title: Estrogen replacement, muscle composition, and physical function: The Health ABC Study.
abstract: OBJECTIVE
  Although the beneficial effects of estrogen use on cardiovascular and cognitive function in postmenopausal women have been recently discredited, controversy remains regarding its usefulness for maintaining skeletal muscle mass or strength. Therefore, the purpose of this study was to determine whether estrogen use is associated with enhanced muscle composition and, if so, whether this translates into improved strength and physical function.
  
  
  METHODS
  Cross-sectional analysis of 840 well-functioning community-dwelling white women (current estrogen replacement therapy (ERT) users = 259, nonusers = 581) aged 70-79 yr participating in the Health, Aging and Body Composition Study. Muscle composition of the midthigh by computed tomography included cross-sectional area (CSA) of the quadriceps, hamstrings, intermuscular fat and subcutaneous fat, and muscle attenuation in Hounsfield units (HU) as a measure of muscle density. Isometric hand grip and isokinetic knee extensor strength were assessed by dynamometry. Physical function was assessed using a summary scale that included usual 6-m walk and narrow walk speed, repeated chair stands, and standing balance.
  
  
  RESULTS
  In analyses of covariance adjusted for relevant confounders, quadriceps muscle CSA and HU were greater in current ERT than non-ERT women (P < 0.05). Grip strength was also greater (P < 0.05) in women taking ERT while knee extensor strength approached significance (P < 0.10). However, differences in muscle composition and strength were modest at < or =3.3%. There was no difference by ERT status for the hamstring muscles, fat CSA, or for physical function.
  
  
  CONCLUSIONS
  The associations between ERT and muscle composition and strength were minor and did not translate into improved physical function. Initiation of ERT for preservation of muscle composition and function may not be indicated.
authors.affiliation: School of Human Movement Studies, Faculty of Health Sciences, The University of Queensland, Brisbane, Australia. dtaaffe@hms.uq.edu.au
authors.forename: Dennis R
authors.initials: DR
authors.lastname: Taaffe
authors.forename: Anne B
authors.initials: AB
authors.lastname: Newman
authors.forename: Catherine L
authors.initials: CL
authors.lastname: Haggerty
authors.forename: Lisa H
authors.initials: LH
authors.lastname: Colbert
authors.forename: Nathalie
authors.initials: N
authors.lastname: de Rekeneire
authors.forename: Marjolein
authors.initials: M
authors.lastname: Visser
authors.forename: Bret H
authors.initials: BH
authors.lastname: Goodpaster
authors.forename: Michael C
authors.initials: MC
authors.lastname: Nevitt
authors.forename: Frances A
authors.initials: FA
authors.lastname: Tylavsky
authors.forename: Tamara B
authors.initials: TB
authors.lastname: Harris
mesh_terms: D000368:Aged; D015986:Confounding Factors, Epidemiologic; D003430:Cross-Sectional Studies; D045166:Estradiol Congeners / Q000494:pharmacology*; D015914:Estrogen Replacement Therapy; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D018482:Muscle, Skeletal / Q000502:physiology*; D010809:Physical Fitness / Q000502:physiology*; D017698:Postmenopause / Q000502:physiology
chemical_list: D045166:Estradiol Congeners