Reliability of gait and dual-task measures in multiple sclerosis

BackgroundSingle-task (ST) and dual-task (DT) assessments are commonly used to evaluate motor and cognitive impairment in people with multiple sclerosis (MS). Although variability can influence repeated DT testing measures, the reliability of several DT variables over time has not been adequately explored. For instance, a third testing session has never been included to observe whether DT has a learning effect. DT cognition rate reliability has not yet been examined and dual-task cost (DTC), a widely used calculation for DT interpretation, has not been proven reliable.Research questionTo evaluate the reliability of ST and DT measures of gait and cognition over three test sessions.MethodsThis was a cross-sectional study involving 18 people with MS and 12 controls. Participants attended three test sessions, each one week apart. ST and DT (serial seven subtraction) gait variables, DTC, coefficient of variability (CV), and cognition rate were extracted and calculated using an instrumented walkway. Reliability was assessed using intraclass correlation coefficients (ICC) or Kendall’s coefficient of concordance (KCC; nonparametric test) and minimum detectable change (MDC); between-session learning effect was assessed using repeated measures ANOVA.ResultsICC/KCC values for ST and DT gait variables ranged from moderate to excellent (0.50-0.99). However, reliability for DT stride width and cognition rate was lower in controls. In general, DTC and CV variables had poor ICCs and high MDC values (49.19–1478.67 %), although some DTC variables had moderate or higher reliability in controls. Cognition rate was reliable in both MS (ICC 0.91) and controls (ICC 0.84). A learning effect between sessions was observed for DT velocity in both groups and for DTC cadence in people with MS.SignificanceST and DT gait measures as well as DT cognition rate are reliable outcomes for repeated testing, while DTC and CV variables may not be suitable for long-term monitoring.     

Enhanced gait variability index and cognitive performance in Asian adults: Results from the Yishun Study

BackgroundAlthough gait variability has been linked to cognitive decline among older adults, the lack of a comprehensive composite gait variability score has dampened the application of gait variability.Research questionDoes the enhanced gait variability index (EGVI) - a composite score gait variability index - provide differential and useful information on cognitive decline in community-dwelling adults from that using gait speed?MethodsHealthy community-dwelling adults (n = 311) aged 21–90 were individually administered the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Habitual gait speed and spatiotemporal parameters were measured using a 6 m instrumented walkway system. The EGVI for each participant was calculated from five spatiotemporal parameters - step length(cm), step time(s), stance time(s), single support time(s) and stride velocity(cm/s). Linear regression models, controlling for age, gender, and education, were built to examine the independent effects of EGVI or gait speed on global cognition and individual domains.ResultsMultiple regression revealed that gait speed contributed significantly to the performance of the domain “Attention” (p = 0.04) whereas EGVI contributed significantly for the performance of the domain “Visuospatial” (p = 0.04) and “Delayed Memory” (p = 0.02).SignificanceEGVI provides differential and useful information from using gait speed alone. The EGVI may offer a solution to measure or track GV changes in relation to cognitive changes.     

Sleep quality is associated with walking under dual-task,but not single-task performance

ObjectivesThe objective of this study was to assess the relationship between sleep behavior and gait performance under single-task (ST) and dual-task (DT) walking conditions in community- dwelling older adults.MethodsWalking under ST and DT conditions was evaluated in 34 community-dwelling older adults, 64.7% women, mean age 71.5 (SD ± 5.8). Gait-speed and gait-variability data were collected using the OPAL wearable sensors of the Mobility Lab. Sleep behavior (sleep efficiency [SE] and sleep latency [SL]) was assessed using actigraphy, over 5 consecutive nights.ResultsLower SE was associated with decreased gait speed and increased stride-length variability during DT (rs = 0.35; p = 0.04; rs = −0.36; p = 0.03, respectively), whereas longer SL was associated with increased stride-length variability during DT (rs = 0.38; p = .03). After controlling for age and cognition, SE accounted for 24% and 33% of the variability in stride length and stride time. No associations were found between sleep and gait measures under ST walking.ConclusionsLower SE is associated with decreased gait speed and increased gait variability under DT conditions that are indicative of an increased risk for falls in older adults. Our findings support clinical recommendations to incorporate the evaluation of sleep quality in the context of risk assessment for falls.     

