Anaerobic Threshold VO2 Research Articles

Abstract 13847: Biomarker-Based Phenomapping in Chronic Stable HFpEF and Exercise Capacity: An Analysis of the RELAX Trial

Introduction: Heart failure with preserved ejection fraction (HFpEF) is a heterogenous disease associated with low exercise capacity. Hypothesis: Unsupervised clustering of biomarker data can identify subgroups of individuals with HFpEF and differences in exercise capacity. Methods: The study included participants with chronic, stable HFpEF from the RELAX trial with available serum biomarker data. We used unsupervised hierarchical clustering analysis of 9 serum biomarkers to derive phenogroups of participants with HFpEF. Adjusted linear regression was used to assess the association between cluster membership with peak oxygen consumption (VO2), maximum exercise watts, and VO2 anaerobic threshold. Results: Among 211 participants in the RELAX trial, 3 phenogroups were identified based on the gain in within-inertia. No significant differences were observed in age, sex, or race across phenogroups. Phenogroup 1 (n=136) participants had the lowest burden of CV (cardiovascular) risk factors, including diabetes, anemia, and kidney disease as well as the lowest overall biomarkers levels ( Fig. A ). Phenogroup 2 (n=61) consisted of participants who were older with a higher burden of CV risk factors and fibrosis biomarkers, including galectin-3, collagen-I, and troponin-I levels. Phenogroup 3 (n=14) participants were younger with high burden of CV risk factors and inflammatory biomarkers including aldosterone, CRP, and uric acid. Compared with phenogroup 1, phenogroup 2 and 3 had significantly lower peak VO2, adjusted for traditional CV risk factors [estimate (95% CI): -1.99 (-2.83, -1.16) and -2.31 (-3.66, -0.95), respectively] (Fig. B ). Additionally, phenogroup 3 vs. 1 had lower exercise watts and VO2 anaerobic threshold. Conclusion: Using serum biomarkers, we identified 3 unique phenogroups of patients with chronic, stable HFpEF and significant differences in CV risk factor burden and exercise capacity.

P295 EXERCISE OXYGEN KINETIC IN HYPERTROPHIC CARDIOMYOPATHY: RESULTS FROM A MULTICENTER CARDIOPULMONARY EXERCISE TESTING STUDY

Abstract Aims Reduced cardiac output (CO) has been considered crucial in symptoms’ genesis in hypertrophic cardiomyopathy (HCM). We evaluated the cardiopulmonary exercise testing (CPET) response in HCM focusing on parameters strongly associated with stroke volume (SV) and cardiac output (CO), such as oxygen uptake (VO2) and O2–pulse, considering both their absolute values and temporal behavior during physical exercise. Methods and Results We enrolled 312 non–end stage HCM patients, divided according to left ventricle outflow tract obstruction (LVOTO) at rest or during Valsalva maneuver (72% with LVOTO<30; 10% between 30 and 49 and 18% ≥ 50mmHg). Peak VO2 (percent of predicted), O2–pulse and ventilation to carbon dioxide production (VE/VCO2) slope did not change across LVOTO groups. Ninety–six (31%) HCM patients presented an abnormal O2–pulse temporal behavior, irrespective of LVOTO values. These patients showed lower peak systolic pressure, workload (106±45 vs. 130±49W), VO2 (74±17 vs. 80±20%) and O2–pulse (12 [9–14] vs. 14 [11–17]ml/beat), with higher VE/VCO2 slope (28 [25–31] vs. 27 [24–31]) (p < 0.005 for all). Only 2 patients had an abnormal VO2/work slope. Conclusion None of CPET parameters, either as absolute values or dynamic relationships, were associated with LVOTO. Differently, an abnormal O2–pulse exercise behavior, which is strongly related to inadequate SV during exercise, correlates with reduced functional capacity (peak and anaerobic threshold VO2 and workload) and increased VE/VCO2 slope, helping identifying more advanced disease irrespectively of LVOTO. Adding O2–pulse kinetics evaluation to standard CPET could lead to a potential incremental benefit in terms of HCM prognostic stratification and, then, therapeutic management.

