Effect of Exercise Training on Postexercise Oxygen Uptake Kinetics in Patients With Reduced Ventricular Function (original) (raw)
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Cardiology Research and Practice, 2012
Background. The purpose of this study was to assess the post-exercise O 2 uptake and heart rate response in patients with heart failure (HF) in comparison to healthy individuals. Methods and Results. Exercise testing of all subjects was conducted according to the RITE-protocol. The study subjects were classified according to their peak oxygen uptake (peak VO 2 ) in four groups: healthy individuals with a peak VO 2 >22 mL/kg/min (group 1, n: 50), and patients with HF and a peak VO 2 of 18-22 mL/kg/min, (group 2, n: 48), 14-18 mL/kg/min (group 3, n: 57), and <14 mL/kg/min (group 4, n: 31). Both peak VO 2 and HR declined more slowly in the patients with HF than in the normal subjects. Recovery of VO 2 and HR followed monoexponential kinetics in the early postrecovery phase. This enabled the determination of a time constant for both HR and VO 2 (TC VO 2 and TC HR). From group 1 to 4 there was a prolongation of the time constant for VO 2 and HR: TC VO 2 (group 1: 110±34, group 2: 197±43, group 3: 238±80, and group 4: 278 ± 50 sec), and TC HR (group 1: 148 ± 82, group 2: 290 ± 65, group 3: 320 ± 58, and group 4: 376 ± 55 sec). Conclusion. The rate of decline of VO 2 and HR in the early post-exercise phase is inversely related to the peak VO 2 . The time constant for oxygen uptake (TC VO 2 ) and heart rate (TC HR) might prove a useful parameter for more precise monitoring and grading of HF.
A Randomized Comparison of Exercise Training in Patients With Normal vs Reduced Ventricular Function
Chest, 1998
Background: Exercise training is recommended after myocardial infarction (MI) or bypass surgery in order to improve exercise tolerance. In some patients, the decrement in exercise capacity secondary to deconditioning and the left ventricular stunning associated with MI or coronary artery bypass graft (CABG) spontaneously improves after the event. However, the impact of the status of the left ventricle on these improvements is unknown. Methods: Sixty-seven patients 1 month after MI or CABG were randomized to a training (n=34; age, 59±7 years) or a control group (n=33; age, 55±6 years). Forty-two patients had an ejection fraction >50% (22 in the training group and 20 in the control group), and 25 patients had an ejection fraction <40% (12 in the exercise group and 13 in the control group). After stabilization for approximately 1 month after the event, patients in the exercise group underwent 8 weeks of twice daily exercise at a residential rehabilitation center, while control patients received usual care. Initially and after 8 weeks, patients in both groups underwent maximal exercise testing with gas exchange and lactate analysis. Results: Exercise training increased peak oxygen consumption (Vo2) only in the reduced ejection fraction group (19.4±3.0 to 23.9±4.8 mL/kg/min; p<0.05); the exercise group with normal ventricular function did not change significantly. Changes in Vo2 at the lactate threshold paralleled those of peak Vo2 for both groups. Conversely, control patients with normal ventricular function increased peak Vo2 spontaneously (20.8±3.9 to 24.8±3.5 mL/kg/min; p<0.01), whereas control patients with reduced ventricular function did not improve peak Vo2. Conclusion: These data suggest that patients with depressed left ventricular function strongly benefit from rehabilitation, whereas most patients with preserved left ventricular function following MI or CABG tend to improve spontaneously 1 to 3 months after the event.
Circulation Journal, 2002
ardiac rehabilitation with exercise training (ET) for patients after acute myocardial infarction (AMI) improves exercise capacity, reduces coronary risk factors, improves quality of life, reduces subsequent hospitalization costs and reduces major coronary artery disease events including fatal MI, sudden death, and all-cause mortality. 1-6 It is a general notion that the magnitude of the improvement in exercise capacity after ET differs among individuals, but despite many reports on the benefits of cardiac rehabilitation with ET, the determinants of the improvement in exercise capacity have not been well documented. For example, Fioretti et al 7 and Digenio et al 8 reported that left ventricular (LV) systolic function, such as ejection fraction, did not correlate with the improvement in exercise capacity after ET. Therefore, the present study examined whether or not an improvement in exercise capacity is determined by, or predic from baseline variables obtained before ET. To this end, we performed left and right heart catheterization during a supine exercise test at the beginning of 3 months of ET and correlated the hemodynamic and oximetric variables with the post-training improvement in exercise capacity.
Chest, 1996
DOI 10.1378/chest.109.1.47 1996;109;47-51 Chest Squires and Gerald T. Gau Hiroyuki Daida, Thomas G. Allison, Bruce D. Johnson, Ray W. ... Hiroyuki Daida, MD; Thomas G. Allison, PhD, MPH; Bruce D. Johnson, PhD; Ray W. Squires, PhD; and Gerald T Gau, MD, FCCP ...