Dual-task training effect on gait parameters in children with spastic diplegic cerebral palsy: Preliminary results of a self-controlled study

BackgroundChildren with cerebral palsy (CP) may have difficulties under dual-task conditions. Spatiotemporal gait parameters have deteriorated with concurrent tasks in children with CP. However, how dual-task training affects gait parameters in children with spastic diplegic CP has not been clarified.Research questionHow does dual-task training program effect gait, functional skills, and health-related quality of life in children with spastic diplegic CP?MethodsEleven children with spastic diplegic CP (median age 11 y, range 7–16 y; 4 female; 7 male) Gross Motor Function Classification System level 1–2 and obtained 27 and higher scores from Modified Mini Mental Test included in the study. The study was planned as a self-controlled clinical research design. Children were recruited to conventional physiotherapy program for 8 weeks and dual-task training program added to conventional physiotherapy program for following 8 weeks. Children were evaluated at baseline, after conventional physiotherapy program, and after dual-task training program. Children’s gait was evaluated with Zebris™ FDM-2 device and Edinburgh Visual Gait Score, functional mobility skills with 1 min Walk Test (1MWT), and health-related quality of life with the Pediatric Quality of Life Inventory (PedsQL) - CP module.ResultsThe difference in step length, step time, stride time, cadence and gait speed of spatiotemporal parameters of gait during dual-task performance were found statistically significant in children with spastic diplegic CP, after dual-task training program (p < 0,05). After dual-task training, statistically significant gains were found in 1MWT, movement and balance subtitle of PedsQL-CP module Parent Form (p < 0,05).SignificanceDual-task training program added to a conventional physiotherapy program provides more gains in terms of functionality of children with spastic diplegic CP will contribute to the improvement of the motor functional level.     

Comparable walking gait performance during executive and non-executive cognitive dual-tasks in chronic stroke: A pilot study

BackgroundFalls are a serious problem among stroke survivors due to subsequent injuries, recovery setbacks, dependence, and mortality. A growing body of dual-task (DT) studies suggests a role of executive functions in gait control and falls, particularly in subacute stroke. However, few studies have compared distinct executive and non-executive tasks, nor their effects on chronic stroke gait. Research question: The purpose of this cross-sectional study was to compare the effects of distinct working memory (2-back) and inhibition (Stroop) tasks on walking gait performance in chronic stroke survivors.MethodsA pilot sample of chronic stroke survivors (n = 11, 8 males, mean age = 70.91, 6-12months post-stroke event) and age-matched healthy controls (n = 13, 4 male; mean age = 68.46) were tested. Gait performance (speed, stride time, stride time variability, stride length and stride length variability) was measured using 2 wireless inertial measurement sensors under 4 walking conditions: 1) preferred walking (single-task: ST), 2) walking with a 2-back DT, 3) walking with a Stroop DT, and 4) walking with a non-executive motor response DT. The secondary tasks were also carried out in both ST (seated) and DT conditions, to examine bidirectional effects.ResultsWhile the stroke survivor sample had a slower gait speed across conditions and tasks, there were no significant differences between the groups [F(1, 22) = 1.13, p =.299, η²p = .049] on the spatial or temporal gait characteristics recorded: gait performance was maintained during executive and non-executive DTs. In addition, we did not find a significant effect of group on cognitive task performance (all p > .052). However, we observed a cost in accuracy on the 2-back DT for both groups, suggesting resource overlap and greater cognitive load (all t > 19.72, all p < .001).SignificanceOur gait data contradict previous studies evidencing impaired gait post-stroke, suggesting functional recovery in this chronic stroke sample.     

Cognitive and visual demands,but not gross motor demand,of concurrent smartphone use affect laboratory and free-living gait among young and older adults