Exercise oxygen pulse kinetics in patients with hypertrophic cardiomyopathy

ObjectivesReduced cardiac output (CO) has been considered crucial in symptoms’ genesis in hypertrophic cardiomyopathy (HCM). Absolute value and temporal behaviour of O2-pulse (oxygen uptake/heart rate (VO2/HR)), and the VO2/work relationship...

53 Exercise oxygen kinetic in hypertrophic cardiomyopathy: results from a multicentre cardiopulmonary exercise testing study

Abstract Aims Reduced cardiac output (CO) has been considered crucial in symptoms’ genesis in hypertrophic cardiomyopathy (HCM). We evaluated the cardiopulmonary exercise testing (CPET) response in HCM focusing on parameters strongly associated with stroke volume (SV) and cardiac output (CO), such as oxygen uptake (VO2) and O2-pulse, considering both their absolute values and temporal behaviour during physical exercise. Methods and results We enrolled 312 non-end stage HCM patients, divided according to left ventricle outflow tract obstruction (LVOTO) at rest or during Valsalva manoeuver (72% with LVOTO < 30; 10% between 30 and 49; and 18% ≥50 mmHg). Peak VO2 (percent of predicted), O2-pulse, and ventilation to carbon dioxide production (VE/VCO2) slope did not change across LVOTO groups. Ninety-six (31%) HCM patients presented an abnormal O2-pulse temporal behaviour, irrespective of LVOTO values. These patients showed lower peak systolic pressure, workload (106 ± 45 vs. 130 ± 49 W), VO2 (74 ± 17% vs. 80 ± 20%) and O2-pulse (12 [9–14] vs. 14 [11–17]ml/beat), with higher VE/VCO2 slope (28 [25–31] vs. 27 [24–31]) (P < 0.005 for all). Only two patients had an abnormal VO2/work slope. Conclusions None of CPET parameters, either as absolute values or dynamic relationships, were associated with LVOTO. Differently, an abnormal O2-pulse exercise behaviour, which is strongly related to inadequate SV during exercise, correlates with reduced functional capacity (peak and anaerobic threshold VO2 and workload) and increased VE/VCO2 slope, helping identifying more advanced disease irrespectively of LVOTO. Adding O2-pulse kinetics evaluation to standard CPET could lead to a potential incremental benefit in terms of HCM prognostic stratification and, then, therapeutic management.

Effects of ticagrelor on cardiorespiratory fitness in patients after percutaneous coronary intervention

Objective: To investigate the effects of ticagrelor on cardiorespiratory fitness in patients with coronary heart disease after percutaneous coronary intervention (PCI). Methods: A total of 1 073 patients, who were diagnosed as coronary heart disease and underwent cardiopulmonary exercise testing (CPET) within 1 year after PCI, were enrolled from September 2017 to September 2019 in Peking University Third Hospital, including 309 patients in ticagrelor group and 764 patients in clopidogrel group. Clinical information, blood test results, echocardiographic parameters, cardiorespiratory fitness related parameters (including peak oxygen uptake (VO(2)), anaerobic threshold VO(2), peak oxygen pulse (VO(2)/HR) and carbon dioxide ventilation equivalent (VE/VCO(2)) slope), coronary lesions and intervention information were obtained. Cardiopulmonary fitness related indexes were compared between the two groups, and the correlation between ticagrelor use and cardiopulmonary fitness related indexes was analyzed by multivariate logistic regression. Patients who underwent CPET within 1 month after PCI were included in the subgroup analysis. Results: In ticagrelor group, the age was (60.3±10.3) years, and 253(81.9%) cases were male. The age of clopidogrel group was (60.6±10.0) years, and there were 608(79.6%) males. No significant differences were observed in peak VO(2), anaerobic threshold VO(2), and peak VO(2)/HR between the two groups (all P>0.05), but the VE/VCO(2) slope was significantly higher in the ticagrelor group than in the clopidogrel group (30.075 (27.207, 33.603) vs. 28.853 (25.970, 32.336), P<0.001). Logistic regression analysis suggested that the peak VO(2), anaerobic threshold VO(2) and peak VO(2)/HR were not significantly correlated with the ticagrelor use (all P>0.05), while the VE/VCO(2) slope was independently correlated with ticagrelor use (OR=1.098, 95%CI 1.032-1.168, P=0.003). Subgroup analysis of patients who underwent CPET within 1 month after PCI also indicated that no significant difference were observed in peak VO(2), anaerobic threshold VO(2), peak VO(2)/HR and VE/VCO(2) slope between the two groups (all P>0.05). Logistic regression analysis suggested that the peak VO(2), anaerobic threshold VO(2) and peak VO(2)/HR were not significantly correlated with ticagrelor use (all P>0.05), while the VE/VCO(2) slope was significantly correlated with ticagrelor use (OR=1.132, 95%CI 1.030-1.244, P=0.010). Conclusion: Among coronary heart disease patients after PCI, treatment with clopidogrel does not result in significant decrease in exercise endurance as compared with patients treated with ticagrelor.

