Obesity is a problem that affects almost every region of the world. In Chile, data indicate that the prevalence of obesity in preschool children aged 4 to 6 years is 58%, which increases as they reach adolescence and adulthood. The role played by physical inactivity in the development of obesity is so relevant that it has been established that in children it is one of the factors that most contributes to the development of obesity. Among factors that influence adherence to healthy lifestyles are motor competence (CM) and physical condition (CF); Both CM and CF are factors that generate an underlying mechanism that decreases the risk of obesity and promotes health. Health-related quality of life [HRQoL] refers to an individual's subjective perception of the impact of health status on their physical, psychological, and social functioning. Overweight and obesity influence HRQoL. Physical activity interventions applied from an early age have proven to be a useful means of preventing childhood obesity, being more effective when implemented in the school environment and is key to achieving long-term results. The ecological model of physical activity favors modifying active lifestyle behaviors including intrapersonal, interpersonal, organizational, community, physical-environmental and political factors. Using the ecological model, physical activity interventions have managed to increase the levels of physical activity since the child and the entire environment that surrounds him or her are involved, that is, they have included the biological and behavioral, along with the motivational, school, in addition to taking into account environmental, cultural and socioeconomic aspects. The general objective of the project is to determine the effect of a physical activity intervention based on the ecological model, in the improvement of obesity parameters and quality of life in preschoolers from 4 to 6 years old. The study is experimental through a cluster-randomized clinical trial; of pre and postest.

The methodological approach is mixed. Physical Condition will be measured through the PREFIT battery with the following components:

body composition (weight, waist circumference; hip circumference, BMI); Musculoskeletal capacity (upper body strength, lower body strength; speed/agility); Cardiorespiratory capacity. Motor competence will be measured through the Children's Movement Assessment Battery (MABC-2) with the following components: Manual dexterity; Marksmanship and catch; Balance. Health-related quality of life will be assessed through the KINDL-R questionnaire for parents, in the validated version in Spanish; Sedentary behaviour and physical activity ActiGraph wGT3X-BT accelerometers will be used. To determine the effect, statistical tests will be applied for intragroup analysis and intrasubject repeated measures, considering p <.05 as significance. When statistically significant differences are found, the effect size will be calculated. In addition, the use of mixed regression models is contemplated where the models will be adjusted for baseline values and age. It is hypothesized that the physical activity intervention based on the ecological model will lead to a 3% decrease in body fat, improves anthropometric measurements, physical condition, improved competence and health-related quality of life.

Inclusion Criteria:

Be enrolled in the selected establishment Have the consent of the parents or legal guardian to participate in the activity Have the consent of the child when asked to participate

Exclusion Criteria:

Health impairments that limit participation in the physical activity intervention Have completed less than 80% of the intervention program

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