Childhood is a crucial period for developing healthy lifestyles [1
] such as regular engagement in physical activity (PA). Physically active children have better physical, psychological, and cognitive health indicators [2
]. However, 80% of children worldwide and 70% of children in Colombia are insufficiently physically active [3
]. Physical inactivity and sedentary behaviors have been independently associated with obesity, poor cardio-metabolic health, and poor psychosocial health [4
]. Longitudinal studies have found that PA levels decrease during adolescence, and thus there is a need to understand the mechanisms of interventions that promote long-term healthy lifestyles [5
Physical education classes and recess time are relevant for the promotion of PA in students since they spend 6 to 8 hours per day in school [7
]. Consequently, strategies involving recess time are promising interventions for the promotion of PA in students [9
], and in Latin America, school interventions are recommended as effective strategies [11
]. In Bogotá, Colombia, there is evidence about the Modulo Activo Recreo Activo (MARA), a PA intervention using information and communication technologies (ICT). Children attending schools with the MARA program increased the average minutes of PA compared to control (Difference(T1
) = 6.1 min, SE = 3.49, p
= 0.005) [7
]. However, there are no studies on the effect of MARA on the formation and dissolution of friendship networks over time, and the potential of the program in fostering social cohesion when potentiated with ICT.
Among school-age children, studies on social networks conducted mainly in high-income countries evidence that children may be significantly influenced by their friends’ PA levels and obesity-related behaviors [12
]. Likewise, evidence of peer influence on healthy behaviors has shown that physically active peers have a positive impact on adolescents’ PA [15
]. A longitudinal study found that adherence to PA guidelines among children increased by 6% for each additional active friend [17
]. Although the importance of social networks and peers influence in healthy behaviors, there is limited evidence on the longitudinal mechanisms that underlie the formation and dissolution of friendships, especially in populations in low- and middle-income countries (LMICs). Previous studies have shown that the use of inherent social networks structures in schools may provide a cost-effective way of encouraging children to be more physically active [9
]. However, there are gaps regarding the potential longitudinal synergic effect of interventions and friendships on the cohesion of the social networks and to promote children’s PA.
In this context, the randomized school-based intervention MARA provided a unique opportunity to assess friendship networks structures longitudinally in a program aimed at promoting PA with ICT. This project, in addition to measuring health-related and network-structure variables, also measured relevant socio-economic and satisfaction variables. Socio-economic variables could be related to the structure of the network and according to socio-ecological frameworks could influence the PA levels of children [18
]. Intervention satisfaction variables are related to motivation and engagement in the program [20
] and could also be related to the structure of the network. This study aims to longitudinally assess the network structure, the mechanisms of the formation and dissolution of friendships, and the potential cohesion effect of the intervention MARA. For this, a four-step analysis was carried out. First, we measured temporal social network changes to determine if a temporal analysis of children’s networks is feasible [21
]. Then, we analyzed the friendships’ homophily [22
] in order to determine what are the attributes that define friendships between children before and after the intervention [23
]. Next, we evaluated friendship formation and dissolution mechanisms over time [25
]. Lastly, we evaluated the effect of text messages (SMS) on network cohesion to determine if the use of ICT generates social benefits in children’s networks [26
]. Findings and recommendations from this study could be used as a guideline in future practice or research in school settings.
This study, for the first time, evaluated longitudinally the network structure, the mechanisms of the formation and dissolution of friendships, and the potential cohesion effect of a school-based governmental PA program in Latin America. The study shows that MARA, a school-based PA intervention that uses ICT, could promote social co-benefits that consist in increasing cohesion in the friendship network and encouraging children to relate with those who have similar levels of cohesion in their individual networks. The study also underscores the heterogeneity among school networks in friendship formation and cohesion that could be explained in part by the acceptability and adherence of the program. Our results provide evidence of the co-benefits of school-based interventions intended to promote healthy behaviors among children living in vulnerable settings.
We found that MARA + SMS could increase cohesion in the friendship network and encourage children to relate with those who have similar levels of cohesion in their individual networks. The potential impact of this benefit is explained in previous studies in high-income countries that have shown that cohesive children networks are related to lower levels of BMI [31
], and cohesive classrooms promoting stable relationships generate sustainable behavior patterns among children [32
]. Therefore, school-based interventions such as MARA could increase the level of cohesion and connectivity between children while facilitating stable environments and the dissemination and sustainable adoption of healthy behaviors.
