A recently published study is part of a larger research project on postmenopausal sarcopenia and the effects of hormone replacement therapy (HRT) and physical activity . Fifteen 54–62-year-old monozygotic female twin pairs, where one twin in each pair was receiving HRT and the other twin was not, were recruited from the Finnish Twin Cohort. This cohort includes all Finnish same-sex twin pairs born in Finland before 1958 and with both co-twins alive in 1967 (n = 13,888 pairs). Among others, women with chronic musculoskeletal disease, diabetes types 1 and 2, acute cancer, drug or alcohol abuse were excluded. Habitual and maximal walking speeds over 10 meters, thigh muscle composition, lower body muscle power (assessed as vertical jumping height), and maximal isometric hand-grip and knee-extension strengths were measured.
The mean duration of HRT usage was 6.9 ± 4.1 years (range 2–6 years). The maximal walking speed was on average 7% (95% confidence interval (CI) 0.9–13.1%; p = 0.019) and muscle power 16% (95% CI – 0.8 to 32.8%; p = 0.023) greater in the HRT users (estradiol 1–2 mg only or combined with progestogenic compounds, and tibolone 2.5 mg orally) than in their co-twin controls. Thigh muscle cross-sectional area, as taken from CT image analysis, tended to be larger (intra-pair difference = 6%; 95% CI – 0.07 to 12.1%; p = 0.065), relative muscle area greater (8%; 95% CI 0.8–15.0%; p = 0.047) and relative fat area smaller (- 5 %; 95% CI – 11.3 to 1.2%; p = 0.047) in the HRT users than in their co-twins. On the other hand, maximal isometric strengths or habitual walking speeds were not significantly different. Subgroup analysis revealed that estrogen-containing therapies (n = 11 pairs) decreased total body and thigh fat content, whereas tibolone (n = 4 pairs) tended to increase muscle cross-sectional area.
Hermann P. G. Schneider
Department of Obstetrics and Gynecology, University of Muenster, Germany
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