muscular

Muscular is an adjective referring to muscles or the muscular system. In anatomy it describes tissue, organs, or actions related to muscle. In common usage, it also describes a person with a well-developed muscular physique.

Muscle tissue is categorized into skeletal, smooth, and cardiac. Skeletal muscles attach to bones via tendons and produce voluntary movements. They are striated and contain muscle fibers organized into myofibrils and sarcomeres that contract when stimulated by motor neurons. Cardiac muscle forms the heart walls and contracts rhythmically; smooth muscle lines organs and vessels and contracts involuntarily.

Contraction depends on energy from ATP and calcium signaling; actin and myosin filaments slide past each other; mitochondria supply energy; blood supply and innervation essential.

Muscular strength and endurance can be increased by training, particularly progressive resistance exercise. Hypertrophy refers to an increase in muscle fiber size; some changes in fiber type can occur. Proper nutrition, including sufficient protein, and recovery support gains.

Muscular disorders include muscular dystrophies, myopathies; disuse atrophy; aging-related sarcopenia reduces muscle mass and function.