Determinants of student’s MVPA level in school and neighborhood environment changing with age: a 12- month follow-up study in Ningxia province

Wei Huang Shanghai University of Sport School of Kinesiology Xiangrong Shi University of North Texas Health Science Center Yujie Wang Shanghai University of Sport School of Kinesiology Xiaoling Li Ningxia University College of Physical education Pengpeng Gao Guizhou Minzu University College of Physical education Jieguo Lu Ningxia provincial Physical education,Health and Art O ce Jie Zhuang (  zhuangjie@sus.edu.cn ) Shanghai University


Abstract Background
The bene ts of physical activity have been identi ed in children and adolescents. However, the prevalence of physical inactivity in school-aged children and adolescents was high in China. Most time of students spends in neighborhood and school, and these play an important role in student's MVPA level. Therefore, we will investigate the impact of implementing the national health promotion policy on PA behavior in school-aged children and adolescents and the effects that in uence the changes in PA behavior in this study.

Methods
This is a longitudinal study with a 12-month follow-up. The study sample came from 2016 and 2017 Physical Activity and Fitness in China-The Youth Study, total 1611 students (aged 7-18 years) from 31 primary, junior high, and high schools were included in this study. The physical and social environment in school and neighborhood were measured by questionnaire at baseline and after 12 months. Multiple logistic regression was used to examine the relationship of in uential factors and moderate-and vigorous MVPA.

Results
There is no signi cant difference in MVPA level between 2016 and 2017. Student's attitudes to PA, neighborhood facilities, and organizations were improved signi cantly after 12 months. The in uential factors changed after 12 months. In 2016 the top three contributors were attitude to MVPA(OR 3.08 with 95% CL 1. 22

Conclusions
The single health policy is not effective for student's MVPA promotion. There may be some factors mediate the relationship between neighborhood environment and MVPA level with age and grade increasing. In the future, more studies are needed to explore the change of in uential factors and mediators with age. The ndings of this study may provide some evidence for future policy-making.

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Cumulative evidence has proved that physical activity(PA) is bene cial for physical and mental health in children and adolescents, such as reduce the prevalence of overweight/obesity, cardiovascular disease, and Type 2 diabetes and even mental health [1,2]. In contrast, the disadvantage of sedentary behavior(SED) has also been identi ed [3][4][5]. Early PA behavior can be traced to adulthood [6], indicating that PA-related health bene ts at adulthood may derive from an active lifestyle in the early lifespan. Although the bene t of PA is obvious, approximately 80% of adolescents globally (13)(14)(15)  Organization has recommended that children and adolescents aged 5-17 years need at least 60 min moderate-to vigorous-intensity physical activity(MVPA) daily, but only 22.7% of students met the recommendation in China [7]. Until 2016, approximately 70% of Chinese students not met the PA recommendation [8]. At the moment, a national health policy named "Healthy China 2030" is issued in 2016 to promote healthy lifestyles and physical tness, which asks school-aged children to physical activity 1 h daily and achieve the goal of 25% "excellent" ratio of physical tness assessment. Even so, only 34.1% of students met the recommendation of 60-minutes moderate-and vigorous-physical activity(MVPA) participation each day [9].
Both school and neighborhood are important for students PA participation [10], lots of researches have explored the factors associated with MVPA to develop an intervention for promoting MVPA. For example, the school environment plays a crucial role for students to engage in physical activity (PA) [11,12]. The PA-friendly school environment positively associated with student's PA participation [13]. Meanwhile, the extramural activity also promotes MVPA effectively, which provides more opportunities for students to participate in PA, such as neighborhood-based PA facilities, organization, and so on [14][15][16][17]. Moreover, student's PA behavior also be in uenced by others when they are in school and neighborhood, including others' support for PA or behaviors. The systematic review has revealed that students with physically active parents are more likely to have an active lifestyle [18], as well as peer support [19,20]. However, most of these studies were cross-sectional investigations. Little is known about whether these factors will change with time and need to be explored. According to the ecological model [21], policy and environment are two important components for behavior changing, which can in uence active living through a variety of mechanisms, such as improving neighborhood PA environment [22]. Compared to small scale intervention programs, the policy is more impactive and it will be effective in national wide. A well-known example of policy intervention for health promotion is U.S Surgeon General's report "Smoking and Health" that adult smoking rate from 50% in 1965 to 18% in 2014 after 50 years of the intervention [23]. A comprehensive health policy named "Health China 2030" issued during follow up that has made a request not only for MVPA but also for the neighborhood PA friendly environment. Therefore, these may also be effective for improving student's MVPA level.
In the current study, we will investigate the impact of implementing the national health promotion policy on PA behavior in school-aged children and adolescents and the effects that in uence the changes in PA behaviors. Further, we will explore the factors contributing to student's MVPA and the change of factors in a 1-year follow-up. The outcomes of this investigation could help develop effective interventions to increase PA at this critical life stage and identify the guidance for the next step in policy-making in health for students.

