Effects of High-Intensity Interval Training versus Continuous Training on Physical Fitness, Cardiovascular Function and Quality of Life in Heart Failure Patients

Introduction Physical fitness is an important prognostic factor in heart failure (HF). To improve fitness, different types of exercise have been explored, with recent focus on high-intensity interval training (HIT). We comprehensively compared effects of HIT versus continuous training (CT) in HF patients NYHA II-III on physical fitness, cardiovascular function and structure, and quality of life, and hypothesize that HIT leads to superior improvements compared to CT. Methods Twenty HF patients (male:female 19:1, 64±8 yrs, ejection fraction 38±6%) were allocated to 12-weeks of HIT (10*1-minute at 90% maximal workload—alternated by 2.5 minutes at 30% maximal workload) or CT (30 minutes at 60–75% of maximal workload). Before and after intervention, we examined physical fitness (incremental cycling test), cardiac function and structure (echocardiography), vascular function and structure (ultrasound) and quality of life (SF-36, Minnesota living with HF questionnaire (MLHFQ)). Results Training improved maximal workload, peak oxygen uptake (VO2peak) related to the predicted VO2peak, oxygen uptake at the anaerobic threshold, and maximal oxygen pulse (all P<0.05), whilst no differences were present between HIT and CT (N.S.). We found no major changes in resting cardiovascular function and structure. SF-36 physical function score improved after training (P<0.05), whilst SF-36 total score and MLHFQ did not change after training (N.S.). Conclusion Training induced significant improvements in parameters of physical fitness, although no evidence for superiority of HIT over CT was demonstrated. No major effect of training was found on cardiovascular structure and function or quality of life in HF patients NYHA II-III

Results of the SF-36 and Minnesota living with HF questionnaire (MLHFQ).

<p>Data is presented as mean±SD. P-values refers to 2-way repeated measures ANOVA between the 2 training groups. Results of the SF-36 were scored on a 0–100 scale, in which a high score represents a better quality of life. Results of the MLHFQ were scored on a 0–105 scale, in which a low score indicates few HF-related complaints.</p><p>^† Data was available for 7 subjects in the HIT-group.</p><p>^‡ Data was available for 8 subjects in the CT-group.</p><p>Results of the SF-36 and Minnesota living with HF questionnaire (MLHFQ).</p

Maximal incremental cycling test.

<p>Data is presented as mean±SD. P-values refer to a 2-way repeated measures ANOVA between the two training groups. One subject in the CT-group did not reach VO_2peak, and therefore only VE/VCO₂ slope and VO₂ at AT could be determined.</p><p>^# For statistical reasons, data was analyzed with three separate tests to determine <i>time</i>, <i>group</i> and <i>time*group</i> P-values.</p><p>Maximal incremental cycling test.</p

Flow-chart of the inclusion of subjects.

<p>Flow-chart of the inclusion of subjects.</p

Brachial (BA) and superficial femoral artery (SFA) endothelium-dependent vasodilation through flow-mediated dilation (FMD), peak diameter and endothelium-independent dilation (GTN), and common carotid artery (CCA) intima-media thickness (IMT).

<p>Data is presented as mean±SD. P-values refer to 2-way repeated measures ANOVA between the 2 training groups.</p><p>^# For statistical reasons, data was analyzed with three separate tests to determine <i>time</i>, <i>group</i> and <i>time*group</i> P-values. Due to technical problems, BA GTN/FMD-GTN ratio/peak blood flow was available for 9 subjects in the HIT-group and SFA FMD was available for 8 subjects in the HIT-group. CCA IMT and IMT-to-lumen ratio were available for 8 subjects in each group. SR_AUC; shear rate area-under-the-curve. CADC; conduit artery dilating capacity.</p><p>Brachial (BA) and superficial femoral artery (SFA) endothelium-dependent vasodilation through flow-mediated dilation (FMD), peak diameter and endothelium-independent dilation (GTN), and common carotid artery (CCA) intima-media thickness (IMT).</p

Subject characteristics and cardiovascular medication.

<p>Data is presented as mean±SD. P-values refer to a 1-way ANOVA.</p><p>^† Data was unavailable for 1 subject in the CT-group and 3 subjects in the control-group.</p><p>* Significantly less females compared to the control-group.</p><p>^§Lower compared to CT-group and HIT-group.</p><p>Subject characteristics and cardiovascular medication.</p

Echocardiographic left ventricular volumes, systolic function, strain and diastolic function.

<p>Data is presented as mean±SD. P-values refers to 2-way repeated measures ANOVA between the 2 training groups.</p><p>^# For statistical reasons, data was analyzed with three separate tests were performed to determine <i>time</i>, <i>group</i> and <i>time*group</i> P-values. 4D data was available for 7 patients in the CT-group and 8 patients in the HIT-group. IVCT-l, IVRT-C, IVRT-S and E/E’-L was available for 9 patients in the HIT-group. IVCT-S and E/E’-S was available for 8 patients in the HIT-group. IVCT-L and S/D ratio was available for 9 subjects in the CT-group. IVRT-L and E/A ratio was available for 8 subjects in the CT-group.</p><p>LVEDV; left ventricular end-diastolic volume. LVESV; left-ventricular end-systolic volume. IVCT-L/S: isovolumetric contraction time, lateral/septal. IVRT-L/S; isovolumetric relaxation time, lateral/septal. E/A ratio; peak mitral flow velocity during early filling/peak mitral flow velocity during atrial contraction. S/D; systolic flow velocity pulmonary vein/diastolic flow velocity pulmonary vein. E/E’-L/S; peak mitral flow velocity during early filling/peak mitral annulus velocity during early filling, lateral/septal.</p><p>Echocardiographic left ventricular volumes, systolic function, strain and diastolic function.</p