Self-estimation of physical ability in stepping over an obstacle is not mediated by visual height perception: a comparison between young and older adults

Motor imagery does not effectively improve walking-related performance in older adults: A randomised controlled trial

BACKGROUND

Inaccurate perception of one's physical abilities is potentially related to age-related declines in motor planning and can lead to changes in walking. Motor imagery training is effective at improving balance and walking in older adults, but most research has been conducted on older adults following surgery or in those with a history of falls. Deficits in motor imagery ability are associated with reduced executive function in older adults with cognitive impairment.

OBJECTIVES

To determine whether walking-specific motor imagery training could improve walking performance (physical and imagined) in healthy older adults, and identify the relationship between actual and imagined movement, motor imagery accuracy and executive function across 5 different walking tasks in healthy older adults.

METHODS

A cohort of 53 community dwelling older adults took part in a 4-wk randomized controlled trial to assess the effect of motor imagery training on the physical and imagined performance of 5 walking-related tasks (3 narrow path walking tasks, Timed-up and go and step-over test), together with motor imagery clarity using the kinesthetic and visual imagery questionnaire (KVIQ-10). The association between physical performance, motor imagery accuracy and executive function were identified at baseline.

RESULTS

Four weeks of motor imagery training did not improve walking-specific performance (imagined or physical) compared to no-training. Motor imagery training did improve the visual clarity of imagined non-walking tasks. Executive function was significantly correlated with 2 out of 5 imagined walking tasks and 4 out of 5 physical walking tasks but was not associated with motor imagery accuracy.

CONCLUSION

Four weeks of motor imagery training is not effective at improving performance in walking-related tasks in healthy older adults. This lack of improvement may be due in part to the high functional ability of the cohort. Future research should assess the relationship between motor planning and executive function with more complex walking tasks.

TRIAL REGISTRATION

ANZCTR registration (ACTRN12619001784101).

The tool effect is lower in older adults with or without cognitive impairments than in young adults

Grabbing a phone from a table or stepping over an obstacle on the ground are daily activities that require the brain to take account of both object and the body's parameters. Research has shown that a person's estimated maximum reach is temporarily overestimated after using a tool, even when the tool is no longer in hand. This tool effect reflects the high plasticity of the perceptual-motor system (e.g., body schema updating)-at least in young individuals. The objective of the present study was to determine whether the tool effect is smaller in older adults. Forty-four young adults, 37 older adults without cognitive impairment and 30 older adults with cognitive impairment took part in the experiment. The task consisted in visually estimating the ability to reach (using the index finger) a target positioned at different locations on a table, both before and after using a rake. We observed a strong after-effect of tool use in the young adults only. Conversely, a tool effect was similarly absent in the older adults without and with cognitive impairment. Moreover, even before the tool was used, the maximum reach was overestimated in each of the three groups, although the overestimation was greatest in the two groups of older adults. In summary, we showed that the tool effect, observed in young adults, was absent in older adults; this finding suggests that with advancing age, the perceptual-motor system is less able to adapt to novel sensorimotor contexts. This lack of adaptation might explain (at least in part) the overestimation of motor skills often reported in the elderly.

The influence of age and age simulation on task-difficulty choices in motor tasks

    Having a realistic perception of one's motor abilities is important for successful aging. We used two different motor tasks, carrying a tray with cube-towers (study 1; n = 20 young adults; n = 20 older adults), and stepping over a crossbar (study 2; n = 23 young adults; n = 21 older adults), to investigate how physical risk influences task-difficulty choices. We also investigated the effect of wearing an age simulation suit on young adults. For the tray-carrying task, older adults were more risk-tolerant in their task-difficulty choices. When stepping over the crossbar, older adults left a larger "safety-buffer" than young adults. When wearing the age suit, young adults adopted a more careful strategy in the stepping task. We conclude that healthy older adults flexibly adjust their strategies to postural risks, and that young adults' strategy-choices can be influenced by experimentally inducing some of the sensory-motor constraints of old age.

