Original ResearchAssociation between levels of physical activity and poor self-rated health in Korean adults: The Third Korea National Health and Nutrition Examination Survey (KNHANES), 2005
Introduction
The benefits of physical activity for health are well documented. Regular physical activity is associated with a reduced risk of cardiovascular disease, coronary heart disease, type 2 diabetes mellitus, osteoporosis, depression, anxiety, selected cancers and all-cause mortality.1 Additionally, physical activity is associated with better health-related quality of life (HRQoL).2 For these reasons, national health promoting programmes, such as ‘Healthy People 2010’ in the USA3 and the ‘Health Plan 2010’ in Korea,4 have been initiated to increase levels of physical activity.
Self-rated health (SRH) ostensibly provides only a subjective assessment of individual health status, but is also a good predictor of mortality5 and functional loss,6, 7 independent of objective health and psychosocial and demographic variables. SRH is strongly associated with successful ageing8 and has a biological component: levels of cytokines such as interleukin (IL)-1β, IL-1ra and tumour necrosis factor-α are higher in persons with lower SRH.9, 10 In practical terms, SRH is readily measured using a single-item question, and, thus, is often included in health surveys and as an outcome in many studies.
According to a recent study about the association between physical activity and self-rated health in the USA, the likelihood of fair or poor health was significantly lower among adults meeting recommended levels of physical activity or having insufficient levels of activity compared with physically inactive adults, after adjusting for age, race/ethnicity, gender, education, smoking status and body mass index.2 In Europe, subjects who were sufficiently or highly active were more likely to report a good SRH status than those who were insufficiently active, regardless of household income and educational status.11
The association between physical activity and SRH has been studied in various populations, such as the USA,2, 12 Europe11, 13, 14 and others; however, it has not been adequately described in Asians. Moreover, some researchers have suggested that the benefits of physical activity for health may depend on the presence of chronic disease or chronic medical conditions.15, 16 Over the past several decades, South Korea has experienced rapid socio-economic growth; indeed, one of the highest growth rates in the world. Korea also went through dramatic changes in its demography and lifestyle. The number and proportion of elderly people is growing, and Korea has one of the fastest growing populations among the world's major regions. As South Korea went through rapid economic development, there were significant changes in physical activity, diet and nutrition in the population.17 Due to the rapid change in demography and lifestyle, the importance of physical activity and health has been emphasized.
Accordingly, the objective of this study was to investigate whether the level of physical activity is associated with poor SRH, and whether the association depends on physical impairments or chronic medical conditions.
Section snippets
Subjects
The Third Korea National Health and Nutrition Examination Survey (KNHANES) was divided into four parts: the Health Interview Survey, the Health Behaviour Survey, the Nutrition Survey, and the Health Examination Survey.
The 2005 KNHANES was conducted using a systematic stratified cluster sampling design. The sampling frame was based on the 2000 National Census Registry. Six hundred enumeration districtse
Results
Thirty-three percent of men and 25.8% of women exercised at a sufficient level. A very good health status was reported by 5.4% of men and 3.5% of women, and 17.3% of men and 25.7% of women reported their health to be poor (i.e. poor or very poor; Table 1).
Table 2 shows the prevalence of physical impairments and chronic medical conditions by gender. The prevalence of limited chewing ability, limited walking ability, arthritis, osteoporosis and anaemia was significantly higher in women than men.
Discussion
A cross-sectional study was conducted in a randomly selected population of 7800 adults aged ≥19 years in Korea to identify any association between level of physical activity and SRH. The results showed that lower physical activity was positively associated with poor SRH, and that this association was similar in healthy respondents and in respondents with physical impairments or chronic medical conditions.
Several studies have advocated that SRH is a valid measure of health status. For example,
Conclusions
Physical activity was positively associated with SRH in a Korean population. The results of the present study may be useful for those designing public health policy or health promotion programmes to encourage regular physical activity. It is hoped that the results of this study will be used to encourage individuals with sedentary lifestyles to exercise regularly. A prospective study is required to identify causal relationships between physical activity and SRH.
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