scholarly journals Physiological determinants of the increase in oxygen consumption during exercise in individuals with stroke

2019 ◽  
Author(s):  
Kazuaki Oyake ◽  
Yasuto Baba ◽  
Nao Ito ◽  
Yuki Suda ◽  
Jun Murayama ◽  
...  
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Tidal Volume ◽  
Cardiorespiratory Fitness ◽  
Ventilatory Threshold ◽  
Peak Exercise ◽  
Cardiorespiratory Response ◽  
Graded Exercise ◽  
Response To Exercise ◽  
Oxygen Difference

AbstractBackgroundUnderstanding the physiological limitations of the increase in oxygen consumption (V̇O2) during exercise is essential to improve cardiorespiratory fitness in individuals with stroke. However, the physiological determinants of the increase in V̇O2 during exercise have not been examined using multivariate analysis in individuals with stroke. This study aimed to identify the physiological determinants of the increase in V̇O2 during a graded exercise in terms of the respiratory function, cardiac function, and ability of skeletal muscles to extract oxygen.MethodsEighteen individuals with stroke (60.1 ± 9.4 years of age, 67.1 ± 30.8 days poststroke) underwent a graded exercise test for the assessment of cardiorespiratory response to exercise. The increase in V̇O2 from rest to ventilatory threshold and that from rest to peak exercise were measured as a dependent variable. The increases in respiratory rate, tidal volume, heart rate, stroke volume, and arterial-venous oxygen difference from rest to ventilatory threshold and those from rest to peak exercise were measured as independent variables.ResultsFrom rest to ventilatory threshold, the increases in heart rate (β = 0.546) and arterial-venous oxygen difference (β = 0.398) were significant determinants of the increase in V̇O2 (adjusted R2 = 0.703, p < 0.001). From rest to peak exercise, the increases in tidal volume (β = 0.611) and heart rate (β = 0.353) were significant determinants of the increase in V̇O2 (adjusted R2 = 0.702, p < 0.001).ConclusionV̇O2 is well-known to increase nearly linearly with increasing heart rate; however, our results suggest that arterial-venous oxygen difference and tidal volume are also significant physiological determinants of the increase in V̇O2 from rest to ventilatory threshold and that from rest to peak exercise, respectively. Our findings could potentially contribute to the development of appropriate therapies to improve cardiorespiratory fitness in individuals with stroke.

Cardiovascular response to graded exercise in the sympathectomized-vagotomized dog

1963 ◽  
Vol 204 (2) ◽  
pp. 291-296 ◽  
Author(s):  
Edmundo Ashkar ◽  
William F. Hamilton
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Mean Arterial Pressure ◽  
Stroke Volume ◽  
Cardiovascular Response ◽  
Peripheral Resistance ◽  
Graded Exercise ◽  
Oxygen Difference

Seven dogs who ran well on a motor-driven treadmill were completely sympathectomized (including adrenal denervation) and subjected to unilateral vagotomy below the recurrent laryngeal branch. After recovery and retraining, a terminal experiment was performed in which, after completing the vagotomy, direct Fick determinations of cardiac output and continuous recordings of mean arterial pressure, heart rate, and oxygen consumption were made at rest and during increasing exercise The results were compared with those described by Barger et al. ( Am. J. Physiol. 184: 613, 1956) for normal dogs running at smaller speeds and grades. The heart rate of the operated dogs increased from 117 to 134. Barger's normal dogs doubled their heart rate. The A-V oxygen difference increased with work slightly less than Barger's normal dogs but the scatter in both groups was wide, as was the case with the stroke volume. The resting cardiac output was nearly normal in the operated dogs but increased only 34% with exercise, as against 200–300% in Barger's normals. Oxygen consumption increased about twofold as against the expected normal of three- to sevenfold. Peripheral resistance in both groups went down about 40%. The blood pressure in the normal increased substantially while that in the operated dogs fell about 20% to an average of 60 mm Hg.