When comparing the group that received SMS (MARA + SMS) with the program without SMS (MARA), we found that when ICT is included, the impact on increasing network cohesion is greater. SMS had an impact on the creation of friendship ties and in increasing closeness between children. Our results show that the inclusion of SMS in the intervention caused, on average, 3.8 additional friendships to form, and that there was 0.01 closeness between the children of the MARA + SMS networks. In a network where there is more closeness, the information can flow more quickly. These results are consistent with the literature, as previous studies have shown the potential in using ICT to promote healthy lifestyles and health-related structural changes that encourage healthy behaviors through immediate feedback and advice [33
]. These studies showed that when using ICT to influence children’s behavior, positive effects can be obtained for promoting PA behavior change [33
]. Some interventions, mostly from high income countries, showed that the use of technology significantly increases interactions and produces collaborative patterns among children [34
]. Our study expands in the impact of the ICT interventions in promoting healthy behaviors in low-income communities in a LMIC, as we found that ICT increases the cohesion of the network.
Moreover, unlike the findings on high income countries [14
], in the studied networks, we did not find an overall effect of assortativity driven by PA before and after MARA. This means that, overall, friendships between children were not formed because they shared similar levels of PA. This finding could be explained in part by the fact that PA occurred in our studied schools mostly through play and dancing, and the fact that no competitive sports were evaluated. These low–middle-income schools do not have specific sport clubs that allow children to form groups according to specific sports. Furthermore, we did not find an overall effect with socio-economic variables besides sex and BMI, which could be due to the fact that most of the children were low to low–middle socioeconomic status (SES) and 65% of children had normal BMI.
When analyzing each school in particular, we found heterogeneity in the assortativity effects and in the mechanisms of formation and dissolution of friendships. Specifically, the program had an effect on friendship homophily and in the mechanisms of formation and dissolution of friendships in the networks. We found that PA levels and BMI began to have effects on friendship homophily and in the formation and dissolution of friendships in most of the intervened networks among time. Children became more likely to stop being friends with children with different BMIs (network 1 of MARA + SMS) and became less likely to become friends with children with different PA levels (network 2 of MARA + SMS and network 3 of MARA). This may be due to the fact that the children could have started to relate with others that had an affinity in PA or BMI. Although the purpose of MARA is to promote PA in an inclusive way, there may be a risk that less-active children will begin to group with sedentary instead of grouping with active children if not all of the children participate in the program. In fact, a previous study showed that there may be heterogeneity in the effects of PA on the network structure and on the processes of formation and dissolution of friendships [9
]. This means that the processes of selecting friends can change, and therefore a static PA intervention could be inefficient for promoting PA [9
]. When designing interventions, it is necessary to take into account the characteristics of the places where the intervention will take place because the network structure can be heterogeneous, and is important to avoid going contrary to the dynamics of the relationships [9
]. Given this, we observed that in the schools that we studied that the context and the dynamics of relationships are different than high-income countries, and each course has its particularities and heterogeneity, and thus it is relevant to consider the friendship drivers when designing and evaluating a program such as MARA. Currently, MARA is implemented in 72 schools. The current study provides additional co-benefits that could help the IDRD for advocating the program.
There were some limitations in this study. First, regarding the sample, the size was reduced due to the exclusion of participants that did not provide valid accelerometer data (Figure 1
). It is possible that children with an important role within the social network were not considered in the study. However, there was a total response rate of 91% in the baseline, and at the end of the study, the total response rate was 75%, and thus a significant percentage of the population was considered. Additionally, in the MARA + SMS intervention, 68% of the children did not have mobile phones and did not directly receive the SMS, but 98% of them reported to receive the messages through their parents. Second, in the DD model, there were variables that did not present statistical homogeneity. To face this limitation, we controlled for these variables in the DD model. Third, at first, the control group STERGM models did not converge, so we had to exclude BMI to obtain a good level of convergence in the models, and we used a diversity of models that allowed us to analyze cohesion from multiple perspectives. It is important to notice that the robustness of the STERGM models depends on a wide variety of factors that are difficult to isolate, such as the type of variables used and the size of the network [38
]. Finally, the study was conducted in 2013 and ICT technology has varied since then. In Colombia, SMS continues to be very relevant, especially for low- to middle-income populations. According to the Ministry of Information Technology and Communications, during the first quarter of 2013, 4 million SMSs were sent [39
], while for the fourth quarter of 2019, 457.2 million SMSs were sent [40
]. This represents a decrease in the use of SMS by Colombians but also shows that the use continues. Regarding this, it is important to keep in mind that by 2019, 61.3% of Colombians had access to mobile internet and there were 131.6 mobile phone lines for every 100 habitants [40
]. This means that a significant percentage of the population still does not have access to mobile internet but does have access to mobile telephony, which is why an intervention that uses SMS as a means of communication is relevant. This may be because Colombia is an LMIC, and in vulnerable environments, SMS could still be a relevant tool.