Older women who spend the most time sitting and resting have a higher risk of dying early, according to a new study.

Surprisingly, the increased risk of early death remained true even even after taking into account other potential factors such as chronic disease, overall fitness, and physical mobility.

The findings add to a bulk of evidence showing that too much sitting is connected with a number of health ills.

"The assumption has been that if you're fit and physically active, that will protect you, even if you spend a huge amount of time sitting each day," study researcher Rebecca Seguin, assistant professor of nutritional sciences at Cornell University's College of Human Ecology, said in a statement. "In fact, in doing so you are far less protected from negative health effects of being sedentary than you realize."

For the study, published in the American Journal of Preventive Medicine, Seguin and her colleagues analyzed Womens Health Initiative Observational Study data of 92,234 postmenopausal women who were between 50 and 79 at the start of the study. The women spent an average of nine to 10 hours a day sitting.

The researchers followed the women for an average of 12 years to find an association between spending more time being sedentary (not counting sleeping) and having a higher risk of dying over the follow-up period, including from cardiovascular disease, coronary heart disease and cancer.

Specifically, women who spent more than 11 hours resting or sitting each day had a 12 percent higher risk of dying early from any cause, compared with women who spent four hours or fewer resting or sitting each day.