Definitions: CORE STRUCTURAL INTEGRATIVE THERAPY: Originated by George P. Kousaleos, CORE is a myofascial, postural and structural somatic therapy combining massage techniques with client-assisted movement. Normally lasting 10 sessions, there are four phases of CORE body therapy organized according to the level or layer of fascia, muscle and supporting soft tissues that are manipulated: Core massage, core extrinsic, core intrinsic and core integration.