Vagal function impairment after exercise training

1992 ◽  
Vol 72 (5) ◽  
pp. 1749-1753 ◽  
Author(s):  
C. E. Negrao ◽  
E. D. Moreira ◽  
M. C. Santos ◽  
V. M. Farah ◽  
E. M. Krieger
Keyword(s):  
Heart Rate ◽  
Electrical Stimulation ◽  
Exercise Training ◽  
Marked Reduction ◽  
Resting Heart Rate ◽  
Pacemaker Cells ◽  
Function Impairment ◽  
Stimulation Of ◽  
Vagal Function

The present investigation was undertaken to evaluate the vagal function of trained (T) and sedentary (S) rats by use of different approaches in the same animal. After 13 wk of exercise training (treadmill for 1 h 5 times/wk at 26.8 m/min and 15% grade), T rats had a resting heart rate (HR) slightly but significantly lower than S rats (299 +/- 3 vs. 308 +/- 3 beats/min). T rats had marked reduction of the intrinsic HR (329 +/- 4 vs. 369 +/- 5 beats/min) after blockade by methylatropine and propranolol. They also exhibited depressed vagal and sympathetic tonus. Baroreflex bradycardia (phenylephrine injections) was reduced, bradycardic responses produced by electrical stimulation of the vagus were depressed, and responses to methacholine injection were decreased in T rats. Therefore several evidences of vagal function impairment were observed in T rats. The resting bradycardia after exercise training is more likely to be dependent on alterations of the pacemaker cells, inasmuch as the intrinsic HR was markedly reduced.

Electrical stimulation of the carotid sinus lowers arterial pressure and improves heart rate variability in l-NAME hypertensive conscious rats

2020 ◽  
Vol 43 (10) ◽  
pp. 1057-1067 ◽  
Author(s):  
Gean Domingos-Souza ◽  
Fernanda Machado Santos-Almeida ◽  
César Arruda Meschiari ◽  
Nathanne S. Ferreira ◽  
Camila A. Pereira ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Carotid Sinus ◽  
Conscious Rats ◽  
Stimulation Of

Controlled 5-mo aerobic training improves heart rate but not heart rate variability or baroreflex sensitivity

2000 ◽  
Vol 89 (5) ◽  
pp. 1825-1829 ◽  
Author(s):  
Antti Loimaala ◽  
Heikki Huikuri ◽  
Pekka Oja ◽  
Matti Pasanen ◽  
Ilkka Vuori
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Exercise Training ◽  
High Intensity ◽  
Baroreflex Sensitivity ◽  
Aerobic Training ◽  
Control Group ◽  
Resting Heart Rate ◽  
Endurance Time ◽  
Low Intensity

Endurance-trained athletes have increased heart rate variability (HRV), but it is not known whether exercise training improves the HRV and baroreflex sensitivity (BRS) in sedentary persons. We compared the effects of low- and high-intensity endurance training on resting heart rate, HRV, and BRS. The maximal oxygen uptake and endurance time increased significantly in the high-intensity group compared with the control group. Heart rate did not change significantly in the low-intensity group but decreased significantly in the high-intensity group (−6 beats/min, 95% confidence interval; −10 to −1 beats/min, exercise vs. control). No significant changes occurred in either the time or frequency domain measures of HRV or BRS in either of the exercise groups. Exercise training was not able to modify the cardiac vagal outflow in sedentary, middle-aged persons.

Inhibition of renal sympathetic nervous activity by area postrema stimulation in rabbits

1987 ◽  
Vol 253 (1) ◽  
pp. H91-H99 ◽  
Author(s):  
E. M. Hasser ◽  
D. O. Nelson ◽  
J. R. Haywood ◽  
V. S. Bishop
Keyword(s):  
Heart Rate ◽  
Electrical Stimulation ◽  
Arterial Pressure ◽  
Nucleus Tractus Solitarius ◽  
Area Postrema ◽  
Nervous Activity ◽  
Sympathetic Nervous Activity ◽  
Consistent Change ◽  
Renal Sympathetic ◽  
Stimulation Of

