Changes in physical activity among overweight and obese Norwegian children aged 6–12: A non-randomized cluster-controlled trial

Aims: To explore whether a family-based intervention with playful activities among overweight and obese Norwegian children promoted moderate to vigorous and light physical activity compared with a waiting list control group, and to examine whether gross motor competence, isometric body mass index and motivational factors, as reported by the children and their parents, could explain changes observed during a six-month observation. Methods: A non-randomized cluster-controlled trial with 131 participants, 76 in the intervention group. Participants were aged 6–12 years, and 55 were boys. We performed linear regressions to compare the intervention and the control groups and adjusted linear models to examine predictors for outcomes with the groups merged into one cohort. Results: We could not demonstrate any intervention effect from the family-based activities. Moderate to vigorous physical activity levels were satisfactory at the start and were maintained during the observation period. None of the predictors could explain outcome status at six months, nor residual change of moderate to vigorous physical activity during the observation. We revealed that parental educational attainment, parental autonomous motivation and the participants’ experience of social support impacted light physical activity negatively after six months. Parental education also impacted the residual change of light physical activity negatively during the observation. Conclusions: The present family-based intervention to improve physical activity among overweight and obese children was ineffective. Baseline activity levels were already satisfactory. Paradoxically, factors such as parental socioeconomic status, autonomous motivation and self-reported support from parents and peers may be associated with diminished physical activity in such contexts. These unexpected findings need to be validated in further studies.