Background
With increasing urbanization, the obesity rate, overweight rate, and chronic disease mortality rate have increased consistently, thus forming a major global public health issue. The most recent US research report showed that about 2.2 billion people worldwide are overweight, accounting for one-third of the world’s total population. Furthermore, about 712 million people (10% of the global population) are obese [
1]. The number of obese people is 106 million in the US and 93.8 million in China. Researchers pointed out that the global goal set by the World Health Organization (not to exceed the 2010 level of obesity by 2025) is almost impossible to reach [
2]. In addition, chronic diseases account for 60% of all deaths, 80% of which occur in low-and middle-income countries (including China), where chronic disease deaths account for three-quarters of all global chronic disease deaths [
3]. With the urbanization and industrialization, China has become the world’s second largest economy; however, Chinese residents’ sedentary behavior (such as going out with the car, watching TV, and using computers) has constantly increased and their physical activity (such as walking and physical exercise) has decreased. According to Chinese Nutrition and Chronic Diseases Report (CNCDR), the overweight rate of Chinese adults is 30.1%, and the obesity rate is 11.9%, indicating increases of 7.3 and 4.8% since 2002, respectively [
4]. In addition, in 2012, the death rate for chronic diseases in China was 533/100,000, accounting for 86.6% of the total number of deaths [
4].
One-third of adults are physically inactive in the world [
5], and a number of studies have shown that physical inactivity not only causes overweight [
6], obesity [
7,
8], and chronic diseases [
9], but also increases the risk of cancer and premature death [
10]. Furthermore, a study by the University of Cambridge in the United Kingdom reported that maintaining moderate physical activity (PA) was key to reduce the risk of premature death. The World Health Organization (WHO) identified physical inactivity as the fourth leading risk factor for global mortality [
11]. Therefore, PA contributes to human health. PA has been reported to reduce obesity [
9], cardiovascular diseases [
12], and mental health problems [
13]. Furthermore, PA was also reported to promote health [
14], reduce stress [
15], and increase mental well-being [
16].
To improve people’s PA level, it is very important to know learn which factors are associated with PA. For the study of the influencing factors of individual behavior, social ecology theory has constructed a very good theoretical framework. The theory was first proposed by Bronfenbrenner, and was further developed by McLeroy et al. [
17]. The social ecology theory distinguishes the influence of five fields on individual behavior: personal factors, interpersonal factors, social factors, natural factors, and environmental factors. Most studies investigated PA from a single dimension and focused on the analysis of the impact of personal factors [
18] or environmental factors [
19] on PA. With the development and the social ecology theory, it was gradually realized that many other factors will also affect individual PA, which can be more in line with the habits of individual PA through policy or planning [
18].
Urban green open spaces (such as parks) are a common space for PA, which can be used by a wide range of people to improve their health [
20,
21]. However, studies on the association between parks and physical activity have used a mixture of self-reports and objective measurements, which may lead to mixed results. Urban green open space has been reported to help promote physical activity [
6] and reduce a variety of chronic illness [
22], and a positive relationship among them has been found [
6,
23‐
25]. Li et al. [
23] reported a positive relationship between built environment factors (density of places of employment, household density, green and open spaces for recreation, and number of street intersections) and walking activity. Liu et al. [
24] reported a positive correlation of urban parks with public PA as well as positive mental health benefits. Akpinar and Cankurt [
25] analyzed the associations between characteristics of urban green spaces and the frequency of PA in the city of Aydın, Turkey, and reported that for the general population, a short distance to urban green spaces, many trees, the availability of exercise equipment, and picnic areas were positively associated with the frequency of PA, while barbecues and fire places were negatively associated with the duration of PA.
Other researchers reported that large and attractive parks could promote walking for health benefits [
20,
26]. Moreover, safety [
27], better access to green spaces, and park facilities may be associated with higher use and in turn increased participation in physical activity [
6,
28]. However, a number of studies found no relationship between urban green open space and PA [
18,
28], and several studies found there was no relationship between distance, park size, and PA [
28,
29]. Coombes et al. [
6] measured the availability of green space within the neighborhoods of participants, and concluded that the availability of green space was not associated with PA. Potwarka et al. [
30] found no relationship between the proximity to parks and overweight. In general, the evidence for an association between green space and PA is mixed. Most studies found positive associations, while few either reported no or negative associations. Although the relationship between these is controversial, many cities have incorporated the idea of increasing urban green space to encourage PA [
24].
