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Paul Muntner, PhD, Donfeng Gu, MD, Rachel P. Wildman, PhD, Jichun Chen, MD, Wenqi Qan, MD, Paul K. Whelton, MD, MSc and Jiang He, MD, PhD

Paul Muntner, Rachel P. Wildman, Paul K. Whelton, and Jiang He are with the Department of Epidemiology, Tulane University School of Public Health and Tropical Medicine, New Orleans, La. Paul Muntner, Paul K. Whelton, and Jiang He are also with the Department of Medicine, Tulane University School of Medicine, New Orleans. Donfeng Gu, Jichun Chen, and Wenqi Qan are with the Cardiovascular Institute and Fuwai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing.

Correspondence: Requests for reprints should be sent to Paul Muntner, Department of Epidemiology, Tulane University SPHTM, 1430 Tulane Ave, SL-18, New Orleans, LA 70112 (e-mail: pmuntner{at}tulane.edu).

	ABSTRACT

TOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION References

 

Objectives. Determining physical activity levels in the community provides a context for the development and implementation of programs aimed at increasing these activity levels. Therefore, we assessed overall, work-related, and leisure-time physical activity in a representative sample of Chinese adults, aged 35 to 74 years, using data from the International Collaborative Study of Cardiovascular Disease in Asia.

Methods. Being physically active was defined as participating in 30 or more minutes of moderate or vigorous activity daily. Work-related and leisure-time physical activities were defined as being physically active and participating in any moderate or vigorous activity at work or during leisure time, respectively.

Results. In rural and urban China, 78.1% and 21.8% of residents, respectively, were physically active; 75.8% and 16.5%, respectively, participated in work-related activity; and 28.9% and 7.9%, respectively, participated in leisure-time physical activity. In both rural and urban settings, younger adults, men, and southern residents were more likely to be physically active and to participate in work-related and leisure-time physical activity than older adults, women, and northern residents.

Conclusions. Intervention strategies to promote leisure-time physical activity, especially among urban residents, should be considered a major health priority in China.

	INTRODUCTION

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The incidence of heart disease among adults in China is lower than that found in most economically developed countries, but it has risen in a strikingly fast rate over the past several decades.¹ During this same time period, the prevalence of cardiovascular disease risk factors has increased dramatically in the adult population in China.^2,3 Current estimates indicate that 28.2% of the Chinese adult population aged 35 to 74 years has hypertension.³ Additionally, the percentage of adults with diabetes or total cholesterol levels of 200 mg/dL or greater is 5.2% and 32.8%, respectively.^4,5 Reasons for the increasing burden of these heart disease risk factors have not been elucidated, but it has been suggested that urbanization and associated adverse changes in diet and physical activity levels may have played a role.^1,6

Several prospective cohort studies in Western populations have found increased physical activity to be a protective cardiovascular disease risk factor.^7–9 Randomized controlled trials have also demonstrated the benefits of aerobic exercise on blood pressure,¹⁰ glycemia,¹¹ and cholesterol levels.¹² Cross-sectional studies of select populations from China and other Eastern populations have confirmed the presence of a strong association between physical inactivity and an adverse heart disease risk factor profile.¹³ A recommendation for increased physical activity based on the results of epidemiological studies and randomized controlled trials has been included in many guidelines for better health in adults.^14–16 For example, the World Health Organization (WHO) developed the Move for Health program, which includes the aim of "increasing regular physical activity practices in the population, men and women of all ages and conditions, in all domains (leisure time, transport, work) and settings (school, community, home, workplace)."¹⁴ Several agencies, including the WHO, recommend that every adult participate in 30 minutes or more of moderate-intensity activity on most, but preferably all, days of the week.

Using data from the population-based International Collaborative Study of Cardiovascular Disease in Asia (InterASIA), we estimated the percentage of the Chinese adult population that was physically active. We also estimated the percentage that participated in work-related or leisure-time physical activity. Because stark contrasts have been noted in cardiovascular disease risk profiles among rural and urban residents of China,^3,17 we calculated estimates for the overall population and stratified by rural or urban residency. We also compared population estimates across 4 age groups, men and women, and residents of northern and southern China.

