Six-minute step test in healthy and sedentary individuals: Is it a safe test?

Abstract

INTRODUCTION: The data of Six-Minute Step Test (6MST) suggest that it has greater energy expenditure than the Six-Minute Walk Test (6MWT). OBJECTIVE: To compare the heart rate (HR) and oxygen saturation at the end of 1^st and 6^st minute of 6MST and 6MWT as well as to compare HR 6^st minute of both tests with subjects' submaximal HR. METHODS: Both 6MWT and 6MST were achieved in Pedro Ernesto University Hospital – State University of Rio de Janeiro/Brazil. It was randomized healthy and sedentary males and females from Rio de Janeiro city; age 20 - 80 y-o and performed chest x-Ray, EKG, respiratory function tests and fulfilled Charlson Index (CI) < 1. Exclusion criteria: history of smoking, previous diseases, any exam abnormality or CI > 1. The HR and SaO₂ were measured every minute in both tests. The submaximal HR was calculated as 85% of maximal HR. The statistical analyses: Prism Graphpath software 6. RESULTS: 253 subjects were randomized. 1^stmin HR median : 6MWT was 101,9 (61-140) vs. 107,22 (56-142) 6MST. p= <0,0001; 6^thmin HR median: 6MWT was 111,47 (53-192) vs. 124,78 (77-198) in 6MST. p= <0,0001; 1^stmin SaO₂ median: 6MWT was 96,75 (74-100) vs. 97,06 (83-100) in 6MST. p= 0,0510; 6^thmin SaO2 median: 6MWT was 96,81 (78-100) vs. 97,55 (92-100) in 6MST. p= <0,0001; The submaximal HR of subjects was also compared with HR 6^thmin in 6MWT and 6MST. The calculated submaximal HR media: 149,91 (119,8-170) and HR median in 6^thmin 6MWT was 111,47 (53-192) (p < 0.0001) and the 6^thmin 6MST was the median 124,78 (77-198) p<0.0001. CONCLUSION: The HR in both minutes didn't exceed the submaximal HR in both tests, concluding that they are safe and that the 6MST can be used when the 6MWT is not possible.