title: The effects of estrogen on indices of skeletal muscle tissue damage after eccentric exercise in postmenopausal women.
abstract: This study examined if estrogen (E) usage (in the form of hormone replacement therapy [HRT]) has a protective effect on skeletal muscle damage in postmenopausal women. Nine postmenopausal women (age 55.2 +/- 9.9 [mean +/- SD]) performed two exercise sessions at 70% of their maximal heart rate on HRT (E-HI) and without HRT (E-LO; following a 28-45 day HRT washout). All subjects followed a condition order of E-HI then E-LO with at least 42 days between exercise sessions. Serum creatine kinase (CK), perceived delayed onset muscle soreness (DOMS), and maximal quadriceps isometric force (MIF) were taken pre-exercise, 24, 48 and 72-hr post exercise. E-HI and E-LO conditions produced a rise in CK (p < 0.001) after exercise; but CK after E-HI was greater than in E-LO (p < 0.001) at 24 hours and at 48 hours. DOMS was significantly elevated at 24, 48, and 72-hr post each exercise session (p < 0.05). The greatest peak DOMS score occurred during the E-HI condition. MIF was similarly reduced after each exercise session (p < 0.05). These results suggest elevated E does not offer a protective effect to skeletal muscle; however, design limitations (i.e., condition order) confound the present data. Interestingly, an association between peak-CK during the E-LO condition and the number of washout days (r = +0.707, p < 0.05) between conditions existed. This suggests a longer washout period may be necessary to elucidate the actual E effects on skeletal muscle. These findings suggest that more work correcting for the present design limitations is warranted on this topic.
authors.affiliation: Endocrine Section-Applied Physiology Laboratory, Department of Exercise and Sport Science, University of North Carolina, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Dobridge
authors.forename: A C
authors.initials: AC
authors.lastname: Hackney
mesh_terms: D003402:Creatine Kinase / Q000097:blood; D015914:Estrogen Replacement Therapy / Q000379:methods*; D004967:Estrogens / Q000008:administration & dosage / Q000627:therapeutic use; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D008875:Middle Aged; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000187:drug effects* / Q000503:physiopathology; D010146:Pain / Q000209:etiology / Q000503:physiopathology; D017698:Postmenopause / Q000502:physiology*
chemical_list: D004967:Estrogens; D003402:Creatine Kinase