title: Plasma matrix metalloproteinase-9 response to eccentric exercise of the elbow flexors.
abstract: Recent efforts to establish a role for plasma matrix metalloproteinase-9 (MMP-9) as a marker of exercise-induced muscle damage have been inconsistent. Methodological and experimental design issues have contributed to confusion in this area. The purpose of this study was to use a damaging eccentric arm task to evaluate the relationship between activity-induced muscle damage and plasma MMP-9 levels in humans while controlling for physical activity history and quantifying day-to-day variability of the dependent variables. Fourteen physically inactive males performed 6 sets of 10 eccentric contractions of the elbow flexors at 120% of their voluntary concentric maximum. Soreness ratings, maximum voluntary isometric strength, range of motion (ROM), limb circumference, and plasma creatine kinase (CK) and MMP-9 levels were measured at 2 time points before, immediately after, and 1, 2, 4, and 7 days post-exercise. Changes in traditional markers of muscle damage mirrored patterns previously reported in the literature, but plasma MMP-9 concentration and activity measured by ELISA and gelatin zymography were unchanged at all time points examined. Plasma levels of the MMP-9 inhibitor, tissue inhibitor of metalloproteinase-1 (TIMP-1), were also unchanged post-exercise. Finally, although mean MMP-9 levels were not significantly different between the two pre-exercise timepoints, the high total error of measurement and low day-to-day correlation suggest substantial within and between subject variability. Plasma MMP-9 levels are not a robust or reliable marker for eccentric exercise-induced damage of the elbow flexor musculature, though this may not preclude a role for MMPs in skeletal muscle remodeling in response to injury.
authors.affiliation: Department of Integrative Physiology, University of Colorado at Boulder, Room C373 Ramaley, Campus Box 354, Boulder, CO 80309-0354, USA.
authors.forename: Molly C
authors.initials: MC
authors.lastname: Madden
authors.forename: William C
authors.initials: WC
authors.lastname: Byrnes
authors.forename: Jacob A
authors.initials: JA
authors.lastname: Lebin
authors.forename: Matthew E
authors.initials: ME
authors.lastname: Batliner
authors.forename: David L
authors.initials: DL
authors.lastname: Allen
mesh_terms: D000293:Adolescent; D000328:Adult; D015415:Biomarkers / Q000097:blood / Q000378:metabolism; D004550:Elbow / Q000502:physiology*; D004551:Elbow Joint / Q000378:metabolism / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D020780:Matrix Metalloproteinase 9 / Q000097:blood* / Q000378:metabolism / Q000502:physiology; D009119:Muscle Contraction / Q000502:physiology; D018763:Muscle Fatigue / Q000502:physiology; D009135:Muscular Diseases / Q000097:blood / Q000175:diagnosis / Q000201:enzymology / Q000378:metabolism; D016059:Range of Motion, Articular / Q000502:physiology; D019415:Torque; D055815:Young Adult
chemical_list: D015415:Biomarkers; D020780:Matrix Metalloproteinase 9