Sedentary behavior among Spanish children and adolescents: findings from the ANIBES study

Sedentary lifestyle is of increasing concern around for decades in European countries and worldwide [1]. In adults, it has been identified as an independent risk factor for chronic diseases [2]. In children and adolescents, results are more controversial [3‐9]. Results from cross-sectional studies indicate that young people who are even slightly sedentary may have greater fat mass, higher BMI, and increased risk of being overweight or obese, independently of their physical activity (PA) [10]. On the contrary, a recent systematic review analyzing the prospective relationship of sedentary behaviors and health outcomes concluded that current evidence is unconvincing [11]. Other authors have proposed that it is not the general sedentary behavior, but the increased use of new technologies, particularly watching television, playing digital games, and using computers that could be critical [12]. This so called screen-based sedentary behavior has been associated with a range of adverse health consequences [12, 13].even independently of their impact on PA [14], such as adiposity, aerobic fitness, quality of life, self-esteem, pro-social behavior, academic achievement, depression and anxiety [15]. Other authors conclude that there is not enough data available to draw conclusions on this issue, specifically if children and adolescents are sedentary but active at the same time [16].

In fact, regular PA is recommended for improvement of overall health and to facilitate weight control [17, 18]. Among young people, PA also fosters optimal physical and cognitive growth and development [14, 19]. Therefore, children and adolescents aged 5 to 17 years should accumulate at least 60 min of moderate- to vigorous-intensity PA daily [20]. In a recent report from the ANIBES study, we observed that a total of 55.4% of Spanish children and adolescents are not meeting these international PA recommendations [21]. More recently, apart from meeting PA guidelines, reducing sedentary behavior has become an additional goal in public health [10], even if the above-mentioned controversy exists.

With the aim of reducing screen time among children and adolescents, the American Academy of Pediatrics (AAP) in 2001 had already recommended that young people should not spend more than 2 h per day on screen viewing [22], although these 2-h cut-off are controversial and families are confused for good reason [23, 24], as just discussed above. Other countries also launched screen-time recommendations for children and adolescents more recently [25]. At a global level, data are inconsistent regarding time spent on sedentary behaviors. In some European countries, 61% of children aged between 11 and 15 years watched TV more than 2 h per day. In adolescents from the HELENA study, 58% of males and 53% of females watched TV more than 2 h per day during weekend days [26]. The publication of these data raised the awareness that adolescents living in Europe are probably not meeting recommendations regarding time spent in front of a screen, especially during weekends. Moreover, the absence of a TV in the adolescents’ bedrooms has been identified as a protective factor [26]. Regardless of the possible negative consequences for health in early life, sedentary behaviors seem to track from childhood to adolescence and into adulthood [27].

To the best of our knowledge, the prevalence of sedentary screen based behaviors among children and adolescents living in Spain is not well known currently. In order to direct policies that promote interesting activities in different settings (family, school, community) for reducing sedentary screen behaviors, we hypothesized that in Spain as happens in other European countries, there is a high degree of children and adolescents who have a high use of screen devices. There could be a sex (gender) and age effects on this behavior that should be considered in public health, concretely that boys and adolescents the most users of screen devices. The ANIBES study allows us to approach this hypothesis by describing the prevalence of sedentary behaviors in a representative sample of children and adolescents from Spain. In particular, the objectives of this study were: (1) to describe sedentary behaviors by age and sex, (2) to describe electronic device availability at home (TV, computer and console), and (3) to examine the determinants for excess (≥2 h/day) screen time in total and by individual device.

Table 1 shows the percentage of participants who spent more than 2 h in front of a screen; 48.4% of the total participants spent > 2 h every day of the week, 49.3% during the week and 84.0% during weekends. There were significant differences between children and adolescents for every day of the week and during weekdays (all p < 0.05). These differences were also observed between females and males.

On Tables 2 and 3, prevalence information of sedentary behaviors on weekdays and weekend days by sex and age group is presented.

The present study describes the prevalence of sedentary behaviors in a representative sample of Spanish children and adolescents. Adolescents spent more time watching TV, playing with computer games, surfing on the internet (both for study and non-study reasons) than children. Except for using the internet for study reasons, for all other sedentary behaviors assessed in the ANIBES study, Spanish children and adolescents reported more screen time on weekend days than on weekdays. The only difference by sex was observed for time spent playing console and computer games, which was higher in males on weekends, the later only among adolescents. Taken together, almost 38.5% of children and 60.2% of adolescents spent > 2 h/day in front of a screen during weekdays, and 82.2 and 85.8%, respectively, during weekend days.