Study design
This was a longitudinal survey study. The baseline sample was taken from 2016 Physical Activity and Fitness in China-the Youth Study (PAFCTYS) project, a nationwide survey of PA and tness among Chinese school-aged children and adolescents. Thirty-one primary, junior-high and high schools were randomly selected from 8 counties/cities at Ningxia province in China. The schools were evenly distributed in urban and rural areas. The students were requested to take the same survey questionnaire again after 12 months. The surveys took place between October and November. Details of the study protocol were described in a previous study [8]. This study was approved by the Ethics Review Committee of Shanghai University of Sport in 2016. Because of the study nature with minimum risk, only verbal assent and consent were required for in the study.

Study participants
A total of 1611 school-aged children and adolescents(aged 7-18 years) were included in the baseline survey in 2016 (T0) and were followed to make the same survey after 12 months (T1),14 of them have been excluded due to the response out of the range. Among them, boys and girls were 48.2% (n = 770) and 51.8% (n = 827), respectively (see Table 1); 725 (45.4%) of them attended the schools in urban area and 872 (54.6%) in rural area; 629 (39.4%) of them were adolescents (13 to 17 years old) and 968 (60.6%) children (9 to 12 years old).

Study procedure
Two trained research assistants were sent to the participant school for assisting the surveys conducted in 2016 and 2017. Before starting the initial survey, verbal assents from parents and teachers, and verbal consent from students were obtained. Detailed instructions for the survey were provided and all questions were answered. The survey questionnaires were completed in the classroom within ≤ 20 minutes, which included the perceived PA environment of the neighborhood and school. Besides, the parents' survey including weekly PA days was conducted off-campus by a parent questionnaire. The numeric identi cation code was assigned to the questionnaire. An experienced research assistant input data into a computer database, which was only accessed by authorized project staff.

PA levels
The modi ed Chinese-version of the International Physical Activity Questionnaire Short Form (IPAQ-SF) was used to assess the PA levels of the students, which has been used in previous studies [8,16,24].
Student's responses to the question "How many days did you have moderate to vigorous physical activity (MVPA), i.e., increased breathing rates and felt sweating, more than 60 minutes in last 7 days" were categorized into three groups: the sedentary group with exercise 0 to 1 day, physically inactive group with exercise 2 to 4 days, and physically active group with exercise 5 to 7 days. Similarly, parent's PA levels (provided by parent survey) also were categorized into three groups according to their response for MVPA days in the past week more than 30 min, i.e., sedentary, physically inactive, and physically active groups.

Neighborhood factors
Students were requested to answer 4 questions about the neighborhood (Qn): Qn-1 "There were game/sport events held for children and/or adolescents in your neighborhood during last year" with possible answers scored from 1 -never, 2 -not often, 3 -so-so, 4 -often, or 5 -very often. Qn-2 "There were free sport and/or exercise skills/training for children and/or adolescents in your neighborhood during last year" with the same 5-score answers as in Qn-1. Qn-3 "Are there sport organizations available for children and/or adolescents in your neighborhood" (1 -yes or 2 -no). Qn-4 "Are there sport facilities for children and/or adolescents conveniently located in your neighborhood" (1 -yes or 2 -no). The answers for Qn-1 and Qn-2 were grouped into three categories, i.e., groups with negative (answers 1 and 2), neutral (answer 3), and positive (answers 4 and 5) neighborhood PA environment for simplicity.

