Two datasheets were obtained from the SIMCE office, one with fitness data (n=29,721) and one with questionnaire data (n=24,564). Both datasheets were broken down and cleaned in order to have a full database with all the data from SIMCE on PE for 2012. A final database with a sample of 23,180 adolescents (11,927 females and 11,253 males aged 13.7±0.7 and 13.8±0.8 respectively) was obtained after removing participants who were found only in one datasheet or mainly without data (see Figure 1). Due to the great amount of sample and the characteristics of the study, there were participants who had missed data in some variables. The final sample differs according to variables included in each analysis, ranging from 16,839 (for regression analysis) to 23,180.

Figure 1.

Participants in the study.

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Results show that there were associations between sex and amount of PA in mild, moderate, vigorous and total activity (see Table 1). Boys practice more PA than girls in all levels of PA. The type of PA that more participants do is moderate, related with play jumping, running, playing with a ball or other similar games.

Table 2 shows the percentage of participant's weekly PA hours for each type of activity based on responses to the questions about parents and PE teacher. There was a statistically significant association between both parents’ and PE teacher's questions and weekly practice hours for all types of analyzed PA.

The percentage of adolescents who were totally sedentary was higher for those who reported their parents did not encourage them to practice sport (32.1%) or whose parents were not physically active (28.4%), while it was lower in those who reported their PE teacher did not encourage them to practice PA. Analyzing adolescents who did not engage in PA by category, percentages were higher in those who reported their parents did not encourage them to practice sport or their parents were not physically active.

The unadjusted and adjusted ORs obtained for each type of PA variable, their respective 95% confidence intervals (CI), and their p values are shown in Table 3. The unadjusted model for mild PA was the only one that did not show significant goodness of fit, but it was improved in the adjusted model. For both, the unadjusted and adjusted model, the OR for the questions related to parents (to encourage to practice sports and physical activity and to be physically active) was higher than the question related to PE teacher encouragement. Based on OR, sex was the most important confounder in all models except for Vigorous PA. OR for functional index was always higher than structural index, and OR for age was near 1 for all models.

This paper presents an analysis on the influence of parents’ and PE teacher's encouragement in adolescents to be physically active using a large nationally representative sample from Chile. Results indicate that parents’ influence is more relevant than PE teachers’ influence in order to promote PA in adolescents, regardless of age, sex and physical condition.

Results showed that more than 50% of participants did not engage at any time in vigorous PA in a week (playing sports, dancing or attending a workshop on PA apart from PE classes at school), and additionally, 35% of females did not engage in moderate PA in a week (jumping, running, playing with a ball or other similar games). These results match data from Latin America from previous studies, and corroborate the high prevalence of characteristic sedentary behaviors in the Latin American Region (Hallal et al., 2012).

Considering the recommendations of World Health Organization for weekly PA (World Health Organization, WHO, 2010) and the importance of PA for the prevention of diseases (Lee et al., 2012), the Chilean Ministry of Education has recently changed the PE curricular bases in order to give more importance to health promotion in this subject at schools (Ministry of Education, 2013). Ministry of Education changed the name of the subject from Physical Education to Physical Education and Health (MINEDUC, 2013). Although results in this study indicate that the encouragement of PE teachers to practice sport is not very relevant for adolescents in order to be physically active, benefits in children's PA outside the school in response to PE teachers’ influence have been proved previously (Cheon et al., 2012; Rosenkranz et al., 2012). These studies were focused on the improvement of motivational strategies in PE classes, more than just encouraging students to practice outside the school. Strategies are oriented to satisfy psychological key needs such as autonomy, competence and relationship. Results of our study show a smaller importance of the PE teacher's influence on PA levels in children, but is also relevant. Notwithstanding, it is necessary for teachers to know these strategies to increase their influence on their students, so they feel themselves more motivated to practice more PA in their leisure time (Chatzisarantis & Hagger, 2009).