BackgroundAs smartphones are an integral part of daily activities, understanding the underlying mechanism associated with concurrent cell phone use while walking may help reduce the risks of injury.Research questionThis study examined the effect of cognitive, visual, and gross motor demands while using a phone during gait among young and older adults in the laboratory and free-living environments.MethodsTwelve young and twelve older adults walked along a 10-m walkway under five conditions: single-task walking (Walk), walking and bi-manually holding a phone (Walk-Hold), walking while looking at a phone held in front of the participants (Walk-Look), walking while answering questions (Walk-Answer), and walking while texting (Walk-Text). All conditions were performed in laboratory and free-living environments. Gait velocity, step time, step length, and cadence were obtained using a smartphone with a built-in accelerometer attached to the body. The dual-task cost (DTC) was also assessed. A three-way ANOVA was utilized for all parameters.ResultsWhile no three-way interactions were found for any parameter, group × condition interactions were significant for gait velocity, step time, step length, cadence and their corresponding DTC. Decreased gait velocity, step length and cadence, with increased step time was demonstrated during Walk-Look, Walk-Answer, and Walk-Text, compared to Walk and Walk-Hold. While older adults markedly changed their gait during Walk-Answer and Walk-Text, these changes were less pronounced among young adults.SignificanceVisual and cognitive demand while concurrently using a phone influenced gait, especially among the elderly. Environment did not accentuate gait alterations during concurrent phone use. Therefore, smartphone technology should be developed to detect dual-task walking and temporarily modify functionality to reduce risk of injury from divided attention.     

Effects of gender on dual-tasking and prioritization in older adults

BackgroundThe ability to produce effective posture and balance while distracted (dual-tasking; DT), is critical for mobility. In particular, individuals implicit prioritization across posture and secondary, distracting stimuli may impact fall risk. However, the impact of gender on DT and prioritization during gait is poorly understood.Research questionDoes gender impact DT effects or prioritization while DT walking?MethodsOne hundred older adults participated. The timed up and go (TUG) was completed with and without a secondary cognitive task (counting backwards by 3′s). Gait (time to complete the TUG), and cognitive (rate of correct numbers listed) performance was recorded during both single tasks and while dual-tasking. DT effects were calculated for cognitive and gait performance. Prioritization was calculated as the difference between cognitive and gait DT effects. The effect of gender on DT and prioritization was assessed, controlling for age and cognitive ability.ResultsGender by condition (single vs. dual-task) interaction effects were observed (Gait: F_1,96 =8.7; p = 0.004; Cognition: F_1,96 =5.2; p = 0.024) such that, compared to male participants, females exhibited smaller cognitive DT effects, and larger gait DT effects. Further, females exhibited significantly larger prioritization scores (F_1,95 =10.0, p = 0.002), indicating a cognitive prioritization compared to males.SignificanceGiven the link between posture-second strategies and falls, the current findings may provide some insight into previous results suggesting an increased fall-risk in older-adult women. However, this study did not investigate falls. Therefore, additional work is necessary to confirm current findings and further investigate the relationship between gender, prioritization, and falls; and its possible clinical relevance.     

Effects of barefoot vs. shod walking during indoor and outdoor conditions in younger and older adults

BackgroundGait stability and variability measures in barefoot and shod locomotion are frequently investigated in younger but rarely in older adults. Moreover, most studies examine gait measures in laboratory settings instead of real-life settings.Research questionsHow are gait stability and variability parameters affected by footwear compared to barefoot walking in younger and older adults as well as under indoor vs. outdoor conditions?MethodsHealthy younger (<35 years) and older adults (>65 years) participated in the randomised within-subject study design. Participants conducted consecutive 25 m walking trials barefoot and with standardised footwear inside and outside. Inertial measurement units were mounted on the participant’s foot and used to calculate local dynamic stability (LDS), velocity and minimal toe clearance (MTC), stride length and stride time, including variabilities for these parameters. Linear mixed models were calculated.ResultsData of 32 younger (17 female, 15 male, age: 30 ± 4 years) and 42 older participants (24 female, 18 male, age: 71 ± 4 years) were analysed. MTC variability was higher in shod conditions compared to barefoot (p = 0.048) and in outdoor conditions (p < 0.001). LDS was different between age groups (p < 0.001). Gait velocity and MTC were higher in shod and outdoor conditions (both p < 0.001). Stride length and time were higher in shod conditions (both p < 0.001) and different between outdoor vs. indoor (longer stride length and shorter stride time outdoor, both (p < 0.001) as well as age groups (shorter stride length (p < 0.021) and stride time in older adults (p < 0.001).SignificanceResults suggest that gait stability and variability in older and younger adults are acutely affected by footwear vs. barefoot and indoor vs. outdoor walking conditions, indicating a high adaptiveness of these parameters to different experimental conditions. Consequently, future studies should be careful with generalising results obtained under certain conditions. Findings stress the clinical potential of barefoot walking.     

