Low-intensity exercise training decreases cardiac output and hypertension in spontaneously hypertensive rats

1997 ◽  
Vol 273 (6) ◽  
pp. H2627-H2631 ◽  
Author(s):  
Acácio Salvador Véras-Silva ◽  
Katt Coelho Mattos ◽  
Nilo Sérgio Gava ◽  
Patricia Chakur Brum ◽  
Carlos Eduardo Negrão ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Exercise Training ◽  
High Intensity ◽  
Peripheral Resistance ◽  
High Intensity Exercise ◽  
Spontaneously Hypertensive ◽  
Low Intensity ◽  
Low Intensity Exercise

The decrease in cardiac sympathetic tone and heart rate after low-intensity exercise training may have hemodynamic consequences in spontaneously hypertensive rats (SHR). The effects of exercise training of low and high intensity on resting blood pressure, cardiac output, and total peripheral resistance were studied in sedentary ( n = 17), low- ( n = 17), and high-intensity exercise-trained ( n = 17) SHR. Exercise training was performed on a treadmill for 60 min, 5 times per week for 18 weeks, at 55% or 85% maximum oxygen uptake. Blood pressure was evaluated by a cannula inserted into the carotid artery, and cardiac output was evaluated by a microprobe placed around the ascending aorta. Low-intensity exercise-trained rats had a significantly lower mean blood pressure than sedentary and high-intensity exercise-trained rats (160 ± 4 vs. 175 ± 3 and 173 ± 2 mmHg, respectively). Cardiac index (20 ± 1 vs. 24 ± 1 and 24 ± 1 ml ⋅ min−1 ⋅ 100 g−1, respectively) and heart rate (332 ± 6 vs. 372 ± 14 and 345 ± 9 beats/min, respectively) were significantly lower in low-intensity exercise-trained rats than in sedentary and high-intensity exercise-trained rats. No significant difference was observed in stroke volume index and total peripheral resistance index in all groups studied. In conclusion, low-intensity, but not high-intensity, exercise training decreases heart rate and cardiac output and, consequently, attenuates hypertension in SHR.

scholarly journals Effect of Chair aerobics as low intensity exercise training on heart rate, blood pressure and six minute walk distance in post coronary artery bypass graft surgery patients through phase I cardiac rehabilitation

2016 ◽  
Vol 13 (1) ◽  
pp. 19-23
Author(s):  
Shaili Thapa ◽  
Renu B. Pattanshetty
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Exercise Training ◽  
Cardiac Rehabilitation ◽  
Phase I ◽  
Walk Distance ◽  
Low Intensity ◽  
Low Intensity Exercise ◽  
Minute Walk Distance ◽  
Minute Walk

Background and Aims: Cardiac Rehabilitation after Coronary arteries bypass graft (CABG) surgery is known to have several favorable effects. Aerobics exercise in the form of chair aerobics shown to have beneficial effects with little evidence. The purpose of the present study was to demonstrate the effect of chair aerobics as low intensity exercise training in heart rate, blood pressure and six minute walk distance in post CABG patients during phase I cardiac rehabilitation.   Methods: It was a single centre, prospective study carried out in Indian tertiary care set-up. Fifty patients post CABG patients were included. Chair aerobics as a low intensity exercise training was given.  Pre and post-exercise outcome measurements in the form of heart rate, blood pressure and six-minute walk distance test were recorded. Results: The study showed statistically significant difference in systolic blood pressure (p= 0.018), heart rate (p≤0.001) and increase in six minute walk distance (p≤0.001). Conclusion: Chair aerobics as low intensity exercise training demonstrated improvement in heart  rate, systolic blood pressure and six minute walk distance test in subjects with CABG through phase I  cardiac rehabilitation.  Nepalese Heart Journal 2016; 13(1) 19-23

scholarly journals Effect of exercise training at different intensities on fat metabolism of obese men

2002 ◽  
Vol 92 (3) ◽  
pp. 1300-1309 ◽  
Author(s):  
Dorien P. C. Van Aggel-Leijssen ◽  
Wim H. M. Saris ◽  
Anton J. M. Wagenmakers ◽  
Joan M. Senden ◽  
Marleen A. Van Baak
Keyword(s):  
Exercise Training ◽  
High Intensity ◽  
Fat Metabolism ◽  
Fat Oxidation ◽  
High Intensity Exercise ◽  
Control Group ◽  
Low Intensity ◽  
Obese Subjects ◽  
Total Fat ◽  
Low Intensity Exercise