The Yo-Yo IR2 test in professional basketball players

The aim of this study was to investigate the relationship between direct method and indirect method (Yo-Yo Intermittent Recovery Test Level II) that are used to determine aerobic capacity and endurance. Fourteen basketball players (22.49 ±04.82 year-old with the height 192.36±5.90 cm, weight 89.21±7.6 kg, Body fat percentage 11.07 ± 1.82 %) voluntarily participated in this study. Yo-Yo Intermittent Recovery Test Level II protocol (YIRT 2) was implemented to participants. Distance covered by the athletes, estimated VO2max, direct VO2max, Anaerobic threshold VO2 and Anaerobic threshold heart rate (HRAT) values were recorded. Direct VO2max and other respiratory parameters were measured with telemetric gas analyzer. After 5 minute rest in supine position heart rates (HRrest), rest lactate levels (LArest) and maximal heart rate (HRmax) during the test and post test lactate levels (LApost) were measured. Pearson Correlation Test was used to determine the relationship between the variables. P value was set at 0,05. According to the findings, positively significant large correlation was found between estimated VO2max and direct VO2max(r = 0.504, p &lt; 0.05), HRmax (r = 0.501, p &lt; 0.05), positively significant large correlation was found between distance and Direct VO2max(r = 0.521, p &lt; 0.05), HRmax (r = 0.516, p &lt; 0.05). There is no significant relationship except above-mentioned variables (p&lt;0.05). YIRT2 can guess VO2max of professional male basketball players and can be used to evaluate endurance.

Lvad pump speed increase is associated with increased peak exercise cardiac output and vo2, postponed anaerobic threshold and improved ventilatory efficiency

BackgroundsPeak exercise cardiac output (CO) increase is associated with an increase of peak oxygen uptake (VO2), provided that arteriovenous O2 difference [Δ(Ca−Cv)O2] does not decrease. At anaerobic threshold, VO2, is related to CO.We tested the hypothesis that, in heart failure (HF) patients with left ventricular assistance device (LVAD), an acute increase of CO obtained through changes in LVAD pump speed is associated with peak exercise and anaerobic threshold VO2 increase. MethodsFifteen of 20 patients bearing LVAD (Jarvik 2000) enrolled in the study successfully performed peak exercise evaluation. All patients had severe HF as shown by clinical evaluation, laboratory tests, echocardiography, spirometry with alveolar-capillary diffusion, and maximal cardiopulmonary exercise testing (CPET). CPETs with non-invasive CO measurements at rest and peak exercise were done on 2days at LVAD pump speed set randomly at 2 and 4. ResultsIncreasing LVAD pump speed from 2 to 4 increased CO from 3.4±0.9 to 3.8±1.0L/min (ΔCO 0.4±0.6L/min, p=0.04) and from 5.3±1.3 to 5.9±1.4L/min (ΔCO 0.6±0.7L/min, p<0.01) at rest and peak exercise, respectively. Similarly, VO2 increased from 788±169 to 841±152mL/min (ΔVO2 52±76mL/min, p=0.01) and from 568±116 to 619±124mL/min (ΔVO2 69±96mL/min, p=0.02) at peak exercise and at anaerobic threshold, respectively. Δ(Ca−Cv)O2 did not change significantly, while ventilatory efficiency improved (VE/VCO2 slope from 39.9±5.4 to 34.9±8.3, ΔVE/VCO2 −5.0±6.4, p<0.01). ConclusionsIn HF, an increase in CO with a higher LVAD pump speed is associated with increased peak VO2, postponed anaerobic threshold, and improved ventilatory efficiency.

