Stand up against heart disease

woman sat down

Spending too much time sitting down increases the risk of developing heart disease, according to a recent study.

This new research, published in the Journal of the American Heart Association examined the sitting habits of older, post-menopausal women with an average age of 63. The study analysed the behaviours of 102 Hispanic women and 416 non-Hispanic overweight or obese women. 

The results found those who spent more time seated, and were either overweight or obese, and had a higher risk of heart disease and diabetes.

Study participants wore accelerometers on their right hip for 14 days, tracking and recording sitting and physical activity. They only removed the device to sleep, shower or swim. Participants also had blood tests, performed concurrently with accelerometer wearing, which measured blood sugar and insulin resistance.

The data was analysed as one overall group and then divided into two ethnic groups - Hispanic and non-Hispanic women. This was in a bid to see if ethnicity affected the the relationship between sitting time and risk of heart disease.

The researchers focused on post-menopausal women because older Americans have the highest levels of sedentary behaviour. Cardiovascular symptoms are also more pronounced after the menopause, but everyone’s risk of heart problems increases with age.

The researchers found that post-menopausal Hispanic women sat, on average, almost one hour less per day than non-Hispanic women of the same age group. They also spent significantly less time in periods of uninterrupted sitting. It was found post-menopausal Hispanic women sat for an average of 8.5 hours per day, compared with 9 hours for non-Hispanic women. 

Long sitting times corresponded to higher fasting insulin (the body is creating a high insulin demand) and increased insulin resistance.  

The connection between sedentary behaviour and the risk of heart disease remained even when researchers took into account women’s physical activity levels. This means that being sedentary was linked to a higher risk of heart disease even in women who exercised regularly.

Results also found that for every 15-minute increase in uninterrupted sitting was associated with an approximately five percent higher fasting blood sugar levels in Hispanic women, compared to less than one percent increase in non-Hispanic women. This suggests that Hispanic women may have genetic differences that increase the negative impacts that sitting has on blood sugar.

The study's lead author, Dr. Dorothy D. Sears, a professor of nutrition at Arizona State University's College of Health Solutions in Phoenix, was very surprised to find such a strong relationship between the amount of time women spent sitting and insulin resistance, even after accounting for exercise and obesity. 

Insulin resistance is understood to be an important factor that increases the risk of heart disease and type 2 diabetes.

Sears commented: "The findings of this study suggest that we need to think about physical activity and time spent sitting as two separate things. Exercise does not make up for excessive sitting times, and that’s why it’s important to get up and move around during the day - be it taking a walk to the supermarket or simply walking around the house.”

The researchers concluded that it is the responsibility of healthcare providers to encourage people to not only exercise more, but also to sit less.

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