Cognitive-motor interference in multiple sclerosis: What happens when the gait speed is fixed?

During the last decade, numerous studies have confirmed a coupling between walking performance and cognition in people with multiple sclerosis (PwMS). Our aim was to provide new insights into a walking-cognitive dual-task (DT) in PwMS. We tested the DT phenomenon by controlling the walking speed using an instrumented treadmill. Thirty PwMS (20 women) with a mean age 40.1 (SD = 12.0) participated in the study. Twenty-one healthy subjects served as controls. Each subject completed a sequence of tests: a) Normal walking (ST) − the participant walked on the instrumented treadmill at a comfortable walking speed for 1 min; b) Cognitive evaluation (ST) − subjects performed two cognitive tests while seated; c) DT cognitive tests performed while walking on the treadmill at the identical speed performed during normal walking. Outcome measures were spatio-temporal parameters of gait (mean and variability), the Word List Generation Test (WLG) and the Serial-3 Subtraction Test. MS participants significantly decreased their cadence while increasing their stride length during the DT condition compared to the ST condition. Non-significant differences were observed for the WLG and Serial-3 Subtraction Cognitive Tests between the ST condition and the DT condition in both the MS and healthy groups. In terms of gait variability parameters, MS subjects demonstrated a 2 to 3-fold greater gait variability compared to the healthy controls. Non-significant differences in gait variability parameters were observed between the ST and DT conditions in both the MS and control groups. This study provides new insights into the DT phenomenon in the MS population.     

The effects of cognitive versus motor concurrent task on gait in individuals with transtibial amputation,transfemoral amputation and in a healthy control group

BackgroundLower limb amputation causes difficulties in mobility together with motor and sensory loss. Challenging situations such as concurrent tasks cause gait parameters to deteriorate. Understanding the effect of concurrent tasks on gait is important for the rehabilitation of amputees.Research questionAre the effects of concurrent cognitive and motor tasks on gait parameters at fixed speed different in individuals with transtibial amputation, or transfemoral amputation compared to healthy individuals?MethodsThe gait parameters were evaluated of 20 individuals with transtibial amputation, 13 individuals with transfemoral amputation and 20 healthy individuals while walking on a motorized treadmill under single task (ST), cognitive dual task (CDT) and motor dual task (MDT) conditions. The self-selected comfortable velocity, which was determined in the single-task gait, was used in all three walking tests.ResultsST, CDT and MDT gait parameters of individuals with transtibial amputation, transfemoral amputation and healthy individuals were significantly different (p < 0.01). Covariance of step length variability increased in amputees when walking under MDT (p < 0.05). The dual task cost (DTC) for all the gait parameters was similar in all three groups (p > 0.05). The motor DTC of covariance of step length was greater than cognitive DTC (p < 0.05).SignificanceIndividuals with lower limb amputation have the capacity to walk with cognitive and motor tasks without changing velocity on the treadmill, but concurrent motor tasks cause an increase in gait variability. The results of this study suggest that there is an increase in gait variability especially with motor tasks, which may cause a higher risk of falling.Trial number: NCT04392466 (clinicaltrials.gov)     

The Primary Gait Screen in Parkinson’s disease: Comparison to standardized measures

BackgroundPersons with Parkinson’s disease exhibit gait deficits during comfortable-pace overground walking and data from pressure sensitive mats have been used to quantify gait performance. The Primary Gait Screen is a new assessment which includes gait initiation, overground walking, turning, and gait termination. Although overground assessments are useful, the Primary Gait Screen offers a more complex evaluation than traditional gait assessments.Research questionIs the overground walking portion of the Primary Gait Screen comparable to traditional gait assessments?MethodsPersons with Parkinson’s disease (N = 175; 47 F, 128 M; 67 ± 9 yrs) prospectively completed 4 passes at a self-selected speed and two trials of the Primary Gait Screen on an 8 m long pressure-sensing mat. Spatiotemporal gait variables were computed and a repeated-measures MANOVA with a Bonferroni correction compared the spatiotemporal variables from the Primary Gait Screen to the self-selected trials: gait velocity, cadence, step length, step time, and stride length.ResultsThe analyses failed to detect differences between the Primary Gait Screen and self-selected trials for gait velocity, step length, or stride length (p > .01). Post-hoc tests revealed decreased cadence and increased step time were the only differences between the Primary Gait Screen trials and the self-selected trial (p < .001).SignificanceDifferences seen in cadence and step time during the Primary Gait Screen may be attributed to patients’ strategy, but are likely not clinically meaningful. The Primary Gait Screen appears to be a comparable assessment of overground walking in persons with Parkinson’s disease, and may be a useful and accurate clinical assessment of walking.     