Physical Activity Levels and Self-perception of Fitness in COVID-19-Recovered Individuals

Background: The preventative measures to reduce the incidence of coronavirus disease 2019 (COVID-19) have reduced the physical activity level (PAL) that might also affect physical and mental health. Objectives: The present study investigated the relationship between self-perception of fitness (SPF) and PAL in COVID-19-recovered individuals (CRI). Methods: The population of this descriptive-analytical study included all CRI (men and women, in the age range of 20 to 70 years) in Kermanshah. In the present study, 890 volunteers (438 men and 452 women) were sampled using a multistage cluster sampling method. The International Physical Activity Questionnaire (IPAQ-SF) was used to assess the PAL and the Delignières et al. questionnaire to assess the SPF. The Pearson correlation coefficient test and independent t-test were used to analyze the data using SPSS version 24 software. Results: The results showed low PAL (men: 876.11 ± 40.23; women: 739.27 ± 8.02) and poor SPF (men: 6.64 ± 1.62; women: 5.27 ± 1.39) in CRI. Also, there was a significant positive relationship between high and moderate PAL and SPF in men (r = 0.67, P = 0.032; r = 0.77, P = 0.018, respectively) and women (R = 0.56, P = 0.041; r = 0.66, P = 0.035, respectively), while there was a significant inverse relationship between low PAL and SPF among men (r = -0.85, P = 0.001) and women (r = -0.89, P = 0.001). Conclusions: Based on the results, wrong SPF in individuals with low PAL might be one reason for being insufficiently active. Thus, a proper understanding of PAL could be the first step of a regular physical activity schedule to enhance the immune system.

Changes in self-estimated step-over ability among older adults: A 3-year follow-up study

OBJECTIVES

There is a growing body of literature examining age-related overestimation of one's own physical ability, which is a potential risk of falls in older adults, but it is unclear what leads them to overestimate. This study aimed to examine 3-year longitudinal changes in self-estimated step-over ability, along with one key risk factor: low frequency of going outdoors (FG), which is a measure of poor daily physical activity.

METHOD

This cohort study included 116 community-dwelling older adults who participated in baseline and 3-year follow-up assessments. The step-over test was used to measure both the self-estimated step-over bar height (EH) and the actual bar height (AH). Low FG was defined as going outdoors either every few days or less at baseline.

RESULTS

The number of participants who overestimated their step-over ability (EH>AH) significantly increased from 10.3% to 22.4% over the study period. AH was significantly lower at follow-up than at baseline in both participants with low and high FGs. Conversely, among participants with low FG, EH was significantly higher at follow-up than at baseline, resulting in increased self-estimation error toward overestimation. Regression model showed that low FG was independently associated with increased error in estimation (i.e., tendency to overestimate) at follow-up.

DISCUSSION

The present study indicated that self-overestimated physical ability in older adults is not only due to decreased physical ability but also due to increased self-estimation of one's ability as a function of low FG. Active lifestyle may be critical for maintaining accurate estimations of one's own physical ability.

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

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.

Does misjudgement in a stepping down paradigm predict falls in an older population?

Although measures of actual and perceived physical ability appear to predict falls in older adults, a disparity between these two, also known as misjudgement, may even better explain why some older adults fall, while their peers with similar abilities do not. Therefore, we investigated whether adding a misjudgement term improved prediction of future falls. Besides conventional measures of actual (physical measures) and perceived abilities (questionnaires), we used a stepping down paradigm to quantify behavioural misjudgement. In a sample of 55 older adults (mean age 74.5 (s.d. = 6.6) years, 33 females and 20 fallers over a 10-month follow-up period), we tested the added value of a misjudgement term and of a stepping-down task by comparing experimental Bayesian logistic-regression models to a default null model, which was composed of the conventional measures: Falls Efficacy Scale international and QuickScreen. Our results showed that the default null model fitted the data most accurately; however, the accuracy of all models was low (area under the receiver operating characteristic curve (ROC) ≤ 0.65). This indicates that neither a misjudgement term based on conventional measures, nor on behavioural measures improved the prediction of future falls in older adults (Bayes Factor₁₀ ≤ 0.5).

Do Older People Accurately Estimate the Length of Their First Step during Gait Initiation?

Background/Study Context: Advancing age is associated with a decrease in step length. In line with previous studies showing that older adults often overestimate their motor abilities, we investigate whether older adults overestimate the length of their first step during gait initiation. The underlying effect could be a failure to update the internal model of motor action as a function of age-related motor decline. Methods: Without taking a step, community-dwelling older women (n = 22, age range: 68-87 years) and younger women (n = 19, age range: 19-33 years) estimated the length of their first step for both preferred step length and largest step length, which were performed without endangerment. Thereafter, the participants performed real gait initiation for both types of steps. The estimated step lengths were compared to the actual step lengths. Results: Older adults judged their first step as larger than it was (mean error: 30% for the preferred step and 9% for the largest step). A fine-grained analysis showed that this effect mainly concerned those for whom an increased risk of falling was suspected. These older adults were also among those who performed the shortest steps, and they presented with a slight decrease in cognitive functioning. Younger participants underestimated their preferred step length. Overall, the estimates were more accurate for the largest steps than for the preferred-length steps. Conclusion: Step length estimation revealed powerful evidence for overestimation in older adults. Those who overestimated step length presented with more signs of motor decline. While this result sustains the idea of an insufficient actualization of the motor-action model, the explanation also refers to more global appraisal processes. Further research should explore the relevance of this task as a clinical laboratory tool for assessing gait capacity and the risk of falling.

