Sitting down for more than 10 hours a day? Could this lead to cardiovascular disease?

This study looked at if sitting down for prolonged periods of time and lack of physical activity are associated with cardiovascular disease. 

Cardiovascular disease (CVD) is a heart disorder caused by narrowed or blocked blood vessels that can lead to a heart attack or stroke. The disease can be prevented or treated by making simple healthy lifestyle choices such as increasing physical activity. Recent studies, however, have suggested that sitting (sedentary behavior) for long periods of time, increases the risk of cardiovascular disease, regardless of exercise. Thus, even among individuals who exercise regularly, excessive sedentary behavior might have negative health implications, particularly in older adults.

This study included participants from the Women’s Health Initiative Observational Study (WHI-OS) carried out in the US. 71,018 postmenopausal women enrolled in the study, aged between 50-79 years. Women were excluded if they had any other exiting diseases that would limit their life expectancy to 3 years, or a history of CVD.

Each participant had an initial clinic visit at which she completed self-administered questionnaires related to medical history, physical activity and lifestyle factors. Sedentary behavior was assessed by questionnaire according to how many hours per day they spent sitting. It was measured at the first clinic visit and twice during follow-up period of 3 years.

The study found that sitting for more than 10 hours per day, regardless of physical activity, gave you an 18% increased risk of developing CVD compared to sitting for less than 5 hours per day. Women who were physically inactive and reported 10 hours per day of sitting time were at 63% greater CVD risk than highly active women who reported sitting 5 hours per day. Low physical activity was also associated with higher CVD risk. Associations between prolonged sitting and risk of CVD were stronger in overweight versus normal weight women and women 70 years of age and older compared with younger women.

The findings suggest that prolonged sitting time significantly increases the risk of developing CVD, regardless of physical activity. Reducing sitting time among older women who are less active could potentially reduce risk of CVD.

This study only included postmenopausal women; therefore, findings cannot necessarily be generalized to men or younger women. Also, sitting time and physical activity were self-reported so their accuracy could be questioned. 

If you are worried about developing cardiovascular disease, think of ways to increase your physical activity and reduce sitting time e.g. going for a walk instead of watching TV.