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

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 (3MST(20)), 3-min step test with 30-cm step box height (3MST(30)), and 6-min walk test (6MWT)) in estimating maximal oxygen consumption (VO(2max)) in young and healthy individuals. Methods: The 3MST(20), 3MST(30), 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: 3MST(20): 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); 3MST(30): 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 3MST(20), 3MST(30), 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 3MST(20), 3MST(30), 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 3MST(20), 3MST(30), and 6MWT were valid in estimating VO(2max) in relatively young and healthy Asian individuals.