Regulation of the Circulation During Exercise

1956 ◽  
Vol 184 (3) ◽  
pp. 613-623 ◽  
Author(s):  
A. C. Barger ◽  
V. Richards ◽  
J. Metcalfe ◽  
B. Günther
Keyword(s):  
Blood Flow ◽  
Cardiac Output ◽  
Oxygen Consumption ◽  
Steady State ◽  
Rest Period ◽  
Moderate Exercise ◽  
Work Intensity ◽  
Short Bout ◽  
Graded Exercise ◽  
Oxygen Difference

Oxygen consumption and cardiac output (direct Fick) have been measured in normal dogs at rest and during graded exercise on the treadmill up to a work intensity of 5 mph and 10°. Systemic and pulmonary artery pressures have also been recorded. The changes in cardiac output produced ‘at rest’ by excitement were frequently as large as those induced by moderate exercise. A short bout of exercise followed by a rest period was far more efficacious in producing lower and more uniform results during rest and subsequent exercise than a prolonged rest period alone. Under such conditions the ‘steady state’ was reached in 3 minutes or less of exercise. The linear relation between oxygen consumption and cardiac output during exercise in the dog is similar to that observed in man, and in the horse. The possible significance of this similarity is discussed and it is suggested that the data are consistent with the hypothesis that the increase in blood flow during exercise is largely the increase in muscle flow with a constant arteriovenous oxygen difference of approximately 14 vol. %.

The Relationship between Heart Rate Deflection and Ventilatory Threshold in Children Following Heart Surgery

1995 ◽  
Vol 7 (3) ◽  
pp. 263-269 ◽  
Author(s):  
Ralph K.L. Rogers ◽  
Tony Reybrouck ◽  
Maria Weymans ◽  
Monique Dumoulin ◽  
Marc Gewillig ◽  
...  
Keyword(s):  
Heart Rate ◽  
Heart Surgery ◽  
Surgical Repair ◽  
Ventilatory Threshold ◽  
Linear Regression Analysis ◽  
Accurate Predictor ◽  
Graded Exercise Test ◽  
Significant Difference ◽  
Graded Exercise ◽  
The Relationship

This study assessed the relationship between the VO2 measured at ventilatory threshold (VT) and the VO2 measured at the point of deflection from linearity of heart rate (HRD). Twelve children (10 boys and 2 girls) with a mean age of 11.3 years (±4.8) performed a graded exercise test to determine VT and HRD. All children had undergone surgical repair for d-transposition of the great arteries at approximately 13 months of age. Because of failure to demonstrate HRD, the data from 4 patients were excluded from statistical analysis. For the remaining 8 patients there was no significant difference between mean VO2 (ml/kg/min) at VT and HRD (26.6 ± 6.4 vs. 26.3 ± 6.8; p > 0.25). Linear regression analysis revealed a correlation of r = 0.92 between the VO2 measured at VT and the VO2 measured at HRD. Only 8 of the 12 patients (66%) in this study satisfied criteria needed to identify the HRD. Therefore HRD may be an accurate predictor of VT in most but not all children who have had surgery for d-transposition of the great arteries.

Heart rate response to exercise and cardiorespiratory fitness of young women at high familial risk for hypertension: effects of interval vs continuous training

2011 ◽  
Vol 18 (6) ◽  
pp. 824-830 ◽  
Author(s):  
Emmanuel G Ciolac ◽  
Edimar A Bocchi ◽  
Julia MD Greve ◽  
Guilherme V Guimarães
Keyword(s):  
Heart Rate ◽  
Exercise Training ◽  
Cardiorespiratory Fitness ◽  
Familial Risk ◽  
Moderate Intensity ◽  
Hypertensive Disorder ◽  
Moderate Intensity Exercise ◽  
Continuous Training ◽  
Response To Exercise

