Aerobic fitness percentiles for U.S. adolescents.

BACKGROUND Although aerobic fitness has been well studied, establishing developmental patterns from previous studies has some limitations including selection bias and the statistical modeling of growth-related data. PURPOSE The purpose of this study was to develop age-, gender-, and race-specific smoothed percentiles for aerobic fitness using the LMS (L=skewness, M=median, and S=coefficient of variation) statistical procedure in a large, multiethnic, nationally representative sample of U.S. adolescents aged 12-18 years. METHODS Data from the National Health and Nutrition Examination Survey (NHANES [1999-2000 and 2001-2002]) were combined. In all, 2997 subjects (1478 boys and 1519 girls) completed a treadmill exercise test from which maximal oxygen consumption (VO(2)max) was estimated from heart rate response. Percentile curves were determined by using the LMS procedure, which fits smooth percentile curves to reference data. RESULTS Separate LMS curves were initially prepared for each gender and race; however, since the overall distribution of the data was not different for whites, blacks, and Hispanics, the participants were combined, and separate centile curves were prepared for boys and girls. Specific percentile values were created from the LMS curves, and the age- and gender-specific values for LMS are provided for calculation of individual z-scores (SD scores). In general, there is a slight increase in estimated VO(2)max of boys aged 12-15 years and then it remains stable. In girls, there is slight decrease in estimated VO(2)max across ages 12-18 years. Boys have higher values than girls at every age-specific percentile. CONCLUSIONS This study presents age- and gender-specific percentiles for U.S. youth aged 12-18 years based on NHANES (1999-2002), and adds to the recent application of the LMS statistical procedure for the construction of growth percentiles for a variety of outcomes. Comparisons are made to current FITNESSGRAM(®) thresholds.