Stride Time Variability Research Articles

Relationship Between Lower Extremity Muscle Function And Gait Variability In Individuals With PD

PURPOSE: Increased variability in motor function can significantly impair performing activities of daily living. The difficulty in performing daily motor tasks is increased in pathological populations, e.g., Parkinson’s disease (PD). The muscular capabilities, e.g., torque production and force control, in PD, are reduced compared to older adults. It is unclear if the reduced muscular capabilities in PD are related to increased difficulty performing regular movements, i.e., gait. This study examined the relationship between muscular capabilities of the lower extremity and gait variability in persons with PD. METHODS: 12 PD and 11 age-matched controls underwent gait and lower extremity muscle testing. Gait was evaluated by having the subjects perform ten over-ground walking trials over a 9-m walkway at a self-selected speed using an 8-camera motion capture system. Linear measures of gait, including stride length, stride time, step width, and velocity, were calculated. Gait variability and force variability were examined using the coefficient of variation (CV = standard deviation/mean × 100%). Lower extremity testing consisted of 1) maximal isometric torque production and 2) submaximal force control using a tracing paradigm at 5, 10, and 20% of their maximal torque production in multiple directions at the hip and ankle. Pearson's correlations were applied to analyze associations between gait variability and force variability. RESULTS: In the PD group, stride time was positively correlated with 20% of ankle dorsiflexion CV (r(21)=.62, p<.05) and velocity was positively correlated with 10 and 20% of ankle plantarflexion CV (r(21)=.59, p<.05) and 20% of hip extension CV (r(21)=.63, p<.05). Maximal torque production of the dorsiflexors (r(21)=.75, p<.05) and plantar flexors (r(21)=.67, p<.05) were positively correlated stride time variability in the PD group. CONCLUSION: The results highlight an association between lower-extremity muscle function and gait function in PD. Interestingly, in those with PD, both maximal strength and control of muscle strength were found to be related to the temporal parameters of gait variability. These results suggest that gait dysfunction could be the result of specific pathological impairments and provide unique opportunities for specialized interventions.

Relations between gait characteristics and subjective visual vertical results in young adults.

Subjective visual vertical (SVV) deviation can indicate impairments of motion perception and spatial orientation in individuals with vestibular disorders. This study investigated the influence of SVV on tandem gait ability by assessing differences between temporal, spatial, and kinematic characteristics in young adults. We recruited sixteen young adults with increased SVV and 17 age-matched control subjects. All subjects recruited for this study were with no history of neurological or musculoskeletal diseases. Knee and hip-joint kinematic data, spatio-temporal parameters, and gait variability were measured during tandem gait. Stride time variability and stride velocity variability were significantly greater in the experimental group than the control group (p < 0.05). In addition, a significant correlation was observed between stride time variability and SVV results (r = 0.345, p < 0.05). However, hip and knee joint angles were non-significantly different in the experimental and control groups (p > 0.05) and spatio-temporal parameters were similar between the two groups (p > 0.05). Stride time variability and stride velocity variability during tandem gait were significantly different in the experimental and control groups. We presume that increased SVV deviation is related to greater gait variability during tandem gait.

Walking Speed Affects Gait Coordination and Variability Among Older Adults With and Without Mobility Limitations

ObjectiveTo determine if poorer gait variability and gait coordination among mobility-limited older adults is related to their slower walking speed. DesignCross-sectional analysis. SettingUniversity research laboratory. ParticipantsCommunity-dwelling adults (N=69) 68 years or older with (Short Physical Performance Battery score ≤9; n=37) and without (n=32) mobility limitations. InterventionsNot applicable. Main Outcome MeasuresThe variability of step length, swing time percent, and step width. Gait coordination was assessed along with the Phase Coordination Index. ResultsThe usual pace gait speed of those without mobility limitations was faster (1.22±0.14m/s vs 0.71±0.14m/s; P<.001) and less variable in all gait characteristics (all P<.001), with the exception of step width (P=.185), than those with limitations. When those without limitations slowed their walking pace (0.71m/s±0.14), their gait coordination became poorer (P<.001), and the variability of all gait characteristics increased (all P<.001) except for step width, which decreased (P=.002). When those without mobility limitations walked at a slow pace, they had better gait coordination (P=.008) and less variable step length (P=.014) and swing time percent (P=.036). The variability of stride time (P=.260) and step width (P=.385) were not significantly different than that of their peers with limitations. ConclusionsIncreased variability in some gait characteristics of mobility-limited older adults appears to be related to their slower walking speed. Gait coordination and the variability of step length and swing time percent may reflect intrinsic differences in mobility-limited older adults that are independent of walking speed.