The present study investigated the effect of exercise training at different intensities on fat oxidation in obese men. Twenty-four healthy male obese subjects were randomly divided in either a low- [40% maximal oxygen consumption (V˙o 2 max)] or high-intensity exercise training program (70%V˙o 2 max) for 12 wk, or a nonexercising control group. Before and after the intervention, measurements of fat metabolism at rest and during exercise were performed by using indirect calorimetry, [U-13C]palmitate, and [1,2-13C]acetate. Furthermore, body composition and maximal aerobic capacity were measured. Total fat oxidation did not change at rest in any group. During exercise, after low-intensity exercise training, fat oxidation was increased by 40% ( P < 0.05) because of an increased non-plasma fatty acid oxidation ( P < 0.05). High-intensity exercise training did not affect total fat oxidation during exercise. Changes in fat oxidation were not significantly different among groups. It was concluded that low-intensity exercise training in obese subjects seemed to increase fat oxidation during exercise but not at rest. No effect of high-intensity exercise training on fat oxidation could be shown.

Phenylephrine decreases frontal lobe oxygenation at rest but not during moderately intense exercise

2010 ◽  
Vol 108 (6) ◽  
pp. 1472-1478 ◽  
Author(s):  
Patrice Brassard ◽  
Thomas Seifert ◽  
Mads Wissenberg ◽  
Peter M. Jensen ◽  
Christian K. Hansen ◽  
...  
Keyword(s):  
Frontal Lobe ◽  
High Intensity ◽  
Sympathetic Activity ◽  
Near Infrared ◽  
Cerebral Metabolism ◽  
High Intensity Exercise ◽  
Mean Flow ◽  
Intense Exercise ◽  
Low Intensity ◽  
Low Intensity Exercise

Whether sympathetic activity influences cerebral blood flow (CBF) and oxygenation remains controversial. The influence of sympathetic activity on CBF and oxygenation was evaluated by the effect of phenylephrine on middle cerebral artery (MCA) mean flow velocity ( Vmean) and the near-infrared spectroscopy-derived frontal lobe oxygenation (ScO2) at rest and during exercise. At rest, nine healthy male subjects received bolus injections of phenylephrine (0.1, 0.25, and 0.4 mg), and changes in mean arterial pressure (MAP), MCA Vmean, internal jugular venous O2 saturation (SjvO2), ScO2, and arterial Pco2 (PaCO2) were measured and the cerebral metabolic rate for O2 (CMRO2) was calculated. In randomized order, a bolus of saline or 0.3 mg of phenylephrine was then injected during semisupine cycling, eliciting a low (∼110 beats/min) or a high (∼150 beats/min) heart rate. At rest, MAP and MCA Vmean increased ∼20% ( P < 0.001) and ∼10% ( P < 0.001 for 0.25 mg of phenylephrine and P < 0.05 for 0.4 mg of phenylephrine), respectively. ScO2 then decreased ∼7% ( P < 0.001). Phenylephrine had no effect on SjvO2, PaCO2, or CMRO2. MAP increased after the administration of phenylephrine during low-intensity exercise (∼15%), but this was attenuated (∼10%) during high-intensity exercise ( P < 0.001). The reduction in ScO2 after administration of phenylephrine was attenuated during low-intensity exercise (−5%, P < 0.001) and abolished during high-intensity exercise (−3%, P = not significant), where PaCO2 decreased 7% ( P < 0.05) and CMRO2 increased 17% ( P < 0.05). These results suggest that the administration of phenylephrine reduced ScO2 but that the increased cerebral metabolism needed for moderately intense exercise eliminated that effect.