	METHODS

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Study Participants
The InterASIA study has been reported in detail previously.¹⁸ In 2000–2001, a 4-stage stratified sampling method was used to select a nationally representative sample of the Chinese general population aged 35 to 74 years. The sampling process was stratified by geographic region (north and south China, relative to the Yangtze River, and urban and rural areas). In the first stage, 10 of the 26 provinces that constitute China were chosen with certainty for inclusion. For purposes of sampling, counties within each of the 10 representative provinces selected in the first stage were divided into urban and rural areas on the basis of administrative data, and for the second stage of sampling, 1 rural area and 1 urban area were randomly selected from each province. Areas that were as densely populated as or more densely populated than the county’s capital were designated urban areas, whereas the remaining areas were designated rural areas. Overall, 79.5% of the Chinese population resides in rural areas. In the third stage, 1 township or street district was randomly selected from each urban and rural area, respectively. In the final stage of sampling, individuals were selected randomly by township or street district. Only 1 participant was selected from each household, without replacement.

A total of 19 012 persons were randomly selected from street districts in urban areas or townships in rural areas and invited to participate in the study. A total of 15 540 persons (7526 men and 8014 women), aged 35 to 74 years, completed the survey questionnaires and examination. The overall response rate was similar among men and women and in urban and rural areas.

Data Collection
Data collection was conducted in examination centers at local health stations or in community clinics in the participant’s residential area. For a few individuals who could not attend examinations at the clinic, home visits were conducted. No proxy data collection was conducted. During these visits, trained research staff administered a standard questionnaire. Of relevance to the current analysis, information on demographics (age, gender, and residential area), socioeconomic status (education level achieved and annual household income), and physical activity was collected. Participants were grouped by population quartile of annual household income and by completion of high school.

Physical Activity Assessment
Participants were asked to indicate the number of hours per day that they devoted to (1) vigorous activity, (2) moderate activity, (3) light activity, (4) watching television, (5) participation in other sedentary activities, and (6) periods of inactivity/sleeping. Overall, 14933 (96%) InterASIA study participants in China completed the physical activity survey questionnaire. The physical activity experience for participants who reported spending more or less than 24 hours per day in the 6 physical activity categories (n=1026; 6.9%) was adjusted to represent a 24-hour period. This was accomplished by dividing the number of hours spent in each activity by the sum of hours reported for all activities and multiplying this result by 24. Being physically active was defined as participating in 30 or more minutes of moderate or vigorous activity per day.

Each participant was asked the following 2 additional questions regarding work-related and leisure-time physical activity: "How much physical activity or heavy labor is involved in your present work?" and "In your leisure time, how much physical activity are you engaged in?" Responses for each of these questions included (1) vigorous, (2) moderate, (3) light, or (4) none/not applicable. Respondents who met the definition for being physically active (i.e., participation in 30 or more minutes of moderate or vigorous activity per day) and reported any vigorous or moderate physical activity during work or leisure time were classified as participating in work-related or leisure-time physical activity, respectively.

Statistical Methods
The percentage of the population who were physically active was determined, both overall and separately, for subgroups defined by urban and rural residence, 4 age groups (35 to 44, 45 to 54, 55 to 64, and 65 to 74 years), both genders, and those living in northern and southern China. All subgroup prevalence estimates were standardized to the year 2000 age and gender population of China. Additionally, the age- and gender-standardized percentage of the population who participated in work-related physical activity and the percentage who participated in leisure-time physical activity were calculated for each subgroup. We used the Wald test to compare differences between each subgroup in the percentage of the population who were physically active and in the percentage who participated in work-related and leisure-time physical activity. The Wald test was also used to calculate the statistical significance of the linear trend in physical activity across the 4 age groups after we modeled age group as a continuous variable. Next, we divided the population who were physically active into 3 mutually exclusive categories: those who participated in work-related physical activity only, those who participated in leisure-time related physical activity only, and those who participated in both work-related and leisure-time physical activity. We calculated the percentage of the physically active population in each of these categories overall, which was then stratified by rural/urban residence and gender. Finally, we used multivariable logistic regression models for the overall population of China and for urban and rural residents to determine the adjusted association of age group, gender, northern/southern residence, quartile of household income, and high school education with overall physical activity and with participation in work-related and leisure-time physical activity. We conducted all analyses with methods appropriate to the complex survey design of InterASIA, using SUDAAN statistical software version 8.0 (Research Triangle Institute, Research Triangle Park, NC).

	RESULTS

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The percentage of Chinese adults aged 35 to 74 years who were physically active was 66.3% overall (Figure 1, left panel), 78.1% for rural residents, and 21.8% for their urban counterparts. In both rural and urban China, as well as the country as a whole, the percentage of the population that was physically active declined with age (Figure 2, top panel; each P<.001). Additionally, being physically active was more common among men than among women (Figure 2, middle panel; P<.01) and among southern than among northern residents (Figure 2, bottom panel; P<.01).