Exercise training is an effective intervention for treating and preventing hypertension, but its effects on heart rate (HR) response to exercise and cardiorespiratory fitness (CRF) of non-hypertensive offspring of hypertensive parents (FH+) has not been studied. We compared the effects of three times per week equal-volume high-intensity aerobic interval (AIT) and continuous moderate-intensity exercise (CME) on HR response to exercise and CRF of FH+. Forty-four young FH+ women (25.0 ± 4.4 years) randomized to control (CON; n = 12), AIT (80–90% of VO2MAX; n = 16), or CME (50–60% of VO2MAX; n = 16) performed a graded exercise test (GXT) before and after 16 weeks of follow-up to evaluate HR response to exercise and several parameters of CRF. Resting, maximal, and reserve HR did not change after the follow-up in all groups. HR recovery (difference between HRMAX and HR at 1 minute of GXT recovery phase) improved only after AIT (11.8 ± 4.9 vs. 20.6 ± 5.8 bpm, p < 0.01). Both exercise programmes were effective for improving CRF parameters, but AIT was more effective than CME for improving oxygen consumption at the respiratory compensation point (VO2RCP; 22.1% vs. 8.8%, p = 0.008) and maximal effort (VO2MAX; 15.8% vs. 8.0%, p = 0.036), as well as tolerance time (TT) to reach anaerobic threshold (TTAT; 62.0 vs. 37.7, p = 0.048), TTRCP (49.3 vs. 32.9, p = 0.032), and TTMAX (38.9 vs. 29.2, p = 0.042). Exercise intensity was an important factor in improving HR recovery and CRF of FH+women. These findings may have important implications for designing exercise-training programmes for the prevention of an inherited hypertensive disorder.

scholarly journals Comparison of Oxygen Consumption and Heart Rate Response to Exercise on Land Versus Water Treadmill

2007 ◽  
Vol 39 (Supplement) ◽  
pp. S483
Author(s):  
Elizabeth S. Greene ◽  
Nicholas P. Greene ◽  
Brent E. Hansen ◽  
Gregory S. Miller ◽  
April Muller ◽  
...  
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Heart Rate Response ◽  
Water Treadmill ◽  
Response To Exercise

Sumatriptan reduces exercise capacity in healthy males: a peripheral effect of 5-hydroxytryptamine agonism?

2000 ◽  
Vol 98 (6) ◽  
pp. 643-648 ◽  
Author(s):  
Gerald P. MCCANN ◽  
Helen CAHILL ◽  
Stephen KNIPE ◽  
Douglas F. MUIR ◽  
Paul D. MACINTYRE ◽  
...  
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Exercise Capacity ◽  
Gas Analysis ◽  
Peak Oxygen Consumption ◽  
Peak Exercise ◽  
Double Blind ◽  
Peripheral Effect ◽  
Expired Gas Analysis ◽  
Exercise Induced

5-Hydroxytryptamine (5-HT; serotonin) has been implicated in the perception of exercise-induced fatigue. Sumatriptan is a selective 5-HT1B/D receptor agonist which does not cross the blood–brain barrier. The aim of the present study was to determine the effect of sumatriptan on exercise capacity. Ten healthy male subjects (mean age 28.4±10.8 years) performed a maximal treadmill exercise test according to the Bruce protocol with expired gas analysis on two occasions. Either 6 mg of sumatriptan or placebo was administered subcutaneously in a randomized, double-blind, placebo-controlled, cross-over design. Exercise time was greater after placebo compared with sumatriptan [914 and 879 s respectively; 95% confidence interval (CI) of difference 12.1 s, 59.1 s; P = 0.008]. There was no significant effect on peak oxygen consumption (placebo, 50.6±6.3 ml·min-1·kg-1; sumatriptan, 51.7±7.6 ml·min-1·kg-1). Sumatriptan administration resulted in decreases in both heart rate (sumatriptan, 188±14 beats/min, placebo, 196±12 beats/min; 95% CI of difference 12.6, 2.6; P = 0.008) and respiratory exchange ratio (sumatriptan, 1.23±0.06; placebo, 1.26±0.07; 95% CI of difference 0.05, 0.01; P = 0.01) at peak exercise. There were no significant differences in blood pressure, heart rate or submaximal oxygen consumption between sumatriptan and placebo treatments at any stage of exercise. Thus sumatriptan reduces maximal exercise capacity in normal males. The failure to demonstrate any haemodynamic or cardiorespiratory effect suggests that sumatriptan enhances perception of fatigue by a peripheral mechanism affecting 5-HT modulation.

