Developing and Validating a Step Test of Aerobic Fitness among Elementary School Children

The tests to estimate aerobic fitness among children require substantial space and maximum effort, which is often difficult for children. We developed a simple submaximal step test (Step Test of Endurance for Pediatrics, or STEP) and assessed its reliability, validity, and ability to estimate aerobic fitness among elementary school children. Children aged 5-10 years completed the STEP with a protocol consisting of 0.1-, 0.2-, and 0.3-metre (4, 8, and 12 in.) step heights. Participants underwent treadmill testing with open circuit spirometry to determine actual maximal oxygen consumption (V̇o_2max). Intra-class correlation coefficients (ICCs) assessed test-retest reliability of the STEP and its component tests. Multivariate linear regression assessed the associations between the STEP and V̇o_2max, adjusting for potential covariates such as age, sex, BMI, and comorbidity count. The STEP showed excellent reliability (ICC ≥ 0.92; N = 170), irrespective of effort level during testing. Significant effort issues and collinearity among the independent variables led us to exclude children aged 5-6 years (n = 45) from the regression analysis. The final regression model for children aged 7-10 years with adequate effort (n = 111), as defined by a respiratory exchange ratio of 1.0 or more, showed that the STEP, sex, and BMI were significantly predictive of V̇o_2max (R ² = 0.51). This new, effort-independent step test can estimate the aerobic fitness of children aged 7-10 years. Regression equations to estimate V̇o_2max from the STEP were provided.