Spatiotemporal gait variables and step-to-step variability in preschool-aged children born < 30 weeks’ gestation and at term in preferred speed,dual-task paradigm,and tandem walking

BackgroundChildren born very preterm (< 32 weeks’ gestation) are at greater risk of motor impairment and executive/attentional dysfunctions than term-born children; however, little is known about how functional tasks, including walking, may be affected by very preterm birth.Research questionHow does the gait pattern of preschool-age children born < 30 weeks compare with term-born controls under a variety of walking conditions?MethodsIn this prospective cohort study, children born < 30 weeks and at term were assessed at 4.5–5 years’ corrected age, blinded to birth group. Four walking conditions were assessed using the GAITRite® system: preferred speed, cognitive dual-task, motor dual-task, and tandem walking. Gait variables analysed included speed, cadence, step length, step time, base of support (BOS), and single and double support time. Spatiotemporal variables were compared between groups using linear regression, adjusting for lower-limb length, corrected age at assessment, and number of trials.Results224 children (112 < 30 weeks and 112 term-born) were assessed. Gait variables of children born < 30 weeks did not differ from their term-born peers when walking at their preferred speed, except for higher BOS variability (mean difference [MD] = 0.19 cm, 95% confidence interval [CI] 0.10, 0.27, p < 0.001). Under the motor dual-task condition, children born < 30 weeks walked faster (MD= 3.06 cm/s, 95% CI 0.14, 5.97, p = 0.040), with a longer step length (MD= 1.10 cm, 95%CI 0.19, 2.01, p = 0.018), and a wider BOS (MD= 0.37 cm, 95%CI 0.06, 0.67, p = 0.019). In cognitive dual-task and tandem conditions, children born < 30 weeks walked with a wider BOS compared with term-born peers (MD= 0.43 cm, 95%CI 0.05, 0.81, p = 0.028; and MD= 0.30 cm, 95%CI 0.09, 0.51, p = 0.005, respectively).SignificanceThis research highlights the need to consider the walking performance of preschool-age children born < 30 weeks under challenging conditions, such as dual-task or tandem walking, when assessing gait patterns and planning interventions.     

Concurrent validity of the ZeroWire® footswitch system for the measurement of temporal gait parameters

BackgroundIn contrast to wearable tools (like in-shoe) sensors, lab-based gait assessment (using pressure-sensitive mats or cameras) only acquire data over short distances in non-ecological environments.Research questionTo examine the concurrent validity of a wearable ZeroWire® footswitch system (Aurion Srl, Milan, Italy) vs. the GAITRite® walkway (CIR systems Inc., NJ, USA) for recording temporal gait parameters.MethodsWe included 40 healthy participants in a prospective, single-center study. Temporal gait parameters were recorded simultaneously with the ZeroWire® and GAITRite® systems while each participant walked at three different speeds (slow (60steps/min), comfortable and maximum). To measure the validity, we calculated the interclass correlation coefficient (ICC) and the coefficient of variation (CV) for each parameter (gait cadence, stride time, step time, stance time, and single-support and double-support times). We also performed a graphical analysis using the Bland and Altman method.ResultsThe footswitch system showed moderate-to-excellent concurrent validity vs. the GAITRite mat. The degree of agreement between the two assessments was greatest at the maximum gait velocity showed, with very good validity (ICC > 0.91) seen for most parameters, whereas agreement ranged from moderate to very good for the other speeds. Independently of the gait speed, the highest levels of agreement were recorded for gait velocity, cadence, stride time, step time, and stance time. According to the CVs, both systems showed the same accuracy and double-support time was the more variable parameter.SignificanceThe ZeroWire® footswitch system appears to be valid for assessing temporal gait parameters (and particularly gait cadence and stride, step and stance times in healthy participants). It is likely to be well suited to the assessment of gait parameters under ecological conditions and in dual-task gait paradigms.     

