Dirk Schepers

Aerobic interval training and continuous training equally improve aerobic exercise capacity in patients with coronary artery disease: the SAINTEX-CAD study.

BACKGROUND Exercise-based cardiac rehabilitation increases peak oxygen uptake (peak VO₂), which is an important predictor of mortality in cardiac patients. However, it remains unclear which exercise characteristics are most effective for improving peak VO₂ in coronary artery disease (CAD) patients. Proof of concept papers comparing Aerobic Interval Training (AIT) and Moderate Continuous Training (MCT) were conducted in small sample sizes and findings were inconsistent and heterogeneous. Therefore, we aimed to compare the effects of AIT and Aerobic Continuous Training (ACT) on peak VO₂, peripheral endothelial function, cardiovascular risk factors, quality of life and safety, in a large multicentre study. METHODS Two-hundred CAD patients (LVEF >40%, 90% men, mean age 58.4 ± 9.1 years) were randomized to a supervised 12-week cardiac rehabilitation programme of three weekly sessions of either AIT (90-95% of peak heart rate (HR)) or ACT (70-75% of peak HR) on a bicycle. Primary outcome was peak VO₂; secondary outcomes were peripheral endothelial function, cardiovascular risk factors, quality of life and safety. RESULTS Peak VO₂ (ml/kg/min) increased significantly in both groups (AIT 22.7 ± 17.6% versus ACT 20.3 ± 15.3%; p-time<0.001). In addition, flow-mediated dilation (AIT+34.1% (range -69.8 to 646%) versus ACT+7.14% (range -66.7 to 503%); p-time<0.001) quality of life and some other cardiovascular risk factors including resting diastolic blood pressure and HDL-C improved significantly after training. Improvements were equal for both training interventions. CONCLUSIONS Contrary to earlier smaller trials, we observed similar improvements in exercise capacity and peripheral endothelial function following AIT and ACT in a large population of CAD patients.

A representative study of cardiac rehabilitation activities in European Union member states: the Carinex survey

PURPOSE Empirical data on the level and nature of service delivery in cardiac rehabilitation (CR) in Europe are unavailable. Such information would facilitate service development across European Union (EU) Member States. A first EU-wide postal survey to provide baseline data was conducted. METHODS Organizations providing CR in 1995 were identified for 13 of 15 EU states (all except Luxembourg and Denmark). Using the World Health Organization definitions, 454 phase II (medium-term recovery after hospital release) and 383 phase III (long-term maintenance) centers were contacted in the relevant language. Staffing, content, duration, cost, and safety aspects of CR were queried. RESULTS Response rates were 57% (phase II) and 56% (phase III). Replies illustrate consistency across the EU; for instance, in having exercise as a core component of phase II programs. They also exemplify the diversity of services, particularly in phase III. The multidisciplinary aspect of CR is less developed in phase III. From this survey it is possible to make general estimates of the level of CR service coverage across EU States. Fewer than 50% of patients eligible to participant do so in most countries, with services in particularly short supply in countries with the greatest cardiovascular burden. CONCLUSION Many cardiac patients who could benefit from CR, an evidence-based treatment, do not participate in such programs. This survey provides important baseline and EU comparison data to monitor patterns of service development in the future.

Exercise performance and training in patients with implantable cardioverter-defibrillators and coronary heart disease

The aim of this preliminary study was to compare exercise performance and the effect of exercise training in cardiac patients with and without an implantable cardioverter-defibrillator (ICD). There are few data on exercise performance and on the effect of exercise training in patients with an ICD. Data in patients with an ICD (n = 8) were compared with those from a matched control group (n = 16). Patients performed maximal cycle-ergometer testing before and after 3 months of exercise training. All patients had to stop the exercise test for reasons of exhaustion. The predetermined heart rate threshold in ICD patients, set at the detection rate of the ICD minus 30 beats/min, was not reached. Before training, peak oxygen uptake was not different in the ICD patients compared with the control group (21.0 +/- 6.9 vs 21.9 +/- 5.0 ml oxygen standard temperature pressure dry/min/kg). Exercise training increased peak oxygen uptake to a similar extent in both groups, 20% and 24%, respectively. One ICD patient developed uneventful ventricular tachycardia at the end of the post-training exercise test, and another during training. Thus, exercise performance and the favorable response to a 3-month exercise training program are comparable in patients with ICD and matched control patients. However, tachyarrhythmias may occur during exercise testing or training and require special attention. Selected patients with ICD can be encouraged to participate in medically supervised exercise training programs. The results of this study should be confirmed with additional studies on larger numbers of subjects.

