The association between choice stepping reaction time and falls in older adults--a path analysis model

Working memory load modulates anticipatory postural adjustments during step initiation

Working memory (WM) can influence selective attention. However, the effect of WM load on postural standing tasks has been poorly understood, even though these tasks require attentional resources. The purpose of this study was to examine whether WM load would impact anticipatory postural adjustments (APAs) during step initiation. Sixteen healthy young adults performed stepping tasks alone or concurrently with a WM task in a dual-task design. The stepping tasks involved volitional stepping movements in response to visual stimuli and comprised of simple and choice reaction time tasks and the Flanker task which consisted of congruent and incongruent (INC) conditions. In the dual-task condition, subjects were required to memorize either one or six digits before each stepping trial. Incorrect weight transfer prior to foot-lift, termed APA errors, reaction time (RT), and foot-lift time were measured from the vertical force data. The results showed that APA error rate was significantly higher when memorizing six-digit than one-digit numerals in the INC condition. In addition, RT and foot-lift time were significantly longer in the INC condition compared to the other stepping conditions, while there was no significant effect of WM load on RT or foot-lift time. These findings suggest that high WM load reduces the cognitive resources needed for selective attention and decision making during step initiation.

The Casual Association Inference for the Chain of Falls Risk Factors-Falls-Falls Outcomes: A Mendelian Randomization Study

Previous associations have been observed not only between risk factors and falls but also between falls and their clinical outcomes based on some cross-sectional designs, but their causal associations were still largely unclear. We performed Mendelian randomization (MR), multivariate Mendelian randomization (MVMR), and mediation analyses to explore the effects of falls. Our study data are mainly based on White European individuals (40-69 years) downloaded from the UK Biobank. MR analyses showed that osteoporosis (p = 0.006), BMI (p = 0.003), sleeplessness (p < 0.001), rheumatoid arthritis (p = 0.001), waist circumference (p < 0.001), and hip circumference (p < 0.001) have causal effects on falls. In addition, for every one standard deviation increase in fall risk, the risk of fracture increased by 1.148 (p < 0.001), the risk of stroke increased by 2.908 (p = 0.003), and a 1.016-fold risk increase in epilepsy (p = 0.009). The MVMR found that sleeplessness is an important risk factor for falls. Finally, our mediation analyses estimated the mediation effects of falls on the hip circumference and fracture (p < 0.001), waist circumference and epilepsy (p < 0.001), and sleeplessness and fracture (p = 0.005). Our study inferred the causal effects between risk factors and falls, falls, and outcomes, and also constructed three causal chains from risk factors → falls → falls outcomes.

Accuracy-speed-stability trade-offs in a targeted stepping task are similar in young and older adults

Introduction

Stepping accuracy, speed, and stability are lower in older compared to young adults. Lower stepping performance in older adults may be due to larger accuracy-speed-stability trade-offs because of reduced ability to simultaneously fulfill these task-level goals. Our goal was to evaluate whether trade-offs are larger in older compared to young adults in a targeted stepping task. Since sensorimotor function declines with age, our secondary goal was to evaluate whether poorer sensorimotor function was associated with larger trade-offs.

Methods

Twenty-five young (median 22 years old) and 25 older (median 70 years old) adults stepped into projected targets in conditions with various levels of accuracy, speed, and stability requirements. We determined trade-offs as the change in performance, i.e., foot placement error, step duration, and mediolateral center of pressure path length, between each of these conditions and a control condition. To assess age-related differences in the magnitude of trade-offs, we compared the change in performance between age groups. Associations between trade-offs and measures of sensorimotor function were tested using correlations.

Results

We found an accuracy-speed and an accuracy-stability trade-off in both young and older adults, but trade-offs were not different between young and older adults. Inter-subject differences in sensorimotor function could not explain inter-subject differences in trade-offs.

Conclusion

Age-related differences in the ability to combine task-level goals do not explain why older adults stepped less accurate and less stable than young adults. However, lower stability combined with an age-independent accuracy-stability trade-off could explain lower accuracy in older adults.

Systematic review of candidate prognostic factors for falling in older adults identified from motion analysis of challenging walking tasks

The objective of this systematic review is to identify motion analysis parameters measured during challenging walking tasks which can predict fall risk in the older population. Numerous studies have attempted to predict fall risk from the motion analysis of standing balance or steady walking. However, most falls do not occur during steady gait but occur due to challenging centre of mass displacements or environmental hazards resulting in slipping, tripping or falls on stairs. We conducted a systematic review of motion analysis parameters during stair climbing, perturbed walking and obstacle crossing, predictive of fall risk in healthy older adults. We searched the databases of Pubmed, Scopus and IEEEexplore.A total of 78 articles were included, of which 62 simply compared a group of younger to a group of older adults. Importantly, the differences found between younger and older adults did not match those found between older adults at higher and lower risk of falls. Two prospective and six retrospective fall history studies were included. The other eight studies compared two groups of older adults with higher or lower risk based on mental or physical performance, functional decline, unsteadiness complaints or task performance. A wide range of parameters were reported, including outcomes related to success, timing, foot and step, centre of mass, force plates, dynamic stability, joints and segments. Due to the large variety in parameter assessment methods, a meta-analysis was not possible. Despite the range of parameters assessed, only a few candidate prognostic factors could be identified: older adults with a retrospective fall history demonstrated a significant larger step length variability, larger step time variability, and prolonged anticipatory postural adjustments in obstacle crossing compared to older adults without a fall history. Older adults who fell during a tripping perturbation had a larger angular momentum than those who did not fall. Lastly, in an obstacle course, reduced gait flexibility (i.e., change in stepping pattern relative to unobstructed walking) was a prognostic factor for falling in daily life. We provided recommendations for future fall risk assessment in terms of study design.In conclusion, studies comparing older to younger adults cannot be used to explore relationships between fall risk and motion analysis parameters. Even when comparing two older adult populations, it is necessary to measure fall history to identify fall risk prognostic factors.

An Analysis of Lower Limb Coordination Variability in Unilateral Tasks in Healthy Adults: A Possible Prognostic Tool

Interlimb coordination variability analysis can shed light into the dynamics of higher order coordination and motor control. However, it is not clear how the interlimb coordination of people with no known injuries change in similar activities with increasing difficulty. This study aimed to ascertain if the interlimb coordination variability range and patterns of healthy participants change in different unilateral functional tasks with increasing complexity and whether leg dominance affects the interlimb coordination variability. In this cross-sectional study fourteen younger participants with no known injuries completed three repeated unilateral sit-to-stands (UniSTS), step-ups (SUs), and continuous-hops (Hops). Using four inertial sensors mounted on the lower legs and thighs, angular rotation of thighs and shanks were recorded. Using Hilbert transform, the phase angle of each segment and then the continuous relative phase (CRP) of the two segments were measured. The CRP is indicative of the interlimb coordination. Finally, the linear and the nonlinear shank-thigh coordination variability of each participant in each task was calculated. The results show that the linear shank-thigh coordination variability was significantly smaller in the SUs compared to both UniSTS and Hops in both legs. There were no significant differences found between the latter two tests in their linear coordination variability. However, Hops were found to have significantly larger nonlinear shank-thigh coordination variability compared to the SUs and the UniSTS. This can be due to larger vertical and horizontal forces required for the task and can reveal inadequate motor control during the movement. The combination of nonlinear and linear interlimb coordination variability can provide more insight into human movement as they measure different aspects of coordination variability. It was also seen that leg dominance does not affect the lower limb coordination variability in participants with no known injuries. The results should be tested in participants recovering from lower limb injuries.

