MARKERS OF CARTILAGE MATRIX METABOLISM IN HUMAN JOINT FLUID AND SERUM- THE EFFECT OF EXERCISE

The concentrations of cartilage proteoglycan (aggrecan), stromelysin-1 , tissue inhibitor of metalloproteinases-1 (TIMP-1) and procollagen II C-propeptide in knee joint fluid and the levels of aggrecan, hyaluron an and keratan sulfate in serum were measured before and after exercis e in 33 healthy athletes. The samples before exercise were obtained af ter 24 h rest from running or soccer and the samples after exercise we re obtained 30-60 min after the exercise. Nine athletes ran on a tread mill for 60 min, 16 ran on road for 80 min and 8 played one soccer gam e (90 min). A reference group of 28 patients with knee pain but not ev idence of joint pathology or injury was used for comparison. In joint fluid no single marker from the degradative processes in cartilage mat rix changed significantly with exercise but all showed a rising trend. All markers except stromelysin showed lower concentrations in athlete s at rest compared to the reference group. In serum from runners befor e exercise the concentration of keratan sulfate was significantly high er than in both the soccer and reference groups and further increased after exercise. The increase in markers after exercise may reflect an effect of mechanical loading in combination with a possible high turno ver rate of body cartilage matrix in these individuals.