Body-sway measurements have been used as one of the methods to diagnose equilibrium disorders. A qualitative evaluation of unique body-sway characteristics of patients with specific disorders has been chiefly used. Recently, quantitatively and objectively evaluating body-sway has been advocated. This evaluation method can diagnose healthy people's body functions and has been noted as an effective body-sway method. However, methods that evaluate body-sway are not necessarily rationally united. In addition, although many evaluation parameters have been proposed, they have not been arranged objectively. It may be important to examine the following two points to rationally establish an evaluation method of the healthy people's body-sway. One is to arrange traditional evaluation methods and measurement conditions used in the past and to clarify the factors related to body-sway. Another is to carefully examine effective evaluation parameters for healthy people and set a proper evaluation criterion after inspecting their statistical validity and reliability. These general remarks clarify the above two points through a comprehensive literature review, and introduce a simple and rational evaluation methods of healthy people's health states in addition to upright standing posture control based on their body -sway.