European Journal of Cardiovascular Prevention & Rehabilitation, 2007
Background Prolonged oxygen uptake kinetics (O 2 kinetics), following the onset of a constant workload of exercise has been associated with a poor prognosis in patients with chronic heart failure. This study aimed to determine both continuous and interval training effects on the different O 2-kinetics phases in these patients. Design Twenty-one patients (60 ± 8 years) with stable chronic heart failure participated in a 36-session exercise rehabilitation program (three times weekly). Patients were randomly assigned to interval training (n = 11; 100% of peak work rate for 30 s, alternating with 30 s-rest) and to continuous training (n = 10; 50% of peak work rate). Methods Before and after the completion of the program, all patients performed both incremental symptom-limited and constant workload submaximal cardiopulmonary exercise tests. Phase I O 2-kinetics was evaluated by time (t), from the start of exercise until the onset of decreased respiratory exchange ratio and phase II by the time constant (s) of the response from the end of phase I until steady state. Results After training, there was a significant increase in peak oxygen uptake and peak work rate in both continuous (15.3 ± 4.4 vs. 16.6 ± 4.5 ml/kg per min;
Effect of Exercise Intensity on Relationship between &OV0312;O2max and Cardiac Output
Medicine & Science in Sports & Exercise, 2004
LEPRETRE, P.-M., J.-P. KORALSZTEIN, and V. L. BILLAT. Effect of Exercise Intensity on Relationship between V O 2max and . Purpose: The purpose of this study was to determine whether the maximal oxygen uptake (V O 2max ) is attained with the same central and peripheral factors according to the exercise intensity. Methods: Nine well-trained males performed an incremental exercise test on a cycle ergometer to determine the maximal power associated with V O 2max (pV O 2max ) and maximal cardiac output (Q max ). Two days later, they performed two continuous cycling exercises at 100% (tlim100 ϭ 5 min 12 s Ϯ 2 min 25 s) and at an intermediate work rate between the lactate threshold and pV O 2max (tlim⌬50 ϭ 12 min 6 s Ϯ 3 min 5 s). Heart rate and stroke volume (SV) were measured (by impedance) continuously during all tests. Cardiac output (Q ) and arterial-venous O 2 difference (a-vO 2 diff) were calculated using standard equations. Results: Repeated measures ANOVA indicated that: 1) maximal heart rate, V E, blood lactate, and V O 2 (V O 2max ) were not different between the three exercises but Q was lower in tlim⌬50 than in the incremental test (24.4 Ϯ 3.6 L·min Ϫ1 vs 28.4 Ϯ 4.1 L·min Ϫ1 ; P Ͻ 0.05) due to a lower SV (143 Ϯ 27 mL·beat Ϫ1 vs 179 Ϯ 34 mL·beat Ϫ1 ; P Ͻ 0.05), and 2) maximal values of a-vO 2 diff were not significantly different between all the exercise protocols but reduced later in tlim⌬50 compared with tlim100 (6 min 58 s Ϯ 4 min 29 s vs 3 min 6 sϮ 1 min 3 s, P ϭ 0.05). This reduction in a-vO 2 diff was correlated with the arterial oxygen desaturation (SaO 2 ϭ Ϫ15.3 Ϯ 3.9%) in tlim⌬50 (r ϭ Ϫ0.74, P ϭ 0.05). Conclusion: V O 2max was not attained with the same central and peripheral factors in exhaustive exercises, and tlim⌬50 did not elicit the maximal Q . This might be taken into account if the training aim is to enhance the central factors of V O 2max using exercise intensities eliciting V O 2max but not necessarily Q max .
JACC. Heart failure, 2018
This study sought to characterize the functional and prognostic significance of oxygen uptake (VO) kinetics following peak exercise in individuals with heart failure (HF). It is unknown to what extent patterns of VO recovery following exercise reflect circulatory response during exercise in HF with preserved ejection fraction (HFpEF) and HF with reduced ejection fraction (HFrEF). We investigated patients (30 HFpEF, 20 HFrEF, and 22 control subjects) who underwent cardiopulmonary exercise testing with invasive hemodynamic monitoring and a second distinct HF cohort (n = 106) who underwent noninvasive cardiopulmonary exercise testing with assessment of long-term outcomes. Fick cardiac output (CO) and cardiac filling pressures were measured at rest and throughout exercise in the initial cohort. A novel metric, VO recovery delay (VORD), defined as time until post-exercise VO falls permanently below peak VO, was measured to characterize VO recovery kinetics. VORD in patients with HFpEF (m...
International journal of cardiology, 2013
Background: Pulmonary VO 2 on-kinetics during light-to-moderate-intensity constant-work-rate exercise, an experimental model mirroring energetic transitions during daily activities, has been shown to speed up with aerobic exercise training (AET) in normal subjects, but scant data are available in chronic heart failure (CHF). Methods and results: Thirty CHF patients were randomized to 3 months of light-to-moderate-intensity AET (CHF-AET) or control (CHF-C). Baseline and end-protocol evaluations included i) one incremental cardiopulmonary exercise test with near infrared spectroscopy analysis of peak deoxygenated hemoglobin + myoglobin concentration changes (Δ[deoxy(Hb + Mb)]) in vastus lateralis muscle, ii) 8 light-to-moderate-intensity constant-work-rate exercise tests for VO 2 on-kinetics phase I duration, phase II τ, and mean response time (MRT) assessment, and iii) circulating endothelial progenitor cell (EPC) measurement. Reference values were obtained in 7 age-matched normals (N). At end-protocol, phase I duration, phase II τ, and MRT were significantly reduced (−12%, −22%, and −19%, respectively) and peak VO 2 , peak Δ[deoxy(Hb + Mb)], and EPCs increased (9%, 20%, and 98%, respectively) in CHF-AET, but not in CHF-C. Peak Δ[deoxy(Hb + Mb)] and EPCs relative increase correlated significantly to that of peak VO 2 (r= 0.61 and 0.64, respectively, p b 0.05). Conclusions: Light-to-moderate-intensity AET determined a near-normalization of pulmonary VO 2 on-kinetics in CHF patients. Such a marked plasticity has important implications for AET intensity prescription, especially in patients more functionally limited and with high exercise-related risk. The AET-induced simultaneous improvement of phase I and phase II, associated with an increase of peak peripheral oxygen extraction and EPCs, supports microcirculatory O 2 delivery impairment as a key factor determining exercise intolerance in CHF.