Do Older Adults Select Appropriate Motor Strategies in a Stepping-Down Paradigm?

Selecting motor strategies in daily life tasks requires a perception of the task requirements as well as of one's own physical abilities. Age-related cognitive and physical changes may affect these perceptions. This might entail that some older adults select inappropriate movement strategies when confronted with daily-life motor tasks, which could lead to balance loss or falls. We investigated whether older adults select motor strategies in accordance with their actual physical ability. Twenty-one older adults were subjected to a stepping down paradigm, in which full-body kinematics of selected and reactive behavior were recorded. Stepping down from a curb can be done with either (1) a relatively low effort but more balance threatening heel landing, or (2) a more controlled but more demanding toe landing. The probability of selecting a toe landing grows with an increase in curb height. We determined the curb height at which participants switched from heel to toe landing during expected stepping down over different heights as an indicator of their perceived ability. During an unexpected step down trial, participants encountered a step down of 0.1 m earlier than expected, because part of the walkway was removed and covered by a black cloth. We evaluated participants' actual physical ability from the reactive behavior, with performance defined as the reduction in kinetic energy between the peak value after landing and the onset of the next step. To unravel whether the selected motor strategies corresponded with actual physical ability, the ability to recover from the unexpected step down was correlated to the height at which the participants switched movement strategy. The switching height was not correlated to the ability to recover from an unexpected step down (ρ = 0.034, p = 0.877). This finding suggests that older adults do not select their movement strategy in stepping down based on their actual abilities, or have an imprecise perception of their actual abilities. Future research should evaluate whether inappropriate motor strategy selection in a stepping down paradigm can explain accidental falls in older adults.

On the validity and consistency of misjudgment of stepping ability in young and older adults

Disparities between perceived and actual physical abilities have been shown in older adults and may lead to balance loss or falls. However, it is unclear whether one’s misjudgment is an inherent trait and thus consistent across different tasks, and whether this misjudgment is age-related. We measured the degree of misjudgment in young and older adults on four different stepping tasks; stepping over a raised bar, crossing a declining cord by stepping over it at a self-selected height, crossing a virtual river by stepping over it at a self-selected width, and making a recovery step after release from an inclined position. Before comparison, we carefully checked the validity of the different tasks to determine the misjudgment. No substantial differences were found in the amplitude of the misjudgment between the age groups, and the degree of misjudgment did not transfer across different stepping tasks. However, since only one task (i.e., stepping over a raised bar) met our criteria for validly assessing one’s misjudgment, it remains unclear whether the degree of misjudgment is task-specific or an inherent trait. These findings stress the importance of testing the construct validity of the task, prior to the examination of the misjudgment of stepping ability.

Neural correlates of older adults' self-overestimation of stepping-over ability

A growing body of literature indicates that cognitively intact older adults tend to overestimate their physical functioning (e.g., step-over ability), which may lead to fall risk. However, the neural correlates underlying this phenomenon are still unclear. We therefore investigated the neural basis of older adults' self-overestimation of stepping-over ability. A total of 108 well-functioning community dwelling older adults (mean age = 73.9 years) performed step-over tests (SOT) in two ways: self-estimation of step-over ability and an actual step-over task. During the self-estimation task, participants observed a horizontal bar at a distance of 7 m and estimated the maximum height (EH) of successful SOT trials. The actual SOT was then performed to determine the actual maximum height (AH) of successful trials. Participants also underwent positron emission tomography with ¹⁸F-fluorodeoxyglucose at rest to assess cerebral neural activity. The SOT showed that 22.2 % of participants overestimated their step-over ability. A regression analysis adjusted for potential covariates showed that increased self-estimation error (difference between EH and AH) was correlated with lower glucose metabolism in the bilateral orbitofrontal cortex (OFC) and left frontal pole. Only the significant correlation between self-estimation error and OFC activity persisted after correcting for multiple comparisons. For well-functioning healthy older adults, overlooking one's own functional decline may be influenced by reduced metabolic activity in the anterior prefrontal cortex, particularly in the OFC. Our findings also suggest that functional decline in the OFC prevents older adults from updating the qualitative/quantitative values of their impaired physical abilities.