School factors
Questions for school PA environment (Qs) included Qs-1 "School exercise facilities and equipment can meet my needs for physical activity and exercise"; Qs-2 "PA class plays an important role for me to participate in physical activity and exercise"; Qs-3 "School teachers encourage me to participate in physical activity and exercise"; Qs-4 "School provides extra time for physical activity and exercise"; and Qs-5 "School has a desirable culture/environment for physical activity and exercise". All these questions had ve possible answers: 1 -completely disagree, 2 -disagree, 3 -not sure, 4 -agree, or 5completely agree. Also, there were two more questions about student's friends: Qs-7 "Friends often encourage me to participate in physical activity and exercise training" and Qs-8 "Friends often participate in physical activity and exercise training with me" with 5-score answers from completely disagree (score 1) to completely agree (score 5). These questions were also categorized into three groups: nondesirable/negative (combined answers 1 and 2), neutral (answer 3), and desirable/positive (combined answers 4 and 5) school PA environment groups, respectively.
Attitude to PA/exercise Student's attitude to PA/exercise was assessed by the survey question "Your attitude to participating in physical activity and/or exercise in future" 1 -don't like PA/exercise and won't plan to participate; 2 -will start PA/exercise; 3 -will do more PA/exercise, but not every day; 4 -will try to do PA/exercise every day; or 5 -will keep exercise every day. The responses were grouped into three categories: negative attitude (answer 1); positive attitude (combined answers 2 and 3); and a very positive attitude (combined answers 4 and 5).

Statistical analysis
Three-factor analysis of variance (ANOVA) was applied to test the effects of sex, age, and school location on baseline body mass index (BMI). Differences in numeric scores between T0 and T1 were examined using paired t-test. Chi-square test and logistic regression analysis were applied to examine the associations of MVPA with sex (boys vs girls), age (children vs adolescents), and the school location (urban vs rural). In addition, associations of overweight/obesity with time points (2016 vs 2017) were also examined by Chi-square test. Furthermore, multiple logistic regression analysis was applied to predict the neighborhood and school PA/exercise factors for MVPA, i.e., the students who had a physically active lifestyle (exercise ≥ 5 days during the last 7 days). Odds ratios (OR) and 95% con dence limits (CL) were estimated to quantify the difference based on Chi-square test or logistic regression analysis. P-value < 0.05 was taken to indicate statistical signi cance. All statistical analyses were performed using SPSS (Version 26.0, IBM Corp., Armonk, NY, USA) or SAS software package (version 9.4, Cary, NC, USA).  The student's MVPA days in the last 7 days were not signi cantly different (P = 0.106) between 2016 (3.8 ± 2.0 days) and 2017 (3.7 ± 2.0 days), see Table 3. In 2016, 36.8% and 6.5% of the surveyed students were physically active and sedentary, respectively (Table 4). These percentages remained similar in 2017 (33.6% and 6.3%). Although there was no signi cant difference in student's PA levels between T0 and T1, the group BMI was signi cantly increased (P < 0.001) from 18.5 ± 3.0 kg/m 2 in 2016 to 19.2 ± 3.7 kg/m 2 in 2017 (Table 3). Furthermore, the overall perceived neighborhood or school PA environment scored signi cantly higher in 2017 than in 2016. In 2017, the neighborhood was likely to have more children/adolescent sport organizations available (OR 1.32, 95% CL 1.24, 1.42) and more sport facilities for children/adolescents (OR 1.29, 95% CL 1.19, 1.40) as compared to 2016 (Table 5). However, there was no change in the parent's physical activity levels (p = 0.23).   In the 2016 survey, the top three predictors that signi cantly contributed to MVPA with 5 to 7 days (physically active) were the student's attitude, Qn-4 "sport facilities for children and/or adolescents in the neighborhood", and age (  The order of the effect is determined by P value, Chi-square and odds ratio from multiple logistic regression analysis to predict MVPA 5 -7 days.

