The effect of aerobic interval training and continuous training on exercise capacity and its determinants.

Objective We aimed to investigate (1) the effects of aerobic interval training (AIT) and aerobic continuous training (ACT) on (sub)maximal exercise measures and its determinants including endothelial function, muscle strength and cardiac autonomic function, and (2) the relationship between exercise capacity and these determinants. Methods Two-hundred coronary artery disease (CAD) patients (58.4 ± 9.1 years) were randomized to AIT or ACT for 12 weeks. All patients performed a cardiopulmonary exercise test and endothelial function measurements before and after the intervention; a subpopulation underwent muscle strength and heart rate variability (HRV) assessments. Results The VO2, heart rate and workload at peak and at first and second ventilatory threshold increased (P-time <0.001); the oxygen uptake efficiency slope (P-time <0.001) and half time of peak VO2 (P-time <0.001) improved. Endothelial function and heart rate recovery (HRR) at 1 and 2 min improved (P-time <0.001), while measures of muscle strength and HRV did not change. Both interventions were equally effective. Significant correlations were found between baseline peak VO2 and (1) quadriceps strength (r = 0.44; P < 0.001); (2) HRR at 2 min (r = 0.46; P < 0.001). Changes in peak VO2 correlated significantly with changes in (1) FMD (ρ = 0.17; P < 0.05); (2) quadriceps strength (r = 0.23; P < 0.05); (3) HRR at 2 min (ρ = 0.18; P < 0.05) and Total power of HRV (ρ = 0.41; P < 0.05). Conclusions This multicentre trial shows equal improvements in maximal and submaximal exercise capacity, endothelial function and HRR after AIT and ACT, while these training methods seem to be insufficient to improve muscle strength and HRV. Changes in peak VO2 were linked to changes in all underlying parameters.

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.

Rationale and design of a randomized trial on the effectiveness of aerobic interval training in patients with coronary artery disease: the SAINTEX-CAD study.

BACKGROUND: Exercise-based cardiac rehabilitation is considered an important adjunct treatment and secondary prevention measure in patients with coronary artery disease (CAD). However, the issues of training modality and exercise intensity for CAD patients remain controversial. OBJECTIVE: Main aim of the present study is to test the hypothesis that aerobic interval training (AIT) yields a larger gain in peak aerobic capacity (peakVO2) compared to a similar training programme of moderate continuous training (MCT) in CAD patients. STUDY DESIGN: In this multicentre study stable CAD patients with left ventricular ejection fraction>40% will be randomized after recent myocardial infarction or revascularization (PCI or CABG) to a supervised 12-week programme of three weekly sessions of either AIT (85-90% of peak oxygen uptake [peakVO2], 90-95% of peak heart rate) or MCT (60-70% of peakVO2, 65-75% of peak heart rate). The primary endpoint of the study is the change of peakVO2 after 12 weeks training. Secondary endpoints include safety, changes in peripheral endothelial vascular function, the evolution of traditional cardiovascular risk factors, quality of life and the number and function of circulating endothelial progenitor cells as well as endothelial microparticles. Possible differences in terms of long-term adherence to prescribed exercise regimens will be assessed by regular physical activity questionnaires, accelerometry and reassessment of peakVO2 12 months after randomization. A total number of 200 patients will be randomized in a 1:1 manner (significance level of 0.05 and statistical power of 0.90). Enrolment started December 2010; last enrolment is expected for February 2013.

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

BACKGROUND: It 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. METHODS: 935 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 VO(2) scores. RESULTS: Carriers 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 peakVO(2) 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 peakVO(2). GPS of data driven models were significantly associated with the increase in peakVO(2) after training. CONCLUSIONS: In 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 peakVO(2).

The CAREGENE study: genetic variants of the endothelium and aerobic power in patients with coronary artery disease.

OBJECTIVES: Aerobic phenotypes show a wide variability to similar aerobic training stimuli, which can be partly attributed to heritability. Endothelial function affects aerobic power. Various physiological pathways may influence the endothelial function. Therefore, we aimed to examine whether polymorphisms of the eNos gene, the CAT gene, the VEGF gene, the GPX1 gene, the subunit P22 phox of the NAD(P)H-odixase gene, the PPAR-alpha gene, and the PGC-alpha gene are associated with aerobic power or with its response to physical training in patients with coronary artery disease (CAD). METHODS: 935 biologically unrelated Caucasian patients with CAD who had exercised until exhaustion during graded bicycle testing at baseline and after completion of 3 months of training were included in the CAREGENE study (Cardiac Rehabilitation and GENetics of exercise performance). Polymorphisms were detected using the invader assay and MassARRAY technology. Haplotype analysis was performed on the polymorphisms of the eNos gene, the VEGF gene and the NAD(P)H-oxidase gene. RESULTS: Physical training significantly increased aerobic power by 24.2 +/- 0.6% (P < 0.001). Associations of P < 0.05 were found between aerobic power and the eNOS 273C>T variant and the catalase -262C>T variant and aerobic power response. Haplotypes of the eNOS polymorhisms were predictive of aerobic power and its response to training (P < 0.05). After Bonferroni correction of multiple testing no significant differences remained. CONCLUSION: We believe that genetic factors are very important in the explanation of the great variability of aerobic power and its response. However, after Bonferroni-correction, differences in these polymorphisms remained no longer statistically significant.

