Hormonal

Aging blunts the ability for serial sarcomerogenesis (addition of new sarcomeres in series), leading to shortened fascicle length and impaired muscle mechanical function, primarily due to age-related impairments in mechanotransduction pathways like mTOR, IGF-1, and SRF signaling.

For older adults, maintaining or improving muscle function may require specific interventions that promote muscle lengthening, such as eccentric resistance training or chronic stretching. While muscle mass loss is common, the shortening of muscle fascicles (due to loss of serial sarcomeres) contributes significantly to stiffness and reduced power. Targeted training that emphasizes the lengthening phase of movements may help mitigate these age-related architectural changes, though the response may be slower or smaller than in younger individuals.