Do Characteristics Of Sitting And Stepping Predict Functional Outcomes In A Heterogenous Sample Of Older Adults?

Older adults engage in high amounts of sedentary behavior (SB). Too much sedentary time in older adults is associated with sarcopenic obesity, increased levels of frailty, declines in skeletal muscle mass, strength, power, and functional capacity, all of which lead to poorer physical function. Understanding different characteristics of SB and physical activity (PA) and its impact on health has not been fully elucidated. PURPOSE: To evaluate the association between sitting and movement characteristics on functional outcomes in older adults. METHODS :Older adults (60+ years) completed physical function and performance assessments including the Short Physical Performance Battery (SPPB), a five repetition sit-to-stand (5STS), usual gait speed (UGS), and fast gait speed (FGS) over 10 meters. Sedentary behavior (total time, hours sitting, hours standing, number of prolonged bouts, STS transitions, mean SB bout duration) and steps were measured over a 7-day period with a triaxial inclinometer. Multiple and logistic regression models, adjusting for age and sex, were used for continuous and binary outcomes to examine the association of SB and PA characteristics with functional outcomes. RESULTS: Participants (N = 73) were 72.6 ± 7.1 years old, 43.8% women, 74% reported some type of medical condition, and 68.5% had SPPB <=10. Results indicate that total sedentary time was related to the highest number of physical function measures (5STS R2 = 13%, p = 0.044; UGS R2 = 25%, p = 0.029; SPPB≤10 OR = 1.54, CI = 1.03-2.30). Other measurements of sedentary behavior were not associated with any measures of physical function. Daily steps were associated with 5STS (R2 = 14.3, p = 0.023), and odds of scoring 10 or less on the SPPB (per 1000 steps; OR = 0.79, CI = 0.66-0.94). CONCLUSIONS: Our results suggest that simple measures of sedentary time and steps may be solid predictors of physical function in older adults, where increasing total sedentary time by 1-hour is associated with a 54% average increase, and an increase in 1000 steps/day was associated with a 21% decrease in the odds of having a SPPB score < =10, holding age and sex constant. While we continue to strive for better ways to characterize our sedentary behavior and its effects, we can rest assured that a simple measure of sedentary time is providing sufficient information. Supported by: Zilber Family Foundation