Shabnam Shokouhi - Department of Mechanical Engineering, Sharif University of Technology
Ehsan Abdolahi - Djavad Mowafaghian Research Center in Rehabilitation Technologies, Sharif University of Technology
Saeed Behzadipour - Department of Mechanical Engineering, Djavad Mowafaghian Research Center in Rehabilitation Technologies, Sharif University of Technology

Given the high prevalence of balance disorders among elderly and many neurological disease conditions which make the assessment and rehabilitation of balance a serious public health concern, we have devised an inexpensive portable balance board that can preciselymeasures the center of pressure (COP), and examined its validity in comparison with a gold standard force platform (Kistler). Eight young injury free subjects performed two sessions of a combination of quiet stance, limit of stability (LOS), and random control (RC) tests.The balance board was placed and centered on the Kistler force plate in order to record data from both devices simultaneously. Outcome measures were mean velocity (MV), RMSAP, RMSML, and Phase plane deviation (PD). Results showed excellent betweendevicevalidity for all three testing conditions and four outcome measures (ICC=0.818-0.989). Moreover, the Bland-Altman plots did not represent any evidence of systemic bias between two devices, however, the balance board tends to slightly exaggerate the value of meanvelocity in some trials of limits of stability. These findings suggest that the presented balance board is a valid tool for training and testing balance and given its portability and low price, it can be used as an alternative for laboratory-grade force plates in every average clinicfor rehabilitation purposes

balance; force plate; validity; reliability; postural sway; COP