Feinberg study finds link between sedentary lifestyle, disability rates

Rebecca Savransky, Assistant Campus Editor

A group of Northwestern researchers published a study last week detailing a strong link between sedentary adults and their risk of being disabled late in life.

Controlling for participants’ activity levels, the Northwestern Medicine study demonstrated that each additional hour adults age 60 years and older spent being sedentary, their likelihood of having a disability increased 50 percent. 

“We anticipated that sedentary behavior would be related to health problems,” said Feinberg Prof. Dorothy Dunlop, the study’s lead author. “The strength of that relationship was very impressive.”

The study required participants use an accelerometer to objectively monitor their activity levels, an attribute that makes it unique to other studies done on similar issues, Dunlop said.

“Most of the studies on sedentary lifestyle of the past relied on self-reported physical activity,” Dunlop said. “While that is informative for understanding some relationships, it’s not reproducible because people tend to overreport the amount of activity they are involved in.”

The accelerometers also have the capability to monitor both the amount of physical activity an individual engages in throughout the day and that activity’s intensity.

Dunlop said the researchers chose to look into the effects sedentary lifestyles had on disabilities specifically because of the significant financial impacts of disabilities in the United States.

“One out of every four health care dollars in the United States is due to disability,” Dunlop said. “So while we know sedentary activity is related to diabetes, we know it’s related to heart disease, the fact that we can tie it to disability immediately has economic consequences.”

The group also focused on older individuals exclusively because of the difficulty in measuring health outcomes in younger children, said Rowland Chang, senior associate dean for public health at the Feinberg School of Medicine and co-author of the study.

“It would be a little harder because the outcomes that we were measuring don’t occur very often in younger people,” Chang said.

Authors of the study said although the research confirmed a strong link, it did not imply a causal relationship. In order to more accurately assess the issue, completing a longitudinal study, which takes place over an extended period of time, would be necessary, Chang said.

He said he and his team are currently analyzing data from a long-term study done on this issue and hope to release the results within the next few months.

“We’ve actually collected the data on that study and we’re in the midst of analyzing that data,” Chang said. “It would be actually a much more compelling causal argument for the relationship.”

Chang said the process of the longitudinal study involved following individuals for at least two years and measuring their physical activity using accelerometers.

He said he was unsure of the results for the longitudinal study, but he was not surprised by the outcomes of the original study.

“We are a very sedentary society,” Chang said. “More than half, up to two thirds or three fourths of our time, is actually done sitting.”

Dunlop said she and her research partners are currently recommending individuals make small changes to attempt to combat the sedentary lifestyle including making rounds through their offices, taking the stairs and walking to do errands instead of driving.

“What we would suggest is that people to start to look for lifestyle changes that allow them to reduce some of that sedentary time,” Dunlop said.

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