Peggy Meinhart-Shibataa, , , Michelle Kramera, James A. Ashton-Millera, b, c and Carol Persadd
aBiomechanics Research Laboratory, Department of Mechanical Engineering, GGB
3208, University of Michigan, Ann Arbor, MI 48109-2125, USA
bDepartment of Biomedical Engineering, GGB 3208, University of Michigan, Ann
Arbor, MI 48109-2125, USA
cInstitute of Gerontology, GGB 3208, University of Michigan, Ann Arbor, MI 48109-2125,
USA
dDepartment of Psychiatry, GGB 3208, University of Michigan, Ann Arbor, MI 48109-2125,
USA
Accepted 2 August 2004. Available online 12 October 2004.
Abstract
Standing turns are associated with an increased risk for falls and fall-related
injuries in the elderly. The purpose of this study was to test the (null) hypothesis
that age has no effect on the kinematics of the 180° turn. Ten young and
10 older healthy women were asked to complete a series of 180° turns in
a standing posture after picking up a light bowl with both hands. Foot–ground
reactions, insole pressures and body segment kinematics were recorded in 62
trials at 100 Hz. Turning strategies were analyzed for effects of both age and
turn direction on linear and angular foot kinematics, as well as pelvic axial
rotation. The older women (OW) used a preparatory stepping strategy more often
(170%, p < 0.002), and employed a lower average pelvic rotation rate (21%,
p < 0.011) than the younger controls. The minimum foot separation distance
for OW was less in their non-preferred than in their preferred turn direction
(29%, p < 0.038), thereby increasing their risk of foot–foot interference
and falling when turning in their non-preferred direction. The older women were
more variable in their turn execution, particularly in minimum foot separation
distance (55%, p < 0.022) and the maximum rate of pelvic rotation (82%, p
< 0.035). Despite the fact that these healthy older women were careful to
employ a preparatory stepping strategy and slower average rotational velocities,
they were also more variable in their turn execution than the young.
Keywords: Turning; Women; Aging; Falls; Kinematics