Validation of Submaximal Step Tests and the 6-Min Walk Test for Predicting Maximal Oxygen Consumption in Young and...

Background: This study aimed to test the validity of three different submaximal tests (i.e., 3-min step test with 20.3-cm step box height (3MST₂₀), 3-min step test with 30-cm step box height (3MST₃₀), and 6-min walk test (6MWT)) in estimating maximal oxygen consumption (VO_2max) in young and healthy individuals. Methods: The 3MST₂₀, 3MST₃₀, 6MWT, as well as the cardiopulmonary exercise test (CPET) were performed in 73 participants (37 men and 36 women; mean age: 30.8 ± 9.3 years). All participants visited the clinic three times in a random order for anthropometric measurements, three submaximal tests, and the VO_2max test. Multiple linear regression analyses were conducted to construct the VO_2max prediction equations for each submaximal test. Results: The prediction equations developed based on multiple regression analyses for each submaximal tests were as follows: 3MST₂₀: VO_2max = 86.0 - 10.9 × sex (male = 1, female = 2) - 0.4 × age - 0.1 × weight - 0.1 × heart rate recovery at 30 s (HRR30s); 3MST₃₀: VO_2max = 84.5 - 10.2 × sex (male = 1, female = 2) - 0.4 × age - 0.1 × weight - 0.1 × HRR30s; and 6MWT: VO_2max = 61.1 - 11.1 × sex (male = 1, female = 2) - 0.4 × age - 0.2 × weight - 0.2 × (distance walked·10^-1). The estimated VO_2max values based on formulated equations were 37.0 ± 7.9, 37.3 ± 7.6, and 36.9 ± 7.9 mL∙kg^-1∙min^-1 derived from the 3MST₂₀, 3MST₃₀, and 6MWT, respectively. These estimated VO_2max values were not significantly different from the measured VO_2max value, 37.3 mL∙kg^-1∙min^-1. The estimated VO_2max based on the 3MST₂₀, 3MST₃₀, and 6MWT results explained 73.4%, 72.2%, and 74.4% of the variances in the measured VO_2max (p < 0.001), respectively. Conclusions: The 3MST₂₀, 3MST₃₀, and 6MWT were valid in estimating VO_2max in relatively young and healthy Asian individuals.