Results
OR: Odds ratio CL: Con dence Limits In 2017 survey, the top three positive contributors to MVPA with 5 to 7 days (physically active) were the student's attitude, Qs-4 "School provides extra time for physical activity and exercise" and Qn-1 "often and/or very often had game/sport events held for children/adolescents in the neighborhood during last year". The likelihood for students to be physically active was signi cantly greater for those who had a positive than the negative answer to Qs-4 (OR 2.29, 95% CL 1.56 to 3.36). Furthermore, not only a positive response (OR 1.84, 95% CL 1.34 to 2.53)but also a neutral response to Qn-1 (OR 1.32, CL 1.02 to 1.71) signi cantly increased a likelihood for students to be physically active as compared to the negative answer (Table 6).
Both surveys in 2016 and 2017 had student's attitudes to PA/exercise as the most signi cant contributor for MVPA 5-7 days, i.e., physically active lifestyle (Table 6). Overall, about 60% of the children/adolescents had a very positive attitude to PA/exercise, and only ∼1% had a negative attitude (Table 7). Inconsistent with a descriptive analysis of MVPA days (see Table 3 (Table 6).

Discussion
In our knowledge, this is the rst longitudinal study to explore the change of in uential factors of student's MVPA level in school and neighborhood with age in China. Our result demonstrated that there was no signi cant improvement in MVPA level after a 12-month follow-up. The likelihood of overweight/obesity will increase with age. Boys and children were more likely to be active lifestyles than girls and adolescents at baseline, but the difference was disappeared at follow-up. However, there was a signi cant increase in student's attitudes to PA, especially in children. Moreover, the PA environment in neighborhoods was also improved after "Healthy China 2030" issued, re ected by PA facilities and sport clubs/organizations in the neighborhood, but these factors were not translated into MVPA level evaluating. Student's attitude for PA and their parental PA behavior were the most important factors to predict the MVPA level at both time points in our study. In addition, in uential factors in neighborhood and school were changed in follow-up compared to 1 year before.
In the present study, we have not found decreasing in MVPA with time signi cantly. This is different from the previous study, which found that MVPA decreasing with age in children and adolescent [25][26][27].Maybe, this is the reason for overweight/obesity increasing after a 12-month follow-up. Nevertheless, two large-scale questionnaire investigation studies have shown that the proportion of students met the MVPA guideline from 29.9% in 2016 to 34% in 2017 in China [8,9]. This may be affected by "Healthy China 2030", which has appealed that students should participate MVPA more than 60 min/day and having more than 25% of them achieve an "excellent" rating in tness. Accordingly, the health policy may be effective to prevent MVPA from decreasing with age. Nevertheless, those two were cross-sectional design study.
Our results manifested that boys were more physically active than girls, this has been identi ed by previous studies [28,29]. Meanwhile, children were more active than adolescents which consistent with many studies that MVPA was decreasing with age [27,30]. In the current study, this phenomenon can be explained partially by the attitude toward PA that children have a more positive attitude than adolescents, and attitude to PA was a mean contributor for the MVPA level. This has been identi ed by the previous study, which found that students who think PA is good and engage in PA enjoyable spent more time in MVPA at school [31]. Nevertheless, the role of attitude for MVPA participation needs to be explored more depth. Neighborhood PA facilities were also a signi cant contributor to student's MVPA level. This is consistent with other studies that available PA facilities are positively associated with MVPA [17,32]. In addition, students live in a neighborhood with sport organization and events are more likely to be physically active, which will provide more PA opportunities for children and adolescents. A study from the UK suggested that neighborhood-based PA is critical for helping students to increase MVPA, but not for sedentary behavior reduction [15]. Therefore, neighborhood-based activity may be an effective measurement to increase student's MVPA out of school. As for the school environment, the results demonstrated that school PA climate and teacher support for PA affected MVPA signi cantly, but school PA facilities and PE classes were not. These results were supported by the previous system review [12]. A possible reason may be that these two factors were similar among different schools, as a unique request for numbers of PE class and the infrastructures of PA, such as basketball and football court, were similar in Chinese primary and middle school. These factors should be considered for future intervention to increase student's MVPA. Finally, we found students with active parents are more likely to be physically active, which has been identi ed by a meta-analysis [33]. Yet we have not found the promoting role of friends in MVPA level, neither support nor accompany. This nding differs from previous studies that friend's encouragement and engagement were positively associated with MVPA [20], but a recent study found that the relationship between friends support and MVPA mediated by self-e cacy and enjoyment [34] This may signify that the difference of MVPA level in school-aged children may from family rather than school by bringing together these evidence.
When analyzed the follow-up data, student's attitude to PA was signi cantly improved after 12 months compared to 1-year before, but the improvement was not translated into increasing MVPA level of students, which were not signi cantly different between the surveys in 2016 and 2017. A similar situation also appeared in the other two neighborhood variables, sport facilities, and sport organizations in the neighborhood. According to the ecological model, the policy is the highest-level factor in four domains, which can in uence PA through change lower-level variables [21]. As positive predictor for MVPA, student's attitude to PA and neighborhood environment (sport facilities and sport organizations in the neighborhood) have improved signi cantly after "Healthy China 2030" issued, partially proved its' validity as a national health promotion policy. Accordingly, we can infer that there are some in uential factors we have not investigated mediated the relationship between attitude, sport facilities, and organizations and MVPA of children [35]. It is likely associated with increased study-load with one year more senior in school, as indicated by the second most signi cant contributor to MVPA in 2017 survey is extra time for PA/exercise. Combining with friend support as a contributor for MVPA level indicated that children more likely participated in MVPA in school. Moreover, this phenomenon also might explain the sex factor (boys vs girls) and age factor (children vs adolescents) both of which are signi cant contributors to MVPA level in 2016, are removed from the logistic regression tting in 2017. In China, every student has to face the stress for entering a higher school, this may explain the phenomenon above.
Our study has some obvious weaknesses. First, we assess the MVPA level by self-report, which will cause bias of MVPA assessment and we can't distinguish the school-day and after-school MVPA by this method. Second, we measure the school and neighborhood PA environment by self-perceived instead of the objective assessment instruments, this may limit the implementation of environmental improvement.
Third, we can't build the causal relationship between the evaluation of in uential factors and "Healthy China 2030". Therefore, we should interpret ndings carefully due to these limitations. Future studies should apply the objective assessment instrument to examine the association between these in uential factors and MVPA in detail. Consequently, we can understand the association between different in uential factors and the distribution of geography and time of PA behavior. In addition, more studies need to explore the transformation of in uential factors of PA behavior with age, this will be more effective for precise intervention for PA behavior.
Findings from our study provide epidemiological evidence for children and adolescents MVPA intervention in the future. Moreover, this evidence is also important for developing policies for promoting school-aged children MVPA participating. In our results, improvement of neighborhood PA environment and attitude can't translate to MVPA level evaluating, indicated that there are some in uential factors impacted MVPA of school-aged children signi cantly with age and school grade increasing. A study from China has reviewed the role of policy to prevent tness decreasing, and revealed that the policy alone did not seem to work [36]. Therefore, a single health policy can't improve the MVPA level of school-aged children. In China, the study is the top priority for school-aged children, result that most of their time is used in the study rather than PA. In the future, concurrent education and health policy may be effective for increasing MVPA level of school-aged children. Furthermore, change of behavior is not an isolated problem, as it in uenced by many factors and from a distinct level [21,22]. Future studies should explore in uential factors more comprehensively, and the intervention should be full-scale and multilevel.