View larger version (12K): [in this window] [in a new window]   FIGURE 1—— Percentage of overall, rural, and urban Chinese aged 35–74 years who reported being physically active and participating in any work-related or leisure-time physical activity in the InterASIA study. Note. Data were age- and gender-standardized to the 2000 population of the People’s Republic of China. Physical activity was defined as participation in 30 or more minutes of daily moderate or vigorous activity. Work-related physical activity was any moderate or vigorous activity during work time among those who reported being physically active (30 or more minutes of daily moderate or vigorous activity). Leisure-time physical activity was any moderate or vigorous activity during leisure time among those who reported being physically active (30 or more minutes of daily moderate or vigorous activity). * P < .001 for urban vs rural populations being physically active.

View larger version (17K): [in this window] [in a new window]   FIGURE 2—— Prevalence of being physically active among overall, rural, and urban Chinese aged 35–74 years in the InterASIA study stratified by (a) age, (b) gender, and (c) region (southern vs northern). Note. Data were age- and gender-standardized to the 2000 population of the People’s Republic of China. Physical activity was defined as participation in 30 or more minutes of daily moderate or vigorous activity. * P < .001 for trend across the 4 age groups.

Figure 3 displays the breakdown of physical activity as work-related only, leisure-time physical activity only, and both work-related and leisure-time physical activity among the Chinese population that was physically active. Overall, a majority (62.2%) of the population that was physically active participated in work-related physical activity only (62.1% and 62.6% among rural women and men, respectively, and 55.0% and 63.1% among urban women and men, respectively), 35.4% participated in work-related physical activity in conjunction with leisure-time physical activity, and only 2.3% participated in leisure-time physical activity alone. Among the population that was physically active, 1.5% and 1.4% of rural women and men, respectively, participated in leisure-time physical activity alone. In contrast, 22.7% and 13.1% of urban women and men who were physically active, respectively, participated in leisure-time physical activity only.

View larger version (19K): [in this window] [in a new window]   FIGURE 3—— Classification of physical activity among Chinese in the InterASIA study who reported daily participation in 30 or more minutes of vigorous or moderate activity: leisure time (white), work related (black), or both leisure time and work related (gray).

	DISCUSSION

TOP ABSTRACT INTRODUCTION METHODS RESULTS DISCUSSION References

 
According to estimates from the current study, 66.3% of the Chinese population spends 30 minutes or more each day participating in moderate or vigorous physical activity and therefore meets the recommendation for participation in physical activity set forth by the WHO. Although the percentage of the overall Chinese population that was physically active was high, only 21.8% of urban Chinese adults were physically active. Additionally, participation in moderate or vigorous leisure-time physical activity was low, being 7.9% and 28.9%, among urban and rural Chinese adults, respectively.

Data from the current study showing that physical activity is primarily achieved in the work environment in China should raise concern. The increasing urbanization taking place in China may result in a progressive and substantial rapid decline in the percentage of the population that is physically active. The large disparity in physical activity between rural and urban residents observed in InterASIA mainly reflects occupational differences. In rural areas, the majority of residents are engaged in jobs involving heavy labor. Additionally, many residents in rural areas hold multiple jobs.¹⁹ In contrast, work activities in urban areas have experienced a major shift toward the service sector, which requires substantially less physical activity. Technological advances in the workplace in urban China have been reported to be associated with declines in physical activity.¹⁹ The Chinese government has developed the Sports for All plan in an effort to improve health and fitness by encouraging the population to be physically active in all domains of daily living (e.g., occupational and leisure time).²⁰ As part of this plan, facilities for exercise are scheduled for expansion. Given the shift toward sedentary occupations, promotion of leisure-time physical activity is extremely important, especially in urban China.

The current study focused on the percentage of the Chinese population that meets the WHO recommendation of being moderately or vigorously active for at least 30 minutes per day. The extent to which those who do not meet the WHO recommendation for physical activity are active but achieve less than 30 minutes of daily moderate or vigorous physical activity has important implications for policy planners and health educators. According to the data from InterASIA, less than 0.1% of those not meeting the WHO recommendation for physical activity achieved some but less than 30 minutes of moderate or vigorous physical activity per day. This percentage was similar among men and women, in urban and rural areas, and in northern and southern China. Increasing the percentage of Chinese adults who meet the WHO guidelines for physical activity will require programs to facilitate the initiation of moderate or vigorous physical activity.

