Biomechanical comparison of rising from two types of chairs.
This study compared the joint moments and ranges of motion of healthy subjects and patients during rising from a standard chair with a seat height of 0.43 m and a specially designed chair (E-Z Up Artherapedic Chair) with a seat height of 0.64 m. Ten healthy male subjects and four male patients with lower extremity disabilities rose from each chair with and without the use of their upper extremities. Hip, knee, and ankle joint moments and angles were calculated with film analysis and force plate data. An analysis of variance with repeated measures showed the following results for the healthy subjects: 1) no effect of upper extremity use on joint angles, 2) no effect of chair type on ankle joint angles or moments, 3) significantly smaller hip and knee flexion angles with use of the E-Z chair than of the standard chair (p less than .05), and 4) significantly smaller hip and knee extension moments with use of the E-Z chair than of the standard chair (p less than .05) or with use of the upper extremities. Similar results were found with the four disabled subjects. Use of the E-Z chair can significantly decrease the joint moments and ranges of motion needed at the hip and knee and thus make rising from a chair less stressful to these joints.