Given that young people have incorporated new technologies into their leisure-time activities to a great extent [30] and that there has been a decreasing trend in Spain of active commuting to school [31], moderate-vigorous activity and active commuting (mainly walking) to school should be encouraged, among other activities [32, 33]. Along the same lines, Bucksch et al. (2016) reported that the amount of screen-time behaviors among adolescents has increased in many parts of Europe and North America during the last decade [34]. In England, 40% of children aged 2 to 15 years reported being sedentary (not including TV viewing) for more than two hours per day on weekdays and 53% on weekend days [35]. Sisson et al. (2009) presented that the total proportion of young people engaged in TV/video viewing, computer use, and total screen time ≥ 2 h daily was 33.0%, 6.7%, and 47.3%, respectively. Data from Canada indicated alarming results with 80.6% reporting that they spent accumulatively a total of more than 2 h/day watching television, playing video games, and using a computer [36]. Martinez-Gómez et al. (2012), observed in 1,724 Spanish adolescents (882 girls), aged 13 to 16 years from the Region of Madrid that over 63% were not meeting the recommendation to avoid sedentary behavior on weekdays and 87% did not comply with this recommendation on weekends [37]. These data are similar to the results obtained in the present study in a representative sample for Spanish children and adolescents. In our study, 37.6% of children and 59.2% of adolescents spent > 2 h/day in front of a screen during every day of week.

On the other hand, in our study, a total of 16.9% of children and 25.1% of adolescents exceeded 2 h/day based only on their TV viewing during weekdays, while this percentage increases on weekends (57.7% of children and 59.8% of adolescents). Along the same lines, other studies have reported higher TV viewing on weekends compared with weekdays [26, 38, 39]. Among German adolescents, TV viewing on weekdays, but not on weekends, declined steadily over time with a difference between 2002 and 2010 of 12.4 min/day in girls and 18.3 min/day in boys in The Health Behaviour in School-aged Children (HBSC) [40]. Data from HBSC Spain indicated that approximately 50% of young people viewed TV >2 h/day in all age groups [41]. In agreement with other studies [26, 42], we obtained significant differences (p < 0.005) between sexes during weekend days for computer games in adolescents and for console games in children and adolescents. Edelson et al. (2016) observed that older children spent more time watching TV and using computers/video games than did younger children (trend across age categories for TV: p < 0.001 and computer: p < 0.001) [43]. Moreover, in our study, electronic games were predominantly chosen by males, and also, males played more than females. Female adolescents surfed the internet more than males, for both study and non-study reasons, which was in accordance with other studies [26, 44, 45]. However, Brooks et al. (2016) have observed that girls are increasingly engaged in game play [45].

New generations have an increased use of communication technologies and available information on the internet [46]. Our results showed that more than 30% had a TV, computer and/or console in their bedrooms. In addition, a total of 44% of the males reported having three or more TVs at home. Brindova et al. (2014) revealed that 70% of their study participants had TV in their bedrooms. Although Rey-López et al. (2010) observed that TV was the dominant device followed by computers and consoles in the bedroom, our results showed that the console was the dominant device used by males and the computer by females. Remarkably, only 12.1% of males and 26.9% of females didn’t have any consoles at home and these data showed significant differences between sexes. Delmas et al. (2009) observed that having a personal TV was associated with higher TV viewing [47]; however, in our study, to have TV in the bedroom was not associated with TV viewing or playing PC or console games >2 h/day on none time. On the other hand, during weekends, to have a console in the bedroom implied more time spent playing with console games (OR = 3.21; 95% CI 1.59–6.50).

Current evidence indicates that the relationship between watching TV and BMI is driven by increased energy intake, and specifically TV commercial viewing [48‐51]. Epstein et al. (2008) found significant reductions in BMI in children who decreased TV viewing [48]. Another intervention study demonstrated the positive effects of the decrease of screen time among schoolchildren [52]. Young people constitute the primary target for public health strategies, which represent the possibility of health promotion and protection against chronic diseases. It is also important to take into account intervention strategies for parents, targeting parental regulation [53]. Regarding family structure (not assessed in the ANIBES study), McMillan R et al. (2015) found in their study that parental structure and child custody arrangements did not have a significant impact on screen time among youth [36].

The ANIBES study has several strengths which include the careful design, protocol, and methodology used, and was conducted among a random representative sample of the Spanish population aged 9–17 years. The validated questionnaires used to collect information on sedentary behaviors have shown good reliability and reproducibility. One limitation of this study is its cross-sectional design, which provides evidence for associations but not causal relationships. Measures of sedentary behaviors relied on self-report and could be biased, although a careful multistep quality control procedure was implemented to minimize bias. Additional limitations could be the high type I error rate due to hundreds of comparisons and secondary outcomes (also inflates type I error rate).

In conclusion, a high percentage (48.4%) of children and adolescents in Spain are not meeting recommendations regarding sedentary behavior, especially and paradoxically during weekends (84.0%). Age appears as an important determinant of a sedentary lifestyle, as adolescents spent more time on screen time than children. Considering our results and the importance of reducing sedentary behaviors, efforts to reduce time spent sitting for non-study reasons are needed. The findings also suggest that the weekend may be a critical target for interventions aiming at reducing screen time because TV viewing and computer use are particularly high on weekend days. In this sense, it would be necessary to promote interesting activities in different settings (family, school, community) as alternatives to these long sitting periods during spare time.