Older adults with history of falls are unable to perform walking and prehension movements simultaneously

Postural Stability When Grasping an Object While Standing: Younger and Older Adults (Fallers and Non-Fallers)

We investigated postural stability through the margin of stability (MoS) while reaching and grasping an object with increasing difficulty levels in younger, fallers and non-fallers. Forty-five individuals distributed into three groups participated in this study: younger adults (YA), non-fallers (OA), and fallers (FOA). They stood upright and reached and grasped a dowel. Six conditions combining the stability of the dowel's base and obstacles close to the dowel were manipulated to characterize different difficulty levels. We computed the MoS in both anterior-posterior (AP) and medial-lateral (ML) directions in the interval between reaching onset and dowel contact. From the MoS time series, we analyzed the minimum and maximum, including the time of occurrence of these events. The MoS was smaller for OA than for YA in both directions. In the ML direction, the minimum MoS was smaller for FOA than for YA. The minimum MoS took place earlier for FOA than YA in the AP direction. FOA and OA exhibited similar behavior with reduced MoS, suggesting impaired postural control during reaching-to-grasping in a standing posture. FOA used a more cautious strategy by reverting the MoS earlier than YA, allowing them to increase their MoS before YA when preparing to grasp the dowel.

The effects of age and postural constraints on prehension

Older adults adapt the execution of complex motor tasks to use compensatory strategies in the reaching-to-grasping (i.e., prehension) movement. The presence of postural constraints may exacerbate these compensatory strategies. Therefore, we investigated the reach-to-grasp action with different postural constraints (sitting, standing, and walking) in younger and older people and evaluated the postural stability during the reach-to-grasp action. Thirty individuals (15 younger and 15 older adults) performed the prehension under three postural tasks: sitting, standing, and walking. The reaching movement was slower in the walking task than in the other two postural tasks; however, there was no difference between the age groups. For the grasping action, the older adults presented a larger grip aperture, and the peak grip aperture occurred earlier during hand transportation in sitting and standing tasks. In the standing task, the margin of stability was smaller for older adults. In the walking task, there was no difference between the groups for the margin of stability. Also, prehension during sitting and standing tasks were similar, and both differed from walking across age groups. Finally, older adults reduced their margin of stability compared to younger adults, but only in the standing task. The margin of stability was similar between age groups during the walking task. We concluded that age affected grasping (distal component) but not reaching (proximal component), suggesting that healthy older adults have more difficulty controlling distal than proximal body segments.

Gait Kinematic and Kinetic Characteristics of Older Adults With Mild Cognitive Impairment and Subjective Cognitive Decline: A Cross-Sectional Study

Background

Older adults with mild cognitive impairment (MCI) have slower gait speed and poor gait performance under dual-task conditions. However, gait kinematic and kinetic characteristics in older adults with MCI or subjective cognitive decline (SCD) remain unknown. This study was designed to explore the difference in gait kinematics and kinetics during level walking among older people with MCI, SCD, and normal cognition (NC).

Methods

This cross-sectional study recruited 181 participants from July to December 2019; only 82 met the inclusion criteria and consented to participate and only 79 completed gait analysis. Kinematic and kinetic data were obtained using three-dimensional motion capture system during level walking, and joint movements of the lower limbs in the sagittal plane were analyzed by Visual 3D software. Differences in gait kinematics and kinetics among the groups were analyzed using multivariate analysis of covariance (MANCOVA) with Bonferroni post-hoc analysis. After adjusting for multiple comparisons, the significance level was p < 0.002 for MANCOVA and p < 0.0008 for post-hoc analysis.

Results

Twenty-two participants were MCI [mean ± standard deviation (SD) age, 71.23 ± 6.65 years], 33 were SCD (age, 72.73 ± 5.25 years), and 24 were NC (age, 71.96 ± 5.30 years). MANCOVA adjusted for age, gender, body mass index (BMI), gait speed, years of education, diabetes mellitus, and Geriatric Depression Scale (GDS) revealed a significant multivariate effect of group in knee peak extension angle (F = 8.77, p < 0.0001) and knee heel strike angle (F = 8.07, p = 0.001) on the right side. Post-hoc comparisons with Bonferroni correction showed a significant increase of 5.91° in knee peak extension angle (p < 0.0001) and a noticeable decrease of 6.21°in knee heel strike angle (p = 0.001) in MCI compared with NC on the right side. However, no significant intergroup difference was found in gait kinetics, including dorsiflexion, plantar flexion, knee flexion, knee extension, hip flexion, and hip extension(p > 0.002).

