Psychological theories propose that anxiety stemming from fear of falling (FoF) can lead to an attentional bias toward threatening stimuli, thereby compromising working memory efficiency and balance performance [3]. As FoF becomes increasingly prevalent in aging societies, it contributes significantly to the risk of falls, which are predominantly incident during movement. Consequently, it is essential for assessment tools and research protocols to reflect real-life risk conditions. This study aimed to examine the impact of FoF intensity on static balance and transitional locomotor tasks.
FoF is more common in women and its prevalence increases with age [28]. Therefore, our study focused on a cohort of healthy older women. The findings revealed that postural sway characteristics were unaffected by FoF levels during static balance tasks, both before and after the transitional locomotor task. The mean vCOP in the anterior–posterior (AP) and medio-lateral (ML) planes did not differ significantly among the LOW, MODERATE, and HIGH concern groups. These results align with those of Taglietti et al., [17], who also found no correlation between FES-I scores and postural sway. The authors also used a QS test in their study to assess static balance, analyzing COP variables. However, in addition, participants performed a QS test with their eyes closed as the second condition of the test. In contrast, clinical populations such as individuals with Parkinson’s disease (PD), multiple sclerosis (MS), or diabetes often exhibit altered COP metrics in relation to FoF. However, in our study, by excluding participants with recent falls and maintaining a homogeneous sample in terms of age, gender, and medical history, we could attribute the lack of impact on static balance directly to FoF levels.
Given that falls most frequently occur during movement, especially over short distances [18], it was logical to employ a more functional motor task like the transitional locomotor task. This task has been effectively utilized in assessing balance across various populations, from children to the elderly [21, 22, 29]. Our findings indicate a tendency for TT to increase with greater FoF. Specifically, the HIGH concern group exhibited significantly longer TT during obstacle clearance, step-up, and step-down conditions compared to the MODERATE concern group—by 26%, 30%, and 25%, respectively—despite instructions to move as quickly as possible. This suggests that participants with higher FoF prioritize balance maintenance over rapid movement initiation. This behavior is consistent with Tisserand et al. [30], who observed that older adults with disturbed balance tend to enhance stability at the expense of speed. In their studies, the participants did not perform a full step but moved the lower limb forward as quickly as possible. The participants responded to light stimuli by reacting with either the right or left lower limb accordingly.
Additionally, as TT increased, the double support period (DSP) also lengthened, particularly during obstacle clearance and step-up conditions, correlating with higher FoF levels. This indicates a shift towards a greater proportion of time spent with both feet on the ground, reducing single support time. Hommen et al. [31] reported similar findings, noting that frail individuals with FoF took shorter first steps compared to non-frail older adults. This was possible to determine because the participants covered a distance of 4 m. They suggested that reduced step length and increased DSP are indicative of altered postural strategies aimed at fall prevention. Furthermore, Åberg et al. [10] found that FoF affects not only step length but also step width, with wider strides not necessarily enhancing stability but potentially serving as predictors of future falls due to increased medio-lateral velocity of the center of mass (CoM). In their studies, they assessed not only kinetic variables but also kinematic variables using markers and a video camera system, which allowed for the analysis of both COP and COM.
When facing a postural threat, the central nervous system (CNS) adjusts agonist and antagonist muscle synergies during the anticipatory phase, favoring muscle reciprocal activation over co-activation [32]. In these studies, the most sensitive variable to the level of FoF turned out to be S1. The S1 variable represents the time required to prepare for taking a step, which includes both the anticipatory postural adjustment (APA) and the stepping phase. Before the stepping leg moves during step initiation, the APA occurs, shifting the COM toward the supporting side to allow the leg to be lifted. Subsequently, the time from exiting steady standing increased by about 21% during unimpeded transition, 33% during obstacle clearance, 34% during step-up, and almost 41% during step-down conditions between low and high concern groups. It can be assumed that each successive measurement condition was characterized by a greater degree of difficulty. Accordingly, the smallest difference between the groups could be observed in the unimpeded transition, compared to others condition. Uemura et al. [16] also noted similar trend. There were no differences between ‘fear’ and ‘no fear’ groups in APA during gait initiation. Only when a cognitive task was introduced into the motor task, a longer APA phase can be observed among ‘fear’ group. In the gait initiation test participants performed at least five steps on a 2-m walkway. In dual – task condition participants were required to count backward aloud while awaiting the visual cue.
When placing individuals in a state of postural threat, it was observed that prolonged APA during step initiation often correlates with a shorter first step [33]. A shorter stride reduces balance safety and increases the risk of falling. According to Ellmers et al. [33], larger APAs negatively impacted the mechanism but were required to produce step initiation. The authors introduced an actual condition that could provoke a FoF. The task of the participants was to cover a distance of about 3 m and four centimeters, as well as 1.1 m above the floor, without a harness. Based on the fear declarations and the Movement Specific Reinvestment Scale, participants were divided into a fearful and a non-fearful group. Fearful participants sought to ensure that the APA was sufficient to position their COM above the support leg prior to initiating the first step, though it resulted in a smaller step. On one hand, a concerning sign in older adults is the prolonged phase of APA, while on the other, its absence is equally worrisome. In the elderly, APAs play a key role in preserving lateral stability [34]. The authors suggested, that elderly without APAs were more prone to falling toward the swing leg side and showed greater lateral velocities compared to those with APAs.
A key finding of this study is that FoF did not affect the time required to regain balance after stepping (S2). There were no significant differences in S2 among the LOW, MODERATE, and HIGH concern groups across all conditions. Similarly, Marone et al. [9] reported no impact of FoF on recovery step length between fear and no fear groups. Their research procedure was different from ours. Participants did not overcome the obstacle, as in our study, but rather, they tripped over it. Trips were induced by using a hidden pneumatically driven obstacle when manually triggered. This suggests that while FoF may delay movement initiation, it does not impair the mechanisms for regaining balance post-step in healthy elderly individuals. However, in populations with neurodegenerative diseases, FoF has been shown to affect compensatory postural adjustments and reaction times [35, 36].
This study has several limitations. The sample was homogeneous, consisting exclusively of healthy older females, which restricts the generalizability of the findings to broader populations, including males and individuals with varying health statuses. Future research should include diverse populations, including those with a history of falls, to better understand the interplay between FoF and balance across different groups.
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