muscle tone

When I refer to muscle tone, I am not referring to how buff a bodybuilder looks, but an involuntary action in muscles. The purpose of this is to help prevent atrophy, but I'll need some preexplanation for it. In a muscle, individual (muscle) cells are wrapped in dense connective tissue, thin groups of cells (common: muscle fibers) are also wrapped in connective tissue, and the fibers are wrapped into groups of... say 24, and wrapped with another coat of connective tissue. Then the entire muscle is wrapped in another covering that connects with the tendon. Within each of the third-level groups (bundles of fibers), the motor axions systematically flex each fiber, in a cycle. This is why unused muscles only become weak, but paralyzed muscles atrophy.

A small number of fibres in most muscles are contracting continuously. They do this to maintain posture, and thereby enable a limb to resist being passively stretched or elongated. This slight persistent contraction is called muscle tone.

Muscle tone is maintained by regular exercise. Well toned muscles are firm and slightly springy to the touch.