title: Habitual physical activity levels in childhood and adolescence assessed with accelerometry.
abstract: OBJECTIVE
  The purposes of this study were: 1) to evaluate age and gender differences in physical activity (PA) of children and adolescents; 2) to find out if children and adolescents fulfill the PA recommendations of 60 min x day(-1) of moderate (MPA) to vigorous PA (VPA).
  
  
  METHODS
  PA was assessed in 265 female and 238 male subjects, ranging from 6 to 18 years of age, grouped in 4 age groups, with MTI ActiGraph model 7164, during 7 consecutive days. The MTI actigraph data was reduced to bouts (30-, 20-, 10-, and 5-min) and minutes spent in MPA, VPA, and very VPA (VVPA).
  
  
  RESULTS
  The oldest boys and girls revealed a lower number of PA bouts than the younger ones. Significant gender differences were found in daily VPA, F(1, 492)=37.67, P<0.001; and VVPA F(1, 494)=24.11, P<0.001. Boys were more active than girls. Significant age group differences were also found in MPA, F(3, 494)=87.4, P<0.001; VPA, F(3, 492)=78.15, P<0.001; and VVPA, F(3, 454)=54.89, P<0.001. In both genders MPA, VPA and VVPA decreased with age. Till the age of 14, children had means between 79.6+/-30.6 and 144.1+/-76.9 min*day(-1) of PA. After this age, there was a decrease to 44.1+/-19.9 min*day(-1) in girls and to 56.3+/-31.9 min*day(-1) in boys.
  
  
  CONCLUSIONS
  Boys had more minutes a day of VPA and VVPA than girls. PA decreased with age. The subjects of this study, aged 6 to 15, fulfilled the recommendations of 60 min x day(-1) of MPA to VPA.
authors.affiliation: School of Education, Polytechnic Institute of Bragança, Portugal. vplopes@ipb.pt
authors.forename: V P
authors.initials: VP
authors.lastname: Lopes
authors.forename: C M S
authors.initials: CM
authors.lastname: Vasques
authors.forename: J A R
authors.initials: JA
authors.lastname: Maia
authors.forename: J C V
authors.initials: JC
authors.lastname: Ferreira
mesh_terms: D000054:Acceleration; D000293:Adolescent; D000704:Analysis of Variance; D002648:Child; D005260:Female; D006801:Humans; D008297:Male; D008991:Monitoring, Physiologic / Q000295:instrumentation*; D009043:Motor Activity / Q000502:physiology*; D012737:Sex Factors