title: Postmenopausal hormone replacement therapy modifies skeletal muscle composition and function: a study with monozygotic twin pairs.
abstract: We investigated whether long-term hormone replacement therapy (HRT) is associated with mobility and lower limb muscle performance and composition in postmenopausal women. Fifteen 54- to 62-yr-old monozygotic female twin pairs discordant for HRT were recruited from the Finnish Twin Cohort. Habitual (HWS) and maximal (MWS) walking speeds over 10 m, thigh muscle composition, lower body muscle power assessed as vertical jumping height, and maximal isometric hand grip and knee extension strengths were measured. Intrapair differences (IPD%) with 95% confidence intervals (CI) were calculated. The mean duration of HRT use was 6.9 +/- 4.1 yr. MWS was on average 7% (0.9 to 13.1%, P = 0.019) and muscle power 16% (-0.8 to 32.8%, P = 0.023) greater in HRT users than in their cotwins. Thigh muscle cross-sectional area tended to be larger (IPD% = 6%, 95% CI: -0.07 to 12.1%, P = 0.065), relative muscle area greater (IPD% = 8%, CI: 0.8 to 15.0%, P = 0.047), and relative fat area smaller (IPD% = -5%, CI: -11.3 to 1.2%, P = 0.047) in HRT users than in their sisters. There were no significant differences in maximal isometric strengths or HWS between users and nonusers. Subgroup analyses revealed that estrogen-containing therapies (11 pairs) significantly decreased total body and thigh fat content, whereas tibolone (4 pairs) tended to increase muscle cross-sectional area. This study showed that long-term HRT was associated with better mobility, greater muscle power, and favorable body and muscle composition among 54- to 62-yr-old women. The results indicate that HRT is a potential agent in preventing muscle weakness and mobility limitation in older women.
authors.affiliation: Dept. of Health Sciences and Finnish Centre for Interdisciplinary Gerontology, Univ. of Jyväskylä, PO Box 35 (Viv), FIN-40014 Jyväskylä, Finland. paula.h.a.ronkainen@jyu.fi
authors.forename: Paula H A
authors.initials: PH
authors.lastname: Ronkainen
authors.forename: Vuokko
authors.initials: V
authors.lastname: Kovanen
authors.forename: Markku
authors.initials: M
authors.lastname: Alén
authors.forename: Eija
authors.initials: E
authors.lastname: Pöllänen
authors.forename: Eeva-Maija
authors.initials: EM
authors.lastname: Palonen
authors.forename: Carina
authors.initials: C
authors.lastname: Ankarberg-Lindgren
authors.forename: Esa
authors.initials: E
authors.lastname: Hämäläinen
authors.forename: Ursula
authors.initials: U
authors.lastname: Turpeinen
authors.forename: Urho M
authors.initials: UM
authors.lastname: Kujala
authors.forename: Jukka
authors.initials: J
authors.lastname: Puolakka
authors.forename: Jaakko
authors.initials: J
authors.lastname: Kaprio
authors.forename: Sarianna
authors.initials: S
authors.lastname: Sipilä
mesh_terms: D015914:Estrogen Replacement Therapy; D004967:Estrogens / Q000097:blood / Q000494:pharmacology*; D005260:Female; D018737:Hand Strength / Q000502:physiology; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008593:Menopause / Q000502:physiology*; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects* / Q000502:physiology; D018482:Muscle, Skeletal / Q000000981:diagnostic imaging / Q000187:drug effects* / Q000502:physiology; D014057:Tomography, X-Ray Computed; D018433:Twin Studies as Topic; D014430:Twins, Monozygotic; D016138:Walking / Q000502:physiology
chemical_list: D004967:Estrogens