Do declines in estrogen and testosterone after menopause reduce muscle mass, strength, and cause fatigue?

The decline of estrogen and androgens following menopause significantly alters muscle homeostasis, contributing to changes in physical capacity and energy levels. For women in their late 60s, these hormonal shifts influence muscle maintenance through distinct biological pathways.

Clinical evidence and physical function

Research highlights a direct relationship between sex steroid levels and physical performance in postmenopausal populations.

• Physical limitations: Longitudinal data from the Study of Women's Health Across the Nation (SWAN) suggests that women with a more gradual decline in estradiol and testosterone have lower odds of experiencing physical functional limitations compared to those with more rapid declines.
• Mobility and strength: Low levels of endogenous testosterone are associated with a greater likelihood of physical function decline in women aged 70 and older. Maintaining muscle mass is strongly correlated with higher scores on objective measures such as the Short Physical Performance Battery (SPPB).
• Fatigue: Low estradiol is consistently linked to increased fatigue. This is often mediated through secondary effects such as vasomotor symptoms (hot flashes) and night sweats, which lead to significant sleep disruption.

Mechanistic explanations

Estrogen and androgens support muscle health through complementary but different mechanisms:

• Satellite cell function: Estradiol (E2), acting through estrogen receptor alpha (ERα), is essential for the maintenance and proliferation of satellite cells (muscle stem cells). These cells are required for skeletal muscle regeneration and repair after injury or exercise. Estrogen deficiency leads to a decline in satellite cell numbers, impairing the muscle's ability to recover and contributing to sarcopenia.
• Protein synthesis: While estrogen supports the regenerative environment, androgens like testosterone are the primary drivers of muscle protein synthesis in postmenopausal women. Testosterone directly stimulates the expression of growth factor genes (such as MYOD1) and modulates myostatin (MSTN). Higher levels of bioavailable testosterone are positively correlated with both muscle mass and overall strength.

Bottom line

The claim is well-supported: estrogen is critical for muscle tissue repair via satellite cell activation, while testosterone drives the protein synthesis necessary for muscle mass and strength. Declines in these hormones contribute to reduced physical function and fatigue through both direct musculoskeletal degradation and indirect pathways like sleep disruption.