Rationale for cardiopulmonary exercise test in the assessment of surgical risk

Although in the past years a reduced mortality in peri-operative care has been observed, cardiovascular mortality and morbidity still is a major burden in patients undergoing noncardiac surgery and its evaluation is still a difficult task. An accurate risk stratification can improve quality of peri-operative care and may improve survival, while reducing healthcare costs. In clinical practice, we make our assessment of a patient's cardiac status based on history, examination and investigations, together with risks related to the surgical procedure, to generate an 'individualized cardiac risk assessment'. At the present, risk stratification with clinical risk score and cardiac testing have been shown to be suboptimal in identifying high-risk patients. Surgery, like exercise, increases oxygen consumption. Indeed, one of the key elements in determining risk assessment is exercise intolerance, but future research in this field is needed to clarify this statement. Cardiopulmonary exercise testing (CPET) provides a global assessment of functional capacity involving and integrating the physiological measurement during incremental exercise. The pattern of CPET's variables identifies the abnormal exercise capacity, often providing an objective evaluation of cause and, moreover, predicting outcomes in both apparently healthy and chronic disease populations. An anaerobic threshold VO2 above 11 ml/kg per min seems to identify individuals with a very low surgical risk even if undergoing major surgery. This review is focused on tools of risk assessment in patients undergoing noncardiac surgery and on the physiological basis for CPET in detecting patients 'at risk'.

Effects of a Phase III Cardiac Rehabilitation Program on Physical Status and Lipid Profiles in Elderly Patients With Coronary Artery Disease Juntendo Cardiac Rehabilitation Program (J-CARP)

Limited data are available regarding the effects of phase III cardiac rehabilitation on the physical status and risk factors in elderly patients with coronary artery disease (CAD). Thirty-four male CAD patients (>65 years old) were randomly assigned to an intervention group (n=18) or a control group (n=16). The intervention group participated in a phase III cardiac rehabilitation program consisting of exercise training, diet therapy, and weekly counseling for 6 months. In the control group, usual outpatient care was provided. In the intervention group, body mass index, waist size and fat weight significantly decreased; peak VO2 and anaerobic threshold VO2 were maintained; isokinetic peak torques of knee extensor and flexor muscles significantly increased; anterior trunk flexibility was significantly improved. In the control group, all parameters were unchanged except for peak VO2, which significantly decreased. In the intervention group, serum total cholesterol levels significantly decreased after cardiac rehabilitation. However, high-density lipoprotein-cholesterol and apoA-I levels also decreased. In the control group, no significant change in lipid profile was observed. The results suggest that phase III cardiac rehabilitation could be beneficial for elderly patients with CAD.

