Sedentary time, for example, time spent sitting, increases the risk of death for middle-aged and older people who are frail and inactive, but does not appear to increase the risk for nonfrail people who are inactive, according to a new study published in CMAJ (Canadian Medical Association Journal).
Many studies have looked at the benefits of physical activity on health, although little data exists on sedentary behaviour and risk of death linked to levels of frailty. Frailty refers to a person's overall health state, determined by the number of health problems this person has.
To understand if level of frailty and prolonged sitting are linked to a higher risk of death, researchers looked at data on 3141 adults aged 50 and over in the US National Health and Nutrition Examination Survey (NHANES) from 2003/04 and 2005/06. Participants used activity trackers during waking hours and were assessed using a 46-item frailty index; they were then followed until 2011 or date of death.
"We found that in people who scored low on the frailty index, sitting time was not linked to risk of death," states Dr. Olga Theou, Department of Medicine, Dalhousie University, Halifax, Nova Scotia. "Prolonged sitting was associated with a higher risk of death only in vulnerable or frail people who did not meet the weekly recommendation for 2.5 hours of moderate physical activity."
The authors note study limitations such as limited activity tracking data for people with higher levels of frailty, which prevented them from segmenting people with severe frailty into one category for analysis.
"Physicians should stress the harms of inactivity with patients, similar to the harms of smoking, to encourage movement," states Dr. Olga Theou. "Even something as simple as getting up and walking around the house with a walker or cane can benefit frailer people."
The authors suggest this key public health message should be included in health promotions about the importance of healthy behaviours.
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Olga Theou et al. Association between sedentary time and mortality across levels of frailty, Canadian Medical Association Journal (2017). DOI: 10.1503/cmaj.161034