We hypothesized individuals with CHD would be less physically active than the general population who do not have CHD. Before PSM, we observed a significantly lower amount of time spent in vigorous, leisure, transport, and total physical activity participation and significantly more sedentary time among individuals with CHD than those without CHD. Considering the differences in sociodemographic and lifestyle variables between the two groups, we used PSM to compare the groups. After matching, individuals with CHD had equivalent physical activity levels to individuals without CHD other than work-related physical activity. Leisure physical activity time was significantly lower in men with CHD, while women reported higher work-related physical activity. Among those < 65 years of age, individuals with CHD spent significantly more time sedentary than those without CHD.
We observed similar physical activity levels in individuals with and without CHD when matched for sociodemographic and lifestyle variables. One study in the United States reported the age-standardized percentage of adults with and without CHD who participated in physical activity at recommended levels. Their data suggested individuals with CHD participated in significantly less total (40% meeting recommendations vs. 49% meeting recommendations), moderate (32% vs. 37%), and vigorous (22% vs. 29%) physical activity compared with individuals without CHD15. Another study reported physical activity participation rates of coronary patients from European countries (moderate or vigorous physical activity for at least 20 min once or more times a week: 38%) but not in comparison to those without CHD16. Furthermore, discrepancies exist between the findings of the current study and those of Baker et al.17, which reported a significant reduction in objectively measured physical activity compared to the health control group. One of the primary distinctions between our study and Baker et al.’s study is the average age of participants. Notably, participants in Baker et al. (2019) are significantly older (no disease: male 61.0 ± 8.0 and female 60.7 ± 7.7 years old; chronic disease: male 65.5 ± 7.1, female 63.5 ± 7.5). Considering that vigorous physical activity tends to decrease with age, the observed lower physical activity participation in individuals with CVD compared to those without CVD could be partially attributed to the higher age among individuals with CVD. In our study, we employed propensity score matching. Consequently, we were able to compare physical activity participation levels between participants who were matched for age, BMI, education, household income, alcohol intake, and smoking status. This approach enhances the robustness of our comparisons, minimizing potential confounding effects and providing a more accurate assessment of the impact of chronic disease on physical activity participation.
When interpreting our data, one should note that physical activity levels are generally low among Korean adults in comparison to other countries. A recent study on physical activity prevalence among Korean adults between the ages of 60 and 69 years reported that 10.2% were engaging in high levels of physical activity18, which is lower than older Czech adults (24.9–28.3%)19 and Iranians between the ages of 55 and 64 years (23.7%)20. In addition, some people with CHD may have recognized the importance of PA and tried to be more physically active. Stewart and colleagues reported that 34% of individuals with CHD increased their physical activity after their CHD diagnosis21 and similar results have been reported in European samples16. The extent to which people are motivated to increase the amount of activity after diagnosis and the effect over time is unclear and may vary by country and/or ethnicity.
Physical activity domains (i.e., leisure, work, and transportation) may have varying associations with CHD. Leisure activity has an inverse linear association with CVD risk factors and mortality22,23. Associations of other physical activity domains with cardiovascular health remain less clear. Regarding work-related physical activity, research has suggested shift work may increase the risk of CVD events, and work-related physical activity may increase all-cause mortality in men24,25. As for transportation-related physical activity, adults living in walkable neighborhoods had lower 10-year CVD risk compared to those who do not live in walkable neighborhoods26. Referred to as the physical activity paradox, it is unclear why occupational or work-related physical activity does not confer similar health benefits as leisure or recreational physical activities7. It is noteworthy that there was no discernible difference in work-related physical activity before PSM; however, individuals with CHD exhibited higher levels of work-related physical activity. This observation may be attributed to significant disparities in age (51 ± 16.8 vs. 68.9 ± 8.9 years old), sex, BMI (23.9 ± 3.6 vs. 24.8 ± 3.2, kg/m2), marital status, and employment status before matching. Prior to PSM, individuals without CHD were notably younger, more likely to be single, leaner, and employed. Consequently, the comparison of work-related physical activity after PSM matching enhances the validity of the analysis by accounting for these baseline differences and ensuring a more balanced and unbiased assessment between the groups.
In our subgroup analyses, we observed a lower engagement in leisure physical activity among men with CHD, while women with CHD demonstrated higher levels of work-related physical activity. It is noteworthy that there was no significant difference in work-related physical activity before matching, but a notable disparity emerged after matching. Upon closer examination through subgroup analyses, we found that this divergence in work-related physical activity was specific to women. The reason for the heightened work-related physical activity in women with CHD remains unclear, especially considering a smaller proportion of participants with CHD were employed. It is essential to recognize that the GPAQ not only assesses occupational physical activity but also encompasses physical activity related to unpaid work, household chores, and harvesting food/crops. Additionally, it is pertinent to highlight that the types of employment were comparable between individuals with and without CHD. Therefore, the observed differences in work-related physical activity in our study may be attributed, at least in part, to variances in socioeconomic status. It is crucial to further investigate and understand the factors contributing to the observed patterns in physical activity among women with CHD in various domains. Among men and women who were < 65 years of age and had CHD, significantly more time was spent sedentary than those without CHD.
It is noteworthy that individuals with CHD showed significantly higher sedentary time in our study, in agreement with findings from previous studies27,28. Since replacing sedentary time with physical activity may reduce inflammation29, CVD mortality, and all-cause mortality30, individuals with CHD should be encouraged to limit the amount of time spent in sedentary pursuits. Replacing sedentary time with leisure physical activity should be strongly recommended. Sociodemographic characteristics of individuals with CHD who report high work-related physical activity levels should be further analyzed. Whether individuals with CHD who report high work-related physical activity levels need additional leisure activity should be a question for future research in this area.
Shorter sedentary time and higher levels of leisure physical activity are associated with beneficial effects on CVD22,30. Higher and prolonged sedentary time has adverse effects on CVD markers, such as blood pressure, high-density lipoprotein, low-density lipoprotein, and C-reactive protein31. Similar to previous research, individuals with CHD were spending significantly more time sedentary compared to those without CHD. Since all activities performed in a single day are interdependent, longer sedentary time could mean less time spent in physical activity. Recent studies point to the need to incorporate more sophisticated measures such as posture-discriminating accelerometry and distinguish between sedentary patterns. Future studies should also apply isotemporal substitution modeling approaches to determine the impact (on health outcomes) of reducing sedentary time and increasing time spent in other physical activity domains.
One limitation of our study is that the diagnosis of CHD was based on a subjective questionnaire. This method may lead to instances where cases of angina, unrelated to CHD, are included, and some patients may not have experienced a MI. Another limitation stems from the broad definition of CHD, encompassing a spectrum of severity, ranging from well-controlled angina with minimal symptoms to those experiencing worsening conditions. Moreover, our study’s measurement of physical activity relied on subjective, self-reported data. Individuals with CHD in our study might have provided socially desirable responses to the physical activity questionnaires, potentially leading to an overreporting of their physical activity levels. Although objective/device-based methods, such as accelerometers, cannot distinguish between different domains of physical activity, our findings remain credible. For future research, a more comprehensive approach would involve simultaneously implementing both objective and self-report methods for assessing physical activity. This would provide a more nuanced and accurate understanding of individuals’ activity levels and contribute to a more robust interpretation of the relationship between CHD and physical activity. Moreover, although we adjusted for major demographic and lifestyle related factors, we cannot rule out unmeasured confounding by other diseases and factors that may influence physical activity level and CHD. Despite these limitations, our study stands as the first to compare physical activity levels between individuals with and without CHD after meticulous matching on sociodemographic and lifestyle variables on a national scale.
link