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

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.

Cross-Sectional Analysis of Fall-Related Factors with a Focus on Fall Prevention Self-Efficacy and Self-Cognition of Physical Performance among Community-Dwelling Older Adults

This study aimed to determine how fall prevention self-efficacy and degree of deviation in self-cognition of physical performance, which have recently received attention for their potential to explain falls in combination with a wide variety of fall-related factors, as well as affect falls. Older adults using day-care services (n = 27 with six men, mean age: 81.41 ± 7.43 years) were included in this study. Fall history in the past year, the modified fall efficacy scale (MFES), and physical performance and cognition errors were examined by evaluating the functional reach test (FRT), the stepping over test, and the timed up and go test (TUG), along with a questionnaire. In the fall (n = 14) and non-fall (n = 13) groups, logistic regression analysis using Bayesian statistical methods was used to identify factors associated with falls. The odds ratios for the MFES ranged from 0.97 to 1.0, while those of cognition-error items ranged from 3.1 to 170.72. These findings suggested that deviation in self-cognition of physical performance, particularly overestimation of timed cognitive ability, was a factor with more explanatory power for fall history. Future studies should analyze differences by disease and age group, which were not clarified in this study, to identify more detailed fall risk factors.

Foot clearance when crossing obstacles of different heights with the lead and trail limbs

BACKGROUND

In order to predict and prevent falls and fall-related injuries, it is crucial to understand the motor control for crossing obstacles. In real life, since obstacles do not always take regular shapes like rectangles, the lead and trail limbs sometimes need to negotiate different obstacle heights. The interlimb interaction in this process has remained unknown, since obstacle crossing studies commonly use a single-obstacle paradigm in which the obstacle height is the same for the lead and trail limbs.

RESEARCH QUESTION

We used a dual-obstacle paradigm to test whether the foot clearance over one obstacle was influenced by the contralateral obstacle's height.

METHODS

Sixteen healthy young male and female participants (age: 22.5 ± 1.9 years) crossed over two obstacles placed side by side. Four obstacle conditions were made by combining obstacles of two heights (low, L, 9.0 cm; high, H, 22.5 cm) of the obstacles.In the LL condition, both obstacles were low, and in the LH condition, there was a low obstacle for the lead limb and a high one for the trail limb. Similarly, we also arranged HL and HH conditions. Each subject performed 20 trials per condition. We compared the vertical foot clearance, prestep distance, and poststep distance between the conditions.

RESULT

The foot trajectory to step over the obstacles were affected by the contralateral obstacle's height. The vertical foot clearance of the trail limb was greater in the HL condition than in the LL condition. The vertical foot clearance of the lead limb was greater in the LH condition than in the LL condition.

SIGNIFICANCE

The results suggest that the foot trajectory was not determined exclusively by the obstacle to be crossed. Instead, comprehensive information, including the height of the obstacle for the other limb, might be used for motor control during obstacle crossing.

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.

Increased Time Difference between Imagined and Physical Walking in Older Adults at a High Risk of Falling

Walking motor imagery ability is thought to be associated with a fear of falling; however, no studies have compared fall risk and motor imagery ability. This study aimed to ascertain the time difference between imagined and physical walking in older adults at low and high risks of falling. Motor imagery ability was assessed using mental chronometry, which measures the imagined time required for movement. Participants included 31 older adults classified as having a high (n = 15) or low (n = 16) risk of falling based on single leg stance time. The time required for imagined and physical walking was measured using 5 m long walkways with three different widths (15, 25, and 50 cm), and the temporal errors (absolute and constant error) were compared. Physical walking time was significantly longer in the high-risk group than in the low-risk group for the 15 and 25 cm wide walkways. The absolute error between the imagined and physical walking times was significantly larger in the high-risk group than in the low-risk group for the 15 and 25 cm wide walkways. There was also a significant difference in the constant error between the high- and low-risk groups between the imagined and physical walking times for all three walkways. Older adults who may be at a higher risk of falling showed longer walking times during action execution but overestimated their performance (i.e., they believe they would be faster) during motor imagery. Therefore, the time difference between imagined and physical walking could, in part, be useful as a tool for assessing fall risk based on motor imagery.

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.