Social and Family Factors as Determinants of Exercise Habits in Japanese Elementary School Children: The Super Shokuiku School Project

Many studies have already reported on the relationship between exercise habits and health among schoolchildren. However, few have examined social and/or family factors as determinants of exercise habits. This study investigated factors related to both dislike and lack of physical activity among schoolchildren. This study’s participants included 1,984 school children (1,001 boys and 983 girls) aged between 6 and 13 from the Super Shokuiku School Project in January 2016. A survey was conducted to assess sex, grade level, physical activity, lifestyle, overall health, enrichment of school life, social background, and parental lifestyles. Both the dislike and lack of physical activity were defined as poor exercise habits; correlates were analyzed using a logistic regression.


Background
The Physical and Athletic Aptitude Survey [1] conducted by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) indicates that there is a widening physical ability gap between children who engage in physical activity and those who do not [2]. Moreover, the number of children who do not exercise increases with age [3]. Such reductions may be associated with lower levels of motivation, emotional strength, and the ability to form interpersonal relationships. Unfortunately, these problems may also negatively influence psychosocial development [4]. The Japan Sports Agency has thus proposed a goal of increasing the rate of sports participation from 58.7% to 80% while decreasing the percentage of junior high school students who dislike sports from 16.4% to 8% by the year 2022 [5]. As such, it is important to research the reasons for the growing lack of physical activity and sedentary lifestyles among these children to determine what measures are needed to develop good exercise habits during early childhood.
Children are now spending less time playing outside and/or participating in sports. By contrast, they are spending longer hours indoors while watching television and playing games. Many studies have linked such physical inactivity to overweightness and obesity [6], peer problems [7], and school-avoidant emotions [8]. Further, children with overweight or obese mothers tend to engage in less physical activity and spend more time watching television and playing games [9]. Similarly, children who are in poorer health and have parents that are heavy internet users tend to engage in longer screen times [10]. These conditions provide evidence that child health is significantly influenced by health-related parental behavior [9][10][11]. On the other hand, studies have reported that even short durations of physical activity effectively reduce anxiety and/or boost selfesteem [7], while consistent physical activity can help mitigate emotional problems [12].
Moreover, elementary schools that successfully reduced the rate of child inactivity were also able to increase the number of students who enjoyed such engagement [13].This indicates that physical activity can be encouraged through enjoyment, thus promoting wholesome physical and mental health while providing fulfilling school experiences.
Meanwhile, Japan has one of the highest rates of child poverty among all Organisation for Economic Co-operation and Development (OECD) nations. In this context, widening socioeconomic disparities and their effects on child health are serious concerns [14,15].
As such, health education should be mandatory in the school setting for both parents and children regardless of academic achievement [14] or socioeconomic status [14][15][16][17]. These measures are now highly anticipated. Notably, previous studies have reported that lifestyle is a major influencing factor for children who dislike and lack physical activity [18,19]. However, few studies have examined how these factors are related to the family environment and other social factors surrounding the child. This study therefore comprehensively investigated the factors related to both the dislike and lack of physical activity among children, including habits that relate to health and lifestyle, the family environment, and other social factors.

(1) Participants and the survey outline
A total of 2,129 children aged between 6 and 13 from the Super Shokuiku School Project (Phase 3: January 2016) [10,20] and who belonged to one of five elementary schools in Takaoka City, Japan participated in this study. The Super Shokuiku School Project was designed to investigate food education and was supported by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT). The overall purpose of the project was to promote healthy lifestyles in school children and improve their health. The survey was approved by the Ethics Committee of University of Toyama. Written informed consent was obtained from the participants' parents, and participation was voluntary.

(2) Questionnaire
Participants were asked to complete questionnaires asking about sex, grade level, physical activity, lifestyle, overall health, enrichment of school life, social background, and parental lifestyles. The children responded with their parents if necessary. The child responded to items concerning sex, grade, physical activity, lifestyle, overall health, and enrichment of school life by themselves, while their parents responded to items concerning social background and parental lifestyles. All completed questionnaire were returned to the respective schools of each participant.