Hydrokinesitherapy in Advanced Heart Failure: The Cardio-HKT Pilot Study. Long Term Adherence to Life Style Modifications

The Cardio-Hydrokinesitherapy Pilot Study (Cardio-HKT) is an innovative rehabilitation program performed in warm water (31°C) completed by educational and psycho-behavioral support sessions to improve adherence to healthy life style changes in optimally treated patients (pts) with stable advanced heart failure (HF). The Cardio-HKT training has been shown to be safe and well tolerated in functionally compromised pts and to significantly improve their quality of life [Minnesota LHFQ = -33 ± 11 (p < 0.001)], exercise capacity [6 min Walking Test = + 117 ± 50 meters (p = 0,009) and peak oxygen consumption (pVO2) = + 1.2 ± 0.6ml/kg/min (p = 0.016)]. Aim: The aim of the present study is to evaluate the long-term effects of the Cardio-HKT program on pts adherence to self-monitoring, home based physical activity and to dietary sodium restriction. Methods: 18 pts with stable advanced HF, on optimal medical treatment, [mean age 62 ± 21.5 years; 94% males; 61% with ischaemic CMD etiology; mean ejection fraction 27 ± 7%; mean peak oxygen consumption (pVO2) 13.6 ± 2.6 ml/kg/min; anaerobic threshold VO2 (ATVO2) 9.3 ± 2.6 ml/kg/min; VE/VCO2 47,5 ± 10.1; NT-proBNP 2731 ± 2551pg/ml; sodium concentration 136.9 ± 4.2 mEq/L] were included in the study. The Cardio-HKT program has been performed for 3 weeks by groups of 4-5 pts participating to 2 daily immersion sessions of progressive intensity, tailored on each pt and supervised continuously by a specialized rehabilitation therapist. After this period, pts were given a dry-land exercise protocol training to be continued daily at home. Heart rate response was monitored by wrist recorder. Results: After 1 year all pts are alive; 33% (6/18 pts) required admission for worsening HF (only 1 pt needed to be readmitted twice). Physical training protocol adherence was 90 % at 3 months, 70% at 6 months and 50% at 1 year. Lifestyle modifications, evaluated as ability to keep the recommended weight, were observed in 89% at 6 months and 83% at one year. After 12 months Minnesota-LHFQ was found improved compared to the baseline test (−18.3 ± 9; p = 0,006). Conclusion: Despite progressive adherence reduction to the home based exercise protocol, the Cardio HKT program favored long-term improvement in quality of life and in healthy life-style modifications, in pts with advanced HF.

Effects of supervised cardiovascular training program on exercise tolerance, aerobic capacity, and quality of life in patients with systemic lupus erythematosus

To determine if supervised cardiovascular training improves exercise tolerance, aerobic capacity, depression, functional capacity, and quality of life in patients with systemic lupus erythematosus (SLE). Sixty women with SLE (ages 18-55 years) were evaluated using Short Form 36, visual analog scale for pain, scale for fatigue, Beck Depression Inventory, and Health Assessment Questionnaire (HAQ), and participated in a training protocol of incremental load on a treadmill with computed gas metabolic analysis. Maximum oxygen consumption (VO(2max)) and anaerobic threshold VO(2) were calculated with a SensorMedics Vmax29C analyzer (Sensor Medics, Yorba Linda, CA), and heart rate was measured by electrocardiogram. Patients were divided into 2 groups: a training group (41 patients) that participated in the supervised cardiovascular training program and a control group (19 patients) that did not participate in the program. All variables were analyzed at baseline and after 12 weeks for both groups. The training program occurred in the morning for 60 minutes, 3 times a week for 12 weeks. Statistical analysis included Wilcoxon's rank sum test, Mann-Whitney U test, chi-square test, and Fisher's exact test. P values <0.05 were considered to be statistically significant. The 2 groups were homogeneous and comparable at baseline. The training group showed a significant improvement of aerobic capacity measured by anaerobic threshold VO(2) (14.67 +/- 3.03 versus 17.08 +/- 3.35 ml/kg/minute, P < 0.001). Comparison of the training group and control group after 12 weeks showed a significant difference relating to VO(2max) (24.31 +/- 4.61 versus 21.21 +/- 3.88 ml/kg/minute, P = 0.01) and anaerobic threshold VO(2) (17.08 +/- 3.35 versus 13.66 +/- 2.82 ml/kg/minute, P < 0.0001). After cardiovascular training, we found a significant improvement of Beck inventory score (8.37 +/- 12.79 versus 2.90 +/- 3.00, P < 0.001) and HAQ score (0.14 +/- 0.21 versus 0.06 +/- 0.19, P < 0.01) in the training group. This study showed significant improvement in exercise tolerance, aerobic capacity, quality of life, and depression after a supervised cardiovascular training program in patients with SLE.

