Attending After-School Physical Activity Club 2 Days a Week Attenuated an Increase in Percentage Body Fat and a Decrease in Fitness Among Adolescent Girls at Risk for Obesity.

PURPOSE

To evaluate the effect of a 17-week intervention, including an after-school physical activity (PA) club 3 d/wk, on moderate-to-vigorous physical activity (MVPA), body mass index (BMI) score, percentage body fat (%BF), and cardiorespiratory fitness (CRF) among fifth to eighth grade girls having a BMI score ≥0, and explore whether intervention outcomes varied by club attendance (1 vs 2 vs 3 d/wk).

DESIGN

Secondary analysis of data from a group randomized controlled trial (N = 1519, 10- to 15-year-old girls: n = 753 intervention; n = 766 control).

SETTING

Twenty-four Midwestern US schools (n = 12 intervention; n = 12 control).

SAMPLE

Subsample (n = 1194 girls) from trial's intervention (n = 593 girls) and control (n = 601 girls) groups having BMI scores ≥0.

MEASURES

Moderate-to-vigorous physical activity (min/h), BMI score, %BF, and CRF (: mL/kg/min) were estimated at baseline and postintervention.

ANALYSIS

Linear mixed-effect models.

RESULTS

Intervention group gained less %BF ( = -0.35, = .016), and their CRF decreased less ( = 0.22, 010) than the control. Marginally significant findings showed girls attending the club an average of 1 d/wk had greater increases in %BF ( = 0.33, = .087) and MVPA ( = 0.20, 083) and a greater decrease in CRF ( = -0.20, 061) than girls attending 3 d/wk. No differences occurred between girls who attended 2 versus 3 d/wk for any outcomes.

CONCLUSIONS

The intervention attenuated an increase in %BF and a decrease in CRF among girls at risk for obesity from baseline to postintervention. Offering the after-school PA club 2 d/wk may be adequate for achieving outcomes.