500-meter and 1000-meter moderate walks equally assess cardiorespiratory fitness in male outpatients with cardiovascular diseases

The walking speed maintained during a moderate 1-km treadmill walk (1k-TWT) has been demonstrated to be a valid tool for estimating peak oxygen uptake (VO2peak), and to be inversely related to long-term survival and hospitalization in outpatients with cardiovascular disease (CVD). We aimed to examine whether 500-meters and 1-k moderate treadmill-walking tests equally estimate VO2peak in male outpatients with CVD. One hundred forty-two clinically stable male outpatients with CVD, aged 34-92 years, referred to an exercise-based secondary prevention program, performed a moderate and perceptually-regulated (11-13/20 on the Borg Scale) 1k-TWT. Age, height, weight, time to walk 500-meter and the entire 1000-meter, and the corresponding heart rates were entered into validated equations to estimate VO2peak. VO2peak estimated from the 500-meters test was not different from that estimated from the 1k test (25.2±5.1 vs. 25.1±5.2 mL/kg/min). The correlation coefficient between the two was 0.98. The slope and the intercept of the relationship between the 500-meter and 1k tests were not different from the line of identity. Bland-Altman analysis demonstrated that 96% of the data points were within two standard deviations (from -1.9 to 1.7 mL/kg/min). The 500-meter treadmill-walking test is a reliable method for estimating VO2peak in stable male outpatients with CVD. A shorter version of the test, 500-meter, provides similar information as that from the original 1k test, but is more time efficient. These findings have practical implications in the context of transitioning patients from clinically based and supervised programs to fitness facilities or self-guided exercise programs.