Effect of different running modes on the morphological, biochemical, and mechanical properties of articular cartilage.

lage oligomeric matrix protein (COMP), and matrilin-3, histomorphometry of femoral cartilage height and femoral COMP staining height, and indentation testing of tibial articular cartilage were performed. Rats subjected to downhill running showed a significantly (P = 0.015) higher COMP staining height and a tendentially (P = 0.084) higher cartilage height in the high-weight bearing area of femoral articular cartilage. Cartilage thickness, mechanical properties, and expression of cartilage network proteins in tibial cartilage remained unaffected by different running modes. Our data suggest that joint loading induced by eccentric muscle contractions during downhill running may lead to a site-specific adaptation. Mechanical loading is known to be essential for the development and maintenance of articular cartilage. Its composition and morphology is optimized for loadbearing function and characterized by the ability to sustain high and repetitive mechanical loads acting during daily living. The unique viscoelastic properties of cartilage are related to its multiphase composition and the structure of its highly organized extracellular matrix