Ventilatory Threshold and Peak Exercise Response in Athletes with CP during Treadmill and Cycle Ergometry

1994 ◽  
Vol 11 (3) ◽  
pp. 329-334
Author(s):  
Gregory B. Dwyer ◽  
Anthony D. Mahon
Keyword(s):  
Cerebral Palsy ◽  
Ventilatory Threshold ◽  
Cycle Ergometer ◽  
Cycle Ergometry ◽  
Peak Exercise ◽  
Exercise Tests ◽  
Men 2 ◽  
Graded Exercise ◽  
Exercise Response ◽  
Track Athletes

Little is known about the responses to graded exercise in athletes with cerebral palsy (CP). This study compared the ventilatory threshold (VT) and peak VO2 among athletes with CP during treadmill and cycle ergometry exercise. Six (4 men, 2 women) track athletes with CP volunteered to participate in the study. Graded exercise tests on a treadmill and cycle ergometer were performed on separate days to assess VT and peak VO2. Paired t tests were used to compare the two exercise modes. The VT, expressed as a percentage of peak VO2, was significantly higher on the cycle ergometer than on the treadmill. The absolute VO2 at the VT was similar during both testing modes, and peak VO2 was significantly higher on the treadmill than on the cycle ergometer. Similar to responses seen in able-bodied individuals, the VO2 at VT was similar during both modes of exercise, while the peak VO2 was 10% lower on the cycle than on the treadmill. Cycle ergometer peak VO2 in these athletes was higher than previous reports of individuals with CP for the cycle ergometer.

The Influence of Exercise Test Protocol on Perceived Exertion at Submaximal Exercise Intensities in Children

2003 ◽  
Vol 28 (1) ◽  
pp. 53-63 ◽  
Author(s):  
Anthony D. Mahon ◽  
David M. Plank ◽  
Molly J. Hipp
Keyword(s):  
Exercise Test ◽  
Perceived Exertion ◽  
Ventilatory Threshold ◽  
Peak Exercise ◽  
Ratings Of Perceived Exertion ◽  
Test Protocol ◽  
Exercise Tests ◽  
Sensory Signal ◽  
Cardiorespiratory Responses ◽  
Graded Exercise

This study examined ratings of perceived exertion (RPE) using Borg's 6-20 scale at 50 W, 80 W, and ventilatory threshold (VT) in 10-year-old children (n = 15) during two different graded exercise tests. Power output was increased by 10 W•min−1 in one protocol and by 30 W•3 min−1 in the other. The cardiorespiratory responses at VT and peak exercise were similar between protocols. At 50 W and 80 W the cardiorespiratory responses were generally lower (P < 0.05) in the 10-W trial. However, RPE was 11.5 ± 2.9 and 12.1 ± 3.2 at 50 W and 15.1 ± 2.7 and 15.3 ± 2.8 at 80 W in the 10-W and 30-W trials, respectively (P > 0.05). The RPE at VT was 13.9 ± 2.4 in the 10-W trial and 12.4 ± 2.4 in the 30-W trial (P < 0.05). In that variations in submaximal RPE did not coincide with variations in central mediators of exertion, locals cues of exertion may have provided the dominate sensory signal. Key words: ventilatory threshold, cardiorespiratory measures, exercise test, peak VO2, cycle ergometry, RPE

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