title: Positive effects of moderate exercise on glycosaminoglycan content in knee cartilage: a four-month, randomized, controlled trial in patients at risk of osteoarthritis.
abstract: OBJECTIVE
  To evaluate the effects of moderate exercise on glycosaminoglycan (GAG) content in knee cartilage in subjects at high risk of knee osteoarthritis (OA).
  
  
  METHODS
  Forty-five subjects (16 women, mean age 46 years, mean body mass index 26.6 kg/m(2)) who underwent partial medial meniscus resection 3-5 years previously were randomized to undergo a regimen of supervised exercise 3 times weekly for 4 months or to a nonintervention control group. Cartilage GAG content, an important aspect of the biomechanical properties of cartilage, was estimated by delayed gadolinium-enhanced magnetic resonance imaging of cartilage (dGEMRIC), with results expressed as the change in the T1 relaxation time in the presence of Gd-DTPA (T1[Gd]).
  
  
  RESULTS
  Thirty of 45 patients were examined by dGEMRIC at baseline and followup. The exercise group (n = 16) showed an improvement in the T1(Gd) compared with the control group (n = 14) (15 msec versus -15 msec; P = 0.036). To study the dose response, change in the T1(Gd) was assessed for correlation with self-reported change in physical activity level, and a strong correlation was found in the exercise group (n = 16, r(S) = 0.70, 95% confidence interval [95% CI] 0.31-0.89) and in the pooled group of all subjects (n = 30, r(S) = 0.74, 95% CI 0.52-0.87).
  
  
  CONCLUSIONS
  This in vivo cartilage monitoring study in patients at risk of knee OA who begin exercising indicates that adult human articular cartilage has a potential to adapt to loading change. Moderate exercise may be a good treatment not only to improve joint symptoms and function, but also to improve the knee cartilage GAG content in patients at high risk of developing OA.
authors.affiliation: Lund University, Lund, Sweden.
authors.forename: Ewa M
authors.initials: EM
authors.lastname: Roos
authors.forename: Leif
authors.initials: L
authors.lastname: Dahlberg
mesh_terms: D002358:Cartilage, Articular / Q000378:metabolism* / Q000473:pathology; D003287:Contrast Media; D005081:Exercise Therapy / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D019786:Gadolinium DTPA; D006025:Glycosaminoglycans / Q000378:metabolism*; D006801:Humans; D007719:Knee Joint / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008592:Menisci, Tibial / Q000601:surgery; D008875:Middle Aged; D020370:Osteoarthritis, Knee / Q000473:pathology / Q000517:prevention & control*; D016896:Treatment Outcome; D016474:Weight-Bearing
chemical_list: D003287:Contrast Media; D006025:Glycosaminoglycans; D019786:Gadolinium DTPA