Conclusion
In conclusion, physical and social environments are important for student's MVPA participation, but it will change with age and grade. Neighborhood sport events and parent's physically active lifestyle are two persistent contributors for MVPA, these may be the measurements for promoting MVPA in the future. Our ndings proved the validity of the national health policy to improve in uencing factors of student's PA behavior, but it will not increase MVPA alone. Some factors that impacted student's MVPA level are not affected by the health policy, which needs to be explored and intervened in the future. This study protocol has been approved by the Ethics Review Committee of Shanghai University of Sport(ERCSUS)(#2017037). We have been approved by ERCSUS for students to participate in this study just need the verbal consent by their teacher, principal of participating school, and student's parents instead of written consent, due to the minimal risk for participants and the enormous sample size. The verbal consent was approved by ERCSUS required researchers to get permission to conduct the study from teachers and principals of the participating school by elaborated on the potential risks and bene ts for participants before data collection. The same protocol has been declared for student's parents/guardians and their consent for student's participation was sought. Finally, the details about the project were informed to all participants before their consent and participation.

Availability of data and materials
The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request Authors' contributions WH analyzed the data and drafted the manuscript. XS help analyze the data, and revised the manuscript.
YW clear up the data. XL, PG, JL help collected the data. JZ conceived and designed the study, supervised all aspects of its implementation, interpreted the data, and revised the manuscript. All authors read and approved the nal manuscript.