Muscle strength and tibolone: a randomised, double-blind, placebo-controlled trial.

ABSTRACT

OBJECTIVE: To investigate the effects of tibolone, a tissue-specific compound with a mixed (estrogenic, progestogenic and androgenic) hormonal profile, on skeletal muscle strength in a group of healthy postmenopausal women. DESIGN: Randomised, parallel group, double-blind, placebo-controlled, single-centre trial conducted between August 1997 and July 1999. PARTICIPANTS: Eighty-five healthy women, between one and 15 years postmenopausal, (mean [SD] age, 54.2 [4.7] years) recruited from local paper advertisements. Participants were randomly assigned to 2.5 mg tibolone or to identically appearing placebo pills daily for 12 months, taken orally in the morning. METHODS: Both maximal handgrip strength, representing upper body strength, and maximal quadriceps strength, representing lower body strength, were measured isometrically. MAIN OUTCOME MEASURES: Treatment effect estimates (between group differences) in handgrip strength and isometric knee extension at last visit. RESULTS: Tibolone significantly (P = 0.04) increased handgrip strength compared with placebo (difference 0.99 kg, [95% CI 0.1-1.9]). No significant treatment effect (P = 0.61) was observed in isometric knee extension strength. Isometric strength adjusted for body mass index resulted in a trend favouring tibolone (P = 0.06). Individual trend analysis showed a significant difference in rate of change throughout the year (6.8% [95% CI 2.1-10.7]) favouring tibolone. CONCLUSIONS: Administration of tibolone increased handgrip strength in postmenopausal women compared with placebo. A trend indicating a positive effect in isometric knee extension strength adjusted for body mass index was observed. Tibolone seems to mitigate the menopause-related decline in muscle strength.