This study investigates an expanded paradigm to improve health outcomes for adults with knee osteoarthritis (OA), through changes in the low end of the physical activity spectrum where much of the knee OA population resides. Our recent study found almost half of adults with knee OA were inactive, as defined by the US Department of Health and Human Services (DHHS) (i.e., no sustained 10 minute periods of moderate-to- vigorous intensity physical activity during a week) based on objective accelerometer measurement of physical activity. It is these inactive people who will be the primary focus of this study. This renewal will investigate predictors and health outcomes related to transitions from and to physical inactivity. It will also to identify evidence-based physical activity metrics and thresholds needed to maintain function and reduce disability. The study builds on our current funded work from the Osteoarthritis Initiative (OAI), a prospective, observational, cohort study of adults with or at high risk for knee OA that encompasses the full spectrum of knee OA disease severity. This proposal will utilize valuable objective longitudinal physical activity data measure by accelerometer on a subsample from the OAI national cohort (n=2015) collected by the parent study to accomplish the following: Technical Aim. Process accelerometer output into usable physical activity measures and determine inactivity/activity transition status for each person.
Aim 1. Evaluate the relationship between a transition from inactivity to activity (T0 toT1) with initia and future changes in disability and function, controlling for baseline total activity, descriptive factors, and modifiable factors.
This aim i s relevant to clinical practice Aim 2. Examine among inactive adults at baseline the relationship between the change in total activity (T0 toT1) with initial and future changes in disability and function, controlling for baseline total activity, descriptive factors, and modifiable factors.
This aim i s relevant to the design of public health interventions.
Aim 3. Identify predictors of becoming inactive.
This aim i s relevant to public policy design.
Aim 4. Develop evidence-based physical activity metrics to predict short-term (T0 toT1) function and long- term (T0 toT2) disability outcomes among adults at high risk or with knee OA (both active and inactive at baseline).
This aim i s relevant to refining physical activity public health recommendations. Findings from this proposed study have important public health implications for the design of future physical activity intervention programs to improve quality of life among the 21 million U.S. adults who have knee OA.

Public Health Relevance

This study is built upon a strong scientific framework to evaluate the longitudinal relationship between changes in physical activity and health outcomes among adults with knee OA.
The aims are designed to broaden the public health and clinical practice paradigm to promote better health for persons at the low end of the physical activity spectrum. Attainable evidence-based physical activity thresholds related to good function and preventing/reducing disability may provide realistic goals to promote increased physical activity, especially in people with arthritis who have pain and mobility problems.

National Institute of Health (NIH)
National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)
Research Project (R01)
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Neurological, Aging and Musculoskeletal Epidemiology (NAME)
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Lester, Gayle E
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Northwestern University at Chicago
Internal Medicine/Medicine
Schools of Medicine
United States
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Pellegrini, Christine A; Song, Jing; Chang, Rowland W et al. (2016) Change in Physical Activity and Sedentary Time Associated With 2-Year Weight Loss in Obese Adults With Osteoarthritis. J Phys Act Health 13:461-6
Gilbert, Abigail L; Lee, Jungwha; Ma, Madeleine et al. (2016) Comparison of Subjective and Objective Measures of Sedentary Behavior Using the Yale Physical Activity Survey and Accelerometry in Patients With Rheumatoid Arthritis. J Phys Act Health 13:371-6
Lo, Grace H; McAlindon, Timothy E; Hawker, Gillian A et al. (2015) Symptom assessment in knee osteoarthritis needs to account for physical activity level. Arthritis Rheumatol 67:2897-904
Dunlop, Dorothy D; Song, Jing; Arnston, Emily K et al. (2015) Sedentary time in US older adults associated with disability in activities of daily living independent of physical activity. J Phys Act Health 12:93-101
Song, Jing; Lindquist, Lee A; Chang, Rowland W et al. (2015) Sedentary Behavior as a Risk Factor for Physical Frailty Independent of Moderate Activity: Results From the Osteoarthritis Initiative. Am J Public Health 105:1439-45
Kretzschmar, M; Lin, W; Nardo, L et al. (2015) Association of Physical Activity Measured by Accelerometer, Knee Joint Abnormalities, and Cartilage T2 Measurements Obtained From 3T Magnetic Resonance Imaging: Data From the Osteoarthritis Initiative. Arthritis Care Res (Hoboken) 67:1272-80
Semanik, Pamela A; Lee, Jungwha; Song, Jing et al. (2015) Accelerometer-monitored sedentary behavior and observed physical function loss. Am J Public Health 105:560-6
Lee, Jungwha; Chang, Rowland W; Ehrlich-Jones, Linda et al. (2015) Sedentary behavior and physical function: objective evidence from the Osteoarthritis Initiative. Arthritis Care Res (Hoboken) 67:366-73
Sohn, M-W; Manheim, L M; Chang, R W et al. (2014) Sedentary behavior and blood pressure control among osteoarthritis initiative participants. Osteoarthritis Cartilage 22:1234-40
Dunlop, Dorothy D; Song, Jing; Semanik, Pamela A et al. (2014) Relation of physical activity time to incident disability in community dwelling adults with or at risk of knee arthritis: prospective cohort study. BMJ 348:g2472

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