Level of physical activity among children and adolescents in Europe: a review of physical activity assessed objectively by accelerometry

This study explored the proportion of European youth who are sufficiently active according to physical activity (PA) recommendations, based exclusively on objective assessment through accelerometers. A systematic electronic search of studies published up to March 2012 was conducted. PubMed was used to identify accelerometry-assessed PA studies that involved European youth. Within the 131 European studies, only 35 clearly reported the proportion of youth meeting the PA recommendations. Different thresholds lying between 1000 and 4000 counts/min (cpm) were used to define moderate-to-vigorous PA (MVPA). Overall, up to 100% of youth may be sufficiently active when using a threshold of approximately >1000-1500 cpm. With the most cited cut-off point (i.e. >2000 cpm), up to 87% of European youth might be considered physically active with reference to the current recommendations. Alternatively, with a cut-off point >3000 cpm, no more than 3-5% of them appeared to achieve these recommendations. The large discrepancy in outcomes released by accelerometer data is mainly due to the variety of cut-off points for MVPA among youth, hindering the definition of a clear goal towards PA promotion in Europe. Standardization of methods is urgently required.