Factors associated with positive outcomes

No information

Suggestions by review authors only:

・ No evidence that enjoyment of physical activity plays a critical role in youth physical activity levels

・ Attendance levels: ≥40% attendance associated with greater improvement in physical fitness (e.g., cardiovascular) compared to control students. <40% attendance was no better than controls

・ No evidence combined physical activity and diet intervention to be more effective on body composition, blood lipids, and psychosocial weight concerns.

Suggestions by review authors only:

・ Single-behaviour interventions may be most effective during these hours.

・ Effective interventions located in school settings; non-effective interventions more likely to take place in combinations of school, home, and community venues.

No information

・ Age: greater effect size on BMI in programs with participants aged 15 - 19 years

・ Gender: girls more receptive to intervention programmes that promoted weight control (always had higher effect sizes than boys) (male r = 0.005, female r = 0.030)

・ Duration: programs of 1 year most effective on BMI reduction (r = 0.095).

・ Content: Programmes combining physical activity and diet were most effective (r = 0.148) in reducing BMI. Programmes involving physical activity only and those combining physical activity with lifestyle changes were not successful in reducing children’s BMI.

・ Frequency: Most programs were 3 - 5 sessions a week. This frequency showed a greater effect size (r = 0.080) than 1 to 2 sessions per week (r = 0.029) or programs held more than 5 times per week (r = 0.077).

・ Gender: in 2/3 studies with separate gender analysis, boys had greater MVPA increase.

・ Weight status: in 4/7 studies with separate analysis based on BMI, overweight/ obese children profited more than those of normal weight.

・ Theory based interventions: no evidence that interventions based on behaviour change theories were more effective than those without underlying theory.


Mixed effectiveness


Not effective

Mixed effectiveness

Small positive effect

Mixed effectiveness