Neural Bases of Age-Related Sensorimotor Slowing in the Upper and Lower Limbs

With advanced age, there is a loss of reaction speed that may contribute to an increased risk of tripping and falling. Avoiding falls and injuries requires awareness of the threat, followed by selection and execution of the appropriate motor response. Using event-related potentials (ERPs) and a simple visual reaction task (RT), the goal of our study was to distinguish sensory and motor processing in the upper- and lower-limbs while attempting to uncover the main cause of age-related behavioral slowing. Strength (amplitudes) as well as timing and speed (latencies) of various stages of stimulus- and motor-related processing were analyzed in 48 healthy individuals (young adults, n = 24, mean age = 34 years; older adults, n = 24, mean age = 67 years). The behavioral results showed a significant age-related slowing, where the younger compared to older adults exhibited shorter RTs for the upper- (222 vs. 255 ms; p = 0.006, respectively) and the lower limb (257 vs. 274 ms; p = 0.048, respectively) as well as lower variability in both modalities (p = 0.001). Using ERP indices, age-related slowing of visual stimulus processing was characterized by overall larger amplitudes with delayed latencies of endogenous potentials in older compared with younger adults. While no differences were found in the P1 component, the later components of recorded potentials for visual stimuli processing were most affected by age. This was characterized by increased N1 and P2 amplitudes and delayed P2 latencies in both upper and lower extremities. The analysis of motor-related cortical potentials (MRCPs) revealed stronger MRCP amplitude for upper- and a non-significant trend for lower limbs in older adults. The MRCP amplitude was smaller and peaked closer to the actual motor response for the upper- than for the lower limb in both age groups. There were longer MRCP onset latencies for lower- compared to upper-limb in younger adults, and a non-significant trend was seen in older adults. Multiple regression analyses showed that the onset of the MRCP peak consistently predicted reaction time across both age groups and limbs tested. However, MRCP rise time and P2 latency were also significant predictors of simple reaction time, but only in older adults and only for the upper limbs. Our study suggests that motor cortical processes contribute most strongly to the slowing of simple reaction time in advanced age. However, late-stage cortical processing related to sensory stimuli also appears to play a role in upper limb responses in the elderly. This process most likely reflects less efficient recruitment of neuronal resources required for the upper and lower extremity response task in older adults.

Participation in cognitive activities is associated with foot reaction time and gait speed in older adults

BACKGROUND

Given the evidence of the links between cognition and mobility, participation in cognitive activities may benefit neuromotor performance and mobility in older adults.

AIMS

To examine the association between participation in cognitive activities and foot reaction time (RT) and gait speed in community-dwelling older adults.

METHODS

The MOBILIZE Boston Study II (MBSII) re-enrolled 354 community-dwelling older adults aged ≥ 70 years from the original MBS cohort. Of these, 310 completed the performance testing and we excluded three participants who had Parkinson's disease. Cognitive Activities Scale (CAS) assessed participation in 17 cognitive activities. Simple and Choice foot RT (SRT, CRT, msec) and gait speed (m/s) were measured using a sensored GAITRite® gait mat.

RESULTS

The average age of the 307 participants was 84 years; 79% were white and 65% were women. The average CAS score was 25.5 ± 11.7, indicating participation in approximately 26 activities per week on average. The average foot SRT was 245 ± 57msec and average CRT was 323 ± 85msec. Usual-paced gait speed was 0.9 ± 0.3 m/s on average. More frequent participation in cognitive activities was associated with shorter SRT (β = - 0.759, p = 0.015) and CRT (β = - 1.125, p = 0.013), and faster gait speed (β = 0.003, p = 0.026), after adjusting for potential confounders.

DISCUSSION

Participation in cognitively stimulating activities may be beneficial for neuromotor performance and mobility in older adults.

CONCLUSIONS

Prospective and intervention studies are needed to determine whether participation in cognitive activities may prevent mobility decline over time, and thus reduce fall risk.

A Randomized Controlled Trial Protocol to Test the Efficacy of a Dual-Task Multicomponent Exercise Program vs. a Simple Program on Cognitive and Fitness Performance in Elderly People

BACKGROUND

The necessity of improve the life quality in elderly people is well-known. The aim of this study was to determine the effects of physical and cognitive training programs, as well as their combination on the cognitive functions and physical capacities in women over 80 years old.

METHODS

Forty-three women took part in this study (80.86 ± 5.03 years). They were divided into four groups (three experimental groups and one control group). Experimental group 1 performed cognitive training. Experimental group 2 did physical-cognitive training, and Experimental Group 3 accomplished physical training. All of training programs had duration of eight weeks (five sessions of 60 min per week). We measured cognitive variables with the Stroop test, D2 test, and Trail Making test. Physical variables were measured with handgrip strength, Minute Step Test, and visual-acoustic reaction time.

RESULTS

Control group reduces his physical and cognitive capacities, while the three experimental groups increase these capacities. We found a strong correlation between the increase of physical and cognitive capacities.

CONCLUSION

Eight weeks of training physical, cognitive or mixed, increased physical and cognitive functions of elderly people which may reduce the negative effects of the aging process.

Stepping impairment and falls in older adults: A systematic review and meta-analysis of volitional and reactive step tests

OBJECTIVE

To systematically examine stepping performance as a risk factor for falls. More specifically, we examined (i) if step tests can distinguish fallers from non-fallers and (ii) the type of step test (e.g. volitional vs reactive stepping) that is required to distinguish fallers from non-fallers.

DATA SOURCE

PubMed, EMBASE, CINAHL, Cochrane Database of Systematic Reviews and reference lists of included articles.

STUDY SELECTION

Cross-sectional and cohort studies that assessed the association between at least one step test and falls in older people (age ≥ 60 and/or mean age of 65).

RESULTS

A meta-analysis of 61 studies (n = 9536) showed stepping performance was significantly worse in fallers compared to non-fallers (Cohen'sd 0.56, 95 % CI 0.48 to 0.64, p < 0.001, I² 66 %). This was the case for both volitional and reactive step tests. Twenty-three studies (n = 3615) were included in a diagnostic meta-analysis that showed that step tests have moderate sensitivity (0.70, 95 % CI 0.62 to 0.77), specificity (0.68, 95 % CI 0.58 to 0.77) and area under the receiver operating characteristics curve (AUC) (0.75, 95 % CI 0.59 to 0.86) in discriminating fallers from non-fallers.

CONCLUSIONS

This large systematic review demonstrated that both volitional and reactive stepping impairments are significant fall risk factors among older adults. Step tests can identify fallers from non-fallers with moderate accuracy.

Neurocognitive measures predict voluntary stepping performance in older adults post-hip fracture

BACKGROUND

Hip fracture is a debilitating injury, especially in older adults. The purpose of this study was to determine the relationships between Trail-Making test performance and parameters of the choice stepping reaction time test in community-dwelling older adults after hip fracture.

METHODS

Twenty-four older adults post-hip fracture repair participated in an ancillary study for physical therapy interventions. Measures included Trail-Making test (Parts A & B) scores, movement time (time from foot liftoff to touchdown), step speed, reaction time (time from cue to foot liftoff), and total response time (time from step cue to touchdown) in the forward and lateral directions. Paired t-tests and multiple linear regressions were used for analysis.

FINDINGS

Significant differences were found in movement time, speed and reaction time between limbs in the lateral direction, and in movement and reaction time in the forward direction. Trails A predicted step speed, reaction time and total response time for the fractured limb in the lateral direction, as well as reaction time and total response time in the forward direction. However, Trails A could not predict performance for the non-fractured limb. Trails B predicted stepping performance for both limbs in the forward and lateral directions.