Nevertheless, our results show that the influence of parents is more relevant than that of the PE teacher for adolescents in order to engage in PA. Specifically OR showed that the probability to engage in some PA increases 156% when adolescents are encouraged by their parents to practice sports and 85% when their parents are physically active, while this probability was only increased by 26% when they were encouraged by their PE teacher. Some studies have previously confirmed parents’ influence on children's physical activity showing that parents are a key factor in health-related behavior development of children. Depending on parents’ behaviors, children could inhibit or promote their PA (Beets et al., 2007; Edwardson & Gorely, 2010a). Our results indicate that encouragement of parents for their children to engage in PA is highly associated with the amount of PA that the children do, regardless if it is vigorous, moderate, mild or total PA. Previous studies examining the relationship between parental correlates and young people's physical activity including encouragement to engage in PA have produced mixed results regarding parents’ encouragement (Edwardson & Gorely, 2010b). Some have concluded that encouragement is positively related to young people's PA (Edwardson & Gorely, 2010b; Pugliese & Tinsley, 2007), while others have reported indeterminate relationships or no association (Ferreira et al., 2007; Sallis, Prochaska, & Taylor, 2000). Our results provide more information about this topic, giving importance to parents¿ encouragement. In view of this, policies to promote physical activity in children and adolescents should consider parents’ influence in order to succeed. There is evidence to suggest that lifestyle intervention effectiveness can be enhanced by including parents (Dellert & Johnson, 2014).

Regarding sex influence on engaging in PA, results showed it is a major issue. Near 20% of female participants reported that they do not engage in any weekly PA, while this number was 9% for males. Regarding regression analysis, sex was not significant for the vigorous PA model, but it was important for moderate, mild and total PA (OR values of 2.26, 1.71 and 2.19 respectively). The absence of differences in vigorous PA could be due to the questionnaire used. Students were asked about “dance and sports”, being an activities more proper of girls, compared with the activities in, i.e., moderate PA, “jumping, running, playing with a ball or other similar games”. Differences in PA by sex have been previously studied and it is well established that, in general, females report a higher level of sedentary lifestyle than males (Bauman et al., 2012). There are three major themes that affect girls’ physical activity, perceptual influences (i.e. girls need to feel and look feminine or they have to have fun during physical activity); interpersonal influences (i.e. ability comparison and competition or family, peer and teacher influences); and situational influences, such as accessibility and availability or physical activity and gender role (Standiford, 2013). Social environment must improve girls chance to be physically active and help them to increase their level of PA so parents not only can influence children through encouragement, but by being a role model they engage them in PA or they support the type of activity the children choose (Wright, Wilson, Griffin, & Evans, 2010). There is a need for more studies analyzing the effects of parents’ and teacher's influence in adolescents to be physically active, mostly longitudinal studies.

This study has some limitations that need to be reckoned. The variables of parents’ and teacher's influence for adolescents to be physically active and the questions about the amount of PA used in this study could be measured more deeply with other validated instruments. However, due to the great size of the sample, it is very difficult to add instruments with more than one question for a variable. However, all items used in SIMCE were extracted from validated questionnaires with international relevance, such as the Spanish version of Global School-based student health survey and California Healthy Kids Survey (Ministry of Education, 2014). Additionally, in this study the classification of PA into vigorous, moderate and mild, was made using questions about different activities instead of intensity, but these activities are similar to those used in the examples of internationally recognized questionnaires like iPAQ (Hagstromer, Oja, & Sjostrom, 2006).

Parents have a bigger influence in adolescents than PE teacher in adolescents for them to be active. Additionally, parents¿ encouragement to practice sports and PA is more related to it than parents’ behaviors on adolescents¿ physical activity. Results indicate that political efforts aimed to reduce sedentary behaviors in adolescents should be focused on parents more than on PE teachers. Ministry, at national level, and schools, at local level, have to implement policies of parent's education. Recommendations of quantity and quality of PA in children have been addressed prior in scientific literature (Saavedra, García-Hermoso, Escalante, & Domínguez, 2014; Slentz, Houmard, & Kraus, 2007), but related to parents it is scarce. Public agents have to inform and instruct parents and families in PA and health, promoting familiar activities where all members can successfully participate. Moreover, school-based interventions cannot be implemented independently of other strategies. The role of PE teacher or health professional, as was previously indicated (Naylor & McKay, 2009), is important to encourage parents in order to pinpoint the importance of family based activities.