The influence of postural threat on strategy selection in a stepping-down paradigm

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 steppingdown 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.

The benefit of knowledge: postural response modulation by foreknowledge of equilibrium perturbation in an upper limb task

“…Although this response contains no voluntary elements, subjects may still unconsciously condition an optimal response execution. Expectancy of a stimulus may determine how supraspinal structures modulate reactive postural responses (Lim et al 2017 ; Cesari et al 2022 ; Dakin and Bolton 2018 ; Ritzmann et al 2018 ; Kluft et al 2020 ). With a StartReact response, the APA is delivered as part of the prepared motor program.…”

“…The visible net result obtained from the EMG in RF when passive leg movement was the trigger to react, includes an APA as part of a motor program, which is not found with a known non-startling acoustic stimulus, and a PR. When the upcoming IS is known, i.e., KF velocity, WE requires the activation of leg extensors as part of the whole-body motor program, but when the subject is uninformed about the upcoming velocity of KF, the imposed uncertainty might cause an uneasy or even threatening situation (Lim et al 2017 ; Cesari et al 2022 ; Kluft et al 2020 ), and the nervous system chooses a motor set that triggers PAs, in addition to APAs when a wrist reaction is required. And finally, when the subject is uninformed, and the intensity of the leg IS is strong enough to trigger a startle reaction, the APA becomes part of the StartReact response.…”

Aberrant decision-making as a risk factor for falls in aging

“…Because an individual’s risk-taking behaviors are not easily observed, clinical assessments instead capture people’s perceptions of their ability to maintain balance in risky environments using scales such as the Falls Efficacy Scale, Activities-Specific Balance Confidence Scale, and the Modified Gait Efficacy Scale ( Delbaere et al, 2010 ; Hadjistavropoulos et al, 2011 ; Moreira et al, 2017 ; Kluft et al, 2020 ). The Falls Efficacy Scale assesses the fear of falling by asking respondents to rate their level of concern about falling while performing different activities.…”

Influence of step-surface visual properties on confidence, anxiety, dynamic stability, and gaze behaviour in young and older adults

“…Increased anxiety during stepping-down behaviour also causes older adults to adopt more conservative landing strategies at the expense of increase muscle force production (Kluft et al, 2020). Furthermore, anxiety has been shown to influence visuomotor behaviour.…”