Postmenopausal hormone replacement therapy modifies skeletal muscle composition and function: a study with...

Area of Science:

• Gerontology
• Endocrinology
• Exercise Physiology

Background:

• Menopause is associated with decreased estrogen levels, potentially leading to reduced muscle mass, strength, and mobility.
• Hormone replacement therapy (HRT) is a common intervention for menopausal symptoms, but its long-term effects on physical function require further investigation.

Purpose of the Study:

• To investigate the association between long-term hormone replacement therapy (HRT) and mobility, lower limb muscle performance, and muscle composition in postmenopausal women.

Main Methods:

• A study involving monozygotic twin pairs (n=15) discordant for HRT use, aged 54-62 years.
• Measurements included habitual and maximal walking speeds, thigh muscle composition (cross-sectional area, fat area), lower body muscle power (vertical jump), and maximal isometric strengths.
• Intrapair differences (IPD%) were calculated to control for genetic and shared environmental factors.

Main Results:

• HRT users exhibited significantly greater maximal walking speed (7%) and muscle power (16%) compared to their non-HRT-using cotwins.
• HRT was associated with a trend towards larger thigh muscle cross-sectional area and significantly greater relative muscle area, with smaller relative fat area.
• No significant differences were observed in maximal isometric strengths or habitual walking speed.

Conclusions:

• Long-term HRT is associated with improved mobility, enhanced muscle power, and favorable body and muscle composition in postmenopausal women.
• HRT may be a beneficial intervention for preventing muscle weakness and mobility limitations in older women.
• Estrogen-containing therapies specifically reduced body and thigh fat, while tibolone tended to increase muscle cross-sectional area.