Effect of dual-tasking on walking and cognitive demands in adults with Alzheimer’s dementia experienced in using a 4-wheeled walker

BackgroundLearning to walk with a 4-wheeled walker increases cognitive demands in people with Alzheimer’s dementia (AD). However, it is expected that experience will offset the increased cognitive demand. Current research has not yet evaluated gait in people with AD experienced in using a 4-wheeled walker under complex gait situations.Research questionWhat is the effect of dual-task testing on the spatial-temporal gait parameters and cognitive performance of people with AD experienced with a 4-wheeled walker?MethodsTwenty-three adults with mild to moderate AD (87.4 ± 6.2 years, 48 % female) and at least 6 months of walker use experience participated. Three walking configurations: 1) straight path (SP), 2) Groningen Meander Walking Test (GMWT), and 3) Figure of 8 path (F8) were tested under two walking conditions: 1) single-task (walking with aid) and 2) dual-task (walking with aid and completing a cognitive task). Tri-axial accelerometers collected velocity, cadence and stride time variability (STV). Gait and cognitive task cost were the percentage difference between single-task and dual-task conditions. Two-way repeated measures ANOVAs were used to answer the study question.ResultsA significant interaction between walking configuration and condition was found for velocity (p = 0.002, ω² = 0.36), cadence (p = 0.04, ω² = 0.15) and STV (p < 0.001, ω² = 0.53). Velocity and cadence decreased and STV increased with increasing walking configuration complexity and upon dual-tasking. Dual-task gait and cognitive task cost deteriorated in all walking configurations, but gait was prioritized in the GMWT and F8 configurations.Despite familiarity, experienced walker users with AD exhibit impaired gait when walking in complex situations which increases falls risk. Upon dual-task, individuals with AD self-prioritized a posture-first strategy in complex configurations.SignificanceDual-task testing in experienced users results in slower walking, fewer steps and increased STV, which increases falls risk in people with mild to moderate AD and becomes most pronounced in complex environments.     

Reliability and minimal detectable change of gait variables in community-dwelling and hospitalized older fallers

PurposeGait variables may constitute surrogate outcomes for fall risk. Their reliability in a specific population of older fallers has not been fully established, which limits their research and clinical applications. This study aimed to determine test–retest reliability and minimal detectable change (MDC) values for selected fall-related gait variables in older adults with a recent fall history.MethodsCommunity-dwelling (n = 30) and hospitalized (n = 30) fallers aged ≥ 65 years were assessed twice using an instrumented pressure-sensitive walkway, under single- and dual-task gait conditions. Intraclass correlation coefficient (ICC_(2,1)), standard error of measurement (SEM; SEM%) and MDC at 95% confidence level (MDC₉₅; MDC₉₅%), were used as reliability estimates.ResultsThe ICC_(2,1) for gait velocity was greater than 0.84 across all gait conditions and groups; SEM% and MDC₉₅% did not exceed 6.5% and 18.1%, respectively. Gait variability measures returned lower ICC_(2,1) (range 0.18–0.79), and markedly higher SEM% (16.3–31.9%) and MDC₉₅% (45.3–88.3%). Overall, hospitalized fallers exhibited larger SEM and MDC₉₅ values for variability measures compared to community-dwellers in all gait conditions, while larger values were found for all variables while dual-tasking compared to single-tasking in both groups.ConclusionsGait velocity was found to be highly reliable and likely to be sensitive to change over repeated sessions in community-dwelling and hospitalized older fallers, both under single- and dual-task conditions. Gait variability measures showed lower reliability, irrespective of gait condition or group, displaying consistently larger measurement error, particularly under dual-task conditions. Clinicians should consider MDC₉₅ values before using gait variability variables as evaluative outcome measures at patient level.     

Temporal and spatial features of gait in older adults transitioning to frailty

Examining gait characteristics in older adults who are transitioning to frailty enhances our understanding of movement control in this fall-prone population and helps to better target preventive interventions. This work presents data on temporal and spatial gait parameters of a group of older adults who have been operationally defined as "transitionally frail". Gait speed, cadence, stride length, stance, swing, double-support, and horizontal heel velocity at heel contact were measured in 50 transitionally frail older adults while walking at a self-selected pace. These data suggest that the temporal and spatial gait features of these older adults differ substantially from published results from other older adults.     

