Article

Turning has frequent occurrence in everyday activities. Despite the prevalence of
turning in everyday life and the challenge it poses to older adults, there is far
less known about the multisegmental control of turning than the control of
standing and straight walking, especially in elderly individuals. The purpose of
this study was to examine the timing and sequence of segments reorientation in
healthy older adults during 90 degrees on-the-spot turns. The role of vision on
segments coordination was also examined by testing the participants in eyes-open
and eyes-closed conditions. When turning on-the-spot, healthy elderly reoriented
their head, shoulder and pelvis simultaneously, followed by foot displacement.
This was a robust behavior not affected by visual condition. Axial segments
turned slower and more synchronously when vision was not available. While all
segments started to turn together in both visual conditions, head turned faster
and reached its peak velocity earlier than shoulder and pelvis. However, the
difference in segmental velocity and the time to reach the peak velocity was
smaller in eyes-closed than eyes-open condition. Without vision, the functional
importance of a faster head turn is diminished. Participants may have adopted a
tighter control of segments to simplify the control of movement by reducing the
degrees of freedom.
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Langue : ANGLAIS