Davis's law is used in anatomy to describe how soft tissue models along imposed demands. It is the corollary to Wolff's law. It is used in part to describe muscle-length relationships and to predict rehabilitation and postural distortion treatments as far as muscle length is concerned.
This is not necessarily describing myohypertrophy (muscle growth)—the shortening of muscle in response to resistance—but it explains also how a muscle will lengthen in response to stretching. Because most major muscles have an opposite, the protagonistic and antagonistic muscles (and their related syntergistic and groups of muscles) will end up reciprocating each other's length. A strong and inflexible gastrosoleus complex (calf) will therefore result in a weak and flexible tibialis anterior (shin muscle).
This law is presumably named after someone, perhaps a researcher, by the name of Davis. The full name is currently unknown.