title: [Determining factors in body mass index of Spanish schoolchildren based on the National Health Surveys].
abstract: BACKGROUND
  Spanish National Health Surveys do not establish synergistic relations between variables. The purpose of this study was to perform a deeper historical analysis of body mass index (BMI) and its relation to other parameters included in the questionnaire for children.
  
  
  METHODS
  Data from interviews conducted (between 1987 and 2006) to parents and guardians of schoolchildren aged 9-15 years were analyzed. Height and weight reported by parents were selected and used to calculate BMI. Subjects were stratified by age, gender, time spent sleeping and watching television and, finally, frequency of physical activity. The historical trend of BMI and its dependence on the above factors were analyzed using ANOVA tests.
  
  
  CONCLUSIONS
  Significant weight and height increases were seen, which were more marked in boys aged 12 to 15 years. Influence of physical activity on BMI was shown, but decreased (P<.001) as exercise time increased. By contrast, BMI increased (P<.001) as time spent watching television increased. On the other hand, the role of sleep as modulator of body size was confirmed, since schoolchildren aged 9-11 years who slept over 9h had lower BMIs (P<.001). In subjects aged 12 to 15, BMI decreased (P<.001) from 6h of sleep.
authors.affiliation: Instituto de Enseñanza Secundaria Santa Eugenia, Consejería de Educación de la Comunidad de Madrid, Madrid, España.
authors.forename: Marisa
authors.initials: M
authors.lastname: González Montero de Espinosa
authors.forename: Angel
authors.initials: A
authors.lastname: Herráez
authors.forename: María Dolores
authors.initials: MD
authors.lastname: Marrodán Serrano
mesh_terms: D000293:Adolescent; D001827:Body Height; D015992:Body Mass Index; D001835:Body Weight; D002648:Child; D005260:Female; D006184:Habits; D006306:Health Surveys; D006801:Humans; D007899:Leisure Activities; D008297:Male; D009017:Morbidity / Q000639:trends; D009043:Motor Activity; D050177:Overweight / Q000453:epidemiology; D012307:Risk Factors; D057185:Sedentary Behavior; D012737:Sex Factors; D012890:Sleep; D013030:Spain / Q000453:epidemiology; D013690:Television
keywords: Actividad física; Body mass index; Encuestas Nacionales de Salud (España); Horas de sueño; Physical activity; Sleep duration; Spanish National Health Surveys; Television watching; Televisión; Índice de masa corporal