title: Objective physical activity measurement in the osteoarthritis initiative: Are guidelines being met?
abstract: OBJECTIVE
  Osteoarthritis (OA) clinical practice guidelines identify a substantial therapeutic role for physical activity, but objective information about the physical activity of this population is lacking. The aim of this study was to objectively measure levels of physical activity in adults with knee OA and report the prevalence of meeting public health physical activity guidelines.
  
  
  METHODS
  Cross-sectional accelerometry data from 1,111 adults with radiographic knee OA (49-84 years old) participating in the Osteoarthritis Initiative accelerometry monitoring ancillary study were assessed for meeting the aerobic component of the 2008 Physical Activity Guidelines for Americans (≥150 minutes/week moderate-to-vigorous-intensity activity lasting ≥10 minutes). Quantile regression was used to test median sex differences in physical activity levels.
  
  
  RESULTS
  Aerobic physical activity guidelines were met by 12.9% of men and 7.7% of women with knee OA. A substantial proportion of men and women (40.1% and 56.5%, respectively) were inactive, having done no moderate-to-vigorous activity that lasted 10 minutes or more during the 7 days. Although men engaged in significantly more moderate-to-vigorous activity (average daily minutes 20.7 versus 12.3), they also spent more time in no or very-low-intensity activity than women (average daily minutes 608.2 versus 585.8).
  
  
  CONCLUSIONS
  Despite substantial health benefits from physical activity, adults with knee OA were particularly inactive based on objective accelerometry monitoring. The proportions of men and women who met public health physical activity guidelines were substantially less than those previously reported based on self-reported activity in arthritis populations. These findings support intensified public health efforts to increase physical activity levels among people with knee OA.
authors.affiliation: Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA. ddunlop@northwestern.edu
authors.forename: Dorothy D
authors.initials: DD
authors.lastname: Dunlop
authors.forename: Jing
authors.initials: J
authors.lastname: Song
authors.forename: Pamela A
authors.initials: PA
authors.lastname: Semanik
authors.forename: Rowland W
authors.initials: RW
authors.lastname: Chang
authors.forename: Leena
authors.initials: L
authors.lastname: Sharma
authors.forename: Joan M
authors.initials: JM
authors.lastname: Bathon
authors.forename: Charles B
authors.initials: CB
authors.lastname: Eaton
authors.forename: Marc C
authors.initials: MC
authors.lastname: Hochberg
authors.forename: Rebecca D
authors.initials: RD
authors.lastname: Jackson
authors.forename: C Kent
authors.initials: CK
authors.lastname: Kwoh
authors.forename: W Jerry
authors.initials: WJ
authors.lastname: Mysiw
authors.forename: Michael C
authors.initials: MC
authors.lastname: Nevitt
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Hootman
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D018450:Disease Progression; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging*; D008297:Male; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000534:rehabilitation*; D017410:Practice Guidelines as Topic; D011634:Public Health; D011859:Radiography; D012307:Risk Factors