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A technique for locating the center of mass and principal axes of the lower limb

Medicine & Science in Sports & Exercise: July 1992
Special Communications: Methods: PDF Only


VERSTRAETE, M. C. A method for locating the center of mass and principal axes of the lower limb. Med. Sci. Sports Exerc., Vol. 24, No. 7, pp. 825–831, 1992. The position of the human body in space is typically recorded using a fixed inertial coordinate system, often referred to as a laboratory coordinate system. Although these fixed reference axes simplify the collection and reduction of such position data, the results produced often have little or no anatomical significance. The purpose of this study was to develop the methods, both experimental and analytical, to construct a set of orthogonal principal axes for each the foot, shank, and thigh segments of the lower limb for use in motion analysis. The axes chosen were determined by targeting specific bony landmarks as suggested by the literature and forming the principal axes with respect to these landmarks. The location of the center of mass of each segment was also determined from these anatomical landmarks. It was found that the foot, due to its less rigid nature and more complex geometry, required a more extensive analysis using a single frame of standing data prior to the analysis of the motion data. The axes formed do not attempt to solve the problems of joint rotation axes, but provide an initial, anatomically significant set of reference axes that may be easily reproduced and utilized in further analyses.

©1992The American College of Sports Medicine