INTERPRETATION

Trails A correlated with the fractured limb's ability to perform the choice stepping test, but not in the non-fractured limb. Meanwhile, Trails B correlated with stepping performance in both limbs, suggesting those with poorer executive function have a lower protective stepping capability and may be at a higher risk for future falls and injury.

Kinetic, muscle structure, and neuromuscular determinants of weight transfer phase prior to a lateral choice reaction step in older adults

The present study aimed to investigate the association between rate of torque development (RTD), rate of activation (RoA), and muscle structure [muscle cross-sectional area (CSA), intramuscular fat (IMAT) and high density lean muscle (HDL)] with the weight transfer phase (WTP) during a choice reaction step test (CST) in older adults. Fifteen healthy older adults (7 females) participated in this study. Stance leg hip adductors RTD at 100, 150, and 200 ms, showed a significant inverse correlation with WTP (r ≥ 0.658, P ≤ 0.010). There was a significant inverse relationship between WTP and adductor magnus and tensor fascia latae RoA at all time points (RoA0-50-RoA0-200; r ≥ 0.707, P ≤ 0.033). In contrast, the WTP was not significantly associated with the hip abductor RTD, gluteus medius RoA, or muscle structure (CSA, IMAT, and HDL). Swing leg showed no significant relationship between WTP and RTD, RoA or muscle structure of the hip abductor or adductor muscles. In conclusion, the present study showed that hip adductor torque-time capacity, as well as neuromuscular activation of the adductor magnus and tensor fascia latae of the stance leg during a maximal isometric test, is associated with the ability to transfer body weight before a step to the side occurs.

Reliability of measurement reliability and optimal number of measurements for mental arithmetic reaction time test

[Purpose] The main objective of this study was to assess the reliability of the method for testing the attention distribution ability of the elderly using mental arithmetic response time. [Participants and Methods] The participants included in the study were 30 healthy elderly people (over 65 years old), 11 males and 19 females, eight of whom had experienced falls in the past year.In the quiet standing position and the free walking state, we recorded the mental calculation response time of the participants by calculating the two-digit plus or minus one-digit values within 100. The test of the two states were tested in 24 hour intervals. [Results] In the quiet standing and free walking state, the correlation coefficient of the mental arithmetic response time group of the elderly was excellent. The intra-group correlation coefficient of mental arithmetic response time of more than three tests under free walking was greater than 0.9. [Conclusion] We found that the mental arithmetic response time can be used to objectively evaluate the ability of attention distribution in the elderly.

Relative contribution of muscle strength, lean mass, and lower extremity motor function in explaining between-person variance in mobility in older adults

BACKGROUND

Approximately 35% of individuals > 70 years have mobility limitations. Historically, it was posited lean mass and muscle strength were major contributors to mobility limitations, but recent findings indicate lean mass and muscle strength only moderately explain mobility limitations. One likely reason is that lean mass and muscle strength do not necessarily incorporate measures globally reflective of motor function (defined as the ability to learn, or to demonstrate, the skillful and efficient assumption, maintenance, modification, and control of voluntary postures and movement patterns). In this study we determined the relative contribution of lean mass, muscle strength, and the four square step test, as an index of lower extremity motor function, in explaining between-participant variance in mobility tasks.

METHODS

In community-dwelling older adults (N = 89; 67% women; mean 74.9 ± 6.7 years), we quantified grip and leg extension strength, total and regional lean mass, and time to complete the four square step test. Mobility was assessed via 6-min walk gait speed, stair climb power, 5x-chair rise time, and time to complete a complex functional task. Multifactorial linear regression modeling was used to determine the relative contribution (via semi-partial r2) for indices of lean mass, indices of muscle strength, and the four square step test.

RESULTS

When aggregated by sex, the four square step test explained 17-34% of the variance for all mobility tasks (p <  0.01). Muscle strength explained ~ 12% and ~ 7% of the variance in 6-min walk gait speed and 5x-chair rise time, respectively (p <  0.02). Lean mass explained 32% and ~ 4% of the variance in stair climb power and complex functional task time, respectively (p <  0.02). When disaggregated by sex, lean mass was a stronger predictor of mobility in men.

CONCLUSION

The four square step test is uniquely associated with multiple measures of mobility in older adults, suggesting lower extremity motor function is an important factor for mobility performance.

TRIAL REGISTRATION

NCT02505529 -2015/07/22.

Chronic Musculoskeletal Pain and Foot Reaction Time in Older Adults

This cross-sectional study examines the association between chronic musculoskeletal pain and foot reaction time (RT) among older community-living adults. Participants were 307 adults aged 71 years and older in the MOBILIZE Boston Study II. Pain severity, interference, and location were measured by the Brief Pain Inventory and a joint pain questionnaire. With participants seated, simple foot reaction time was measured as self-selected foot response time to an intermittent light, and choice foot reaction time was measured as response time to the light on the corresponding side of the sensored gait mat. We performed multivariable linear regression to determine associations of pain and foot RT, adjusted for sociodemographic and health characteristics, and serially adjusted for cognitive function (MMSE or Trail Making A). Pain severity and interference were associated with slower simple foot reaction time (P < .05). Pain severity and knee pain were associated with slower choice foot reaction time (P < .05). Adjustment for cognitive measures had little impact on the pain-RT relationship. This significant relationship was only observed among participants with less education. These results support the idea that chronic pain may lead to slower foot RT, thus could represent a fall hazard in older adults. Neuromotor mechanisms underlying the pain-fall relationship warrant further investigation. PERSPECTIVE: This study provides insights on the mechanisms underlying the pain-fall relationship. Chronic pain may contribute to slower foot RT thus increase fall risk in older adults. This may help inform interventions such as stepping training to reduce fall risk in older adults living with chronic pain.

Effects of Ankle Angular Position and Standing Surface on Postural Control of Upright Stance

The purpose of the study was to investigate the effects of ankle angular position and standing surface type on static upright balance. Ten young adults stood on a force platform or on a firm wedge that induced 15° of either dorsiflexion or plantarflexion. In addition, a piece of foam was placed on top of the force platform and on the wedge. The center of pressure distance and velocity in the anteroposterior and mediolateral directions were calculated. Significantly larger magnitudes in most of the investigated variables were seen while standing with ankles in the dorsiflexion when compared with standing with the ankle joints in a natural position (p < .05). Plantarflexion increased the center of pressure anteroposterior velocity by 87% when compared with a natural stance (p < .05). Standing on the foam surfaces resulted in increases in all of the center of pressure measures by an average of 38% in all of the ankle conditions.

A Novel Square-Stepping Exercise Program for Older Adults (StepIt): Rationale and Implications for Falls Prevention

The ability to effectively execute compensatory steps is critical for preventing accidental falls, and consequently stepping training is an essential ingredient of fall prevention programs. In this paper, we propose a concept for stepping training that aims to maximize training effects by taking into account recent research evidence and a precise dosing of training ingredients. The concept addresses motor as well as cognitive falls-related aspects, it is suitable for individual as well as group based training, and it does not require costly equipment. Theory and evidence behind all of the training principles is reviewed, and an example of an exercise protocol is described in detail. Participants are presented with stepping patterns which they have to memorize and implement on a mat. In order to enable investigation of dose-response effects, the difficulty level systematically and gradually increases session by session based on four principles: execution speed, pattern complexity, pattern length and execution in dual-/multi-tasking conditions. The presented concept can be used as a framework for the development of further prevention and/or rehabilitation stepping exercise programs. Further studies using this exercise regimen or modified versions of it are encouraged.