Assessment of diurnal variation of stride time variability during continuous, overground walking in healthy young adults

Background: There is emerging evidence that gait variability outcomes provide unique insights regarding the status of an individual’s locomotor control system; however, there is currently limited evidence on the within-day reliability of stride time variability (STV) outcomes, or whether they demonstrate diurnal variation, when measured during continuous, overground walking in healthy young adults. Research Questions: 1) Are STV outcomes measured in the morning and afternoon during continuous, overground walking significantly different in healthy young adults? 2) What is the within-day reliability of STV outcomes measured during continuous, overground walking in healthy young adults?. Methods: Thirty-one healthy young adults (20.8 ± 3.7 years) completed two 10-minute continuous, overground walking trials on the same day (9:00-11:00am and 3:00-5:00pm) at their preferred walking speed. Data from a waist-mounted tri-axial accelerometer were used to determine the series of consecutive stride times for each trial. Results: There were no significant differences between sessions for average walking speed, average stride time, or STV. The within-day reliability was excellent for average walking speed and stride time, and generally poor to fair for STV. Significance: Healthy young adults do not appear to demonstrate diurnal variation in STV outcomes during continuous, overground walking; however, the development of a protocol to improve their reliability, as well as the establishment of normative ranges for such outcomes, would be beneficial to improve their application and interpretation in research and clinical settings.

Walking barefoot vs. with minimalist footwear \u2013 influence on gait in younger and older adults

BackgroundIn recent years, minimalist footwear has been increasingly promoted for its use in sportive and recreational activities. These shoes are considered to function naturally like barefoot walking while providing a protective surface. Despite a growing popularity of these shoes in the older population, little is known about the influence of minimalist footwear on gait patterns. This study investigated whether overground walking with minimalist shoes is comparable to barefoot walking regarding gait stability and variability parameters.MethodsIn a randomized within-subject study design, 31 healthy younger (29 ± 4 years) and 33 healthy community-dwelling older adults (71 ± 4 years) volunteered. Participants walked on flat ground, once barefoot and once with minimalist shoes. Gait variability of minimum toe clearance (MTC), stride length, stride time, and local dynamic gait stability were analysed.ResultsThe results for both age groups showed significant condition effects (minimalist shoes vs. barefoot walking) for the outcomes of local dynamic stability (p = .013), MTC variability (p = .018), and stride length variability (p < .001) indicating increased local dynamic stability and decreased gait variability during the minimalist shoe condition. Group effects (young vs. older adults) were detected in all gait outcomes.ConclusionWalking with minimalist shoes appeared to be associated with better gait performance than walking barefoot in both age groups. Thus, walking with minimalist shoes is not similar to barefoot walking. With respect to reducing the risk of falling, we suggest that minimalist shoes could be an alternative to barefoot walking or a transition option between shoes to barefoot for older adults.

The interplay between physical activity and aging in locomotor fractal behavior

The complex organization of gait variability, or fractal dynamics, theoretically represents the adaptive capacity of the locomotor system. Prior studies suggest that fractal dynamics are sensitive to various individual constraints (e.g., age, neurological disease) and task constraints (e.g., walking speed or novel gait tasks). The purpose of this study was to determine if physical activity levels represent an additional individual constraint during walking. Fifteen young and 15 older adults walked on a treadmill at their preferred walking speed and at half of their preferred speed. Detrended fluctuation analysis was used to estimate the statistical persistence of stride time variability. Volume of physical activity was determined using a wearable monitor for 3-7 days. Habitual physical activity levels did not appear to have an effect on the fractal nature of stride-to-stride fluctuations in young adults. However, the least active older adults displayed higher scaling exponents compared to the more active older adults during slow walking. That is, less active older adults responded to the slow walking task by increasing fractal scaling, suggesting this task is more challenging and complex. These findings suggest that lower levels of habitual physical activity may represent an additional individual constraint in older but not young adults. When age and physical activity constraints are combined with a challenging slow walking task, the locomotor system of older adults may be more highly taxed, ultimately manifesting as stronger statistical persistence.