Characterization of baroreflex impairment in conscious dogs with pacing-induced heart failure

1993 ◽  
Vol 265 (5) ◽  
pp. R1132-R1140 ◽  
Author(s):  
N. B. Olivier ◽  
R. B. Stephenson
Keyword(s):  
Heart Failure ◽  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Peripheral Resistance ◽  
Open Loop ◽  
Ventricular Pacing ◽  
Baroreflex Control ◽  
Rapid Ventricular Pacing ◽  
Reflex Control

Open-loop baroreflex responses were evaluated in eight conscious dogs before and during congestive heart failure to determine the effects of failure on baroreflex control of blood pressure, heart rate, cardiac output, and total peripheral resistance. Heart failure was induced by rapid ventricular pacing. Baroreflex function was determined by calculation of the range and gain of the open-loop stimulus-response relationships for the effect of carotid sinus pressure on blood pressure, heart rate, cardiac output, and total peripheral resistance. The range and gain of blood pressure responses were substantially reduced as early as 3 days after induction of heart failure (161 +/- 6 to 99 +/- 8 mmHg and -2.7 +/- 0.3 to -1.5 +/- 0.1, respectively) and remained depressed for the 21 days of heart failure. This depression in baroreflex control of blood pressure was associated with similar depressions in reflex range and gain for heart rate (125 +/- 9 to 78 +/- 11 beats/min and -2.05 +/- 0.2 to -1.16 +/- 0.2 beats/min, respectively) and cardiac output (1.74 +/- 0.2 to 0.46 +/- 0.2 l/min and -0.81 +/- 0.02 to -0.027 +/- 0.008 l/min, respectively). The group-averaged range and gain for reflex control of vascular resistance were not altered by heart failure. In three dogs, discontinuation of rapid ventricular pacing led to resolution of heart failure within 7 days and partial restoration of the range and gain of reflex control of blood pressure. We conclude that heart failure reversibly depresses baroreflex control of blood pressure principally through a concurrent reduction in reflex control of cardiac output, whereas reflex control of vascular resistance is not consistently affected.

scholarly journals Psychological distress and its associated risk factors among university students

2020 ◽  
Vol 66 (4) ◽  
pp. 414-418
Author(s):  
Tingting Li ◽  
Xu Zhang ◽  
Mingming Chen ◽  
Rui Wang ◽  
Lianping He ◽  
...  
Keyword(s):  
Risk Factors ◽  
Psychological Distress ◽  
University Students ◽  
High Intensity ◽  
Education Level ◽  
High Intensity Exercise ◽  
Low Intensity ◽  
Significant Difference ◽  
Associated Risk Factors ◽  
Low Intensity Exercise

SUMMARY OBJECTIVE Psychological distress is an important mental health problem among university students. The goal of this study was to determine psychological distress and its associated risk factors among students in the Anhui province. METHODS A cross-sectional study was conducted in a sample of 1304 students. In this study, a self-administered questionnaire consisting of the general demography and General Health Questionnaire (GHQ-12) was completed. Psychological distress was assessed using the GHQ-12-item questionnaire. A dichotomous category split was imposed on the GHQ-12 for the purpose of analysis. A GHQ-12 score of 4 or higher indicated psychological distress. The data were analyzed by SPSS 20.0 system. RESULTS A total of 1304 samples were analyzed in this study. The results indicated that the education level of the father and mother was associated with the students’ psychological distress (P<0.001). A significant association was found between high-intensity exercise and low-intensity exercise and psychological distress. However, no significant difference was identified between gender and psychological distress (P=0.173). CONCLUSION The education level of parents, high-intensity exercise, and low-intensity exercise were associated with psychological distress. Our results suggest that it is indispensable to raise awareness of psychological disorders and its associated risk factors among university students. Further studies are required to develop appropriate interventions for high-risk groups.

Pet CO2 inversely affects MSNA response to orthostatic stress

2001 ◽  
Vol 281 (3) ◽  
pp. H1040-H1046 ◽  
Author(s):  
J. Kevin Shoemaker ◽  
Debbie D. O'Leary ◽  
Richard L. Hughson
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Orthostatic Intolerance ◽  
Muscle Sympathetic Nerve Activity ◽  
Peripheral Resistance ◽  
Burst Frequency ◽  
Head Up Tilt ◽  
End Tidal ◽  
Combined Data