Effect of bisoprolol and atenolol on endurance exercise capacity in healthy men

Objectives To compare the effects of a highly β1-selective adrenoceptor antagonist bisoprolol with those of atenolol and placebo on endurance exercise capacity in young, healthy male volunteers. Design Twelve subjects randomly received oral placebo, atenolol (100 mg/day) or bisoprolol (10 mg/day) for 3 weeks, following a double-blind cross-over design. Methods At the end of each period, the subects performed an endurance exercise test on the bicycle ergometer at 70% of maximal aerobic power. Cardiac output was measured by means of an automated CO2-rebreathing method. Venous blood was sampled before, during and after exercise. Results Exercise duration was not significantly different between the two drugs tested. Total exercise duration was significantly reduced by bisoprolol (−19.4 ± 6.7%, P < 0.01) (mean ± SEM) and by atenolol (−29.8 ± 6.6%, P < 0.001), compared with placebo. Atenolol and bisoprolol were equally effective in lowering resting plasma renin activity, heart rate and systolic blood pressure. Resting and exercise stroke volume were significantly increased by both drugs, so that cardiac output was not significantly affected. Both drugs induced significant decreases in plasma-free fatty acid concentrations during recovery and blunted the exercise-induced increase. There were no significant relationships between the reduction of exercise duration and the haemodynamic changes or the degree of impairment of the exercise-induced increase in free fatty acid release resulting from β-blockade. Conclusions It is concluded that both drugs affect endurance exercise capacity in young, normotensive men, with a tendency to a smaller reduction during bisoprolol treatment. Haemodynamic variables are unlikely to be involved in the reduction of endurance exercise capacity. The role of the reduced availability of plasma free fatty acids remains unclear.

Assessment of cardiorespiratory exercise function in obese children and adolescents by body mass-independent parameters.

The parameters used to assess aerobic exercise function by gas exchange are usually adjusted for body mass and are expressed as millilitres per minute per kilogram. In the case of obese children this could lead to overcorrection with an underestimation of their exercise capacity. The purpose of the present study was to assess cardiorespiratory exercise function in obese subjects using body mass-independent parameters. As both carbon dioxide output (˙VCO2) and oxygen uptake (˙VO2) are usually corrected for body mass, the slope of ˙VCO2 versus ˙VO2 can be considered to be independent of body mass. This slope was calculated below the ventilatory threshold (S1) and above the ventilatory threshold (S3). Exercise tests were performed on a treadmill and respiratory gas exchange was measured breath-by-breath. A group of 29 obese children [mean age 11 (SD 2.5) years] were compared to 16 normal controls of the same age range [mean age 10.8 (SD 2.2); P > 0.05. The patients were overweight by 36 (SD 17.9)% and had a body mass index of 25.0 (SD 3.8). The results showed that S3 in the obese subjects was significantly steeper compared to the normal controls [1.30 (SD 0.20) vs 1.10 (SD 0.20); P < 0.05. The steepest values for S3 were found in the subjects with the highest degree of obesity. This method has some limitations, since in a large proportion of the patients (48%) no ventilatory threshold could be detected, which is prerequisite for calculation of these slopes. The latter was already suppressed at the onset of exercise in 21% of the sample or could not be detected because of breathing irregularity in 27%. It is suggested from this study that cardiorespiratory exercise function in obese children is reduced, especially when assessed by parameters of aerobic exercise which cancel the confounding effect of body mass.

Exercise performance and training in cardiac patients with atrial fibrillation.

PURPOSE Exercise training in cardiac patients with chronic atrial fibrillation (AF) has received little attention in the literature. Therefore, this study compared exercise performance and the effect of an exercise training program over a period of 3 months in patients with and without AF. METHODS Data in patients with AF (n = 19) were compared with a control group of patients in sinus rhythm (n = 44), drawn from a database of 2,116 patients. Patients performed a maximal exercise test on the bicycle until exhaustion before and after an ambulatory exercise training program where exercise training was offered 3 times a week for 3 months. RESULTS Before training, peak oxygen uptake (VO2) was significantly lower in patients with AF compared with the control group (1271 +/- 368 versus 1496 +/- 414 mL/min, P < 0.05). Exercise training significantly increased peak VO2 in both groups (+31%, P < 0.001 in AF and +25%, P < 0.001 in the control group). The gain in peak VO2 did not significantly differ between both groups. A significant decrease in resting heart rate was achieved in both groups after exercise training. AF was also a significant and independent determinant of peak VO2 in the total database, but not of the change in peak VO2. CONCLUSIONS Exercise training significantly improves exercise performance in cardiac patients with AF. AF affects exercise performance but does not impair the beneficial effects of training. Patients with chronic AF should therefore not be dissuaded from participating in exercise training after a cardiac event.

Comparison of cardiac output measured by two automated methods of CO2-rebreathing

