Abstract
To walk safely in their environment, people need to select adequate movement strategies during gait. In situations that are perceived as more threatening, older adults adopt more cautious strategies. For individuals with excessive fear, selecting adequate strategies might be troubling. We investigated how a postural threat affects the selection of strategies within and between older adults by using a stepping-down paradigm. In twenty-four older adults we determined the height at which they switched in stepping-down strategies from a less demanding but more balance threatening heel landing to a more demanding yet safer toe landing. We expected that this switching height would be lower in the high (0.78 m elevation) compared to low threat (floor level) condition. Furthermore, we investigated if older adults, for which the postural threat evoked an increase in the perceived fear, presented a different stepping down strategy due to the postural threat. Our results indicated that the postural threat changed older adults’ strategies selection towards a more conservative toe landing. Hence, despite the additional effort, older adults prefer more cautious strategies during a postural threat. No effects of perceived fear on strategy selection between individuals were observed, potentially due to relatively small differences in fear among participants.
Highlights
To walk safely in their environment, people need to select adequate movement strategies during gait
Participants presumably switch from heel landing to toe landing with increasing step height, to dissipate the kinetic energy generated by the height difference, despite the higher muscle activity associated with toe landing[16]
Twenty-four healthy older adults were measured, of which 14 participants started in the low threat condition and 10 participants started in the high threat condition
Summary
To walk safely in their environment, people need to select adequate movement strategies during gait. Standing at an elevation can be challenging and such postural threat has been shown to affect the control of static motor tasks in both young and older adults[6]. Older adults seemed to select more cautious strategies, in terms of higher toe clearance, when crossing obstacles at elevation[12] These studies did not constrain walking speed which might be problematic as walking slower is an effective strategy to reduce the risk of erroneous movement and may explain the observed changes in strategy selection. Davis and colleagues[8] examined the association between height-related changes in balance control and fear between young adults They found that fearful individuals at high threat leaned farther away from the platform edge and their centre of pressure featured larger amplitudes and higher frequencies than in less fearful peers. During our stepping-down paradigm at elevation, older adults with higher perceived fear might respond stronger by choosing even more cautious behaviour than their less fearful peers
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