Kinematic variability of the head, lumbar spine and knee during the “walk and turn to sit down” task in older and young adults

- Coordinate the motion variability among body segments as a sign of adaptability.
- The velocity variability of head was smaller than in lumbar and knee joints.
- Older adults limit movement amplitude and velocity to maintain balance in turning.
- Older adults cannot precisely control the variability of head for smooth turning.

This study investigates the kinematic variability of the head, lumbar spine and knee during the various walk and turn to sit phases in older and young adults. Sixteen older adults and eighteen young adults were recruited for this study. Each subject performed the “Walk and turn to sit down” test. A 16-channel telemetry system with electrogoniometers and an inclinometer was used to record the kinematic data. The turning step was divided into braking, mid-stance, swing and terminal load phases for kinematic analysis. The results showed that the older adults had a lower displacement angle and velocity of the lumbar spine, head and knee during different turning phases than the young adults. However, older adults performed turning with a higher variability in angular velocity of head flexion than the young adults during the turning step. The onset of lumbar movement and lateral flexion of the head occurred significantly earlier in older adults than in the young adults during turning.ConclusionOlder adults more cautiously control their motion by changing their trunk movement amplitude, velocity and timing in relation to their lower extremity movements during turning. The larger variability in angular velocity of head flexion may imply that older adults cannot precisely estimate the required movement for smooth turning.