Explaining Upper or Lower Extremity Crossover Effects of Visuomotor Choice Reaction Time Training

Current evidence indicates a strong relation between improved visuomotor choice reaction time (VMRT) and a reduced risk of lower extremity injury, making both lower- and upper extremity VMRT training paradigms valuable to athletes. This investigation studied as yet unconfirmed crossover effects of upper extremity training on lower extremity performance; and we evaluated underlying relevant perceptual and cognitive adaptations. In this three-armed, randomized, controlled intervention, we used a computerized training device to compare participants receiving four weeks of upper ( n = 12) and lower ( n = 12) extremity VMRT training with a control group ( n = 13) of healthy participants. Collectively, our participants had a mean age of 24.6 years ( SD = 2.2), a mean height of 173 cm ( SD = 10), and a mean weight of 69.6 kg ( SD = 12.1); 57% ( n = 21) were female and 43% ( n = 16) were male. We assessed participants’ upper and lower extremity VMRT performance and domain-specific perceptual and cognitive abilities before and after intervention and analyzed differences between their before and after performances. Lower extremity training enhanced VMRT performances for both lower extremity and crossover upper extremity. Upper extremity training improved VMRT for upper extremity and increased cognitive choice reaction performance but yielded no crossover effects to lower extremity. We found no effects of VMRT training on other domain-specific cognitive performance markers (attention, executive function, memory, or working memory). VMRT training modulated only task-specific cognitive performance and induced crossover effects from lower extremity training to upper extremity performance but not vice versa.

Influence of Chronic Stroke on Functional Arm Reaching: Quantifying Deficits in the Ipsilesional Upper Extremity

Purpose

The purpose of this study was to quantify ipsilesional upper extremity (UE) stand-reaching performance (kinematics and kinetics) among chronic stroke survivors.

Method

Community-dwelling chronic stroke survivors (n=13) and age-similar healthy adults (n=13) performed flexion- and abduction-reaching tasks. Surface EMG and acceleration were sampled using wireless sensors from the prime movers (anterior and middle deltoid) and provided performance-outcome (reaction time, burst duration, movement time, and movement initiation time) and performance-production (peak acceleration) measures and were then evaluated.

Results

Individuals with chronic stroke demonstrated significantly reduced performance outcomes (i.e., longer reaction time, burst duration, movement time, and movement initiation time) and performance production ability (i.e., smaller peak acceleration) compared to their healthy counterparts (p < 0.05) for both flexion- and abduction-reaching movements.

Conclusion

Our results are suggestive of post-stroke deficits in ipsilesional motor execution during a stand-reaching task. Based on these findings, it is essential to integrate ipsilesional UE training into rehabilitation interventions as this might aid functional reaching activities of daily living and could ultimately help community-dwelling chronic stroke survivors maintain their independent living.

Inhibition and decision-processing speed are associated with performance on dynamic posturography in older adults

Changes in cognition due to age have been associated with falls and reduced standing postural control. Sensory integration is one component of postural control that may be influenced by certain aspects of cognitive functioning. This study investigated associations between measures of cognitive function and sensory integration capabilities for healthy young and older adults. Dynamic posturography was performed using the Equitest Sensory Organization Test (SOT) protocol to evaluate sensory integration during standing using sway-referencing of the platform and/or visual scene to alter somatosensory and visual inputs. The Equilibrium Score was used as a measure of sway. Cognitive testing examined aspects of cognitive function that have been associated with falls in older adults. A correlational analysis investigated associations between the cognitive measures and postural sway during the altered sensory conditions of the SOT. For older subjects only, slower decision-processing speed was associated with increased sway during SOT conditions whenever somatosensation was altered. Reduced perceptual inhibition was associated with increased sway whenever somatosensation was intact, and particularly when vision was altered in the presence of somatosensation. Visuospatial construct ability was associated with sway only when the eyes were closed during altered somatosensation. Task-switching was associated with sway only when vision and somatosensation were intact. With increased age, deficits in decision speed and inhibition appear associated with the sensory integration crucial for balance maintenance. Associations are modulated by the availability of somatosensation and vision. These associations define situations and individual differences in aspects of cognition that may relate to situational loss of balance in older adults.

Test-retest Reliability and Sensitivity to Change of a New Fall Risk Assessment System: A Pilot Study

Background

The new fall risk assessment (FRA) system is a composite and comprehensive assessment tool developed to predict the risk of falls. The aim of this pilot study was to examine the new FRA system’s test-retest reliability and sensitivity to change in community-dwelling older adults.

Methods

This was an observational study with a test-retest design and an 8-week fall prevention exercise program. A sample of 28 community-dwelling older adults with a mean age of 73.0 years (range, 65–80 years) participated in the study. The new FRA system was administered twice within a 7-day period for test-retest reliability expressed as intraclass correlation coefficient (ICC) and standard error of measurement (SEM) assessment. Eighteen subjects of them completed the 8-week fall prevention exercise intervention to evaluate the new FRA system’s sensitivity to change.

Results

In the evaluation of interrater reliability for the new FRA system, the ICC (95% confidence interval) of the total score was 0.77 (0.47–0.98), with good reliability. The SEM was 11.61 for the total FRA score. A good to excellent reliability was observed, with ICC levels of 0.73 to 0.91 for the 4 composite scores of the new FRA system. Following the 8-week exercise intervention, the mean total FRA score (effect size, 0.58) significantly increased (p=0.028).

Conclusion

The new FRA system has generally moderate to excellent interrater reliability and reliable sensitivity to change in community-dwelling older adults. Our findings provide support for the reliability of the new FRA system in healthy older adults without a fall history.

Modulation of EMG-EMG Coherence in a Choice Stepping Task

The voluntary step execution task is a popular measure for identifying fall risks among elderly individuals in the community setting because most falls have been reported to occur during movement. However, the neurophysiological functions during this movement are not entirely understood. Here, we used electromyography (EMG) to explore the relationship between EMG-EMG coherence, which reflects common oscillatory drive to motoneurons, and motor performance associated with stepping tasks: simple reaction time (SRT) and choice reaction time (CRT) tasks. Ten healthy elderly adults participated in the study. Participants took a single step forward in response to a visual imperative stimulus. EMG-EMG coherence was analyzed for 1000 ms before the presentation of the stimulus (stationary standing position) from proximal and distal tibialis anterior (TA) and soleus (SOL) muscles. The main result showed that all paired EMG-EMG coherences in the alpha and beta frequency bands were greater in the SRT than the CRT task. This finding suggests that the common oscillatory drive to the motoneurons during the SRT task occurred prior to taking a step, whereas the lower value of corticospinal activity during the CRT task prior to taking a step may indicate an involvement of inhibitory activity, which is consistent with observations from our previous study (Watanabe et al., 2016). Furthermore, the beta band coherence in intramuscular TA tended to positively correlate with the number of performance errors that are associated with fall risks in the CRT task, suggesting that a reduction in the inhibitory activity may result in a decrease of stepping performance. These findings could advance the understanding of the neurophysiological features of postural adjustments in elderly individuals.

Resident Vignettes for Assessing Care Quality in Nursing Homes

OBJECTIVES

Validated process measures that correlate with patient outcomes are needed for research and quality improvement.

DESIGN

Cross-sectional analysis within a cluster-randomized fall prevention study.

SETTING

Nursing homes in North Carolina (n = 16).

PARTICIPANTS

Nursing home staff (n = 541) and residents with 1 or more falls in 6 months (n = 597).

MEASUREMENTS

Fall-prevention process measures in 4 categories derived from Assessing Care of Vulnerable Elders quality indicators were measured in 2 ways: (1) chart abstraction; and (2) staff responses to clinical vignettes of hypothetical residents at risk for falls. Recurrent fall rates (falls/resident/year) were measured. The proportion of the total variation in falls rates explained by the scores for each method (chart abstraction or vignette) was calculated using multilevel adjusted models.

