Can we use the 6-minute step test instead of the 6-minute walking test? An observational study.

OBJECTIVE: To verify whether or not heart rate is maintained below the calculated submaximal level in healthy, sedentary subjects when they perform the 6-minute step test (6MST) and the 6-minute walking test (6MWT), and to compare the maximal heart rate achieved by the subjects at the end of each test.

DESIGN: Observational, cross-sectional study.

SETTING: One tertiary centre.

PARTICIPANTS: Two hundred and fifty-three participants from a pool of 330 healthy and sedentary subjects between 20 and 80 years of age.

INTERVENTIONS: Both the 6MWT and the 6MST were performed in accordance with the American Thoracic Society's statement. Dyspnoea, blood pressure, oxygen saturation and heart rate were measured before and after each test.

RESULTS: Mean heart rate immediately after the 6MST was significantly higher than mean heart rate immediately after the 6MWT {125 [standard deviation (SD) 19] vs 111 (SD 17) beats/minute; mean difference 13 (95% confidence interval of the difference 10 to 16); P<0.001}. Moreover, mean heart rate during (3minutes after commencement) the 6MST [118 (SD 18) beats/minute] was statistically higher than mean heart rate at the end of the 6MWT [111 (SD 18) beats/minute; P<0.001]. None of the subjects achieved the calculated submaximal heart rate.

CONCLUSIONS: The 6MST and 6MWT are safe and produce submaximal effort in healthy participants. However, they are not interchangeable, and the 6MST requires more energy than the 6MWT.