title: Accelerometer-monitored sedentary behavior and observed physical function loss.
abstract: OBJECTIVE
  We examined whether objectively measured sedentary behavior is related to subsequent functional loss among community-dwelling adults with or at high risk for knee osteoarthritis.
  
  
  METHODS
  We analyzed longitudinal data (2008-2012) from 1659 Osteoarthritis Initiative participants aged 49 to 83 years in 4 cities. Baseline sedentary time was assessed by accelerometer monitoring. Functional loss (gait speed and chair stand testing) was regressed on baseline sedentary time and covariates (baseline function; socioeconomics [age, gender, race/ethnicity, income, education], health factors [obesity, depression, comorbidities, knee symptoms, knee osteoarthritis severity, prior knee injury, other lower extremity pain, smoking], and moderate-to-vigorous activity).
  
  
  RESULTS
  This cohort spent almost two thirds of their waking hours (average=9.8 h) in sedentary behaviors. Sedentary time was significantly positively associated with subsequent functional loss in both gait speed (-1.66 ft/min decrease per 10% increment sedentary percentage waking hours) and chair stand rate (-0.75 repetitions/min decrease), controlling for covariates.
  
  
  CONCLUSIONS
  Being less sedentary was related to less future decline in function, independent of time spent in moderate-to-vigorous activity. Both limiting sedentary activities and promoting physical activity in adults with knee osteoarthritis may be important in maintaining function.
authors.affiliation: Pamela A. Semanik is with the College of Nursing, Rush University, Chicago, IL. Barbara E. Ainsworth is with the School of Nutrition and Health Promotion, College of Health Solutions, Phoenix, Arizona. Jungwha Lee, Jing Song, Rowland W. Chang, and Dorothy D. Dunlop are with the Feinberg School of Medicine, Northwestern University, Chicago. Min-Woong Sohn is with the School of Medicine, University of Virginia, Charlottesville. Linda S. Ehrlich-Jones is with the Center for Rehabilitation Outcome Research, Rehabilitation Institute of Chicago. Michael M. Nevitt is with the Coordinating Center, University of California, San Francisco. C. Kent Kwoh is with University of Arizona Medical Center, Tucson.
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Semanik
authors.forename: Jungwha
authors.initials: J
authors.lastname: Lee
authors.forename: Jing
authors.initials: J
authors.lastname: Song
authors.forename: Rowland W
authors.initials: RW
authors.lastname: Chang
authors.forename: Min-Woong
authors.initials: MW
authors.lastname: Sohn
authors.forename: Linda S
authors.initials: LS
authors.lastname: Ehrlich-Jones
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Ainsworth
authors.forename: Michael M
authors.initials: MM
authors.lastname: Nevitt
authors.forename: C Kent
authors.initials: CK
authors.lastname: Kwoh
authors.forename: Dorothy D
authors.initials: DD
authors.lastname: Dunlop
mesh_terms: D061725:Accelerometry / Q000295:instrumentation / Q000379:methods; D000368:Aged; D000369:Aged, 80 and over; D015992:Body Mass Index; D005260:Female; D005684:Gait / Q000502:physiology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000295:instrumentation / Q000379:methods; D009043:Motor Activity; D020370:Osteoarthritis, Knee / Q000209:etiology* / Q000517:prevention & control; D065840:Protective Factors; D012307:Risk Factors; D057185:Sedentary Behavior; D013997:Time Factors; D014481:United States