Serum concentrations of collagen degrading enzymes and their inhibitors after downhill running

In the present study the release of proteins degrading extracellular matrix compounds to circulation was measured after damaging exercise in humans. M uscle damage was induced by downhill running; furthermore, the exercise was performed at both cold temperature (5 degreesC) and room temperature (22 d egreesC) to study also the possible effect of environmental temperature on serum concentrations of matrix metalloproteinases MMP-2 and MMP-9, tissue i nhibitors of metalloproteinases TIMP-1 and TIMP-2, and MMP-2/TIMP-2 complex , and muscle damage monitored by serum creatine kinase measurements. Result s were compared with those obtained from patients having rhabdomyolysis, my ositis and Becker muscular dystrophy. The present study demonstrates an acu te increase in serum concentrations of MMP-9, TIMP-1, and MMP-2/TIMP-2 comp lex, but no changes in serum MMP-2 concentrations in response to eccentric exercise. Serum creatine kinase activity data suggest greater muscle damage after downhill running in a cold environment than at room temperature. The present observations about at most slight changes in serum MMP and TIMP co ncentrations and lack of their correlation to increased serum creatine kina se after exercise indicate that serum measurements of MMPs and TIMPs do not sensitively respond to exercise induced skeletal muscle damage and extrace llular matrix regeneration. On the other hand, severe skeletal muscle damag e, such as rhabdomyolysis, myositis and Becker muscular dystrophy, seemed t o have an effect on serum MMP and TIMP concentrations.