Comparison of the accuracy of measurement of floor reaction force and lower extremity joint moments calculated using different force plate measurement methods

Abstract

The purpose of this study was to compare the accuracy of measurement of lower extremity joint moments calculated using data obtained by a force plate embedded on a stair tread with that using combined data obtained by two force plates under the staircase. We captured ascending and descending movement by a healthy young subject using a three-dimensional motion analysis system. We calculated ankle, knee and hip joint moments using data from the same trial captured by the two measurement methods. No differences were observed in lower extremity joint moments between the two methods. Our theoretical assumptions were confirmed by our results; floor reaction force obtained from the force plates positioned under the stairs was the same as that obtained on the stair tread, and joint moment could be calculated accurately using either measurement method. The use of our simplified experimental setup using force plates positioned under the staircase could facilitate future measurement of floor reaction force and calculation of joint moment during ascending and descending stairs.