Alternative devices for the quantification of human motion.

Force platforms and video tracking systems have been used to characterize subject movements and resultant forces to identify common characteristics of individuals who have experienced recurring falls. Short-term training using force platforms with feedback has been effective in reducing sway. Because of the expense and size requirements of these systems, researchers have pursued alternate means of quantifying postural motion. Most recently, this has involved various combinations of accelerometers and gyroscopes. This review article summarizes the main aspects of many of these designs and shows the high correlation of results obtained relative to video tracking methods. Most notably, measurements of the lower leg have reached correlation coefficients as high as 0.98 when using high-pass filters to eliminate signal drift. Many complications have been overcome, such that accelerometers and gyroscopes are considered acceptable for use in human motion measurement devices.