Serum concentrations MMP-1, MMP-3, and MMP-9, acutely adapt to mechanical loading [47], with rapid increases at the beginning of physical activity followed by a fairly rapid stabilization thereafter [46]; moreover, MMP-2, MMP-3, and MMP-9 are highly expressed in patients afflicted by arthritis [60]. The gene discussed is MMP2; the disease is arthritic joint disease.