Muscle atrophy

Muscle atrophy is a reduction in muscle mass caused by muscle fibers shrinking or being lost. It can follow disuse, aging, malnutrition, or disease.

Muscle protein synthesis: The cellular process of producing proteins that build and maintain muscle tissue. Atrophy develops when muscle protein production fails to keep pace with breakdown.
Disuse atrophy: Muscle loss caused by reduced use or loading of a muscle. It is a specific form of atrophy that follows immobilization or inactivity.
Muscle strength testing: Assessment of the force a person can produce with selected muscles. Strength testing helps determine whether muscle loss has impaired function.
Muscle weakness: Reduced ability to generate force with one or more muscles. Weakness can occur without muscle loss, while atrophy can exist before obvious weakness.
Muscle protein breakdown: The cellular degradation of proteins in muscle tissue. Increased protein breakdown can shrink muscle fibers and reduce their mass.
Sarcopenia: The progressive loss of skeletal muscle mass and function associated with aging. It describes age-related muscle loss, often accompanied by declining strength.
Dual-energy X-ray absorptiometry: An imaging method that estimates bone mineral density and body composition using two X-ray energies. It can estimate lean mass, though it does not directly measure muscle tissue.
Muscular dystrophy: A group of inherited disorders that progressively damage skeletal muscles. It is a set of diseases that can cause muscle wasting, not a synonym for atrophy.
Ubiquitin-proteasome system: A cellular pathway that marks proteins with ubiquitin for degradation by proteasomes. This pathway helps dismantle muscle proteins during many forms of atrophy.
Cachexia: A complex wasting syndrome involving involuntary weight and muscle loss, often associated with chronic disease. It causes muscle wasting through disease-related metabolic and inflammatory changes.

Linked from 8 pages