The low rates of leisure-time physical activity noted in our study should raise special concern, given that approximately 20% of the world’s population resides in China. Recent data indicate that 60% of the world’s population fails to meet the WHO recommendation that adults participate in a minimum of 30 minutes of moderate or vigorous physical activity every day.²¹ Additionally, 1.9 million deaths annually are attributable to physical inactivity, and 22% of all ischemic heart disease deaths can be attributed to physical inactivity. In the United States, 32.0% of adults meet or exceed national recommendations that they participate in at least 30 minutes per day of moderate or vigorous leisure-time physical activity on 5 or more days of the week.²² This estimate is similar to that observed for leisure-time physical activity in rural China and is substantially higher than the corresponding estimates from urban China. The low percentage of the United States population meeting guidelines for leisure-time physical activity is considered a major public health problem, and the American Heart Association and Centers for Disease Control and Prevention’s Division of Nutrition and Physical Activity have developed several public health programs aimed at increasing levels of physical activity in the general population. The low prevalence of leisure-time physical activity in China, especially in urban dwellers, observed in the current study is worrisome and needs to be considered in the context of future projections of chronic disease morbidity and mortality. In 2002, the Chinese Preventive Medical Association launched China’s first weeklong campaign against obesity; this campaign includes components aimed at increasing physical activity.

The fact that detailed information on specific forms of physical activity was not available is a limitation of the current study. In addition, hindrances precluding the achievement of physical activity and day-to-day variability in physical activity were not assessed. Likewise, data on travel/commuting-related activity would have provided an important domain that was not explicitly addressed in InterASIA. Given the broad aims of InterASIA, administration of a more detailed physical activity questionnaire was not feasible.

Strengths of the current report include the multistage sampling process used in InterASIA, which allowed the production of results that can be used to generate physical activity prevalence estimates for all adult residents of China and for population subgroups (e.g., urban and rural populations). Although several regional studies have reported low rates of overall and work-related physical activity in China,^23–25 we believe that the current report provides the first nationally representative data. Additionally, InterASIA included questions related to overall, work-related, and leisure-time physical activity. Dividing activity into work-related and leisure-time activity showed that although the percentage of the population that was physically active was relatively high in rural China, only a small percentage of the population participated in leisure-time physical activity. Our findings highlight the need for future epidemiological studies in economically developing countries to ascertain work-related and leisure-time physical activity, separately. Additionally, special efforts should be made to increase leisure-time physical activity.

In summary, the proportion of the population in urban China that is physically active is low. Additionally, a majority of the physical activity that occurs in China is work related, and rates of leisure-time physical activity are low, especially in urban settings. With the increasing urbanization taking place in China, rates of physical activity could decline substantially over a relatively short period of time. This could have a profound impact on future rates of cardiovascular disease. The application of multifaceted approaches to increase leisure-time physical activity in China should be given a high priority, as such interventions have the potential to positively impact the rapidly increasing incidence of cardiovascular disease.

	Acknowledgments

 
The InterASIA study was funded by a contractual agreement between Tulane University, New Orleans, La, and Pfizer Inc, New York, NY. Several researchers employed by Pfizer Inc were members of the study steering committee that designed the study. However, the study was conducted, analyzed, and interpreted by the investigators independently of the sponsor. Data analysis and publication of this article were partially supported by a Scientist Development Award from the American Heart Association (0235134N) to P. Muntner and by the COBRE Program of the National Center for Research Resources (grant P20 RR17659-01).

	Footnotes

 
Peer Reviewed

Contributors
P. Muntner conducted all statistical analyses and drafted the article. D. Gu supervised field work and data collection and reviewed drafts. R. P. Wildman provided statistical advice and assistance and reviewed drafts. J. Chen and W. Qan assisted in the data collection and reviewed drafts. P. K. Whelton conceptualized the study, designed data collection instruments, and assisted in monitoring quality control. J. He conceptualized the study, designed the study protocol and data collection instruments and procedures, provided key statistical guidance, and reviewed drafts.

Human Participants Protection
The institutional review board at Tulane University Health Sciences Center approved the InterASIA study. In addition, ethics committees and other relevant regulatory bodies in China approved the study. Written informed consent was obtained from each participant before the data were collected. Participants with untreated conditions identified during the examination were referred to their usual primary health care provider.

Accepted for publication August 24, 2004.

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This Article Abstract Figures Only Full Text (PDF) All Versions of this Article: AJPH.2004.044743v1 95/9/1631    most recent Submit a response Purchase Article View Shopping Cart Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (8) Citing Articles via Google Scholar Google Scholar Articles by Muntner, P. Articles by He, J. Search for Related Content PubMed PubMed Citation Articles by Muntner, P. Articles by He, J. Related Collections Cardiovascular Disease Exercise/Physical Activity Asians Surveys