RESULTS

Chart and vignette measures of comorbidity management were moderately correlated (Pearson correlation coefficient 0.43), whereas other process measure categories had low or negative correlation between the 2 methods (psychoactive medication reduction 0.13, environmental modification -0.42, and exercise/rehabilitation -0.08). Measures of environmental modification and comorbidity management explained a moderate amount of the total variation in recurrent fall fates, vignettes (7%-10% variation explained) were superior to chart abstraction (2%-6% variation explained). Vignette responses from unlicensed staff (nurse aides and rehabilitation aides) explained more variance than registered nurses, licensed practical nurses, or other licensed staff in these categories. Process measures for psychoactive medication reduction and exercise/rehabilitation did not explain any of the variation in fall outcomes. Overall, vignette process measures explained 3.9% and chart abstraction measures explained 0% of the variation in fall outcomes.

CONCLUSIONS

Clinical vignettes completed by nursing home staff had greater association with resident recurrent fall rates than traditional chart abstraction process measures.

Auditory stimulus has a larger effect on anticipatory postural adjustments in older than young adults during choice step reaction

PURPOSE

The study aim was to compare the influence of an auditory stimulus (AS) on anticipatory postural adjustments (APAs) between young and older adults during a choice step reaction.

METHODS

Sixteen young and 19 older adults stepped forward in response to a visual imperative stimulus of an arrow. We used a choice reaction time (CRT) task and a Simon task which consisted of congruent and incongruent conditions. The direction of the presented arrow and its spatial location matched in the congruent condition while they did not in the incongruent condition. The AS was presented randomly and simultaneously with the visual stimulus. Incorrect weight shifts before lifting off the foot, termed APA errors, stepping errors, temporal parameters, and APA amplitudes were analyzed.

RESULTS

The APA error rate was higher in trials with than without AS in all task conditions for the older group, while this increase occurred only in the incongruent condition for the young group. The stepping error rate was also increased in the presence of AS in the incongruent condition for the older group. Reaction times were faster with AS in both groups. The APA amplitude of erroneous APA trials became larger with AS in the incongruent condition for both groups, and this effect appeared greater for the older group.

CONCLUSIONS

The effect of AS on APAs is larger in the elderly during a choice step reaction. In the presence of incongruent visual information, this effect becomes even greater, potentially inducing not only APA errors but also stepping errors.

Balance and mobility training with or without concurrent cognitive training improves the timed up and go (TUG), TUG cognitive, and TUG manual in healthy older adults: an exploratory study

BACKGROUND AND AIMS

The purpose was to explore the impact of balance and mobility training (BMT), balance and mobility plus cognitive training (BMT + C) and no training on the timed up and go (TUG), TUG cognitive (TUGcog), and TUG manual (TUGman) in older adults. A preliminary experiment examined the stability of these TUG measures over a 5-week period in older adults.

METHODS

Fifteen participants in the BMT group (70.2 ± 3.2 years) and 14 participants in the BMT + C group (68.7 ± 5.5 years) trained one-on-one, 3×/week for 12 weeks on a balance obstacle course. The BMT group and the BMT + C group completed two or three tasks simultaneously, respectively. Fifteen participants in the control group received no training (66.7 ± 4.2 years). The TUG, TUGcog, and TUGman were measured in seconds at baseline, after the 12-week training, and after the 12-week follow-up. During the preliminary experiment, ten participants (67.0 ± 6.9 years) completed the three TUG measures 1/week for 5 weeks.

RESULTS

Both the BMT and BMT + C groups, but not the control group, exhibited significantly faster TUG, TUGcog, and TUGman after the intervention and maintained these improvements at the 12-week follow-up. No differences between the BMT and BMT + C groups emerged. The preliminary experiment showed that the three TUG measures were stable across five testing sessions.

DISCUSSION AND CONCLUSION

Both training groups improved functional mobility after the interventions and sustained these improvements over 12 weeks. This is likely not a function of repeating the TUG, TUGcog, and TUGman tests since no repeated exposure effect was shown.

Sleep duration and falls: a systemic review and meta-analysis of observational studies

Several epidemiological studies have linked sleep duration with falls; however, the findings yielded inconsistent results. No quantitative analysis has specifically assessed the influence of sleep duration on falls. PubMed and Embase were screened for observational studies from inception to 13 September 2016. A generic inverse-variance method was used to pool the outcome data for sleep duration categories of the lowest category versus reference, and the highest category versus reference with a random-effects model. Dose-response analysis was performed to evaluate the potential relationship of sleep duration with falls. Finally, seven eligible observational studies involving a total of 212 829 participants were included in the present meta-analysis. Compared with the reference category, both short and long sleep duration were significantly associated with falls, and the pooled odds ratios (95% confidence intervals) were 1.32 (1.21, 1.46) and 1.35 (1.17, 1.56), respectively, both with evidence of significant heterogeneity. An approximately 'U-shaped' curve was observed, and the lowest risk of falls was shown at 7-8 h day-1 of sleep duration. Further subgroup analysis found that the association of long sleep duration and falls was more pronounced among Caucasians. The present study is limited to its small number of included studies, considerable heterogeneity, observational study design and the large contribution of a single article. Further researches are still needed to confirm the causal association between sleep duration and falls in populations with different gender, age and ethnicity.

Evaluation of Walking Balance Based on Pose Difference Between Normal Walking and Walking Under Multi-Task Conditions

[abstFig src='/00290002/02.jpg' width='270' text='Appearance of a subject' ] In this study, we present a method for the evaluation of the perturbation of walking balance resulting from additional task loads. For the evaluation, we compared pose differences between normal walking and walking under multi-task conditions. We employed an inertial measurement unit (IMU) sensor attached to the hips and the shoulders of subjects, through which we determined the orientation of the shoulder with respect to the hip. We focused on the variation width of orientation and utilized the increase rate from the variation width for normal walking to that for walking under multi-task conditions. By analyzing the correlation between the rate and the evaluation factor determined by employing a conventional fall-risk assessment method, which is related to cognitive and motor functions, we defined a walking balance evaluation criterion. The results indicate that calculation and auditory tasks affect the walking balance.

Translating exercise interventions to an in-home setting for seniors: preliminary impact on physical activity and function

AIMS

The purpose of this study is to investigate whether an in-home, individually tailored intervention is efficacious in promoting increases in physical activity (PA) and improvements in physical functioning (PF) in low-active older adults.

METHODS

Participants were randomized to two groups for the 8-week intervention. The enhanced physical activity (EPA) group received individualized exercise programming, including personalized step goals and a resistance band training program, and the standard of care (SoC) group received a general activity goal. Pre- and post-intervention PF measures included choice step reaction time, knee extension/flexion strength, hand grip strength, and 8 ft up and go test completion time.

RESULTS

Thirty-nine subjects completed this study (74.6 ± 6.4 years). Significant increases in steps/day were observed for both the EPA and SoC groups, although the improvements in the EPA group were significantly higher when including only those who adhered to weekly step goals. Both groups experienced significant PF improvements, albeit greater in the EPA group for the 8 ft up and go test and knee extension strength.

CONCLUSION

A low cost, in-home intervention elicited improvements in both PA and PF. Future research is warranted to expand upon the size and scope of this study, exploring dose thresholds (and time frames) for PA to improve PF and strategies to further bolster adherence rates to maximize intervention benefits.