Physical Activity
The physical activity portions of the questionnaire included the items of "frequency of physical activity" [21] and "preference for physical activity." [18] Responses to "frequency of activity" were answered according to a 4-point scale and divided into the two following categories: "Very often (very often, often)" or "Not often (rarely, almost never)." Responses to "preference for physical activity" were also answered according to a 4-point scale, and were divided into the two following categories: "Like very much (like very much, like)" or "Dislike (don't like so much, dislike)." Validity for both these items had already been determined by a previous study [21]. In this context, a high frequency of physical activity was significantly associated with an increasing trend in energy expenditure originating from physical activity.

Social background and parental lifestyles
Social background was assessed based on the following items: Mother's employment status, family structure, perceived family affluence, communication with parents, individual parental internet usage at home h/day (i.e., both the mother and father), and parental health behaviors according to Breslow (1980) (i.e., both the mother and father). The item concerning "mother's employment status" [20,22] included three response categories (i.e., "full-time," "part-time," and "unemployed (housewife)"), while "family structure" [22,23] was categorized as either "three-generation family" or "nuclear family." Further, "socioeconomic status" was determined according to perceived "family affluence" [20,22] (i.e., "affluent," "neither," or "not affluent"), while "communication with parents" [22,24] was categorized as either "often" or "rarely." We also asked for the total time parents spent using the internet at home h/day. Here, responses were given according to a 6-point scale and divided into the two categories of "< 2hr (no or almost none, <1hr, and 1hr to <2hr)" and "≧ 2hr (2hr to <3h, and ≥3hr)." This was based on a 2018 report indicating that Japanese adults in their 30s spent an average of about 1.5 hours per day on the internet [10,25]. Breslow's (1980) seven good health-related behaviors have been widely accepted for use in Westernized countries, and were thus used as parental health indicators in this study [26]. The behaviors include (1) adequate sleep time, (2) no smoking, (3) appropriate weight control, (4) not drinking excessively, (5) regular physical activity, (6) no skipping of breakfast, and (7) not frequently snacking. We divided respondents into three groups based on their indicated number of behaviors (i.e., "low (0-3)," "middle (4-5)," and "high (6-7)"); higher numbers indicated healthier behaviors.
The question about "screen time h/day" for children included television and film viewing, gaming, and internet use [20]. Here, responses were given according to a 6-point scale and divided into the two categories of "< 2h (no, almost none, <1h, and < 2h )" and "≧2h (< 3h, 3 to < 4h, and ≧4h)." In this context, the Japan Pediatric Association recommends that total screen time be limited to < 2h per day[25].

Overall health among child participants
A question from a validated Japanese version of the Dartmouth Primary Care Cooperative Information Project (COOP) was used to evaluate overall health among children [18,19,28].
They were specifically asked the following: "During the past 4 weeks, how would you rate your physical and mental health in general?" Subjects who rated their overall health as "excellent," "very good," or "good" were classified as having "good health status," while those who answered "fair" or "poor" were classified as having "poor health status."

Enrichment of school life
We asked two questions to subjectively assess "enrichment of school life," including "Do you have close friends?" [29] and "Are you able to understand school lessons well?" [20] Responses were given according to 4 and 5-point scales, respectively, and then divided into the following respective categories for each question: "yes (many, a few)" or "no (not many, no friends)" and "understand well (well, relatively well)" or " do not understand (neither, relatively poor, and poor)."

(3) Statistical analyses
Logistic regression analyses were conducted to evaluate the strengths of the associations between child physical activity and the items of social background, parental lifestyles, child lifestyles, child health, and enrichment of school life. All variables were simultaneously entered into the model during multivariate analyses. Odds ratios (ORs) and 95% confidence intervals (CIs) were also calculated. Finally, logistic regression analyses were performed to determine the strengths of the associations between "lack of physical activity" regardless of "prefer physical activity" with the items of social background, parental lifestyles, child lifestyles, overall child health, and enrichment of school life. All analyses were conducted using the statistical package for social scientists (SPSS) software version 22.0 J (SPSS, Chicago, IL, USA). Two-tailed P-values less than 0.05 were considered statistically significant for all tests.

