Prediction of maximal oxygen consumption using the Young Men's Christian Association-step test in Korean adults

Purpose To develop accurate and practical prediction models of maximal oxygen consumption (VO(2)max) using the Young Men's Christian Association (YMCA)-step test in South Korean adults. Methods In total, 568 adults (20-66 years) were included in this study. To develop and cross-validate prediction models of VO(2)max, the total sample was divided into 80% training and 20% testing using a simple random sampling method. VO(2)max was measured using the maximal-graded exercise treadmill test. Sex, age, 1-min recovery heart rate, body weight, and height were measured as potential predictors. Each test was conducted within a 2- to 3-day interval, ensuring sufficient rest. Preliminary prediction models were developed from training datasets, which were cross-validated using regression analyses and/or repeated-measures analysis of variance. The accuracy of prediction models was evaluated using R-2, standard error of estimate (SEE), and mean difference (MD) against a criterion-measured VO(2)max. Results The average age and VO(2)max were 43.5 +/- 12.9 years and 39.1 +/- 7.5 ml/kg/min, respectively. For model development, three practical models with acceptable accuracy were developed (R-2 = 0.56-0.61; SEE = 4.74-5.01). For model cross-validation, significant relationships between the criterion-measured and predicted VO(2)max were observed in all three models (R-2 = 0.56-0.61; SEE = 4.62-4.88). The difference between criterion-measured and predicted VO(2)max was not significant in the models (MD = -0.03 to -0.14). Conclusions The prediction models included 3-5 variables as significant predictors of VO(2)max and had acceptable accuracy in a large sample of South Korean adults. The selected models provide a simple and practical method to estimate VO(2)max using the YMCA-step test for South Korean adults.