Elderly Fallers Enhance Dynamic Stability Through Anticipatory Postural Adjustments during a Choice Stepping Reaction Time

In the case of disequilibrium, the capacity to step quickly is critical to avoid falling in elderly. This capacity can be simply assessed through the choice stepping reaction time test (CSRT), where elderly fallers (F) take longer to step than elderly non-fallers (NF). However, the reasons why elderly F elongate their stepping time remain unclear. The purpose of this study is to assess the characteristics of anticipated postural adjustments (APA) that elderly F develop in a stepping context and their consequences on the dynamic stability. Forty-four community-dwelling elderly subjects (20 F and 24 NF) performed a CSRT where kinematics and ground reaction forces were collected. Variables were analyzed using two-way repeated measures ANOVAs. Results for F compared to NF showed that stepping time is elongated, due to a longer APA phase. During APA, they seem to use two distinct balance strategies, depending on the axis: in the anteroposterior direction, we measured a smaller backward movement and slower peak velocity of the center of pressure (CoP); in the mediolateral direction, the CoP movement was similar in amplitude and peak velocity between groups but lasted longer. The biomechanical consequence of both strategies was an increased margin of stability (MoS) at foot-off, in the respective direction. By elongating their APA, elderly F use a safer balance strategy that prioritizes dynamic stability conditions instead of the objective of the task. Such a choice in balance strategy probably comes from muscular limitations and/or a higher fear of falling and paradoxically indicates an increased risk of fall.

Cerebellar volume mediates the relationship between FMR1 mRNA levels and voluntary step initiation in males with the premutation

Recent evidence indicates that adults with a premutation (PM: 55-199 CGG repeats) expansion in the fragile X mental retardation 1 (FMR1) gene show postural control deficits that may reflect disruption to cerebellar motor regions. Less is known about the influence of reduced cerebellar volume and structural changes, and increase in CGG repeat and FMR1 mRNA levels on the attentional demands of step initiation in PM males. We investigated the effects of a concurrent cognitive task on choice stepping reaction time (CSRT) and explored the associations between CSRT performance, cerebellar volume, CGG size, and FMR1 mRNA levels in blood in PM males. We examined 19 PM males (ages 28-75) and 23 matched controls (CGG <44; ages 26-77), who performed a verbal fluency task during CSRT performance and single-task stepping without a secondary cognitive task. Our results provide preliminary evidence that smaller cerebellar volume (β = -2.73, p = 0.002) and increasing CGG repeat length (β = 1.69, p = 0.003) were associated with greater dual-task step initiation times in PM males, but not in controls. There was evidence of a mediating effect of cerebellar volume on the relationship between FMR1 mRNA levels and single-task CSRT performance in PM males (estimate coefficient = 8.69, standard error = 4.42, p = 0.049). These findings suggest increasing CGG repeat and FMR1 mRNA levels have neurotoxic effects on cerebellar regions underlying anticipatory postural responses during stepping. Cerebellar postural changes may be predictive of the increased risk of falls in older PM males.

Evaluating the fall risk among elderly population by choice step reaction test

Falls during daily activities are often associated with injuries and physical disabilities, thereby affecting quality of life among elder adults. Balance control, which is crucial in avoiding falls, is composed of two elements: muscle strength and central nervous system (CNS) control. A number of studies have reported that reduced muscle strength raises the risk of falling. However, to date there has been only limited research focused on the relationship between fall risk and the CNS. This study aimed to investigate the relationship between CNS and risk of falling among the elderly. A total of 140 elderly people (92 females and 48 males) were divided into faller and nonfaller groups based on questionnaire responses concerning falls in their daily life. Participants undertook a choice step reaction test in which they were required to respond to random visual stimuli using foot movements as fast as possible in the left or right directions. Response time was quantified as premotor time (PMT) and motor time (MT). In addition, the participants’ electro-myography data were recorded during the choice step reaction test. A maximal isokinetic torque test was also performed. PMT was greater in the fallers than in the nonfallers group. There was a significant difference between fall status and direction on PMT. PMT of the left limb in nonfallers was faster than the right, but in fallers there was no difference between left and right limbs. A similar phenomenon was also observed for MT. There were significant differences between fallers and nonfallers in maximum isokinetic torque at knee and ankle joints. The correct rate of PMT was higher than other variables, such as MT and maximal isokinetic torque, in evaluating elderly fall risk by using logistic regression analyses. The results suggest that PMT in the choice step reaction test could be a useful parameter to assess risk of fall among elder adults. In addition, decreased maximal isokinetic torque was related to greater PMT and disappearance of asymmetry in older adults who were at higher risk of fall, especially in the lower limb.

Performance monitoring and response conflict resolution associated with choice stepping reaction tasks

Choice reaction requires response conflict resolution, and the resolution processes that occur during a choice stepping reaction task undertaken in a standing position, which requires maintenance of balance, may be different to those processes occurring during a choice reaction task performed in a seated position. The study purpose was to investigate the resolution processes during a choice stepping reaction task at the cortical level using electroencephalography and compare the results with a control task involving ankle dorsiflexion responses. Twelve young adults either stepped forward or dorsiflexed the ankle in response to a visual imperative stimulus presented on a computer screen. We used the Simon task and examined the error-related negativity (ERN) that follows an incorrect response and the correct-response negativity (CRN) that follows a correct response. Error was defined as an incorrect initial weight transfer for the stepping task and as an incorrect initial tibialis anterior activation for the control task. Results revealed that ERN and CRN amplitudes were similar in size for the stepping task, whereas the amplitude of ERN was larger than that of CRN for the control task. The ERN amplitude was also larger in the stepping task than the control task. These observations suggest that a choice stepping reaction task involves a strategy emphasizing post-response conflict and general performance monitoring of actual and required responses and also requires greater cognitive load than a choice dorsiflexion reaction. The response conflict resolution processes appear to be different for stepping tasks and reaction tasks performed in a seated position.

Validity and reliability of a simple ‘low-tech’ test for measuring choice stepping reaction time in older people

Objective:

To establish the psychometric properties of a simple ‘low-tech’ choice stepping reaction time test (CSRT-M) by investigating its validity and test–retest reliability.

Design:

Cross-sectional.

Setting:

Community.

Subjects:

A total of 169 older people from the control arm of a clinical trial and a convenience sample of 30 older people.

Main measures:

Demographic, physical, cognitive and prospective falls data were collected in addition to CSRT-M. The CSRT-M time was taken as the total time to complete 20 steps onto four targets printed on a portable rubber mat. Assessment of the original electronic version (CSRT-E) and re-administration of the CSRT-M the next day was done in 30 participants.

Results:

Multivariate regression analysis showed that the CSRT-M time was best explained by leaning balance control, quadriceps strength and cognitive functioning (R2 = 0.44). Performance on the CSRT-M was worse in older participants and participants with a presence of fall risk factors, supporting good discriminant validity. The odds of suffering multiple future falls increased by 74% (odds ratio (OR) = 1.74, 95% CI (confidence interval) = 1.14–2.65, p = 0.010) for each standard deviation increase in CSRT-M, supporting good predictive validity. Criterion validity was confirmed by a strong bivariate correlation between CSRT-M and CSRT-E (0.81, p < 0.001). Test–retest reliability for the CSRT-M was good (intraclass correlation coefficient = 0.74, 95% CI = 0.45–0.88, p < 0.001).

Conclusions:

A simple test of unplanned volitional stepping (CSRT-M) has excellent predictive validity for future falls, good inter-day test–retest reliability and excellent criterion validity with respect to the well-validated CSRT-E. The CSRT-M, therefore, may be a useful fall risk screening tool for older people.

