Age-related changes in the passive resisting moments at the hip

Abstract

The purpose of this study was to investigate age-related changes in the passive resisting moments at the hip. The changes in the passive resisting moments were hypothesized to occur due to age-related changes in muscle stiffness. Two groups of healthy men participated in this study: young men (approximately 24 years of age) and old men (approximately 68 years of age). Subjects were positioned in a left lateral decubitus position with their left limb supported on a table. With a subject relaxed, an experimenter slowly moved the subject’s limb by pulling or pushing the handle attached to the lower limb via a load cell. The subject’s hip was moved in passive range of flexion-extension motions. The joint kinematics, measured by a motion capture system, and load cell readings were used to compute the passive resisting moments-joint angle curves at the hip. The passive resisting moments at the hip were found to considerably depend on the adjacent knee angle. The maximal resisting moments, when the hip was extended, were larger for the older group than for the younger group. The measured resisting moments were finally validated against the resisting moments calculated by a musculoskeletal computer model for the same movements. The computer model was able to predict measured tendencies of the moments at the hip. However, further adjustments of the computer model are required to represent the aging effects precisely.

Keywords

• aging
• hip
• passive moment
• joint stiffness
• musculoskeletal computer model