Differences in Trunk Kinematics and Ground Reaction Forces between Older and Younger Adults during Lifting

Abstract

Trunk kinematics, ground reaction forces, and the motion of the center of pressure (COP) of older and younger subjects were compared in lifting to study age-related differences between the two age groups. Ten older (55 - 63 years old) and ten younger (19 - 29 years old) adults performed lifting tasks under six different conditions; three destination heights and two asymmetry angles of origin. Subjects' trunk kinematics, ground reaction forces and COP motions were measured by the Lumbar Motion Monitor (LMM) and a force plate. Older subjects showed significantly less trunk kinematics, peak ground reaction forces, and COP motions than younger subjects, indicating older subjects chose more stable lifting strategy and it might compensate for the decreased ability of postural control over age. Less ground reaction forces and motion of COP suggested that risks of falls and slips of older subjects were less than younger subjects.