air delivered through hypoxicator (FiО2 = 12.3% ± 1.5%) for 1 h in 10 consecutive days. Pulse oximetry and electrocardiography were monitored during the visit and HRV was calculated for the entire 1-h hypoxic period. Results Comparing the last hypoxic visit to the first, subjects had higher standard deviation of normal-to-normal interbeat intervals (SDNNs) (65.7 ± 32.5 vs. 81.1 ± 32.0 ms, p = 0.013) and root mean square of successive R–R interval difference (RMSSD) (58.1 ± 30.9 vs. 76.5 ± 34.6 ms, p = 0.029) as well as higher lnTotal power (8.1 ± 1.1 vs. 8.5 ± 0.9 ms2, p = 0.015) and high frequency (lnHF) (6.8 ± 1.3 vs. 7.5 ± 1.2 ms2, p = 0.05) and lower LF/HF (2.4 ± 1.4 vs. 1.5 ± 1.0, p = 0.026). Changes in saturation (87.0 ± 7.1 vs. 90.8 ± 5.0%, p = 0.039) and heart rate (67.1 ± 8.9 vs. 62.5 ± 6.0 beats/min, p = 0.040) were also observed. Conclusions Intermittent hypoxic training consisting of 1-h hypoxic exposure for 10 consecutive days could diminish the effects of acute exogenous hypoxia on the ANS characterized by an increased autonomic control (SDNN and total power) with augmentation of the parasympathetic nervous system activity (increased RMSSD and HF and decreased LF/HF). Therefore, it could be applied as a pre-acclimatization technique aiming at an increase in the autonomic control and oxygen saturation in subjects with upcoming sojourn to high altitude.

Heart Rate Variability before and after Knee Surgery in Amateur Soccer Players

2007 ◽  
Vol 16 (4) ◽  
pp. 336-342
Author(s):  
Nicolas Olivier ◽  
Renaud Legrand ◽  
Jacques Rogez ◽  
FX Gamelin ◽  
Serge Berthoin ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Nervous System ◽  
Autonomic Nervous System ◽  
Knee Surgery ◽  
Soccer Players ◽  
Total Power ◽  
Autonomic Nervous ◽  
Hospitalization Period ◽  
Before And After

Objective:To analyze the consequences on heart rate variability (HRV) of a hospitalization period due to surgery of the knee in sportsmen.Patients:Ten soccer players who had undergone knee surgery took part in this study.Design:HRV was measured before and after hospitalization within a 7-day interval.Results:After the hospitalization phase, heart rate at rest increased significantly (3 beats/minute). A significant decrease of 7% in the cardiac inter beat interval (R-R interval), P < 0.05 and a 66% decrease in total power spectral density: −66%, P < 0.05 were observed. The disturbance of the autonomic nervous system could be due to a variation in cardiac vagal activity resulting in a 64% decrease in the high frequencies (P < 0.05). This variation was not associated with a modification in normalized markers (LFn.u., HFn.u.) and LF/HF ratio (P > 0.05).Conclusion:In sportsmen, a hospitalization period led to an increase in resting heart rate and was associated with a disturbance of the autonomic nervous system.

On the fractal nature of heart rate variability in humans: effects of vagal blockade

1995 ◽  
Vol 269 (4) ◽  
pp. R830-R837 ◽  
Author(s):  
Y. Yamamoto ◽  
Y. Nakamura ◽  
H. Sato ◽  
M. Yamamoto ◽  
K. Kato ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Harmonic Component ◽  
Coarse Graining ◽  
Normal Subjects ◽  
Atropine Sulfate ◽  
Total Power ◽  
Scaling Exponent ◽  
Fractal Nature ◽  
Mean Values

The purpose of the present study was to investigate the effects of the vagal blocker atropine on the fractal nature of human heart rate variability (HRV) at rest. Approximately 10-min segments of beat-to-beat heartbeat intervals, i.e., HRV, of 10 normal subjects and 11 cardiac disease patients were measured before and after intravenous injection of 0.5-0.75 mg atropine sulfate. 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 into harmonic and nonharmonic (fractal) components. The harmonic component was used to calculate the contribution of high (> 0.15 Hz)-frequency components to total HRV power (%HF). From the fractal component, the contribution of the fractal component to total HRV power (%fractal), the spectral exponent beta, and Hurst scaling exponent (H) were calculated. For both normal subjects and cardiac patients, atropine resulted in significantly (P < 0.05) less mean HRV and significantly (P < 0.05) greater beta compared with control, whereas mean values for %fractal were as high as 70% and were not significantly (P > 0.05) different between atropine and control. The mean value of H with atropine was significantly (P < 0.05) greater than that for control. Directional changes in %HF and beta were consistent with only one exception for a patient who had the smallest change in log %HF by atropine. The normally irregular fractal pattern of resting HRV was decreased by atropine as shown by the decrease in %HF and the increase in beta.(ABSTRACT TRUNCATED AT 250 WORDS)

Nonlinear Analysis of Heart Rate Variability During Qi Therapy (External Qigong)

2005 ◽  
Vol 33 (04) ◽  
pp. 579-588 ◽  
Author(s):  
Myeong Soo Lee ◽  
Young Hoon Rim ◽  
Dong-Myong Jeong ◽  
Mo Kyung Kim ◽  
Min Cheol Joo ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Nervous System ◽  
Autonomic Nervous System ◽  
Nonlinear Analysis ◽  
Control Group ◽  
Placebo Control ◽  
Poincaré Plot ◽  
Cardiac Autonomic Nervous System ◽  
Autonomic Nervous

Heart rate variability (HRV) was compared in 30 subjects receiving external Qi therapy (EQT) or placebo control therapy, in a crossover design experiment. Subjects who received the EQT reported more pleasant and calm emotions than did the placebo group. Qi therapy reduced the heart rate and increased HRV as indicated by a reduced low frequency/high frequency power ratio of HRV. With nonlinear analysis, the Poincaré plot index of HRV and approximate entropy was greater in the EQT group than in the control group. These findings suggest that EQT stabilizes the sympathovagal function and cardiac autonomic nervous system by inducing more positive emotions than the placebo therapy. In conclusion, EQT may act by stabilizing both the autonomic nervous system and the emotional state.

Sign in / Sign up

Export Citation Format

Share Document