title: Efficacy of Exercise Intervention for Weight Loss in Overweight and Obese Adolescents: Meta-Analysis and Implications.
abstract: BACKGROUND
  The global rise in obesity prevalence among children and adolescents has been linked to modifiable lifestyle factors, including lack of physical activity. However, no known meta-analysis has been conducted on the effects of exercise intervention on body composition and cardiometabolic risk factors in overweight and obese adolescents.
  
  
  OBJECTIVE
  The aim of this study was to (1) estimate whether exercise intervention meaningfully improves body composition and cardiometabolic risk factors in overweight and obese adolescents; and (2) discuss the implications of the findings in terms of primary healthcare provision and public health policy, using New Zealand as an exemplar context.
  
  
  METHODS
  Electronic databases (PubMed, Web of Science, SPORTDiscus, Google Scholar) from inception to May 2015. The reference lists of eligible articles and relevant reviews were also checked.
  
  
  METHODS
  Inclusion criteria were (1) randomized controlled trial; (2) structured exercise intervention, alone or combined with any other kind of intervention; (3) control group received no structured exercise or behavioural modification designed to increase physical activity; (4) participants overweight or obese (body mass index [BMI] ≥85th percentile); and (5) participants aged between 10 and 19 years.
  
  
  METHODS
  Initially, 1667 articles were identified. After evaluation of study characteristics, quality and validity, data from 13 articles (15 trials) involving 556 participants (176 male, 193 female, 187 unknown) were extracted for meta-analysis. Meta-analyses were completed on five body composition parameters and ten cardiometabolic parameters. Effect sizes (ESs) were calculated as mean differences, as well as standardized mean differences in order to determine effect magnitude.
  
  
  RESULTS
  Exercise intervention reduced BMI (mean 2.0 kg/m2, 95 % CI 1.5-2.5; ES moderate), body weight (mean 3.7 kg, 95 % CI 1.7-5.8; ES small), body fat percentage (3.1 %, 95 % CI 2.2-4.1; ES small), waist circumference (3.0 cm, 95 % CI 1.3-4.8; ES small), but the increase (improvement) in lean mass was trivial (mean 1.6 kg, 95 % CI 0.5-2.6). The response to an oral glucose tolerance test following exercise intervention was for a decrease in the area under the curve for insulin (mean 162 μU/μl, 95 % CI 93-231; ES large) and blood glucose (mean 39 mg/dl, 95 % CI 9.4-69; ES moderate). Improvements in the homeostatic model assessment were also noted (mean 1.0, 95 % CI 0.7-1.4; ES moderate) and systolic blood pressure (mean 7.1 mmHg, 95 % CI 3.5-10.7; ES moderate). The effects of exercise on total cholesterol, low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, fasting insulin and fasting blood glucose were inconclusive.
  
  
  CONCLUSIONS
  Most of the included trials were short term (6-36 weeks) and 13 had methodological limitations. Additionally, the meta-analyses for some of the secondary outcomes had a small number of participants or substantial statistical heterogeneity.
  
  
  CONCLUSIONS
  The current evidence suggests that exercise intervention in overweight and obese adolescents improves body composition, particularly by lowering body fat. The limited available evidence further indicates that exercise intervention may improve some cardiometabolic risk factors.
authors.affiliation: Centre for Public Health Research, Massey University, PO Box 756, Wellington, New Zealand. dr.l.stoner@gmail.com.|School of Sport and Exercise, Massey University, Wellington, New Zealand. dr.l.stoner@gmail.com.
authors.forename: Lee
authors.initials: L
authors.lastname: Stoner
authors.affiliation: School of Sport and Exercise, Massey University, Wellington, New Zealand.
authors.forename: David
authors.initials: D
authors.lastname: Rowlands
authors.affiliation: School of Public Health, New Mexico State University, Las Cruces, NM, USA.
authors.forename: Ariel
authors.initials: A
authors.lastname: Morrison
authors.affiliation: School of Human Performance and Recreation, University of Southern Mississippi, Hattiesburg, MS, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Credeur
authors.affiliation: Department of Tourism, Sport and Society, Lincoln University, Christchurch, New Zealand.
authors.forename: Michael
authors.initials: M
authors.lastname: Hamlin
authors.affiliation: School of Sport and Exercise, Massey University, Wellington, New Zealand.
authors.forename: Kim
authors.initials: K
authors.lastname: Gaffney
authors.affiliation: Faculty of Health Sciences, University of Southampton, Hants, UK.
authors.forename: Danielle
authors.initials: D
authors.lastname: Lambrick
authors.affiliation: Centre for Public Health Research, Massey University, PO Box 756, Wellington, New Zealand.
authors.forename: Anna
authors.initials: A
authors.lastname: Matheson
mesh_terms: D000293:Adolescent; D001823:Body Composition; D015444:Exercise; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D006801:Humans; D008297:Male; D009765:Obesity / Q000628:therapy*; D050177:Overweight / Q000628:therapy; D016032:Randomized Controlled Trials as Topic; D016896:Treatment Outcome; D015431:Weight Loss / Q000502:physiology*