Treadmill walking alters stride time dynamics in Parkinson’s disease

BackgroundTreadmill training may be used to improve gait rhythmicity in people with Parkinson’s disease. Treadmills, however, alter dynamical stride time fluctuations in healthy adults in a manner that mimics pathologic states, indicating the stride-to-stride fluctuations that characterize healthy gait are constrained. It is unclear if treadmills similarly alter dynamic gait properties in Parkinson’s disease. Research questionDo stride time fractal dynamics in individuals with Parkinson’s disease differ between treadmill and overground walking? MethodsFifteen participants with Parkinson’s disease and 15 healthy age-similar adults walked for 6 min in a conventional overground condition and on a treadmill while wearing inertial measurement units. Gait speed, stride times and stride time variability were measured. Fractal exponents (α) were computed with adaptive fractal analysis. Inferential statistics were analyzed with mixed model analyses of variance and post hoc simple effects tests. ResultsMean gait speeds decreased and stride times increased on the treadmill but did not differ between the Parkinson’s and control groups. Stride time variability was greater in the Parkinson’s than control group in both conditions. Most relevant to our research question, stride time fractal exponents were greater on the treadmill (mean α = .910) than overground (mean α = .797) in individuals with Parkinson’s disease, but not in healthy controls. SignificanceThe fractal scaling exponent α emanating from stride time fluctuations during treadmill walking increased toward a 1/f signal of α = 1.0 that has been interpreted as an optimal structural variability for gait. The clinical implication is that treadmill training may promote more efficient walking dynamics in people with Parkinson’s disease than conventional overground training.

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.

Speeding Up Gait in Parkinson's Disease.

Gait speed is an important outcome that relates to mobility, function, and mortality, and is altered in people with Parkinson's disease (PwPD). However, changes in gait speed may not reflect changes in other important aspects of gait. To characterize which outcomes change concomitantly with walking speed in PwPD. This information can inform the choice of outcome variables for characterizing and tracking gait performance in this population. 67 PwPD and 40 neurotypical adults completed 2-minute overground walking bouts at comfortable and fast self-selected speeds. Eight inertial sensors were used to characterize gait and turning. We identified a subset of participants (38 per group) where the PD participant's "fast" walk was similar speed to neurotypical participants "comfortable" walk, facilitating an across-group gait comparison controlling for gait speed. Walking at fast gait speed compared to comfortable lead to significant changes in stride length, cadence, and stride time variability, but not in steps to turn, trunk ROM, and trunk and lumbar stability in PwPD. Sub-group analyses showed that despite walking at a similar speed as neurotypical adults, PwPD exhibit altered turning outcomes, lumbar stability, and stride length/cadence. Gait speed is a critical outcome for characterizing mobility. However, in PwPD, several important outcomes do not exhibit a uniform relationship with gait speed, and remain altered compared to neurotypical adults despite "normalizing" walking speed. Given the complex relationship between gait speed and other gait quality measures, care should be taken when choosing outcome measures to characterize the breadth of gait abnormality in PwPD.

Estimation of Stride Time Variability in Unobtrusive Long-Term Monitoring Using Inertial Measurement Sensors.

Stride time variability is an important indicator for the assessment of gait stability. An accurate extraction of the stride intervals is essential for determining stride time variability. Peak detection is a commonly used method for gait segmentation and stride time estimation. Standard peak detection algorithms often fail due to additional movement components and measurement noise. A novel algorithm for robust peak detection in inertial sensor signals was proposed in a previous contribution. In this work, we present a novel approach for estimation of stride time variability based on the formerly proposed peak detection algorithm applied to an unobtrusive sensor setup for motion monitoring. The unobtrusive sensor setup includes a wrist sensor, a pocket or belt sensor, and a necklace sensor, all equipped with both accelerometer and gyroscope. The goal of this work is to implement a generalized approach for accurate and robust stride interval determining algorithm for different sensor locations. Therefore, treadmill and level ground walking experiments were conducted with ten healthy subjects at increasing walking speeds and an age-simulating suit. With the proposed algorithm, we achieved a RMSE of 0.07s for the stride interval estimation during treadmill walking experiments. The results give promising indications that detection of variation of stride time variability is possible using the proposed unobtrusive sensor setup.

Differences in reproducibility of gait variability and fractal dynamics according to walking duration.

BACKGROUND: Gait variability and fractal dynamics may be affected by the walking duration.OBJECTIVE: The purpose of this study is to examine the reproducibility of stride time while walking on a self-paced treadmill.METHODS: Fifteen young and healthy subjects walked on the treadmill for 10 minutes. Three to eight minutes duration of the data were used to compare the trial-to-trial and day-to-day reproducibility of the average, variability, and fractal dynamics of stride time.RESULTS: The results show that all variables had high trial-to-trial reproducibility. In the day-to-day results, the average walking speed and mean stride time showed reproducibility without regard for duration, but the variability and gait fractal dynamics showed differences in reproducibility according to duration. The variability and fractal dynamics showed better reproducibility in less than 5 minutes and over time, respectively. However, both variables generally showed improved reproducibility when average data from two to three rounds were used.CONCLUSION:Based on the results of this study, it is proposed that variability should be examined using data of 5 min or less, and fractal dynamics should be examined using 5 min or more of repeated data when performing walking tests from a gait dynamics perspective.

