Chair rise strategies in the elderly.

The elderly often have difficulty with rising from a chair. The purpose of this study was to characterize their rising strategies. A group of 22 elderly adults with a range of functional impairments was asked to rise from chairs of varying heights. Videotape motion analysis was used to identify strategies, estimate centre of mass, and measure time to rise. Three movement strategies were identified, "momentum transfer", "stabilization", and "combined" based on the velocity of trunk movement and base of support rearrangement. "Momentum transfer" uses horizontal momentum developed in the trunk to rise; "stabilization" uses centre of mass and base of support repositioning but very little momentum; "combined" uses elements of both momentum transfer and stabilization. Differences in the time to rise and the centre of mass to base of support separation between the momentum transfer and stabilization strategies were significant at each chair height. The momentum transfer, combined, and stabilization may form a continuum of chair rise strategies.