Sitting in Front of TV Associated with Increased Risk of Heart Disease

A recent study has found that leisure-time sitting, but not sitting at work, was associated with a greater risk of heart disease and deaths.

After examining more than 3,500 patients, investigators from Columbia University found that 2 additional hours of TV viewing per day increases a person’s risk of cardiovascular events and death by 50%.

"Our findings show that how you spend your time outside of work may matter more when it comes to heart health," said study author Keith M. Diaz, PhD, assistant professor of behavioral medicine at Columbia University Vagelos College of Physicians and Surgeons. "Even if you have a job that requires you to sit for long periods of time, replacing the time you spend sitting at home with strenuous exercise could reduce your risk of heart disease and death."

Investigators examined data from 3592 individuals that were enrolled in the Jackson Heart Study between 2000 and 2004— a community-based study of African-Americans in Jackson, MS. All individuals enrolled were 21 or older, had baseline testing done, and represented, both, urban and rural residents. Follow-up exams were performed between 2005 to 2008 and again from 2009 to 2013.

Primary outcome was a composite end point of CVD events, defined as coronary heart disease or stroke, and all-cause mortality. Each type of event was analyzed separately as secondary outcomes.

Investigators created 3 categories for participants based on their TV viewing times, defined as less than 2 hours per day (32.7%), 2 to 4 hours per day (36.3%), or more than 4 hours per day (31.0%). For occupational sitting, 28% (n=1007) of participants report “never or seldom” sitting at work, 28.8% (n=1033) reported sitting “sometimes”, and 43.2% (n=1552) reported sitting “often or always”.

The median follow-up was 8.4 years and investigators observed 129 CVD events and 205 deaths. In an unadjusted model, investigators found that more than 4 hours of TV viewing time per day was associated with an increased risk of CVD event and mortality — this association remained statistically significant in all adjusted models.

Of the 334 total events, 143 took place in the group that spent more than 4 hours per day watching TV, 104 took place in the 2 to 4 hours group, and 87 occurred in the group watching less than 2 hours per day. Conversely, the group that “never or seldom” sits at work experienced 111 events, the group that “sometimes” sits experienced 101, and the “often or always” group experienced 122 events.

Diaz theorized that the nature of this association may be linked to the lower activity levels while watching TV than performing duties at work.

"It may be that most people tend to watch television for hours without moving, while most workers get up from their desk frequently," Diaz said. "The combination of eating a large meal such as dinner and then sitting for hours could also be particularly harmful."

Investigators noted that the study’s results imply a need for greater encouragement of physical activity during leisure time and that this may be especially important for African-American patients as they are at a greater risk of heart disease. Additionally, high levels of physical activity could eliminate the increased risk of CVD events and all-cause mortality associated with greater TV viewing hours.

This study, titled “Types of Sedentary Behavior and Risk of Cardiovascular Events and Mortality in African-Americans: The Jackson Heart Study,” is published in the Journal of the American Heart Association.