title: Lifelong physical activity and knee osteoarthritis development in mice.
abstract: OBJECTIVE
  To examine the effect of lifelong physical activity on the development of knee osteoarthritis (OA).
  
  
  METHODS
  Fifteen C57Bl/6J mice (8 male and 7 female) were individually caged with a running wheel, magnetic sensor and digital odometer, and 15 mice (7 male and 8 female) were individually housed without a running wheel. Each mouse was provided with standard chow and water ad libitum. Running wheel distance, duration and speed were recorded daily. A diagnostic ultrasound (SONOS 5500 Ultrasound and 15-6L ultrasound probe) was used to measure medial and lateral knee joint space in both hind limbs every month until the end of the mice's lifespans.
  
  
  RESULTS
  Right medial (P = 0.002), right lateral (P < 0.0001), left medial (P = 0.01), and left lateral (P = 0.007) knee joint spaces were significantly larger from months 3 to 12 in the physically active C57Bl/6J mice. However, there was no significant difference between all knee joint spaces of the running and sedentary C57Bl/6J mice throughout the remainder of the lifespan. All hindlimb knee joint spaces significantly declined with aging (P < 0.0001).
  
  
  CONCLUSIONS
  During the first 12 months of the lifespan, physical activity seemed to protect the joint from degeneration; however; after that there was no protective benefit. This may be due to the fact that C57Bl/6J mice are genetically known to develop OA at 9 months of age. Physical activity may have no impact on this genetic predisposition. Further study in mice not genetically predisposed to develop OA is needed.
authors.affiliation: Department of Kinesiology, The University of North Carolina at Charlotte, Charlotte, North Carolina, USA; Department of Mechanical Engineering & Engineering Science, Center for Biomedical Engineering Systems, The University of North Carolina at Charlotte, Charlotte, North Carolina, USA.
authors.forename: Tricia
authors.initials: T
authors.lastname: Hubbard-Turner
authors.forename: Sophie
authors.initials: S
authors.lastname: Guderian
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Turner
mesh_terms: D000367:Age Factors; D000818:Animals; D005260:Female; D020022:Genetic Predisposition to Disease; D007596:Joints / Q000000981:diagnostic imaging / Q000503:physiopathology*; D008297:Male; D008810:Mice, Inbred C57BL; D009043:Motor Activity; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000209:etiology* / Q000235:genetics / Q000503:physiopathology / Q000517:prevention & control; D065840:Protective Factors; D012307:Risk Factors; D012420:Running; D057185:Sedentary Behavior; D013997:Time Factors; D014463:Ultrasonography
keywords: diagnostic ultrasound; exercise; joint degeneration; running wheel