Purpose: 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 ≤3.3%. There was no difference by ERT status for the hamstring muscles, fat CSA, or for physical function.
Conclusion: 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.
1School of Human Movement Studies, The University of Queensland, Brisbane, AUSTRALIA; 2Department of Medicine, University of Pittsburgh, Pittsburgh, PA; 3Department of Kinesiology, University of Wisconsin, Madison, WI; 4Laboratory of Epidemiology, Biometry, and Demography, National Institute on Aging, Bethesda, MD; 5Institute for Research in Extramural Medicine and Department of Nutrition and Health, Vrije Universiteit, Amsterdam, THE NETHERLANDS; 6Preventive Sciences Group, University of California at San Francisco, San Francisco, CA; and 7Department of Epidemiology, University of Tennessee Health Science Center, Memphis, TN
Address for correspondence: Dennis R. Taaffe, Ph.D., School of Human Movement Studies, Faculty of Health Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia; E-mail: firstname.lastname@example.org.
Submitted for publication March 2005.
Accepted for publication May 2005.
This study was funded by NIA contract numbers N01-AG-6-2102, N01-AG-6-2103, and N01-AG-6-2106.