PURPOSE The aim of the present study was to investigate the reproducibility of the exponential method of CO2 rebreathing with the use of automated curve fitting and to determine whether this method is superior to the equilibrium method in terms of reproducibility and clinical practicability. METHODS Repeated measurements of cardiac output were performed using the automated equilibrium and exponential methods. These measurements were compared in 12 healthy male subjects at rest and during incremental exercise tests. RESULTS Estimated cardiac output was not significantly different between duplicate measurements at rest nor at any level of exercise with either method. At rest the exponential method showed a tendency toward larger variability than the equilibrium method. The exponential method produced significantly higher (P < or = 0.001) estimates at rest (averaging up to 9.8 L x min(-1)) compared with the equilibrium method (averaging up to 6.5 L x min(-1)). Reproducibility improved for both methods with increasing workloads, and a second measurement at rest also seemed more reproducible and valid than the first. During exercise, both methods produced comparable values for cardiac output, and highly significant relations between cardiac output and oxygen uptake were observed for both methods (ranging from r2 = 0.79 to r2 = 0.88, P < or = 0.001). The equilibrium method produced unpleasant side effects more frequently (75% vs 21%, P < or = 0.001) compared with the exponential method and lead more subjects to premature interruption of the exercise test because of the rebreathing maneuver (42% vs 17%, P = 0.058). CONCLUSIONS Automated curve fitting for the exponential method gave reproducible and valid results during submaximal and maximal exercise but not at rest. The equilibrium method on the other hand interfered with exercise. Therefore, the equilibrium method is recommended at rest and at lower levels of exercise and the exponential method at higher intensities.

The CAREGENE study: ACE gene I/D polymorphism and effect of physical training on aerobic power in coronary artery disease

In coronary artery disease (CAD) the individual variation in aerobic power and the response to physical training are largely unexplained.1 The gene coding for the angiotensin converting enzyme (ACE) is expressed in several types of somatic cells, including vascular cells, heart, lung, and muscles.2 Intron 16 contains a polymorphism characterised by the presence (insertion (I)) or absence (deletion (D)) of a 287 bp Alu repeat sequence,3 which has been associated with endurance related phenotypes and the response to training.4 The objective of the present study was to investigate the role of ACE I/D polymorphism on aerobic power and its response to physical training in patients with CAD enrolled in the CAREGENE (cardiac rehabilitation and genetics of exercise performance) study. Biologically unrelated white patients with CAD (mean (SE) age 56 (0.3) years) who had achieved evident exhaustion during graded cycle ergometer testing before and after three months of physical training (three sessions weekly) from 1990 through 2001 (n  =  1095) were eligible for inclusion. The methods for graded exercise testing and training have been …

A genetic predisposition score for muscular endophenotypes predicts the increase in aerobic power after training: the CAREGENE study

BackgroundIt is widely accepted that genetic variability might explain a large part of the observed heterogeneity in aerobic capacity and its response to training. Significant associations between polymorphisms of different genes with muscular strength, anaerobic phenotypes and body composition have been reported. Muscular endophenotypes are positively correlated with aerobic capacity, therefore, we tested the association of polymorphisms in twelve muscular related genes on aerobic capacity and its response to endurance training.Methods935 Coronary artery disease patients (CAD) who performed an incremental exercise test until exhaustion at baseline and after three months of training were included. Polymorphisms of the genes were detected using the invader assay. Genotype-phenotype association analyses were performed using ANCOVA. Different models for a genetic predisposition score (GPS) were constructed based on literature and own data and were related to baseline and response VO2 scores.ResultsCarriers of the minor allele in the R23K polymorphism of the glucocorticoid receptor gene (GR) and the ciliary neurotrophic factor gene (CNTF) had a significantly higher increase in peakVO2 after training (p < 0.05). Carriers of the minor allele (C34T) in the adenosine monophosphate deaminase (AMPD1) gene had a significantly lower relative increase (p < 0.05) in peakVO2. GPS of data driven models were significantly associated with the increase in peakVO2 after training.ConclusionsIn CAD patients, suggestive associations were found in the GR, CNTF and the AMPD1 gene with an improved change in aerobic capacity after three months of training. Additionally data driven models with a genetic predisposition score (GPS) showed a significant predictive value for the increase in peakVO2.

Effect of creatine supplementation as a potential adjuvant therapy to exercise training in cardiac patients: a randomized controlled trial:

Objective: To investigate the effect of oral creatine supplementation in conjunction with an exercise programme on physical fitness in patients with coronary artery disease or chronic heart failure. Design: Single centre double-blind randomized placebo controlled trial. Setting: Cardiac rehabilitation centre. Subjects and intervention: 70 (4 women) cardiac patients (age 57.5 (8.4) years) were randomized to a placebo (n = 37) or creatine (n = 33) treatment for three months. Combined aerobic endurance and resistance training (three sessions/ week) was performed during supplementation. Main Measures: Aerobic power was determined during graded bicycle testing, knee extensor peak isometric and isokinetic strength, endurance and recovery were assessed by an isokinetic dynamometer, and health related quality of life was evaluated with the SF-36 and MacNew Heart Disease questionnaires. In addition, blood samples were taken after an overnight fast and 24 hour urinary collection was performed. Results: At baseline there were no significant differences between both groups. We observed main time effects for aerobic power, muscle performance, health related quality of life, high density lipoprotein cholesterol and triglycerides (pre vs post; P<0.05 for all). However, changes after training were similar between placebo group and creatine group (P>0.05). Further, no detrimental effect on renal or liver function was observed nor were there any reports of side effects. Conclusion: Oral creatine supplementation in combination with exercise training does not exert any additional effect on the improvement in physical performance, health related quality of life, lipid profile in patients with coronary artery disease or chronic heart failure than exercise training alone.