title: Participation in organized weekly physical exercise in obese adolescents reduced daily physical activity.
abstract: OBJECTIVE
  The aim of this study was to describe the impact of organized weekly exercise for 13 weeks on aerobic fitness, objectively assessed habitual physical activity and body weight in obese adolescents.
  
  
  METHODS
  After inclusion and diagnostic evaluation, the adolescents were randomized to either an exercise group or to a control group which lasted for 13 weeks and consisted of a variety of group exercise activities. Out of 47 adolescents 31 (66%) could be evaluated, 16 in the exercise group and 15 in the control group.
  
  
  RESULTS
  After the intervention, the exercise group had decreased the daily time spent in moderate activity by 17 (32) min/day (p < 0.05), and the average intensity by 60 (96) counts/min (p < 0.05). A tendency for increased time spent in inactivity was found (37 min/day). No differences were seen in the control group for any of the variables measured.
  
  
  CONCLUSIONS
  The exercise group showed, in contrast to expectations, a reduction in total daily physical activity with organized physical exercise compared to the control group. This may partly explain the failure of many intervention trials.
authors.affiliation: Unit for Preventive Nutrition, Department of Biosciences and Nutrition, Karolinska Institutet, Stockholm, Sweden. maria.hagstromer@ki.se
authors.forename: Maria
authors.initials: M
authors.lastname: Hagströmer
authors.forename: Karin
authors.initials: K
authors.lastname: Elmberg
authors.forename: Staffan
authors.initials: S
authors.lastname: Mårild
authors.forename: Michael
authors.initials: M
authors.lastname: Sjöström
mesh_terms: D000293:Adolescent; D002648:Child; D015444:Exercise; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000628:therapy*; D013997:Time Factors