Results
Participant characteristics are shown in Table 1. Of the 2,129 respondents who returned their questionnaires, 1,984 (1,001 boys and 983 girls) answered all relevant items and were thus included for analysis. Regarding child physical activity, 13.2% of respondents (n=260) did not like physical activity, while 27.4% (n=540) lacked physical activity.
Regarding social background factors, the most frequent answers to the items assessing the mother's employment status, family structure, and perceived family affluence were "part time," "nuclear family," and "neither," respectively. Regarding parental lifestyles, the most frequent answers to the questions assessing parental internet use at home were "< 2h, and parental (e.g., mother and father) health behaviors according to Breslow (1980) [26] were "father is low," and "mother is middle," respectively.
The results of the logistic regression analyses conducted to determine the strengths of the associations between "do not like physical activity" and social background, parental lifestyles, child lifestyles, overall child health, and enrichment of school life are available in Table 2. The multivariate analysis revealed the following results: "do not like physical activity" for children in middle grades (3rd and 4th graders, ages 8-10) ( The results of the logistic regression analyses conducted to determine the strengths of the associations between "lack of physical activity" and social background, parental lifestyles, child lifestyles, overall child health, and enrichment of school life are available in Table 3. The multivariate analyses revealed the following: girls (adjusted OR 1.40; 95% CI,1.11-1.76), middle grades (3rd and 4th graders, ages 8-10) ( While children who lacked physical activity comprised 27.4% of the total, more than half said that they did prefer physical activity. However, many still did not engage in physical activity. The logistic regression analysis results conducted to determine the strengths of the associations between "lack of physical activity" regardless of "prefer physical activity" and social background, parental lifestyles, child lifestyles, overall child health, and enrichment of school life are available in Table 4 friends (OR 4.14; 95% CI, 1.80-9.51) were associated with "lack of physical activity" regardless of "prefer physical activity."

Discussion
Among the potential determinants of child exercise habits, this study revealed that a lack of close friends was likely the most influential factor for both disliking and lacking physical activity. Further, the status of having close friends was independently associated with child exercise habits even after adjusting for other potential confounding factors, the social and family environment, and child lifestyle factors. Previous studies have already shown that peer support is important for promoting exercise habits This study had several limitations. First, it used a cross-sectional design that employed a self-reported survey about exercising habits. Thus, a longitudinal survey is needed to investigate the causal relationships behind these results to measure both the quality and quantity of physical activity through objective indicators. Second, more detailed surveys on social context (e.g., community characteristics, maternal employment status, and social assistance) are required to investigate the measures that are best-suited for community-specific needs.
This study found that a fulfilling school life, family environment, parental lifestyle-related habits, and the activities of the children themselves were factors that influenced childhood exercise habits. This indicates that educational policies and interventions should consider linking these items to healthy exercise habits.

Conclusions
This study investigated factors related to both dislike and lack of physical activity among schoolchildren as part of The Super Shokuiku School Project in Japan. "Lack of close friends" have the strongest links with both dislike and lack of physical activity. Children who engaged in long periods of screen time and lacked parental communication also tended to dislike and lack physical activity. In addition, children were highly influenced by parental lifestyles, even those who like physical activity. Although a longitudinal study is needed to determine causality, substantial attention should thus be paid to these factors when promoting physical activity.

Acknowledgements
We thank all children and their guardians for participating in this study. We also thank Toyama Prefecture and Takaoka City Education Committee, as well as the principals and school nurses at five elementary schools Takaoka city, Toyama prefecture, who agreed to take part in this study.
This study was funded through the Super Shokuiku School Project by the Ministry of Education, Culture, Sports, Science and Technology, Japan.

Authors' Contributions
S.S conceptualized and designed the study, carried out statistical analysis, drafted the initial manuscript, and reviewed and revised manuscript. M.S, M.Y obtained the fund, designed the study, collected data, and critically reviewed the manuscript. Y.F, Y.H critically reviewed the manuscript. All authors approved the final manuscript as submitted and agreed to be accountable for all aspects of the work.

Funding
No funding.

Availability of data and materials
The data we used to derive our findings are unsuitable for public deposition due to ethical restrictions and specific legal framework in Japan. It is prohibited by the Act on the

Ethics approval and consent to participate
The survey was approved by Ethics Committee of University of Toyama (H28-137). Written informed consent was obtained from all the school children and their parents, and participation was voluntary.

Consent for publication
Not applicable.