Physical activity (PA) plays a crucial role in the development of children. Physical activity is any bodily activity enhancing or maintaining physical fitness, health, and wellness. There are three forms in the level of physical activity(Gomes et al., 2020). For example, light physical activity, moderate physical activity, and vigorous physical activity. Many researchers have shown that the regular moderate-to-vigorous physical activity (MVPA) was extremely beneficial for physical and mental health(Janssen & LeBlanc, 2010). At least 60 minutes per day of MVPA was recommended by the WHO(Bull et al., 2020; Nader, Bradley, Houts, McRitchie, & O'Brien, 2008; Piercy et al., 2018). However, according to the Global Status Report on Physical Activity 2022 launched by WHO, 81% of adolescents and 27.5% of adults around the world failed to meet the WHO physical activity recommendations(Milton, Gomersall, & Schipperijn, 2023). Nowadays, insufficient physical activity has increasingly become a global public health problem. A large number of evidence-based researchers have found that insufficient physical activity in childhood was harmful to the children’s body and mind, which increased the risk of chronic diseases such as obesity(Hills, Street, Soan, Mokhtar, & Byrne, 2013), type 2 diabetes(Fan et al., 2015), cardiovascular diseases(Perry et al., 2023), cancer(Clague & Bernstein, 2012). Therefore, health promotion should pay close attention to the significance of increasing MVPA on the children.
Based on the social cognitive theory(Schunk & DiBenedetto, 2020), inactive children are closely related to the family. Although many researchers took actions to increase physical activity utilising the school intervention(Aburto et al., 2011; Larsson & Jakobsson, 2023; Loucaides, Jago, & Charalambous, 2009; van de Kop, van Kernebeek, Otten, Toussaint, & Verhoeff, 2019), the family-based intervention should come before school intervention because the parents affect their children's behaviour and cognition as they are born and grow. The newborn children first build relationships with their parents in the full life circle. Parents are primary caregivers who exert an important influence on children from the biological point of view. That is to say. Biological influence contributes to physical activity and development. Additionally, the family dynamics, including relationships within the family, also play a role. When children enter into a good school, they come into contact with good classmates, teachers, and the environment. This interaction is extremely complex, but it is impossible to deny the influence of this “pre-effect” on the “post-effect”. In other words, parents influence their child's choice of school. School choice affects the kind of educational resources children receive and who contact classmates. Parenting factors are integrated into all aspects of the children. As is an old chinese saying: "The son is not filial, but the father is wrong." Family intervention might be an effective way to promote the family’s physical and mental health. First, the family intervention would benefit both sides, parents and children, in the whole family environment. What’s more, physical activity intervention promotes sustainable family development in the long term, including their physical and mental health in the future. The parents engage in their children’s physical activity, which contributes to setting a good example for their children. Guiding and accompanying their children to exercise, parents will help the children to adopt good exercise habits automatically. Lastly, not only would it be conducive to their physical health and parents, but it would also promote their intimate relationship.
Physical activity is defined as any bodily movement produced by skeletal muscles that results in energy expenditure(Piggin, 2020). According to the definition, the “skeletal muscles” and “energy expenditure” in the physical activity framework is a unique body mechanistic act. This is explained by the emphasis which is placed directly on the definition. Based on the energy expenditure in the definition, the researchers initially focus on how energy is measured. At present, the amount of energy of accomplishing an activity can be measured in kilojoules (kJ) or kilocalories (kcal)(Piggin, 2020). There are two forms of measurement, including the self-report and Actigraph accelerometer. Different kinds of questionnaires were used to measure physical activity all around the world, such as, International Physical Activity Questionnaire(IPAQ)(Hagströmer, Oja, & Sjöström, 2006), Global Physical Activity Questionnaire (GPAQ)(Cleland et al., 2014; Keating et al., 2019), Physical Activity Questionnaire - Adolescent (PAQ-A)(Martínez-Gómez et al., 2009). Some studies for these questionnaires have been proved that it was adequate reliability and reasonable validity for assessing the level of physical activity(Bervoets et al., 2014; Hagströmer et al., 2006). Currently, International Physical Activity Questionnaire (IPAQ) is one of the most widely popular in the large population as it is feasible and cost-effective. There are two versions of IPAQ, the short form and long form, were designed to satisfy the needs of different groups. However, IPAQ could not be a better approach to measuring physical activity as its validity has not been appraised. On the one hand, various evidence has highlighted that IPAQ had reasonable measurement properties in diverse settings, which monitored the levels of physical activity among adults from 18 to 65 years old in the 12 countries. The short IPAQ form was recommended for national monitoring and the long form was recommended research for requiring more detailed assessment separately(Craig et al., 2003). On the other hand, considerable findings have shown that there still was a difference between self-reported and accelerometer by the cross-validating two measures. The researchers have indicated that comparing with the accelerometer, the participants report through IPAQ-Short Form had more vigorous physical activity and less sedentary time. The difference between self-reported and accelerometer-measured MVPA grew gradually when higher activity and intensity levels appeared(Dyrstad, Hansen, Holme, & Anderssen, 2014). The study has shown that the short IPAQ form overestimated physical activity in general. In fact, the evidence that the application of the IPAQ-SF, which was used as an indicator of physical activity relatively and absolutely, was inadvisable(Lee, Macfarlane, Lam, & Stewart, 2011). Other researchers have proved that although IPAQ-Long Form had good validity for measuring total physical activity and VPA and relatively reasonable reliability coefficients for application in this Spanish population, it showed unsatisfactorily validity for measuring MVPA(Roman-Viñas et al., 2010). And of all the outcomes, MVPA was vital for the physical activity research. What’s more, it could not be suitable for the younger children. The study has indicated that for adolescents aged 14 years and younger children in European, the validity of the questionnaire was unsatisfied. And objective methodology, such as the ActiGraph accelerometer, might be a suitable alternative(Hagströmer et al., 2006). It was also found that ActiGraph accelerometer based on the energy expenditure’ equation can predict commendably children and youth's energy expenditure of physical activity(Zhu, Chen, & Zhuang, 2013).
In summary, there is still a gap in the reliability and validity of physical activity between self-report questionnaires and objective measurements. With the development of modern technology, more and more researchers apply wearable devices or ActiGraph accelerometers to measure physical activity. There is no denying that physical activity’s data in the accelerometers would be more accurate than the objective measurement. Thus, this paper aims to investigate the effectiveness of the family-based physical activity intervention program in children by objective measurement.