Plasma matrix metalloproteinase-9 response to downhill running in humans.
Matrix metalloproteinase-9 is a proteolytic enzyme capable of degrading proteins of the muscle extracellular matrix. Systemic levels of MMP-9 or its inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), have the potential to serve as blood markers of exercise-induced muscle damage. The purpose of this study was to determine if an eccentrically-dominated task, downhill running (DHR), produces changes in plasma MMP-9 or TIMP-1 and examine the relationship between MMP-9/TIMP-1 levels and indirect indicators of muscle damage. Subjects were sedentary (SED, n=12) or had a history of concentrically-biased training (CON, n=9). MMP-9 and TIMP-1 were measured before (Pre-Ex), immediately after (Post-Ex), and 1-, 2-, 4-, and 7-days post-DHR (-10°), and compared to discomfort ratings, creatine kinase activity and strength loss. At 1-day Post-Ex, discomfort increased (5.6 ± 7.8 to 45.5 ± 19.9 mm; 0-100 mm scale), strength decreased (-6.9 ± 1.6%) and CK increased (162.9 ± 177.2%). MMP-9 was modestly but significantly increased at Post-Ex in both CONC and SED (32.7 ± 33.6%) and at 4-days in SED (66.9 ± 88.1%), Individual responses were variable, however. There were no correlations between MMPs and discomfort ratings, plasma CK or strength. While plasma MMP-9 changes may be detectable in the systemic circulation after DHR, they are small and do not correspond to other markers of damage.
Department of Integrative Physiology, University of Colorado at Boulder, United States.
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MC
Welsh
Department of Psychology and Neuroscience, University of Colorado at Boulder, United States.
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DL
Allen
Department of Integrative Physiology, University of Colorado at Boulder, United States.
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WC
Byrnes
D000328:Adult; D015415:Biomarkers / Q000097:blood; D003402:Creatine Kinase / Q000097:blood; D005260:Female; D006801:Humans; D007866:Leg / Q000502:physiology; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000097:blood*; D053580:Muscle Strength / Q000502:physiology; D018482:Muscle, Skeletal / Q000293:injuries*; D012420:Running / Q000502:physiology*; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000097:blood*; D055815:Young Adult
D015415:Biomarkers; D019715:Tissue Inhibitor of Metalloproteinase-1; D003402:Creatine Kinase; D020780:Matrix Metalloproteinase 9