Preparatory state and postural adjustment strategies for choice reaction step initiation

A loud auditory stimulus (LAS) presented simultaneously with a visual imperative stimulus can reduce reaction time (RT) by automatically triggering a movement prepared in the brain and has been used to investigate a movement preparation. It is still under debate whether or not a response is prepared in advance in RT tasks involving choice responses. The purpose of the present study was to investigate the preparatory state of anticipatory postural adjustments (APAs) during a choice reaction step initiation. Thirteen young adults were asked to step forward in response to a visual imperative stimulus in two choice stepping conditions: (i) the responding side is not known and must be selected and (ii) the responding side is known but whether to initiate or inhibit a step response must be selected. LAS was presented randomly and simultaneously with the visual imperative stimulus. LAS significantly increased the occurrence rates of inappropriately initiated APAs while reducing the RTs of correct and incorrect trials in both task conditions, demonstrating that LAS triggered the prepared APA automatically. This observation suggests that APAs are prepared in advance and withheld from release until the appropriate timing during a choice reaction step initiation. The preparatory activity of APAs might be modulated by the inhibitory activity required by the choice tasks. The preparation strategy may be chosen for fast responses and is judged most suitable to comply with the tasks because inappropriately initiated APAs can be corrected without making complete stepping errors.

Effects of Short-Term Physical Activity Interventions on Simple and Choice Response Times

Objective. Response time (RT) is important for health and human performance and provides insight into cognitive processes. It deteriorates with age, is associated with chronic physical activity (PA), and improves with PA interventions. We investigated associations between the amount and type of PA undertaken and the rate of change in RT for low-active adults across the age range 18–63 yr. Methods. Insufficiently active adults were assigned to either a walking (n = 263) or higher-intensity (n = 380) exercise program conducted over 40 days. Active controls were also recruited (n = 135). Simple response time (SRT) and choice response time (CRT) were measured before and after the intervention and at 3-, 6-, and 12-month follow-up. Results. SRT and CRT slowed across the age range; however, habitually active participants at baseline had significantly faster CRT (p < 0.05). The interventions increased weekly PA with corresponding increases in physical fitness. These changes were mirrored in faster CRT across the study for both intervention groups (p < 0.05). No changes were found for SRT. Conclusions. Both PA interventions resulted in improvements in CRT among adults starting from a low activity base. These improvements were relatively rapid and occurred in both interventions despite large differences in exercise volume, type, and intensity. There were no effects on SRT in either intervention.

Age differences in reactive strategies and execution time during choice stepping with visual interference

PURPOSE

We aimed to explore the effects of visual interference from a flanker task on a reactive strategy and execution speed of choice stepping among young and older adults.

METHODS

Twenty-two healthy young (21.9 ± 1.4 years) and 21 older participants (72.6 ± 4.9 years) were instructed to execute forward stepping as quickly and accurately as possible on the side indicated by a central arrow (←left vs. right→) of a visual cue during a neutral condition. During a flanker condition, participants were additionally required to ignore flanker arrows on each side of the central arrow (→→→→→ congruent or incongruent →→←→→). Errors in the direction of the initial weight transfer [anticipatory postural adjustment (APA) errors], step execution time, and divided phases (reaction, APA, and swing phases) were measured from the data of vertical force.

RESULTS

Incongruence had larger effects on step execution times and APA phase in older adults than in young adults, while incongruence had smaller effects on reaction phase in older adults than in young adults. Step execution times were prolonged for trials with APA errors relative to trials without those in both groups. Only older adults showed that step execution times during trials with APA errors increased prominently in the incongruent condition as compared to the other conditions.

CONCLUSION

Older adults might have a tendency to make hastier judgments, and might be vulnerable to potential motor program errors caused by an interference effect. Composite measurement of inhibition and stepping in a functional context may increase discriminative ability for age-related deficits in postural control.

Kinect-based choice reaching and stepping reaction time tests for clinical and in-home assessment of fall risk in older people: a prospective study

Background

Quick protective reactions such as reaching or stepping are important to avoid a fall or minimize injuries. We developed Kinect-based choice reaching and stepping reaction time tests (Kinect-based CRTs) and evaluated their ability to differentiate between older fallers and non-fallers and the feasibility of administering them at home.

Methods

A total of 94 community-dwelling older people were assessed on the Kinect-based CRTs in the laboratory and were followed-up for falls for 6 months. Additionally, a subgroup (n = 20) conducted the Kinect-based CRTs at home. Signal processing algorithms were developed to extract features for reaction, movement and the total time from the Kinect skeleton data.

Results

Nineteen participants (20.2 %) reported a fall in the 6 months following the assessment. The reaction time (fallers: 797 ± 136 ms, non-fallers: 714 ± 89 ms), movement time (fallers: 392 ± 50 ms, non-fallers: 358 ± 51 ms) and total time (fallers: 1189 ± 170 ms, non-fallers: 1072 ± 109 ms) of the reaching reaction time test differentiated well between the fallers and non-fallers. The stepping reaction time test did not significantly discriminate between the two groups in the prospective study. The correlations between the laboratory and in-home assessments were 0.689 for the reaching reaction time and 0.860 for stepping reaction time.

Conclusion

The study findings indicate that the Kinect-based CRT tests are feasible to administer in clinical and in-home settings, and thus represents an important step towards the development of sensor-based fall risk self-assessments. With further validation, the assessments may prove useful as a fall risk screen and home-based assessment measures for monitoring changes over time and effects of fall prevention interventions.

The risk for falls in older people in the context of objective functional studies

Falls may occur in each ontogenesis phase, but they become more frequent in the elderly and lead to serious health consequences. Dynamic changes in senior citizens’ environment and lifestyle makes studies of risk for falls necessary. To determine the relationship between the risk for falls and the objective functional and structural examination in the elderly living in Poland. The research consisted of 196 females and 61 males aged 60-88 recruited from health clinics, senior citizen centers and Universities of the Third Age between 2009-2012. Following parameters were collected: functional physical tests “30 second Chair Stand Test” and Timed Up and Go Test”, the flexor muscles and knee extensors force, the bone mineral density was measured in distal radius of the forearm with the EXA - 3000, the total risk for fall assessed by 5 tests by abbreviated version of Fallscreen test. Multiple linear regression and linear correlation were used for assessment of relationship with total estimated risk for fall and other parameters. The subjects displayed significant dimorphic differences within the range of the functional parameters and bone mineral density to the advantage of males. Only in women results revealed a significant link between the risk for falls and the dynamic balance, as well as the maximum quadricep muscle force equal. Strength of the lower limb muscles seems to be critical for decreasing the risk for fall. Special programs for strengthening this part of the body for older people should be elaborate.

Age-related differences in muscle recruitment and reaction-time performance

Previously, we showed that prolonged reaction-time (RT) in older persons is related to increased antagonist muscle co-activation, occurring already before movement onset. Here, we studied whether a difference in temporal agonist and antagonist muscle activation exists between young and older persons during an RT-test. We studied Mm. Biceps (antagonist muscle) & Triceps (agonist muscle) Brachii activation time by sEMG in 60 young (26 ± 3 years) and 64 older (80 ± 6 years) community-dwelling subjects during a simple point-to-point RT-test (moving a finger using standardized elbow-extension from one pushbutton to another following a visual stimulus). RT was divided in pre-movement-time (PMT, time for stimulus processing) and movement-time (MT, time for motor response completion). Muscle activation time 1) following stimulus onset (PMAT) and 2) before movement onset (MAT) was calculated. PMAT for both muscles was significantly longer for the older subjects compared to the young (258 ± 53 ms versus 224 ± 37 ms, p=0.042 for Biceps and 280 ± 70 ms versus 218 ± 43 ms for Triceps, p<0.01). Longer agonist muscle PMAT was significantly related to worse PMT and RT in young (respectively r=0.76 & r=0.68, p<0.001) and elderly (respectively r=0.42 & r=0.40, p=0.001). In the older subjects we also found that the antagonist muscle activated significantly earlier than the agonist muscle (-22 ± 55 ms, p=0.003). We conclude that in older persons, besides the previously reported increased antagonist muscle co-activation, the muscle firing sequence is also profoundly altered. This is characterized by a delayed muscle activation following stimulus onset, and a significantly earlier recruitment of the antagonist muscle before movement onset.

