Influence of age on dynamics of rising from a chair.

This article describes the sit-to-stand movement in nine healthy elderly adults, ages 61 to 74 years, and compares peak joint angles, torques, and velocities of 11 body segments with data collected from nine young women, ages 25 to 36 years. The subjects in this study rose from a chair under a controlled protocol. An optoelectronic system, two force plates, and two computers were used for data collection and processing. The data are described in relationship to three phases of the task previously described for the young subjects' data. Percentages of difference were calculated for the torques and the velocities. Independent t tests were conducted on maximum angles achieved and total joint excursions. Consistency between groups was demonstrated in the duration of each phase, as well as the body kinematics and kinetics occurring within each phase. There was little difference in maximum torques or velocities. Maximum angles of head-to-trunk extension, head-to-ground flexion, head-to-trunk excursion, and trunk-to-pelvis flexion were significantly different between groups. The differences in head position demonstrated between these two groups may have clinical implications for loss of balance during this task in older patients.