A moderate 500-m treadmill walk for estimating peak oxygen uptake in men with NYHA class I-II heart failure and reduced left ventricular ejection fraction

Background: Maximal cardiopulmonary exercise testing (CPX) is the gold-standard for cardiorespiratory fitness assessment in chronic heart failure (CHF) patients. However, high costs, required medical supervision, and safety concerns make maximal exercise testing impractical for evaluating mobility-impaired adults. Thus, several submaximal walking protocols have been developed and currently used to estimate peak oxygen consumption (VO 2 peak) in CHF patients. However, these tests have to be performed at close to maximum exercise intensity. The aim of this study was to examine the validity of a 500-m treadmill-walking test carried out at moderate intensity for estimating VO 2 peak in community-dwelling adult and elderly patients with CHF and reduced left ventricular ejection fraction (HFrEF). Methods: Forty-three clinically stable men with HFrEF (age 67.7±9.2 years, and left ventricular ejection fraction, LVEF 38%±6%) underwent exercise testing during an outpatient cardiac rehabilitation/secondary prevention program. Each patients completed a CPX, and a moderate and self-paced (11-13/20 on the Borg scale) 500-m treadmill-walking test. Age, weight, height, walk time, and heart rate during the 500-m test were entered into prediction equations previously validated for VO 2 peak estimation from a 1000-m walking test in patients with cardiovascular disease and preserved LVEF. Results: Directly measured and estimated VO 2 peak values were not different (21.6±4.9 vs 21.7±4.6 mL/kg/min). The comparison between measured and estimated VO 2 peak values yielded a correlation of R =0.97 (SEE=0.7 mL/kg/min, P <0.0001). The slope and the intercept coincided with the line of identity (Passing and Bablock analysis, P =0.50). Residuals were normally distributed, and the examination of the Bland-Altman analysis do not show systematic or proportional error. Conclusions: A moderate and self-regulated 500-m treadmill-walking test is a valid tool for VO 2 peak estimation in patients with HFrEF. These findings may have practical implications in the context of transitioning from clinically based programs to fitness facilities or self-guided exercise programs in adults and elderly men with HFrEF.