Association between physical activity paradox and risk variables for cardiovascular disease

By Shanet Susan AlexMay 11 2022Reviewed by Aimee Molineux

In a recent article posted to the Public Library of Science (PLOS) ONE journal, investigators analyzed the significance of the physical activity paradox in the risk variables for cardiovascular disease (CVD).

Background

Physical activity during leisure time has been shown to reduce the likelihood of CVD and death. On the contrary, workplace physical activity probably raises the risk of all-cause and CVD-specific fatality, especially among males. Furthermore, there is equivocal evidence on the link between workplace physical activity and the incidence of major cardiovascular events, ischemic heart disease (IHD), and CVD risk factors.

The contradictory relationship between physical activity during work and leisure with CVD susceptibility variables is known as the physical activity health paradox.

The present physical activity guidelines are primarily derived from data on physical activities during leisure time. Nevertheless, the majority of the daily physical activity of a considerable segment of the general public, particularly those from lower socioeconomic backgrounds, happens at work. As a result, it is critical to look at the negative health impacts of workplace physical activity.

About the study

In the present cross-sectional analysis, in an adult general population sample, the researchers determined the mechanism behind the correlations of high-intensity physical activity (HIPA), walking, and sedentary behavior during work and leisure with CVD risk variables using compositional data analysis (CoDA). The risk factors for CVD included systolic blood pressure (SBP), low-density lipoprotein cholesterol (LDL-C), and waist circumference (WC). The team used information from the fifth assessment of the Copenhagen City Heart Study (CCHS), procured between October 2011 and February 2015.

Study volunteers wore accelerometers 24 hours/day for a week in their iliac crest and the right thigh and had their WC, LDL-C, and SBP monitored. The Acti4 software was used to analyze accelerometer data to determine daily physical activity and sedentary behavior types. The measure of correlation was computed by redistributing time across 1) HIPA: the sum of rowing, climbing stairs, cycling, and running, and 2) walking in work and leisure categories.

Results

The study results indicated that the final trial population included 652 subjects from CCHS research, and they had a median accelerometer wear duration of six days at 23.8 hours/day. While more walking or HIPA and less sedentary behavior were related to lower SBP during leisure, they were associated with higher SBP in work. Moreover, the extent of the projected variations in SBP varied significantly between the two domains.

The data showed that a more HIPA and less sedentary behavior were linked to a lower LDL-C and smaller WC in both work and leisure sectors, albeit minimal estimates during work. Nonetheless, independent of domain, the data showed that more walking and less sedentary behavior were correlated with a higher LDL-C and larger WC. Additionally, given the temporal reallocations, the estimated variance in WC was not symmetrical. 

Findings similar to the main study were obtained throughout the WC, LDL-C, and SBP outcomes when subjects consuming diuretics, cholesterol-lowering medicines, or antihypertensives were included in the sensitivity analyses. When the evaluations were restricted to 146 persons administering these three medicines, the estimated changes in SBP for time reallocations across walking and sedentary behavior exhibited the same pattern yet were higher than the main assessments. In contrast to the main study, the estimated variances in SBP considering time reallocations among HIPA and sedentary behavior followed an opposite trend.

Additionally, LDL-C and WC showed opposite trends as well. Specifically, WC in the walk and sedentary behavior-reallocations during leisure and the HIPA and sedentary behavior-reallocations during work; and LDL-C in the walk and sedentary behavior-reallocations in both domains and the HIPA and sedentary behavior-reallocations in work.

Conclusions

According to the study findings, more HIPA or walking and less sedentary activity appeared to be linked to a lower SBP during leisure; yet, in work, it seemed connected to a higher SBP. For LDL-C and WC, there were no significant variations across domains. These findings emphasize the significance of accounting for the physical activity-health paradox, minimum for certain CVD risk variables. Besides, the authors mentioned that physical activity guidelines should consider the negative health impacts of workplace physical activity.

The team stated that investigations using prospective data and larger study samples were required to enhance the knowledge of the health implications of walking and several physical activity types in both work and leisure. Furthermore, future studies might benefit from integrating device-based measures with data from job-exposure matrices, past job titles, questionnaire data, or routinely gathered administrative data by improving exposure assessment and reducing misclassification.

According to the authors, an in-depth comprehension of how existing work could be applied to raise physical activity levels in public and what to propose to population cohorts with high levels of workplace physical activity about their leisure-time physical activity is crucial.