Chair rise strategy in the functionally impaired elderly.

Many elderly people have difficulty with the common functional activity of rising from a chair. Previous work has identified different strategies that are used to assist the young, the healthy elderly, and the functionally impaired elderly subjects in this activity. For the young and the healthy elderly, modification of these strategies with decreased chair height has been examined. This study examined the changes in chair rise strategy in 18 moderately functionally impaired elderly as the difficulty with rising was increased. The results show that the functionally impaired elderly, when rising from their lowest successful chair compared to a chair of knee height, significantly increase peak hip flexion velocity (11 degrees/sec, p < 0.01) and time to rise (1.25 sec, p < 0.01), and significantly decreased their mean center of mass/base of support (COM/BOS) separation at lift-off (1.96 cm, p < 0.05). These alterations in strategy suggest that while the functionally impaired elderly attempt to increase their momentum in rising by increasing their hip flexion velocity, they simultaneously attempt to increase their stability by taking more time to rise and shortening the distance between their COM/BOS at lift-off. These changes suggest a more conservative strategy with increased difficulty, resulting in decreased success in rising from a chair.