[Body mass index, motives for extracurricular sport practice and family type in grade 6 Primary Education children].

Introduction: obesity has many edges. Therefore, three complementary studies were conducted.
Objectives: study 1: determining body mass index (BMI) of the whole population of grade 6 students of a middle-size city and assessing their extracurricular sport habits. Study 2: assessing the motives for sport practice. Study 3: examining the role that family plays in extracurricular sport practice.
Methods: mixed focus, ex-post-facto transversal design. Study 1: 377 grade 6 students.
Instruments: measuring rod, scale and questionnaire. Study 2: 275 grade 6 students.
Instruments: questionnaire (BREQ-3; MPAM-R). Study 3: 228 parents.
Instrument: Families' Perception Questionnaire.
Results: study 1: BMI: 20.73 ± 4.12 kg/m2, 38.7% overweight, 10.1% obesity, 73% practice sport. BMI: no significant differences between those who practice sports and those who do not; significant differences based on socioeconomic status. Study 2: high intrinsic motivation; motive to participate: enjoyment. Study 3: parents value the importance of doing physical activity; significant differences favor those whose children play sports and have medium-high socioeconomic status. Parents whose children play sport: good for their health/development, he/she likes/choses it, socialization and values; parents whose children do not play sport: children's lack of time, he/she does not like it (can't find a sport he/she likes), parent's lack of time.
Conclusions: BMI close to overweight; extracurricular sports do not make a difference in BMI, socioeconomic status does (study 1). Sport participants intrinsically motivated, playing sports for enjoyment (study 2). Family: a model for sport practice (study 3).