Conclusion

An increase of right knee peak extension angle and a decrease of right knee heel strike angle during level walking were found among older adults with MCI compared to those with NC.

Visual cues two-steps ahead are adequate to grasp an object while walking without compromising stability

In our prior studies, participants walked and grasped a dowel using an anticipatory mode of control. However, it is unknown how this combined task would change in a less predictable environment. We investigated the online control aspects involved in the combined task of walking and grasping under different coordination patterns between upper- and lower-limbs in young adults. Fifteen young adults walked and grasped a dowel under several experimental conditions combining the instant of visual cue appearance and coordination pattern of upper and lower limbs used to grasp the dowel. Visual cues provided two steps ahead or earlier were enough for executing the combined task of walking and prehension appropriately. Visual cues provided within this window impacted both walking stability and the execution of the prehension movement. Although an ipsilateral arm-leg coordination pattern increased mediolateral stability, a contralateral pattern significantly decreased mediolateral center of mass stability when the visual cue appeared one-step before grasping the object. These results imply that acquiring information to plan the combined task of walking and reaching for an object two steps ahead allows the maintenance of the general movement characteristics present when the decision to reach out for the object is defined two or more steps ahead. These results indicate that the prehension movement is initiated well before heel contact on that side when given sufficient planning time, but that a disruption of the natural arm-leg coordination dynamics emerges to accomplish the task when the cue is provided one step before the object.

Can dual-task paradigms predict Falls better than single task? - A systematic literature review

With about one third of adults aged 65 years and older being reported worldwide to fall each year, and an even higher prevalence with advancing age, aged-related falls and the associated disabilities and mortality are a major public health concern. In this context, identification of fall risk in healthy older adults is a key component of fall prevention. Since dual-task outcomes rely on the interaction between cognition and motor control, some studies have demonstrated the role of dual-task walking performance or costs in predicting future fallers. However, based on previous reviews on the topic, (1) discriminative and (2) predictive powers of dual tasks involving gait and a concurrent task are still a matter of debate, as is (3) their superiority over single tasks in terms of fall-risk prediction. Moreover, less attention has been paid to dual tasks involving postural control and transfers (such as gait initiation and turns) as motor tasks. In the present paper, we therefore systematically reviewed recent literature over the last 7 years in order to answer the three above mentioned questions regarding the future of lab-based dual tasks (involving posture, gait initiation, gait and turning) as easily applicable tests for identifying healthy older adult fallers. Despite great heterogeneity among included studies, we emphasized, among other things, the promising added value of dual tasks including turns and other transfers, such as in the Timed Up and Go test, for prediction of falls. Further investigation of these is thus warranted.

A taxonomy of cognitive tasks to evaluate cognitive-motor interference on spatiotemoporal gait parameters in older people: a systematic review and meta-analysis

Background

Walking in natural environments can be considered a dual-task (DT) scenario that requires increasing cognitive resources with advancing age. Previous reviews concluded that gait speed under DT conditions is equivalent to gait speed as a single task (ST) in the prediction of future falls in older people. However, without a clear taxonomy, these conclusions might be premature. The aim of this review is to use a taxonomy for classifying cognitive tasks of cognitive-motor interference (CMI) paradigms while walking to identify which task domains lead to more pronounced cognitive-motor decrements due to fall risk and concern about falling (CoF) in older people.

Methods

A systematic literature research following PRISMA guidelines was conducted using MEDLINE, Psych-Info and EMBASE. Inclusion criteria were: older people ≥60 years with a previous fall or CoF, use of a DT paradigm to discriminate fallers and non-fallers, straight overground walking, reported gait measurements during ST and DT conditions. A meta-analysis estimated the effect of DT costs for the cognitive task domain and spatiotemporal gait parameters.

Results

N = 3737 studies were found within the databases. Nineteen studies were included (n = 14 for meta-analysis). Fallers and people with CoF showed reduced walking speed for ST and DT conditions. Effects of DT were examined for mental tracking tasks. The combined odds ratio (OR [95% confidence interval]) for fallers vs. non-fallers for ST was 3.13 [0.47, 5.80] with moderate heterogeneity (I² = 48%). For DT, the OR was 5.17 [2.42, 7.93] with low heterogeneity (I² = 37%). Comparing participants with and without CoF, the OR for ST was 12.41 [9.97, 14.84] with high heterogeneity (I² = 85%) and OR for mental tracking DT was 10.49 [7.58, 13.40] with moderate heterogeneity (I² = 51%).

