Head-trunk coordination in elderly subjects during linear anterior-posterior translations.

Head-trunk coordination in elderly subjects during linear anterior-posterior translations. Research Abstract Details 

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Head-trunk coordination in elderly subjects during linear anterior-posterior translations. Abstract Text:

Emily A Keshner,

This study examined whether the head of elderly subjects was less stable in space when the trunk was free to move than when the trunk was fixed to a linearly moving platform. Fourteen healthy elderly subjects were seated on a linear sled with their trunk either fixed to the seat or free to move. Subjects received 10 cm, 445 cm/s2 anterior-posterior ramps and 0.35-4.05 Hz sum-of-sines translations while performing a mental distraction task in the dark. Kinematics of the head and trunk were derived from an Optotrak motion analysis system and a linear accelerometer placed on the head. Electromyographic (EMG) signals were collected for neck and paraspinal muscles. Data were tested for significance with paired t-tests corrected for multiple testing and compared (Mann-Whitney U-test) with previously published data from 12 healthy young adults (Keshner 2003). Linear acceleration trajectories of the head corresponded to the direction of sled linear acceleration when the trunk was fixed and countered the direction of the sled when the trunk was free. Angular head accelerations countered the sled or the trunk when the trunk was fixed or free, respectively. Peak amplitudes of head angular acceleration in space were greater with a fixed trunk. With the trunk free, amplitudes of head linear peak acceleration, angular accelerations, and response gains exceeded those of the young adults. Muscle EMG response latencies did not vary with the timing of head acceleration onset but the neck muscles were activated more frequently in a direction consistent with a vestibulocollic or cervicocollic reflex. Differences in angular motion of the head could be explained by the biomechanical constraints of the two tasks having one freely moving mass (head) with the trunk fixed and two freely moving masses (head and trunk) with the trunk free. These data suggest that elderly subjects rely upon active trunk mechanics in order to coordinate their head and trunk motion; however, a contribution by vestibular and ascending segmental inputs cannot be completely ruled out. A less flexible trunk in the elderly could explain why they were not as successful as young adults in stabilizing their heads in space when the trunk was free to move.

Head-trunk coordination in elderly subjects during linear anterior-posterior translations. Publishing Authors By Initials

EA Keshner,

For similar body regions: thorax research abstracts see: body regions: thorax research

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Head-trunk coordination in elderly subjects during linear anterior-posterior translations. Journal Published:

PUBLICATION TYPE: Research Support, U.S. Gov't,

Journal: Experimental brain research. Experimentelle Hirnfo

VOLUME: 158

Page Numbers: 213-22

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ISSN: 0014-4819

DAY: 8

MONTH: 04

YEAR: 2004

Head-trunk coordination in elderly subjects during linear anterior-posterior translations. Information

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LANGUAGE: eng

NlmUniqueID: 43312

Head-trunk coordination in elderly subjects during linear anterior-posterior translations. Keywords Mesh Terms:

KEYWORDS: Thorax

MESH TERMS: physiology

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Grant and Affiliation Information for Head-trunk coordination in elderly subjects during linear anterior-posterior translations.

AFFILIATION: Sensory Motor Performance Program, Rehabilitation Institute of Chicago, Room 1406-E809, 345 East Superior Street, Chicago, IL 60611, USA. eak@northwestern.edu

Country: Germany

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MEDLINETA: Exp Brain Res

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