Moderate‐to‐Vigorous Physical Activity among Children: Discrepancies in Accelerometry‐Based Cut‐off Points

Objective : To highlight the discrepancies in accelerometry cut‐off points of moderate‐to‐vigorous physical activity (MVPA) according to the definitions of Puyau et al. (MVPA P ) and Trost et al. (MVPA T ). Research Methods and Procedures : Forty‐five children from 8 to 11 years old were monitored with the ActiGraph (ActiGraph, LLC, Fort Walton Beach, FL) for 3 consecutive days. Daily time spent at MVPA obtained with MVPA P was compared with that obtained with MVPA T using variability, regression, and agreement statistics. Data were then discussed with regard to physical activity recommendations. Results : The mean daily time spent at MVPA P (28 ± 18 minutes) was significantly lower ( p < 10 −4 ) than that spent at MVPA T (141 ± 39 minutes). The coefficient of determination between the two definitions was low ( R 2 = 0.49 ± 0.71). There was a lack of agreement between the two definitions, with a mean error or bias of 113 min/d. Thirty‐four point eight percent and 100% of children underwent 30‐minute MVPA/d with MVPA P and MVPA T definitions, respectively. Discussion : Comparability between studies devoted to describing children's physical activity or to assessing interventions may lack consistency according to the definition, with a real risk of misclassification.