The CAREGENE study: polymorphisms of the beta1-adrenoceptor gene and aerobic power in coronary artery disease.

AIMS: The heritability of aerobic power and of the response to physical training has been shown in healthy subjects. beta(1)-Adrenergic receptor (beta(1)AR) function affects exercise performance. This study aims to investigate whether the Ser49Gly and Gly389Arg polymorphisms of the beta(1)AR gene or their haplotypes are associated with aerobic power or its response to physical training in coronary artery disease (CAD). METHODS AND RESULTS: Nine hundred and thirty-five biologically unrelated Caucasian patients with CAD who had exercised until exhaustion during graded bicycle testing at baseline and after completion of 3 months of exercise training from 1990 to 2001 (n = 1095) were eligible for inclusion in the CAREGENE (CArdiac REhabilitation and GENetics of Exercise performance) study. Polymorphisms were detected using the invader assay (Third Wave Technologiestrade mark, Madison, Wisconsin, USA). Patients with the Gly49Gly genotype had significantly higher covariate-adjusted aerobic power at baseline than those with Ser49Ser and Ser49Gly (P < 0.05). Adjusted aerobic power at baseline was highest in the Ser49-Gly389/Gly49-Gly389 and Gly49-Arg389/Gly49-Arg389 haplotype combinations. Aerobic power increased significantly (P < 0.001) with physical training. There was no association with the effect of physical training. CONCLUSION: Ser49Gly and haplotype combinations of Ser49Gly and Gly389Arg of the beta(1)AR gene are associated with aerobic power, but not with the response to physical training in patients with CAD included in the CAREGENE study.

The caregene study: muscle-specific creatine kinase gene and aerobic power in coronary artery disease.

In 927 biologically unrelated Caucasian patients with coronary artery disease it was investigated whether the NcoI restriction fragment length polymorphism of the muscle-specific creatine kinase (CKMM) gene is associated with aerobic power and with the response to physical training. Physical training significantly (P<0.001) increased peak oxygen consumption in the GG, AG and AA NcoI genotypes. Covariate-adjusted peak oxygen consumption at baseline, after training and the response to training were not different across CKMM NcoI genotypes.

Determinants of the effects of physical training and of the complications requiring resuscitation during exercise in patients with cardiovascular disease.

BACKGROUND: Benefits of cardiac rehabilitation with exercise therapy are well-established, although individual reactions are heterogeneous. The identification of determinants of training effects is useful from a prognostic point of view, but data regarding this are scarce. Furthermore, limited data exist on the determinants of complications during exercise in cardiac patients. This study aimed to investigate the determinants (1) of training effects in cardiac rehabilitation and (2) of complications requiring resuscitation during exercise activities at the hospital and during continued exercise at a sports club for cardiac patients. DESIGN: Clinical association study. METHODS: Determinants of changes in peak oxygen uptake (VO2) after 3 months of cardiac rehabilitation were determined by multiple regression analysis (n=1909). Determinants of events requiring resuscitation (n=21) were assessed by logistic regression analysis. RESULTS: Improvements in peak VO2 and exercise duration averaged 26%. Eighteen per cent of the variance in absolute improvements of peak VO2 was explained, with age and training characteristics as the strongest determinants. Twenty-one per cent of the variation in relative improvements was explained, with baseline exercise performance and training characteristics being the strongest determinants. The intake of anti-arrhythmics (odds ratio=5.5; P<0.001) and the presence of ST-segment depression (> or =1 mm) at baseline exercise testing (odds ratio=1.6; P<0.001) were predictive for serious complications. The occurrence of events requiring resuscitation was higher at the sports club (1/16,533 versus 1/29,214 patient-hours). CONCLUSIONS: Age, baseline exercise performance and training characteristics were predictive for training effects in cardiac rehabilitation. Anti-arrhythmics and ST-segment depression at baseline exercise testing were predictive for complications.

Effect of exercise training in patients with an implantable cardioverter defibrillator.

AIMS: Little research exists on exercise performance and training in patients with an implemented cardioverter defibrillator (ICD) and only in a limited number of patients. This study aims to investigate the effect of exercise training in ICD patients in comparison to the effects in other cardiac patients without an ICD. METHODS AND RESULTS: 92 ICD patients were compared with a control group of 473 patients. A maximal cycle-spiroergometric test was performed until exhaustion before and after an ambulatory exercise training programme. Exercise training was offered 3 times a week for 3 months. The cut-off heart rate was set at (ICD detection rate -20 beats/min). At baseline, the ICD patients had a lower peak oxygen uptake (VO(2)) compared to the control group. Training effects were smaller for peak VO(2) (mL/min/kg) and oxygen pulse in the ICD group (18 vs. 27%, p = 0.006 and 11 vs. 17%, p = 0.016, respectively). Several appropriate shocks were delivered during (n = 5), and in between (n = 7), testing or training and one inappropriate shock during training. CONCLUSIONS: ICD patients can safely participate in an exercise training programme with favorable results. A randomised control study with evaluation of the physical and the psychosocial effects is warranted.

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.