Abstract MP40: A Steps/Day Translation of the Moderate-to-Vigorous Physical Activity Guideline for Children and Adolescents
Background: An evidence-based steps/day translation of U.S. federal guidelines for youth to engage in ≥60 minutes/day of moderate-to-vigorous physical activity (MVPA) would help health researchers, medical practitioners, and lay professionals charged with increasing youth’s physical activity (PA). The purpose of this study was to determine the number of free-living steps/day (both raw and adjusted to a pedometer scale) that correctly classified children (6-11 years) and adolescents (12-17 years) as meeting the 60-minute MVPA guideline using the 2005-2006 National Health and Nutrition Examination Survey (NHANES) accelerometer data, and to evaluate the 12,000 steps/day recommendation recently adopted by the President’s Challenge Physical Activity and Fitness Awards Program.
Methods: NHANES children (n=915) and adolescents (n= 1,302) were included in this analysis. Receiver Operating Characteristic (ROC) curve plots and classification statistics (i.e., false positive and negatives, positive and negative predictive values) revealed candidate steps/day cut points that discriminated meeting/not meeting the MVPA threshold by age group, gender and different accelerometer activity cut points. The Evenson cut point and two Freedson age-specific (3 and 4 METs) cut points were used to define minimum MVPA, and optimal steps/day were examined for raw steps and adjusted to a pedometer-scale to facilitate translation to lay populations.
Results: For boys and girls (6-11 years) with ≥ 60 minutes/day of MVPA, a range of 11,500-13,500 raw steps/day for children was the optimal range that balanced classification errors. For adolescent boys and girls (12-17) with ≥60 minutes/day of MVPA, 11,500-14,000 raw steps/day was optimal. Translation to a pedometer-scaling reduced these minimum values by 2,500 step/day to 9,000 steps/day. Area under the curve was ≥84% in all analyses.
Conclusions: A persistent question in the physical activity literature has been “How many steps/day are enough?” No single study has definitively identified a precise and unyielding steps/day value for youth. Considering the other evidence to date, we propose a reasonable ‘rule of thumb’ value of ≥ 11,500 steps/day for both children and adolescents (and both genders), accepting that more MVPA is better. For practical applications, 9,000 steps/day appears to be a more pedometer-friendly value. These steps/day values provide a marker that medical practitioners and lay professionals can use in clinical settings to estimate and increase youth’s moderate-to-vigorous physical activity.
- © 2013 by American Heart Association, Inc.