Arterial hypocapnia has been associated with orthostatic intolerance. Therefore, we tested the hypothesis that hypocapnia may be detrimental to increases in muscle sympathetic nerve activity (MSNA) and total peripheral resistance (TPR) during head-up tilt (HUT). Ventilation was increased ∼1.5 times above baseline for each of three conditions, whereas end-tidal Pco 2 (Pet CO2 ) was clamped at normocapnic (Normo), hypercapnic (Hyper; +5 mmHg relative to Normo), and hypocapnic (Hypo; −5 mmHg relative to Normo) conditions. MSNA (microneurography), heart rate, blood pressure (BP, Finapres), and cardiac output (Q, Doppler) were measured continuously during supine rest and 45° HUT. The increase in heart rate when changing from supine to HUT ( P < 0.001) was not different across Pet CO2 conditions. MSNA burst frequency increased similarly with HUT in all conditions ( P < 0.05). However, total MSNA and the increase in total amplitude relative to baseline (%ΔMSNA) increased more when changing to HUT during Hypo compared with Hyper ( P < 0.05). Both BP and Q were higher during Hyper than both Normo and Hypo (main effect; P < 0.05). Therefore, the MSNA response to HUT varied inversely with levels of Pet CO2 . The combined data suggest that augmented cardiac output with hypercapnia sustained blood pressure during HUT leading to a diminished sympathetic response.

Effect of sympathetic blockade on diurnal variation of hemodynamic patterns

1989 ◽  
Vol 256 (3) ◽  
pp. R778-R785 ◽  
Author(s):  
M. I. Talan ◽  
B. T. Engel
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Stroke Volume ◽  
Total Peripheral Resistance ◽  
Peripheral Resistance ◽  
Base Line ◽  
Sympathetic Blockade ◽  
Selective Blockade ◽  
Arterial Blood

Heart rate, stroke volume, and intra-arterial blood pressure were monitored continuously in each of four monkeys, 18 consecutive h/day for several weeks. The mean heart rate, stroke volume, cardiac output, systolic and diastolic blood pressure, and total peripheral resistance were calculated for each minute and reduced to hourly means. After base-line data were collected for approximately 20 days, observation was continued for equal periods of time under conditions of alpha-sympathetic blockade, beta-sympathetic blockade, and double sympathetic blockade. This was achieved by intra-arterial infusion of prazosin, atenolol, or a combination of both in concentration sufficient for at least 75% reduction of response to injection of agonists. The results confirmed previous findings of a diurnal pattern characterized by a fall in cardiac output and a rise in total peripheral resistance throughout the night. This pattern was not eliminated by selective blockade, of alpha- or beta-sympathetic receptors or by double sympathetic blockade; in fact, it was exacerbated by sympathetic blockade, indicating that the sympathetic nervous system attenuates these events. Because these findings indicate that blood volume redistribution is probably not the mechanism mediating the observed effects, we have hypothesized that a diurnal loss in plasma volume may mediate the fall in cardiac output and that the rise in total peripheral resistance reflects a homeostatic regulation of arterial pressure.

Carotid baroreceptor control of liver and spleen volume in cats

1991 ◽  
Vol 260 (1) ◽  
pp. H254-H259
Author(s):  
R. Maass-Moreno ◽  
C. F. Rothe
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Arterial Blood Pressure ◽  
Total Peripheral Resistance ◽  
Venous Pressure ◽  
Peripheral Resistance ◽  
Normal Brain ◽  
Spleen Volume ◽  
Arterial Blood

We tested the hypothesis that the blood volumes of the spleen and liver of cats are reflexly controlled by the carotid sinus (CS) baroreceptors. In pentobarbital-anesthetized cats the CS area was isolated and perfused so that intracarotid pressure (Pcs) could be controlled while maintaining a normal brain blood perfusion. The volume changes of the liver and spleen were estimated by measuring their thickness using ultrasonic techniques. Cardiac output, systemic arterial blood pressure (Psa), central venous pressure, central blood volume, total peripheral resistance, and heart rate were also measured. In vagotomized cats, increasing Pcs by 100 mmHg caused a significant reduction in Psa (-67.8%), cardiac output (-26.6%), total peripheral resistance (-49.5%), and heart rate (-15%) and significantly increased spleen volume (9.7%, corresponding to a 2.1 +/- 0.5 mm increase in thickness). The liver volume decreased, but only by 1.6% (0.6 +/- 0.2 mm decrease in thickness), a change opposite that observed in the spleen. The changes in cardiovascular variables and in spleen volume suggest that the animals had functioning reflexes. These results indicate that in pentobarbital-anesthetized cats the carotid baroreceptors affect the volume of the spleen but not the liver and suggest that, although the spleen has an active role in the control of arterial blood pressure in the cat, the liver does not.

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.

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