Results of this study suggest that only children's intention and self-identity explained a small proportion of variance in their participation in physical activities. Nonetheless, this result compared very favourably with previous predictive studies based on the TPB among children [25
] and give new insight on key beliefs associated with high intention to be physically active. In these previous studies, the explained variance did not reach 10%, except for one study by Rhodes et al. [25
], in which 35% and 50% of the variance of behaviour was explained by intention, perceived behavioural control, and past behaviour for the two follow-ups, respectively. None of the parental variables contributed to the prediction of either behaviour or intention. This result is quite surprising, given that many studies have observed the positive influence of multiple dimensions of parental support on children's and adolescents' physical activity behaviour [44
]. In fact, the results of the mediation analysis suggest that the influence of these variables on children's motivation toward physical activity is mediated by cognitions. Consequently, parental support appears to play a significant role in the development of a high level of self-efficacy, positive attitude, and a perception of being the sporty type or an active youth. Such results confirm previous observations that indicated that environmental factors are mediated by the TPB variables [48
]. It is also interesting to note that self-identity towards being the sporty type and an active child plays a significant role in explaining behaviour as well as intention. This suggests that promoting a positive image of being an “active” youth could be an effective way of encouraging participation in regular physical activity.
The importance of intention suggests that educational strategies aimed at increasing children's motivation remain an important strategy to promote physical activity. To increase motivation, however, some additional information from the structure of beliefs is required. Results of the present study suggest that the strategies adopted should be different for girls than for boys. Indeed, a deeper analysis of their key beliefs revealed that although two of the important barriers to physical activity were similar for boys and girls (i.e., perceived difficulty and time management), the cognitive foundation of the motivation toward physical activity was slightly different. Indeed, for girls, having fun while participating in physical activities and perceiving themselves as active individuals were two additional significant elements associated with positive intention, whereas these two aspects were not salient for boys. Consequently, parents and physical educators should make sure that girls have positive experiences with physical activity. It would be important to facilitate access to a variety of activities allowing girls to discover physical activities in line with their personal interests and in which they can excel. The creation of contexts in which children, and girls in particular, have the possibility to explore a set of physical activities and choose their favourite could stimulate more enthusiastic participation. In this study, the activities most often reported for girls were playing outside (99%), dancing (73%), playing ball (72%), and skating (68%). It was also observed that the frequency of sedentary activities was negatively associated with physical activity in girls but not in boys. Decreasing time spent in sedentary behaviour has been proposed as an effective strategy to increase level of physical activity in youths [50
]. In the context of the present study, it appears that promoting a decrease in sedentary behaviour would prove effective among girls only, given that the motivation of boys toward physical activity is not influenced by watching TV and playing video/computer games or working on a computer.
Children who perceived having many other activities or homework to do demonstrated less intention to be physically active. This observation supports the idea that the allocation of priority periods during or after school and on weekends, when children could be physically active, should help to increase their motivation towards physical activity. To minimize difficulties related to the physical activities, it would be determinant that children develop and practice skills during physical education classes. Indeed, physical education is taught to create a positive social environment, especially for girls, and to facilitate skills and confidence for physical activity in children. Hence, the acquisition of such skills could increase children's feelings of competence and, as such, enjoyment. Also, using some of Bandura's strategies aimed at increasing self-efficacy such as increasing gradually the level of difficulty could help children to develop feelings of mastery of physical activities, thereby increasing their perception of self-efficacy [13
The above suggestions for the promotion of physical activity among children are likely to be effective. Indeed, a recent mass media campaign (the VERB campaign), aimed at promoting physical activity among children aged from 9 to 13 years and developed and tested by the Centers for Disease Control and Prevention (CDC), showed positive results. This mass media intervention, based on TPB and SCT, was designed to encourage playing, promote physical activity as fun, cool, and socially appealing behaviour, and to provide abilities to overcome barriers to physical activity [52
]. After one year, their results indicated that children who were aware of the campaign were involved in 34% more free-time physical activity periods than children who were not aware of the campaign [53
]. Also, children exposed and aware of the campaign remained more active and had more positive attitudes toward physical activity behaviour after follow-up two years later [54
Traditionally, environmental variables have not received much attention within the TPB framework. In this study, the implication of parents in their children's sports organization was analyzed. Although none of the parental variables (i.e., involvement, transportation, presence, and physical activity level) and children's related perception (i.e., facilitating factors) of environmental variables were significant correlates of children's physical activity, this study provides some explanations for this lack of direct environmental influence. Indeed, the mediation analysis provided results well aligned with previous observations that environmental variables could be mediated by intention or self-efficacy rather than having a direct effect on behaviour [45
]. In this respect, this study has added information regarding the interplay among environmental factors (family-related factors) and cognitions. However, more research is still needed to understand the relationships between environmental factors, psychosocial variables, and children's physical activity behaviour.
Finally, some limitations of this study must be noted. First, although Rhodes and Plotnikoff [56
] documented the relevance of proxy measures of physical activity as an expression of future or current physical activity behaviour, a longitudinal study would allow stronger conclusions regarding the direct predictors of children's physical activity or the moderating effects of environmental factors on this behaviour. Secondly, all information was self-reported. Consequently, because children are sensitive to social desirability bias [57
], they could have responded more favourably to psychosocial variables and overestimated their physical activity participation. Finally, these findings should not be generalized to the child population, since the study was conducted among a convenient sample recruited in specific schools.
To conclude, the present study provides promising theory-based information on ways better to promote the regular practice of physical activity among children. In particular, emphasis should be placed in the development of self-identity regarding physical activity and the development of children's motivation by focusing on the management of specific barriers to physical activity such as time management associated with conflicting activities and the perceived difficulty of physical activities. Also, it is important to ensure that girls have positive experiences in physical activity and identify themselves as active young girls.