Accessory stimulus modulates executive function during stepping task

When multiple sensory modalities are simultaneously presented, reaction time can be reduced while interference enlarges. The purpose of this research was to examine the effects of task-irrelevant acoustic accessory stimuli simultaneously presented with visual imperative stimuli on executive function during stepping. Executive functions were assessed by analyzing temporal events and errors in the initial weight transfer of the postural responses prior to a step (anticipatory postural adjustment errors). Eleven healthy young adults stepped forward in response to a visual stimulus. We applied a choice reaction time task and the Simon task, which consisted of congruent and incongruent conditions. Accessory stimuli were randomly presented with the visual stimuli. Compared with trials without accessory stimuli, the anticipatory postural adjustment error rates were higher in trials with accessory stimuli in the incongruent condition and the reaction times were shorter in trials with accessory stimuli in all the task conditions. Analyses after division of trials according to whether anticipatory postural adjustment error occurred or not revealed that the reaction times of trials with anticipatory postural adjustment errors were reduced more than those of trials without anticipatory postural adjustment errors in the incongruent condition. These results suggest that accessory stimuli modulate the initial motor programming of stepping by lowering decision threshold and exclusively under spatial incompatibility facilitate automatic response activation. The present findings advance the knowledge of intersensory judgment processes during stepping and may aid in the development of intervention and evaluation tools for individuals at risk of falls.

Age-related changes in trunk neuromuscular activation patterns during a controlled functional transfer task include amplitude and temporal synergies

While healthy aging is associated with physiological changes that can impair control of trunk motion, few studies examine how spinal muscle responses change with increasing age. This study examined whether older (over 65 years) compared to younger (20-45 years) adults had higher overall amplitude and altered temporal recruitment patterns of trunk musculature when performing a functional transfer task. Surface electromyograms from twelve bilateral trunk muscle (24) sites were analyzed using principal component analysis, extracting amplitude and temporal features (PCs) from electromyographic waveforms. Two PCs explained 96% of the waveform variance. Three factor ANOVA models tested main effects (group, muscle and reach) and interactions for PC scores. Significant (p<.0125) group interactions were found for all PC scores. Post hoc analysis revealed that relative to younger adults, older adults recruited higher agonist and antagonistic activity, demonstrated continuous activation levels in specific muscle sites despite changing external moments, and had altered temporal synergies within abdominal and back musculature. In summary both older and younger adults recruit highly organized activation patterns in response to changing external moments. Differences in temporal trunk musculature recruitment patterns suggest that older adults experience different dynamic spinal stiffness and loading compared to younger adults during a functional lifting task.

Religious beliefs or physicians' behavior: what makes a patient more prone to accept a physician to address his/her spiritual issues?

The present study aims to understand the relation between religious beliefs, physicians' behavior and patients' opinions regarding "Spirituality, religiosity and health (S/R)" issues, and what makes a patient more prone to accept a physician to address his/her spiritual issues. A cross-sectional study was carried out in outpatients from a tertiary hospital, and a path analysis was used to examine the direct and indirect relationships between the variables. For the final analysis, 300 outpatients were evaluated. Most patients would like their doctors to address S/R issues but did not feel comfortable to ask them. In contrast, they reported most doctors have never addressed S/R issues, and they believe doctors are not prepared to address these issues. The path analysis revealed that patients' previous experiences with their doctors may be as important as their religious/spiritual beliefs in proneness to accept a physician to address his/her spiritual issues.

Choice stepping reaction time test using exergame technology for fall risk assessment in older people

Accidental falls remain an important problem in older people. Stepping is a common task to avoid a fall and requires good interplay between sensory functions, central processing and motor execution. Increased choice stepping reaction time has been associated with recurrent falls in older people. The aim of this study was to examine if a sensor-based Exergame Choice Stepping Reaction Time test can successfully discriminate older fallers from non-fallers. The stepping test was conducted in a cohort of 104 community-dwelling older people (mean age: 80.7 ± 7.0 years). Participants were asked to step laterally as quickly as possible after a light stimulus appeared on a TV screen. Spatial and temporal measurements of the lower and upper body were derived from a low-cost and portable 3D-depth sensor (i.e. Microsoft Kinect) and 3D-accelerometer. Fallers had a slower stepping reaction time (970 ± 228 ms vs. 858 ± 123 ms, P = 0.001) and a slower reaction of their upper body (719 ± 289 ms vs. 631 ± 166 ms, P = 0.052) compared to non-fallers. It took fallers significantly longer than non-fallers to recover their balance after initiating the step (2147 ± 800 ms vs. 1841 ± 591 ms, P = 0.029). This study demonstrated that a sensor-based, low-cost and easy to administer stepping test, with the potential to be used in clinical practice or regular unsupervised home assessments, was able to identify significant differences between performances by fallers and non-fallers.

Effects of speed and accuracy strategy on choice step execution in response to the flanker interference task

The purpose of this study is to examine the effects of a speed or accuracy strategy on response interference control during choice step execution. Eighteen healthy young participants were instructed to execute forward stepping on the side indicated by a central arrow (←, left vs. →, right) under task instructions that either emphasized speed or accuracy of response in the neutral condition. In the flanker condition, they were additionally required to ignore the 2 flanking arrows on each side (→→→→→, congruent or →→←→→, incongruent). Errors in the direction of the initial weight transfer (APA errors) and the step execution times were measured from the vertical force data. APA error was increased in response to the flanker task and step execution time was shortened with a speed strategy compared to an accuracy strategy. Furthermore, in response to the visual interference of the flanker task, speed instructions in particular increased APA errors more than other instructions. It may be important to manipulate the level of the speed-accuracy trade-off to improve efficiency and safety. Further research is needed to explore the effects of advancing age and disability on choice step reaction in a speed or accuracy strategy.

Can the Ordered Multi-Stepping Over Hoop test be useful for predicting fallers among older people? A preliminary 1 year cohort study

BACKGROUND AND AIMS

To prevent falls among older people, we developed a new fall-risk assessment, the "Ordered Multi-Stepping Over Hoop (OMO)" test. The aims of this study were preliminary: to investigate the association of the OMO with cognitive and physical function and to investigate whether the OMO could predict incidents of falling.

METHODS

Fifty-nine community-dwelling older people (mean age = 88.0 ± 0.87, female = 49) were recruited. We assessed cognitive and physical function including the OMO test at baseline and monitored the falls of participants during a 12-month follow-up period from the baseline. We investigated whether the OMO was associated with cognitive function, physical function, and incidents of falling. To investigate whether the OMO could predict incidents of falling, a receiver operating characteristic analysis was conducted.

RESULTS

The OMO time in fallers was significantly slower than for non-fallers. There were significant correlations between slower OMO times and lower physical functions and executive function. The area under the ROC curve in the OMO was 0.71 (p < 0.05). Times above 21.9 s for the OMO identified those more likely to fall.

CONCLUSIONS

The OMO time was correlated with cognitive function, physical function, and incidents of falling. Our preliminary study indicates that the OMO may help to make a distinction between fallers and non-fallers among older people as effectively as other tests.