title: Physical activity decreased by a quarter in the 11- to 12-year-old Swedish boys between 2000 and 2013 but was stable in girls: a smartphone effect?
abstract: OBJECTIVE
  This study explored physical activity, body mass index (BMI) and overweight and obesity from 2000 to 2013 using a convenience sample of second- and fifth-grade Swedish schoolchildren aged 8-9 years and 11-12 years, respectively.
  
  
  METHODS
  We examined cross-sectional cohorts of 126 second-grade children in 2000, 84 in 2006 and 44 in 2013 and 105 fifth-grade children in 2000 and 38 in 2013. No fifth graders were available in 2006. Physical activity data were collected based on pedometer readings over four consecutive weekdays, and height and weight were measured. Identical instruments and procedures were used in all three years.
  
  
  RESULTS
  There was an increase in physical activity in second-grade girls from 2000 to 2006 (p < 0.01), which then stabilised between 2006 and 2013, but second-grade boys and fifth-grade girls were stable throughout the study period. Fifth-grade boys decreased significantly (24%) from 16 670 to 12 704 steps per day (p < 0.01) from 2000 to 2013. Mean BMI scores remained stable over time.
  
  
  CONCLUSIONS
  Time trends in physical activity differed between boys and girls. Second-grade boys and fifth-grade girls were stable throughout, whereas second-grade girls increased from 2000 to 2006 before stabilising. Fifth-grade boys showed a significant 24% reduction from 2000 to 2013. Changes in recess and leisure time habits, such as smartphone use, may have influenced the result.
authors.affiliation: Linnaeus University, Kalmar, Sweden.|University of Gothenburg, Gothenburg, Sweden.
authors.forename: Anders
authors.initials: A
authors.lastname: Raustorp
authors.affiliation: Linnaeus University, Kalmar, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Pagels
authors.affiliation: University of Gothenburg, Gothenburg, Sweden.
authors.forename: Andreas
authors.initials: A
authors.lastname: Fröberg
authors.affiliation: Karolinska Institutet, Stockholm, Sweden.|Center for Epidemiology and Community Medicine, Stockholm County Council, Stockholm, Sweden.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Boldemann
mesh_terms: D015992:Body Mass Index; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D009043:Motor Activity; D050177:Overweight / Q000453:epidemiology; D063766:Pediatric Obesity / Q000453:epidemiology; D017678:Sex Distribution; D012737:Sex Factors; D000068997:Smartphone; D013548:Sweden; D013997:Time Factors
keywords: Body mass index; Obesity; Overweight; Physical activity; Schoolchildren