In summary, urban green open space is a valuable resource for the improvement of human health by encouraging more participation in PA to reduce morbidity. In China in particular, people are increasingly interested in the positive impact of green space on PA and other health benefits. Liu et al. [
24] studied the relationship between Beijing urban parks, PA, and mental health, and found a positive correlation. However, this study only selected a single type of green space in urban parks, and only used personal factors (gender, age, and occupation) and environmental factors (accessibility). Environmental factors also did not include information about park characteristics, such as park size or infrastructure. Moreover, the impact of natural factors (landscape quality), interpersonal factors (company and family), and social factors (security) on PA were not included; therefore, further research on this topic in China is needed. In addition, the obtained research conclusions of urban planning and PA in western countries are not necessarily applicable to Chinese cities. As the largest developing country and the second largest economy of the world, China applies its own particular urban planning system, which includes a considerable amount of urban green space, as well as unique national conditions and customs.
Since the Chinese economy currently enters a stable and favorable trend, under the policy of “adhering to the people-centered development thinking, vigorously developing a healthy cause, and being a healthy nation”, the Central Government works toward improving the quality of life of the residents by building urban green open spaces and emphasizing the vital role of maintaining a healthy 76lifestyle. Given the Chinese preference for outdoor group sports, China uses urban green open space as the main driving force to enhance the residents’ level of PA. According to statistics, the green area of urban built-up areas in China has reached 1,971,000 ha in 2016, which constitutes an increase of 20.6%; furthermore, the per capita green area of the open space has reached 13.5 m
2, constituting an increase of 9.8% [
31]. Therefore, the urban green open space for residents’ fitness and leisure has already been formed in China.
The relationship between urban green space and PA is not only of academic interest, but also provides important significance for improving public health and rational urban land planning. This provides both reference and guidance for the planning of urban green open spaces, including the size of open space, landscape, and infrastructure. However, the empirical basis of these policy recommendations is often weak [
32]. Consequently, more research is needed to better quantify and describe the optimal plan of green open space, especially for the promotion of PA to improve resident health. Early studies focused on Western developed countries; however, people from different socio-economic strata and cultural backgrounds use green space differently, and their PA behavior is affected by different factors. Therefore, developing countries also need corresponding empirical research [
33]. Related academic research however, remains limited research in China.
At present, China has entered a new era that emphasizes green open spaces and has been facing a contradiction between the people’s growing need for a better life and the inadequate development and imbalance of their physical fitness. Therefore, the rational use of green open space for PA has become an important means for improving the physical quality of Chinese residents. The objective of this study is to analyze the influence of all types of urban green open spaces on residents’ physical activity using social ecology theory.
The following research questions were explored: (1) Among social and ecology factors, which factors are significantly associated with PA? (2) How is PA influenced by social and ecology factors? (3) What is the unique of PA pattern and urban green open space use among Chinese?
Conclusion and recommendations
The ecological civilization construction aims to promote environments and physical activity as a part of daily life, but research has so far provided mixed results between urban green open space and physical activity. Besides, previous research has mainly been conducted on western developed countries, those findings cannot simply be transposed to the eastern developing context where PA form and urban green open space are quite different. Our study was both innovative in combining the social ecology theory with the questionnaire and was policy-relevant. Based on our results among the respondents in Nanning, suggestions for the planners of urban green open space in China can be made.
For community factors, no significant positive correlation was found between accessibility and the PA time, but a significant positive correlation was found to PA frequency. Consequently, improving the accessibility of urban green open spaces can encourage more residents to participate in PA to increase their use of green space and enhance the health of residents. Moreover, maintaining the safety of the urban green open space and shortening the distance from residence to the green open space can ensure the security of residents and reduce the time spent on the road, which can further promote PA.
For natural factors, the space environment and landscape quality have a positive effect on residents’ PA. Therefore, the urban green open space should be planted with a variety of vegetation types to green the open space, to freshen the air in the green open space, and to regulate residents in the green open space.
For built environmental factors, infrastructures, the area of green space, the size of the open space, whether a basketball court exists or a volleyball court, and a swimming pool are all significantly positively correlated with residents’ PA time, while the existence of a table tennis court is significantly negatively correlated with PA time. A significant positive correlation was found between the presence of a volleyball court or entertainment facilities and residents’ PA frequency. The size of green open space, a rolling field and a table tennis field have a significant negative correlation with PA frequency. This is because Chinese residents have a strong preference for group sports, which leads to all green open spaces being specially designed as “square dancing” and “Tai Chi” squares. Consequently, expanding the per capita area of urban green space, adding swimming pools and adding ethnic characteristics and culture to sports activities can promote residents’ PA.
Apart from the attributes of the green open space, there are also several other factors that influence residents’ PA in the urban green open space: individual and interpersonal factors. In individual factors, age and PA time as well as PA frequency are significantly and positively correlated; and gender is significantly correlated to PA time. The majority of the PA groups in China are elderly, and women spend more time with PA than men. In interpersonal factors, a strong sense of community exists in China, and choosing colleagues, a team, or others for group sports can promote PA. Therefore, to improve the health of the entire population, the urban green open space should be designed with a number of additional group sports that are suitable for both men and young people in particular.
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