Older women spend large portion of their time sitting, making them susceptible to developing a disease or disability, according to a new study.

Researchers from the Harvard School of Public Health in Boston found that older women spent nearly two-thirds of their time sitting. Sedentary behavior has been linked to ailments because people who spend a lot their time sitting tend not to meet physical activity guidelines.

"Even people who go to the gym every day and run 6 miles on a treadmill can be at risk for bad outcomes from being sedentary if they spend 8-10 hours seated at a desk and then watch TV with their spouse after dinner," Dr. Catherine A. Sarkisian, director of the Los Angeles Community Academic Partnership for Research in Aging Center and a geriatrician at UCLA, told Reuters.

Sarkisian was not involved in the new report.

In their study, researchers led by Eric J. Shiroma of gave about 7,200 women accelerometers to measure how much they moved around during the day. The women, who were in their early 70s, on average, wore the device for a week.

Researchers found that the women spent two-thirds of their waking time, or just under 10 hours each day, being sedentary. This sedentary time recorded on the accelerometers most likely meant the participants were sitting but could have reflected time spent standing still as well, Shiroma and his colleagues wrote Tuesday in the Journal of the American Medical Association.

Based on the study, older and heavier senior citizens were more likely to spend large portions of their day being sedentary.

He said it is also not clear whether what really matters is how much total time people spend being sedentary throughout the day or how many breaks they take to walk around and how often, Shiroma added.

"Most of us had thought that people were sitting a lot longer, and maybe people who are sitting a lot longer are at greater risk, but we're going to have to wait and see," he said. "We don't necessarily know where the threshold is for, how long is sitting too long?"

In other women, most "bouts" of sedentary behavior seen in the women participating in the study were short, and they tended to get up and start moving regularly throughout the day. About one-third of their sedentary time was spent being totally inactive for at least a half hour, Reuters reported.

Many older people are able to participate in a wide range of activities in their communities, Sarkisian said. Walking is an especially accessible way to get exercise in old age.

"Being sedentary should not be accepted as a normal part of aging," Sarkisian said.

In their study, researchers noted that most of the women that participated in the study were white and relatively well-off. They said it's not clear if sedentary behavior would be the same among women of other races or poorer women.