The aim of this study is to test whether a parent-focused participatory intervention in addition to gym lessons can enhance preschoolers physical activity compared to gym lessons alone.

Over the last 20 years, physical activity (PA) in children has rapidly decreased in both developed and developing nations. More effective interventions to prevent inactivity in childhood thus are urgently needed. The preschool years, including the adiposity rebound period, might represent a good window of opportunity. Study literature suggests that targeting parents is crucial for lasting changes in young childrens' behavior. However, it is not known which methods are effective for involving parents in physical activity promotion. Consistent with experience from community-based participatory research, encouraging parents to participate the intervention in terms of content and structure might lead to higher intervention effectivity and sustainability. In our study, we therefore "enriched" a child-centered physical activity intervention in preschools (twice weekly gym lessons over 6 months) with a parent-focused participatory community intervention component.

Inclusion Criteria:

• age 3-6 years

Exclusion Criteria:

• severe atopic dermatitis,
• serious acute infectious diseases,
• physical malformations, and
• severe physical disabilities.