Effects of exercise training on maximal oxygen uptake in heart failure : a systematic review and meta-analysis

SUMMARY Aims. Low cardiorespiratory fitness is a common physical status among patients with heart failure. Several studies have examined the effects of exercise training on maximal oxygen uptake (VO2max) in heart failure. Though, these studies had relatively small sample sizes and highly variable results. Therefore the aim of this study was to systemically review the effects of exercise training on VO2max in heart failure patients. Methods. Database search of randomized controlled trials was conducted from Ovid MEDLINE and Cochrane Central Register of Controlled Trials. Search was allocated to studies with patients with heart failure, structured exercise intervention, control group receiving usual medical care, at least eight weeks duration and direct VO2max measurement method. Results. Seventeen studies with eighteen comparisons met the inclusion criteria. The pooled results indicated that VO2max changed by 17.2±13.2% in the training groups and 0.4±5.4% in control groups. The absolute change in VO2max was 2.9±2.3 in the exercise groups and 0.1±0.9 in the control groups. Thus, the net change in VO2max between the groups was 2.8 mL/kg/min. Aerobic training led to a larger change in VO2max between the groups than other training modes. Studies with higher exercise intensities and longer durations tended to produce larger improvements in VO2max. Additionally, gradually increasing workload was found effective method when targeting increase in VO2max through training. Conclusions. Long, moderate to moderate to high intensity aerobic exercise training with gradually increasing workload has statistically and clinically most significant effect on VO2max in heart failure patients