Researchers find that prolonged sitting raises the risk of death for frail, inactive adults.
The Physical Activity Guidelines for Americans state that adults aged 18 to 64 and those aged 65 and older should aim to get at least 150 minutes of moderate-intensity or 75 minutes of vigorous-intensity aerobic physical activity every week.
For adults who are unable to meet these guidelines, it is recommended that "they should be as physically active as their abilities and conditions allow."
According to statistics from the 2016 National Health Interview Survey, just 44.9 percent of older adults aged 65 to 74 met the physical activity guidelines last year.
What is more, previous research has shown that older adults spend more than 9 hours of their day sitting down.
The harms of sedentary behavior have been well documented. A study reported by Medical News Today last year, for example, suggested that sitting for more than 3 hours daily is responsible for more than 430,000 deaths across 54 countries every year.
For this latest study, Dr. Olga Theou, of the Department of Medicine at Dalhousie University in Canada, and colleagues set out to determine whether or not frailty plays a role in the increased death risk associated with sedentary behavior.
The results were recently reported in the Canadian Medical Association Journal.
Higher death risk for frail adults
The study included the data of 3,141 adults aged 50 and older who participated in the 2003-2004 and 2005-2006 United States National Health and Nutrition Examination Survey.
As part of the survey, subjects were required to wear activity trackers during waking hours, and the researchers used these data to calculate how much time each adults spent sedentary.
The team also used a 46-item index to assess the frailty of each subject. Frailty is generally defined as an aging-related process characterized by weakness, unintended weight loss, slowness, and fatigue.
Participants were followed up until 2011, or until their date of death.
Among adults who scored highly on the frailty index and did not meet the physical activity guidelines, the researchers found that prolonged sitting was associated with an increased risk of death. This was not the case for adults with low frailty who met exercise guidelines.
"Thus, among people who are inactive and vulnerable or frail, sitting time increases mortality risk, but among those who are non-frail or active, sitting time does not affect the risk of mortality," say the researchers.
There were some limitations to their study. For example, the team had limited activity data on adults with higher frailty levels.
"Thus, our sample size was substantially reduced, especially among the group with the highest level of frailty, which made it necessary to merge frailty groups for some analyses and prevented us from isolating those with severe frailty into one category," the researchers explain.
Still, the authors say that their study further highlights the harms of sedentary behavior, particularly for frail adults.
"Physicians should stress the harms of inactivity with patients, similar to the harms of smoking, to encourage movement. Even something as simple as getting up and walking around the house with a walker or cane can benefit frailer people."
Dr. Olga Theou