Plain language summary
The global number of overweight and obese children/adolescents is increasing at an alarming rate. This systematic review and meta-analysis aimed to assess the impact of exercise for overweight children/adolescents. Fourteen randomised controlled trials (RCTs) were included in the analysis. Overall the reduction in average body weight and central obesity was not significant. However, it was found that exercise did significantly reduce body fat percentage by 0.6% in studies that involved more exercise (more than 3 days a week) for children with an average age of 12. When results were grouped by exercise amount, it was found that higher amounts had greater effect. Additionally, trials with longer intervention length saw greater effects. None of the trials reached the level of exercise recommended for children by UK/US guidelines (at least 60 minutes a day). The author suggested further studies of longer duration in this area are required to clarify exercise amount response.
Abstract
BACKGROUND Overweight prevalence among children/adolescents is increasing, while adult obesity may potentially cause a decline in life expectancy. More exercise is uniformly recommended, although treatment efficacy remains unclear. OBJECTIVE To determine the efficacy of exercise alone for treating overweight in children/adolescents. DESIGN A systematic review and meta-analysis of randomized trials published in English were completed following multiple database searches performed on December 10, 2004. Studies of isolated or adjunctive exercise/physical activity treatment in overweight/obese children or adolescents which reported any overweight outcome were included. Literature searches identified 645 papers which were manually searched, of which 45 were considered for inclusion, of which 13 papers which reported 14 studies were included (N=481 overweight boys and girls, aged approximately 12 years). Two reviewers independently identified relevant papers for potential inclusion and assessed methodological quality. Principal measures of effects included the mean difference (MD) (between treatment and control groups), the weighted MD (WMD), and the standardized MD (SMD). RESULTS Few studies were of robust design. The pooled SMD was -0.4 (-0.7, -0.1, P=0.006) for percent body fat, and -0.2 (-0.6, 0.1, P=0.07) for central obesity outcomes, whereas the pooled WMD was -2.7 kg (-6.1 kg, 0.8 kg, P=0.07) for body weight, all of which favored exercise. Pooled effects on body weight were significant and larger for studies of higher doses, whereas nonsignificant and smaller effects were seen for studies of lower doses of exercise (155-180 min/weeks vs 120-150 min/weeks). CONCLUSIONS Based on the small number of short-term randomized trials currently available, an aerobic exercise prescription of 155-180 min/weeks at moderate-to-high intensity is effective for reducing body fat in overweight children/adolescents, but effects on body weight and central obesity are inconclusive. Recommendations for future study designs are discussed.
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