Determination of maximal power output at neuromuscular fatigue threshold

The purpose of this study was to determine the maximal power output at the neuromuscular fatigue threshold (EMGFT), as estimated from electromyographic (EMG) data from representative leg muscles during cycling. The rate of rise in integrated EMG activity as a function of time (iEMG slope) was calculated at each of four constant-power-output ergometer bouts for 20 subjects. The iEMG slopes were plotted against work rates that were well described as linear functions (0.84 < R2 < 0.99). This iEMG slope vs. work rate relationship was extrapolated to zero slope to give an intercept on the power axis that was interpreted as the highest work rate sustainable without EMG evidence of neuromuscular fatigue (EMGFT). Each individual EMGFT was then expressed in terms of an O2 output (VO2) equivalent on the basis of the individual delta efficiency calculated during a linearly increasing maximal exercise test on the same bicycle ergometer. Results indicated a highly significant correlation (r = 0.92, P < 0.01) between EMGFT VO2 and anaerobic threshold VO2, as determined by conventional gas exchange criteria. The mean EMGFT VO2 (1.84 +/- 0.55 l/min) was, however, significantly greater (P < 0.01) than the anaerobic threshold VO2 (1.72 +/- 0.54 l/min). It was suggested that the EMGFT may provide an attractive alternative to the measurement of the highest work rate that can be sustained without evidence of neuromuscular fatigue.

Gas exchange parameters, muscle blood flow and electromechanical properties of the plantar flexors.

Sixteen men were tested to determine VO2max (ml X kg-1 X min-1), anaerobic threshold VO2 (ATVO2) and oxygen kinetics (time constant, T.C.) during running on a treadmill. For measuring maximal calf blood flow (maxBF, ml X 100 ml-1 X min-1), venous occlusion plethysmography was employed immediately following a combination of arterial occlusion and toe raising exercise to exhaustion. In addition, supramaximal electrical stimulations were given to determine maximal calf twitch force (Fmax, N), maximal rate of twitch force development (dF/dt) and relaxation (R X dF/dt, N X ms-1) and electro-mechanical delay time (EMD, ms). Results demonstrated that VO2max, ATVO2 and maxBF were all inversely related to T.C. (p less than 0.05). MaxBF and ATVO2 showed the highest correlation (r = 0.89, p less than 0.01). Stepwise multiple linear regression analyses revealed that variance in VO2max (60%) and ATVO2 (84%) could be accounted for by the combined effects of the following peripheral factors: VO2max = 51,25-3.24(dF/dt) + 0.14(maxBF), and ATVO2 = 11.68 + 0.42(maxBF) - 0.2(Fmax). These findings, together with the results of cluster analysis, suggest a tight link between ATVO2 and peripheral blood flow capacity. On the other hand, a moderate correlation (r = 0.64, p less than 0.01) between VO2max and maxBF might be due in part to individual differences in oxygen extraction-utilization capacity during heavy exercise above anaerobic threshold.

Rate-responsive pacing in patients with left ventricular failure.

Aerobic and hemodynamic performance, at rest and during exercise, has been explored in patients with either atrial synchronous ventricular or respiratory-dependent ventricular pacing. In patients with chronic AV block and normal left ventricle, the cardiac output, VO2 at maximal exercise, and work tolerance increased significantly with rate-responsive pacing in comparison with fixed ventricular pacing. Chronic AV block and left ventricle dysfunction in patients with respiratory-dependent ventricular pacing improved maximal cardiac output, VO2 anaerobic threshold, and physical work capacity. The benefit of rate-responsive pacing was found to be significantly greater in patients with left ventricle dysfunction than in patients with normal left ventricle function.