It is said that postural stability means almost the same as balance, but the meaning of the word balance has changed. Previously it was the capacity to maintain a quiet position such as standing and sitting. At present, it involves the capacity to excute movement in a task in the environment. This paper asks "What kind of features does a construction of balance have?" and "What is the nature of balance testing?" In physical therapy, it is useful to perform balance testing because it is related to active daily living (ADL) in patients.