Residual standard deviation: Validation of a new measure of dual-task cost in below-knee prosthesis users

We developed and evaluated properties of a new measure of variability in stride length and cadence, termed residual standard deviation (RSD). To calculate RSD, stride length and cadence are regressed against velocity to derive the best fit line from which the variability (SD) of the distance between the actual and predicted data points is calculated. We examined construct, concurrent, and discriminative validity of RSD using dual-task paradigm in 14 below-knee prosthesis users and 13 age- and education-matched controls. Subjects walked first over an electronic walkway while performing separately a serial subtraction and backwards spelling task, and then at self-selected slow, normal, and fast speeds used to derive the best fit line for stride length and cadence against velocity. Construct validity was demonstrated by significantly greater increase in RSD during dual-task gait in prosthesis users than controls (group-by-condition interaction, stride length p = 0.0006, cadence p = 0.009). Concurrent validity was established against coefficient of variation (CV) by moderate-to-high correlations (r = 0.50–0.87) between dual-task cost RSD and dual-task cost CV for both stride length and cadence in prosthesis users and controls. Discriminative validity was documented by the ability of dual-task cost calculated from RSD to effectively differentiate prosthesis users from controls (area under the receiver operating characteristic curve, stride length 0.863, p = 0.001, cadence 0.808, p = 0.007), which was better than the ability of dual-task cost CV (0.692, 0.648, respectively, not significant). These results validate RSD as a new measure of variability in below-knee prosthesis users. Future studies should include larger cohorts and other populations to ascertain its generalizability.     

Hearing loss and increased gait variability among older adults

BackgroundThe influence of age-related hearing loss on slow gait has been suggested; however, whether it is associated with increased gait variability, an important predictor of fall risk, remains unclear.Research questionIs poor auditory acuity associated with increased gait variability, and does this gait change relate to accidental falls among older adults with hearing loss?MethodsWe studied 107 older adults (mean age, 76.5 years; 80.5 % women). Auditory acuity was measured using a pure tone average (PTA) of hearing thresholds for 0.5–4 kHz tones in the better-hearing ear. Hearing loss was defined as a PTA of >25 dB. Gait speed and spatiotemporal variability (i.e., stride length and time variabilities) were assessed using a 5-m electronic walkway. We also assessed the occurrence of multiple falls within the previous year.ResultsFifty-two participants (48.6 %) experienced hearing loss. Multiple regression analysis adjusted for potential covariates showed that poor PTA was associated with slower gait speed and stride length variability, but not stride time variability. Among older adults with hearing loss, fall occurrence was associated with an increased stride length variability and not a slow gait or increased stride time variability.SignificanceThe association between hearing loss and increased gait variability observed in the present study suggests that age-related hearing loss can jeopardize gait control during daily activities. This leads to increased gait variability and increased risk of accidental falls. Our results provide additional information on how age-related hearing loss increases the risk of falls.     

Basic gait and symmetry measures for primary school-aged children and young adults whilst walking barefoot and with shoes

This study investigated the basic spatio-temporal gait measures of 898 primary school-aged children (5–13 years) and 82 young adults (18–27 years). Participants completed 6–8 walks at preferred speed along a GAITRite walkway whilst barefoot and whilst wearing athletic shoes or runners. Outcome measures (non-normalized and normalized) were gait speed, cadence, step and stride length, support base, single and double support, stance duration, foot angle and associated symmetry measures. Non-normalized measures of speed, step and stride length, support base and foot angle increased with age whereas cadence reduced. Normalized measures remained unchanged with age in children whereas the young adults (both conditions) exhibited a 2.3% reduction in single support, a 5.1% increase in double support and a 2.6% increase in stance duration (p < 0.0001). For the entire sample, shoes increased walking speed by 8 cm s⁻¹, step length by 5.5 cm, stride length by 11.1 cm and base of support by 0.5 cm. In contrast, foot angle and cadence reduced by 0.1° and 3.9 steps min⁻¹ respectively. Shoes increased both double support (1.6%) and stance time (0.8%), whereas single support reduced by 0.8%. Symmetry remained unaffected by age. On average, measures of step and stride symmetry (combining both conditions) fell around 0.7 cm, whereas measures of symmetry for step and stance time, single and double support fell around 0.6%. Footwear significantly affected gait (p < 0.0001). Gait may not be mature by age 13. Gait is symmetrical in healthy children and young adults but may change with pathology.