Association between sedentary time and mortality across levels of frailty

Abstract

Sedentary behaviours are increasingly recognized as conferring health risks, independent of physical activity. The health benefits of physical activity are well established, and meeting minimum guidelines for physical activity is associated with reduced risk of many chronic conditions, functional decline, development of psychologic disorders and mortality. [1][2][3][4][5][6][7][8][9] However, even among people who engage in periods of purposeful exercise, sedentary behaviours can increase the risk of adverse outcomes, such as metabolic risk factors, functional limitations, and all-cause and cardiovascular disease mortality. [10][11][12][13][14][15][16] Even so, a recent meta-analysis showed that engaging in moderate physical activity, such as exercise, for at least 1 hour/day could eliminate the detrimental effects of prolonged sitting. 17Although most of the research on sedentary behaviours has focused on children and younger adults, middle-aged and older adults are the most sedentary group. A study using data from the Canadian Health Measures Survey showed that Canadians over the age of 40 are highly sedentary, spending about 9.5-10 of their waking hours in sedentary behaviours (age 40-59 yr, 9.5 h for men and 9.8 h for women; age 60-79 yr, 9.9 h for men, 10 h for women). 18Only 14.6% of the Canadian population aged 40-59 years and 13.1% of those aged 60-79 years met the recommended 2.5 hours/ week of moderate-to-vigorous physical activity. 18 Another study using data from the US National Health and Nutrition Examination Survey (NHANES) showed that participants over the age of 50 years spent on average 8.5 of their waking hours in sedentary behaviours. 19 Only 7.1% of the population met the recommended 2.5 hours/week of moderate-to-vigorous physical activity. 19Reducing sedentary behaviours could improve health outcomes in middle-aged and older adults. Replacing 30 minutes of sedentary time with an equal amount of light activity or moderate-to-vigorous activity was associated with 14% and 50% reductions in risk of mortality, respectively. 20,21 Even so, studies have shown a strong relation between sedentary behaviours and frailty, independent of moderate-to-vigorous activity.

Time Spent in Sedentary Behaviour as Discriminant Criterion for Frailty in Older Adults

“…These results corroborate the findings of recent investigations [34,35,36]. This fact confirms sedentary behaviour as a behavioural aspect that may determine the state of frailty and it is consequently an adverse health behaviour in the elderly [28].…”

What Enables Individuals to Be More Physically Active across Levels of Frailty?

“…A 46-item FI developed in NHANES was used and created in accordance with previously published guidelines [13,14]. FI development guidelines recommend that the presence of health-related deficits increase with older age, are not too prevalent (>80%) and not too rare (<1%).…”

“…Individuals were stratified into frailty groups: non-frail (FI < 0.10), minimally frail (FI 0.10-0.20) and frail (>0.20). These frailty cut-offs are based on our previous research [6,13]. The excluded sample were slightly younger than the included sample (43.1 vs 47.5), were more likely to have a lower education, and less likely to be married, There were no differences in sex, FI, smoking status, or ethnicity between the excluded vs. included sample.…”

Frailty, inequality and resilience

“…20 Smoking is potentially modifiable, so a continued focus on smoking cessation in older age is appropriate. Low physical activity, sedentary behaviour, being underweight and obesity are also associated with increased risk of development and progression of frailty, [21][22][23] and there is evidence that interventions to increase physical activity may improve outcomes for older people with frailty. 24 Frailty, inequality and resilience…”