Aerobic Fitness Percentiles for U.S. Adolescents Joey C. Eisenmann, PhD, Kelly R. Laurson, PhD, Gregory J. Welk, PhD Background: Although aerobic fıtness 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-specifıc smoothed percentiles for aerobic fıtness using the LMS (L=skewness, M=median, and S=coeffıcient 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 fıts 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. Specifıc percentile values were created from the LMS curves, and the age- and gender-specifıc 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-specifıc percentile. Conclusions: This study presents age- and gender-specifıc 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. (Am J Prev Med 2011;41(4S2):S106 –S110) © 2011 American Journal of Preventive Medicine Introduction T here has been considerable interest in the health- related physical fıtness of contemporary children and adolescents. 1,2 Besides body composition, and more specifıcally body fatness or its clinical outcome— obesity—aerobic (or cardiorespiratory) fıt- ness also receives considerable attention as a health- related fıtness trait. A main reason why aerobic fıtness receives attention is the link between aerobic fıtness and chronic disease in adults. 3,4 In children and adolescents, aerobic fıtness is associated with cardiovascular disease risk factors 5,6 and other health outcomes. 2 Recent reports have indicated that approximately one third of U.S. ado- lescents possess inadequate levels of aerobic fıtness. 7,8 The development of clinical thresholds or recommended levels of health outcomes in youth generally takes on two approaches. The fırst is to understand the general develop- mental pattern in the trait of interest (i.e., age- and gender- associated variation). The second is to determine a specifıc level that adversely affects risk of health or disease outcome. The developmental pattern of aerobic fıtness has been well studied, including the classic cross-sectional investigations of Robinson 9 and Astrand, 10 and longitudinal studies (e.g., Saskatchewan Growth and Development Study 11 ), and has From the Departments of Kinesiology and Pediatrics and Human Develop- ment (Eisenmann), Michigan State University, East Lansing; The Healthy Weight Center at Helen DeVos Children’s Hospital (Eisenmann), Grand Rapids, Michigan; the School of Kinesiology and Recreation, Illinois State University (Laurson), Normal, Illinois; and the Department of Kinesiology, Iowa State University (Welk), Ames, Iowa Address correspondence to: Joey C. Eisenmann, PhD, 27P IM Circle, Department of Kinesiology, Michigan State University, East Lansing MI 48824. E-mail: jce@msu.edu. 0749-3797/$17.00 doi: 10.1016/j.amepre.2011.07.005 S106 Am J Prev Med 2011;41(4S2):S106 –S110 © 2011 American Journal of Preventive Medicine • Published by Elsevier Inc.