This study investigated the effect of chemical and electrical stimulation of the area postrema on renal sympathetic nerve activity (RSNA), arterial pressure, and heart rate in urethan-anesthetized rabbits. Electrical stimulation of the area postrema at 2, 5, 10, 20, 40, and 80 Hz using constant currents of 7.5, 15, and 30 microA (pulse duration = 0.3 ms, train duration = 5 s) produced progressive decreases in RSNA and heart rate, with no consistent change in arterial pressure. To control for electrical activation of fibers of passage in or near the area postrema, L-glutamate was injected into the area postrema using glass micropipettes. Micropressure injection of L-glutamate (10 mM) in volumes of 5-10 nl produced rapid decreases in RSNA averaging 27 +/- 5% (P less than 0.05) accompanied by a small bradycardia. The effects of electrical stimulation of the area postrema, but not the adjacent nucleus tractus solitarius, were totally eliminated by micropressure injection of kainic acid (40 ng in 40 nl) into the area postrema. During continuous electrical stimulation of the area postrema using parameters that produced small decrements in RSNA and heart rate, the slope of the line relating baroreflex inhibition of RSNA to increases in arterial pressure during graded infusions of phenylephrine was significantly enhanced (-6.77 +/- 1.30 vs. -3.81 +/- 0.66% RSNA/mmHg). These data are consistent with the hypothesis that activation of neurons in the area postrema results in an inhibition of RSNA. Furthermore, stimulation of the area postrema augments baroreflex inhibition of RSNA during increases in arterial pressure with phenylephrine.

Determination of minimal recording period to assess resting heart rate variability during pregnancy

2020 ◽  
Vol 45 (4) ◽  
pp. 431-436
Author(s):  
Danilo Fernandes da Silva ◽  
Shuhiba Mohammad ◽  
Kelly Ann Hutchinson ◽  
Kristi Bree Adamo
Keyword(s):  
Heart Rate ◽  
Heart Rate Variability ◽  
Exercise Training ◽  
Pregnant Women ◽  
Resting Heart Rate ◽  
Time Segment ◽  
Natural Logarithm ◽  
Resting Heart Rate Variability ◽  
Measurement Period

Traditionally, resting heart rate variability (rHRV) is measured for 10 min using the last 5 min for analyses (e.g., criterion period). It is unknown whether the measurement period can be shortened in pregnant women as there are currently no established standards. We aimed to compare shorter time segments (e.g., from the 1st to 10th minutes) of the parasympathetic index natural logarithm transformation of root mean square of successive R–R differences (Ln rMSSD) with the criterion period in pregnant and nonpregnant women. Twelve pregnant (age: 30.8 ± 3.4 years; gestational age: 20.1 ± 5.0 weeks) and 15 nonpregnant women (age: 29.8 ± 4.0 years) were included. rHRV was measured using a portable heart rate monitor for 10 min while sitting. Ln rMSSD difference/agreement between shorter time segments and criterion period was analyzed. The result observed between the 4th–5th minutes was the shortest time segment not different from/highly agreed with the criterion period in pregnant women (difference [95% confidence interval (CI)]: −0.10 [−0.22 to 0.02]/bias ± 1.96 × SD: −0.06 [−0.38 to 0.25]). In nonpregnant women, the 2nd–3rd-minute segment was the shortest with similar results (difference [95% CI]: −0.04 [−0.15 to 0.07]/bias ± 1.96 × SD: −0.03 [−0.39 to 0.32]). The Ln rMSSD was found to be stable from the 5th–10th minutes and the 3rd–10th minutes in pregnant and nonpregnant women, respectively. A shortened rHRV assessment can increase its applicability in clinical/exercise-training settings. Novelty Ln rMSSD can be measured for 5 min in pregnant women, with the last 1-min segment analyzed. The last 1-min segment from 3 min can be used for rHRV measurement in nonpregnant women. The shortened rHRV assessment can facilitate its applicability in clinical/exercise-training settings.

Endurance exercise training has a minimal effect on resting heart rate: the HERITAGE study

1996 ◽  
Vol 28 (7) ◽  
pp. 829-835 ◽  
Author(s):  
JACK H. WILMORE ◽  
PHILIP R. STANFORTH ◽  
JACQUES GAGNON ◽  
ARTHUR S. LEON ◽  
D. C. RAO ◽  
...  
Keyword(s):  
Heart Rate ◽  
Exercise Training ◽  
Endurance Exercise ◽  
Minimal Effect ◽  
Resting Heart Rate ◽  
Endurance Exercise Training
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