Are current body mass index referenced pedometer step-count recommendations applicable to US youth?
The purpose of this study was to cross-validate international BMI-referenced steps/d cut points for US girls (12,000 steps/d) and boys (15,000 steps/d) 6 to 12 years of age. Secondary pedometer-determined physical activity data from US children (N=1067; 633 girls and 434 boys, 6 to 12 years) were analyzed. Using international BMI classifications, cross-validation of the 12,000 and 15,000 steps/d cut points was examined by the classification precision, sensitivity, and specificity for each age-sex stratum. For girls (boys) 6 to 12 years, the 12,000 (15,000) steps/d cut points correctly classified 42% to 60% (38% to 67%) as meeting (achieved steps/d cut point and healthy weight) and failing (did not achieve steps/d cut point and overweight). Sensitivity ranged from 55% to 85% (64% to 100%); specificity ranged from 23% to 62% (19% to 50%). The utility of pedometer steps/d cut points was minimal in this sample given their inability to differentiate among children who failed to achieve the recommended steps/d and exhibited an unhealthy weight. Caution, therefore, should be used in applying previous steps/d cut points to US children.