171 Journal of Aging and Physical Activity, 2008, 16, 171-187 © 2008 Human Kinetics, Inc. Michel-Pellegrino, Hewson, and Duchêne are with the Charles Delaunay Institute, Troyes University of Technology, BP 2060 Troyes, France. Hogrel is with the Myology Institute, Pitié-Salpêtrière Hospital Group, 75651 Paris, Cedex 13, France. Biomechanical Analysis of Older Adults Stepping Up: A Method of Evaluating Balance Valérie Michel-Pellegrino, David Hewson, Jean-Yves Hogrel, and Jacques Duchêne The aim of this study was to analyze differences in biomechanical parameters between elderly and control participants when stepping up, to evaluate control of balance. Eleven control and 14 elderly participants performed a step from an initial static posture onto a 7-cm-high force plate. For the spontaneous-velocity condition, elderly participants performed a slower progression velocity than control participants. Elderly participants spent proportionally more time in stance phase, with a corresponding decrease in swing phase, than the control partici- pants, irrespective of movement velocity. In contrast, at spontaneous velocity the parameters related to ground-reaction force (GRF) showed that anteroposterior and mediolateral forces at toe-off of the support limb and the slope of vertical force during weight transfer were significantly smaller for the elderly than for control participants. These GRF parameters depended on the stepping-up velocity. The elderly develop a spatiotemporal strategy and reduced movement velocity to control support balance. Keywords: postural balance, elderly, ground-reaction forces, force plate Falls in the elderly are one of the most important public health problems for health care services in the 21st century. As part of a fall-prevention strategy, it would be of interest to evaluate balance regularly to detect risk of falls. Clinical tests such as the timed get-up-and-go (Mathias, Nayak, & Isaacs, 1986), the Berg Balance Scale (Shumway-Cook, Baldwin, Polissar, & Gruber, 1997), and the Tinetti Balance Scale (Tinetti, Speechley, & Ginter, 1988) are used regularly to evaluate movement and thus dynamic balance. All of these tests are descriptive, however, and thus cannot explain the motor process related to any underlying degradation of balance and the concomitant increase in fall risk. Although the incidence of falls is well known to increase with age, the motor mechanisms related to this phenomenon remain poorly understood. Therefore, it is necessary to develop a biomechanical analysis to