Gender differences in response to a physical activity intervention in overweight and obese children.

Background: This study evaluated the effects of gender on response to a behavioral intervention that rewarded increases in physical activity (PA) with increases in access to TV viewing.

Methods: We performed a secondary analysis of a clinical trial that randomized 30 overweight or obese, 8- to 12-year-old children to an intervention (8 boys, 6 girls) or control (7 boys, 9 girls) group. Participants wore accelerometers every day for 8 weeks and attended biweekly meetings to download the activity monitors. For the intervention group, accumulating 400 counts of PA on accelerometers earned 1 hour of TV time, which was controlled by a Token TV electronic device. Controls wore activity monitors but had free access to TV.

Results: Compared with girls, boys in the intervention group exhibited greater increases in overall daily PA counts (110% versus 40%, P < .05) and minutes per day of moderate-to-vigorous physical activity (MVPA; +18.1 versus +2.7, P < .05). Neither boys nor girls in the control group showed significant changes in overall PA or intensity of PA.

Conclusion: Wearing an accelerometer in combination with rewarding PA with TV might be a more effective intervention for increasing overall PA and time spent in MVPA in overweight and obese boys than it is for overweight or obese girls.