Conclusion

CMI was not significantly different between fallers and non-fallers or people with and without CoF; however, our taxonomy revealed a large variety of cognitive conditions and a higher number of studies using mental tracking tasks, which make it impossible to draw firm conclusions. Future studies should use a more standardised and ecologically valid approach when evaluating the validity of DT gait performance in the prediction of falls, CoF or other age-related conditions.

Trial registration

This review was registered at Prospero with the ID: CRD42017068912.

The difference of gait characteristic according to the variety of dual tasks in young healthy adults

BACKGROUND

Walking in daily life is often accompanied by an attention-demanding task, which requires a different attentional load and external environments. Therefore, various gaits require complex and systematic interactions between several nervous systems, such as sensory association, cognitive functions, and the musculoskeletal system.

OBJECTIVE

Dual-task conditions during gait can affect the interaction between cognitive processing and motor behavior. This study investigated the effect of two types of cognitive dual tasks and one type of manual dual task (MDT) on kinematic and spatiotemporal parameters of gait in young healthy adults.

METHODS

We recruited 30 healthy young adults in this study. All participants performed normal gait, and two types of cognitive tasks (subtraction dual task, SDT; and working memory dual task, WMDT) and MDT (carrying a cup filled with water) during gait. This study assessed kinematic data during the stance and swing phases and spatiotemporal parameters.

RESULTS

MDT gait showed a significant decrement of hip-joint movement during the stance phase compared to the normal gait (p < 0.05). Stride velocity significantly decreased during SDT and WMDT gait compared with the normal gait (p < 0.05). MDT gait showed significant decrement of all spatiotemporal parameters of gait compared with normal gait (p < 0.05).

CONCLUSION

We reported that MDT gait can induce decreased hip-joint motion during the stance phase and reduced all spatiotemporal parameters to maintain balance and reduce the risk of falling. Therefore, motor dual tasks while walking would be useful as an intervention strategy to rehabilitate or train people at risk for falling.

Walking combined with reach-to-grasp while crossing obstacles at different distances

BACKGROUND

Obstacle avoidance and object prehension occur regularly in real-world environments (walking up/down steps and opening a door). However, it is not known how walking and prehension change when there is an increase in the level of difficulty of the walking task.

RESEARCH QUESTION

We investigated the changes in walking and reach-tograsp when performing these two motor skills concomitantly in the presence of an obstacle on the ground positioned in different locations in relation to the object-to-be-grasped.

METHODS

Fifteen young adults walked and grasped a dowel placed on a support with the obstacle positioned at the step before (N-1), during (N) and after (N + 1) the prehension task.

RESULTS

The prehension task did not affect leading limb obstacle negotiation. Toe clearance and maximum toe elevation were lesser at obstacle position N + 1 than at obstacle position N-1 when combining grasping and obstacle-crossing task for the trailing limb. Step width increased in the presence of the obstacle-crossing task independent of obstacle location. The correlation between foot position before the obstacle and toe clearance revealed that the addition of the prehension task disrupted the relationship between these variables for the trailing limb. Foot placement and limb elevation were unaffected by the prehension task. The reaching component was unaffected by the increased level of difficulty of the walking task. The grasping component was affected by the increased level of difficulty of the walking task, as the time to peak grip aperture occurred earlier in the presence of the obstacle at position N, and may indicate a cautious strategy to grasp the dowel successfully.

SIGNIFICANCE

Our results showed that prospective control is affected after the prehension since the attention to grasping may have impaired the acquisition of visual information for planning the trailing limb elevation.

Performance of Faller and Nonfaller Older Adults on a Motor-Motor Interference Task

Typically, falls in older adults occur when 2 tasks are performed simultaneously, due to the increased motor demand required to maintain stability and attention to perform the other task. The authors' purpose was to investigate walking while grasping, transporting, and placing a dowel on a predetermined target while manipulating difficulty levels of the manual task. Faller and nonfaller older adults performed a walking block (manual tasks combined with gait) and a stationary block (upright stance combined with manual tasks). The manual task involved grasping, transporting, and placing the dowel over a target. The results showed that fallers underperformed when compared with nonfallers in the task of placing the dowel over the target. The main difference observed between the groups was found in the condition that required allocation of attention between tasks and greater accuracy in the final placement of the object. Fallers showed gait stability similar to the nonfallers, but fallers were less accurate than nonfallers in the object placement task, especially for the highest level of difficulty. Thus, fallers seem to use a stability-first strategy. Fallers had problems in executing the manual tasks, which suggests a more global change in motor behavior rather than specific changes to balance control.