title: Influence of estrogen on markers of muscle tissue damage following eccentric exercise.
abstract: This study tested the hypothesis that estrogen levels of women influences the development of a muscle-tissue damage (creatine kinase, CK) marker and delayed onset muscle soreness (DOMS) following eccentric exercise. Seventeen oral contraceptive (OC) users and ten eumenorrheic (EU) subjects completed a 30-min downhill running bout at approximately 60% VO2max. The OC completed the exercise during the mid-luteal phase (day 22.9 +/- 1.5; high estrogen) while the EU did their exercise in the mid-follicular phase (day 9.6 +/- 4.4; low estrogen) of the menstrual cycle, respectively. The CK activity and DOMS were assessed pre-exercise, immediately post-, 24, 48 and 72 h post-exercise. ANOVA results indicated that there was a significant increase in CK activity in response to the downhill run (p < 0.001), and the interaction of group x time was significantly different (p < 0.01). The OC group had lower CK at 72 h post-exercise than did the EU group. Pre-exercise estrogen levels correlated with the overall mean CK (r = -0.43, p < 0.05) and 72 h (r = -0.38, p < 0.05) responses, respectively. Exercise caused an increase in DOMS in both groups (p < 0.001); but, no significant interaction was observed. These findings suggest that elevated estrogen levels have a protective effect on muscle tissue following eccentric exercise. The mechanism of this protective effect is unclear but may be related to the anti-oxidant characteristics and membrane stability properties associated with estrogen and its derivatives.
authors.affiliation: Endocrine Section, Applied Physiology Laboratory, University of North Carolina, Chapel Hill, NC 27599, USA.
authors.forename: A
authors.initials: A
authors.lastname: Carter
authors.forename: J
authors.initials: J
authors.lastname: Dobridge
authors.forename: A C
authors.initials: AC
authors.lastname: Hackney
mesh_terms: D003278:Contraceptives, Oral, Hormonal / Q000008:administration & dosage; D003402:Creatine Kinase / Q000378:metabolism; D004967:Estrogens / Q000502:physiology*; D015444:Exercise; D005260:Female; D006801:Humans; D008597:Menstrual Cycle; D018482:Muscle, Skeletal / Q000201:enzymology / Q000502:physiology*
chemical_list: D003278:Contraceptives, Oral, Hormonal; D004967:Estrogens; D003402:Creatine Kinase