Prolonged sitting at work linked to increased mortality risk

By Dr. Sanchari Sinha Dutta, Ph.D.Jan 23 2024Reviewed by Benedette Cuffari, M.Sc.

A recent study published in JAMA Network Open reports that prolonged sitting at the workplace can potentially increase the risk of all-cause mortality and mortality from cardiovascular disease. A workplace arrangement of alternating sitting and non-sitting might help reduce this mortality risk.

Study: Occupational Sitting Time, Leisure Physical Activity, and All-Cause and Cardiovascular Disease Mortality. Image Credit: fizkes / Shutterstock.com

Background

A sedentary lifestyle has become increasingly pervasive in modern life. Many workplaces now demand prolonged sitting arrangements despite awareness of the adverse health effects associated with prolonged sedentary behavior.

In 2020, the World Health Organization (WHO) issued guidelines recommending reduced sedentary behaviors due to their health consequences. These guidelines agree with the 2018 United States and 2019 United Kingdom guidelines on physical activity that discourage prolonged sitting.

Previous studies investigating leisure-time physical activity indicate that a certain level of daily physical activity may mitigate the adverse health effects of prolonged sitting.

Study design

In the current study, scientists investigate the impact of prolonged occupational sitting on all-cause mortality and cardiovascular disease-related mortality among individuals residing in Taiwan. They also quantify the amount of leisure-time physical activity and intensity required to mitigate the negative health effects associated with prolonged sitting.

The current study included 481,688 adult individuals without a history of cardiovascular disease at baseline. Study participants were monitored for approximately 12 years between 1996 and 2017. During each follow-up visit, the participants completed a questionnaire on their medical history and lifestyle risk factors and provided biological samples for testing.

Three types of occupational sitting arrangements were considered in the study, which included mostly sitting, alternating sitting and non-sitting, and mostly non-sitting. Study participants were asked to provide their weekly leisure-time physical activity intensity and duration in the last month. Based on the reports, study participants were categorized into five leisure-time physical activity groups, including inactive, low, medium, high, and very high.

Physical activity levels were estimated using the personal activity intelligence (PAI) metric, a physical activity tracker that can incorporate personalized heart rates in response to activity. Information on all-cause and cardiovascular disease-related mortality was obtained from the Taiwan National Death Registry. Deaths that occurred within the initial two years of follow-up were excluded to prevent reverse causality.     

Important observations

About 60% of the study cohort was in the mostly sitting group, 10% in the mostly non-sitting group, and 29% in the alternating sitting and non-sitting group. Physically inactive status was reported by 47% of the mostly sitting group participants, 51% of the alternating sitting and non-sitting group participants, and 57% of the mostly non-sitting group participants.

A total of 26,257 deaths were recorded during the study's follow-up period of 12 years. Of these deaths, approximately 57% occurred in the mostly sitting group. Among 5,371 cardiovascular disease-related deaths, 60% occurred in the mostly sitting group.

After adjusting for sex, age, education level, smoking, and drinking status, and body mass index (BMI), the analysis revealed that individuals mostly sitting at work have 16% and 34% greater risks of all-cause mortality and cardiovascular mortality, respectively, as compared to those with mostly non-sitting occupational arrangements. Compared to mostly non-sitting participants, alternating sitting and non-sitting participants were not associated with an increased mortality risk.

A significantly increased all-cause and cardiovascular mortality risk in the mostly sitting group was observed among men, women, participants younger and older than 60 years of age, smokers, never smokers, and individuals with chronic health conditions, such as diabetes and hypertension.

Considering individuals with leisure-time physical activity levels ranging from inactive to high, a significantly higher all-cause mortality risk was observed in the mostly sitting group as compared to those in the mostly non-sitting and alternating sitting and non-sitting groups. However, no significant differences in mortality risk were observed between the studied occupational sitting groups at a very high leisure-time physical activity level.   

For individuals mostly sitting at work with low or no leisure-time physical activity, an increase in leisure-time physical activity by 15 and 30 minutes every day reduced their mortality risk to a level similar to that of inactive individuals mostly non-sitting at work. A significantly reduced mortality risk was also observed for individuals with a PAI score of more than 100.

Study significance

The current study finds that prolonged occupational sitting can increase all-cause and cardiovascular mortality risks. This risk can be attenuated by taking regular breaks at work and completing daily 15-30 minutes of leisure-time physical activity.