title: Physical activity cut-offs and risk factors for preventing child obesity in Japan.
abstract: BACKGROUND
  There is no official recommendations for physical activity level or steps for preventing and improving child obesity in Japan.
  
  
  METHODS
  Three hundred and two Japanese children aged 9-12 years were recruited wore 3-D speed sensors. Subjects were divided into two groups using the criteria for child obesity in Japan. Body composition was measured on bioelectrical impedance analysis. Physical fitness test was done to evaluate physical strength. Twenty-four hour total steps, energy expenditure, and metabolic equivalents (MET) from Monday to Sunday were consecutively measured. The cut-offs for steps and physical activity level for preventing child obesity were evaluated on receiver operating characteristic curves. Daily life-related risk factors for child obesity were assessed on logistic regression analysis.
  
  
  RESULTS
  In both sexes, body volume; bodyweight, body mass index, fat mass, and percentage body fat in the obese group was significantly higher than in the normal group, but age and height were not different (P < 0.001). Aerobic power, running speed, and explosive strength in the obese group were inferior to those in the normal group (P < 0.001). More than 40 min of 4 MET exercise, defined as moderate-vigorous exercise, and 11,000 steps per day are essential to prevent child obesity. Additionally, >2 h TV viewing per day is a significant risk factor for child obesity (OR, 3.43; 95%CI: 1.27-9.31).
  
  
  CONCLUSIONS
  Cut-offs for physical activity and potential risk factors for child obesity have been identified. Recommendations for changes to daily lifestyle for school-aged Japanese children are given.
authors.affiliation: Department of Public Health, School of Medicine, Juntendo University, Tokyo, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Minematsu
authors.forename: Ryosuke
authors.initials: R
authors.lastname: Kawabuchi
authors.forename: Hiromi
authors.initials: H
authors.lastname: Okazaki
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tomita
authors.forename: Takuro
authors.initials: T
authors.lastname: Tobina
authors.forename: Takeshi
authors.initials: T
authors.lastname: Tanigawa
authors.forename: Noriaki
authors.initials: N
authors.lastname: Tsunawake
mesh_terms: D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D003430:Cross-Sectional Studies; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008019:Life Style; D008297:Male; D009043:Motor Activity / Q000502:physiology*; D063766:Pediatric Obesity / Q000453:epidemiology* / Q000503:physiopathology / Q000523:psychology; D010809:Physical Fitness / Q000502:physiology*; D012307:Risk Factors
keywords: Japan; child obesity; metabolic equivalent; school-aged children; step