Using Body-Worn Sensors to Detect Changes in Balance and Mobility After Acute Aerobic Exercise in Adults with Multiple Sclerosis.

Current mobility and functional assessments do not capture the subtle changes in balance and gait that may predispose people with multiple sclerosis (MS) to falling. The purpose of this study was to use clinical and instrumented measures to examine the effects of an acute bout of aerobic exercise on balance and gait in individuals with MS. Ten adults with MS performed 15 minutes of moderate-intensity recumbent cycling or 15 minutes of rest. Exercise and rest visit order was randomized and separated by 1 week. Balance and mobility were assessed before, immediately after, and 2 hours after each test condition. There were no significant differences across measurement periods for Timed 25-Foot Walk test times or Brief Balance Evaluation Systems Test scores. Significant improvements in mean sway radius and sway velocity when standing on foam and in percentage of stance stride time variability were found immediately after exercise compared with immediately after rest. This study lends further evidence that individuals with MS can safely engage in single bouts of aerobic exercise without detrimental short-term effects on function and may actually receive some short-term benefit regarding standing postural sway and gait variability. Future research should examine the dose-dependent relationship of varying types, intensities, or timing of exercise necessary to elicit short-term functional benefit and long-term health outcomes.

Mapping Associations Between Gait Decline and Fall Risk in Mild Cognitive Impairment.

Compared to their cognitively healthy counterparts, older adults with mild cognitive impairment (MCI) exhibit higher risk of falls, specifically with injuries. We sought to determine whether fall risk in MCI is associated with decline in higher-level brain gait control. Longitudinal study. Community-dwelling adults from the Gait and Brain Study Cohort. A total of 110 participants, aged 65 years or older, with MCI. Biannual assessments for medical characteristics, cognitive performance, fall incidence, and gait performance for up to 7 years. Seven spatiotemporal gait parameters, including variabilities, were recorded using a 6-meter electronic walkway. Principal components analysis was used to identify independent gait domains related to higher-level (pace and variability domains) and lower-level (rhythm domain) brain control. Associations between gait decline and incident falls were studied with Cox regression models adjusted for baseline covariates. Of participants enrolled, 40% experienced at least one fall (28% of them with injuries) over a mean follow-up of 31.6 ± 23.9 months. From the pace domain, slower gait speed (adjusted hazard ratio [aHR] per 10-cm/s decrease = 4.62; 95% confidence interval [CI] = 1.84-11.61; P = .001) was associated with severe injurious falls requiring emergency room (ER) visit; from the variability domain, stride time variability (aHR per 10% increase during follow-up = 2.17; 95% CI = 1.02-4.63; P = .04) was associated with higher risk of all injurious falls. Rhythm domain was not associated with fall risk. Decline in pace domain was significantly associated with falls with ER visit (aHR = 3.67; 95% CI = 1.46-9.19; P = .005). After adjustments for multiple comparisons, gait speed and pace domain remained significantly associated with falls with ER visits. No statistically significant associations were found between gait domains and overall falls (P ≥ .06). Higher risk of injurious falls in older adults with MCI is associated with decline in gait parameters related to higher-level brain control. J Am Geriatr Soc 68:576-584, 2020.

Does variability in motor output at individual joints predict stride time variability in gait? Influences of age, sex, and plane of motion

Old age is associated with variability in gait motor output, particularly in females, and is linked to fall risk. However, little is known about how older age and sex affect variability in the outputs of individual joints, and how these variabilities contribute to the collective gait output. Healthy adults aged 18–99 years (N = 102, 57 females) completed six trials of straight walking at self-selected speed. Stride time variability (coefficient of variation) and variabilities of lower limb tridimensional joint angles (standard deviations: SD) were calculated. Age * Sex (A * S) mixed models were conducted on all measures and year-by-year rates of change were subsequently estimated. Correlations and stepwise linear regression analyses were computed between joint angular variabilities and stride time variability. Each year of age was associated with 0.022% higher stride time variability (A: p = .002), 0.07° lower variability in peak ankle dorsiflexion (A: p = .004), 0.002–0.098° higher variability in mean ankle inversion/eversion, mean pelvic obliquity, and pelvic rotation range of motion (A: p < .05), and 0.024° higher variability in knee flexion/extension range of motion in males (A * S: p = .003). Higher variability in mean ankle and hip flexion/extension and in mean ankle inversion/eversion correlated with (ρ = 0.211–0.336; ps < 0.05) and independently predicted higher stride time variability (ps < 0.05), together explaining 21.9% of variance. Results suggest that higher stride time variability with older age may be produced by a shift from sagittal plane variability to frontal plane variability at the ankle.

Self-Reported Head Trauma Predicts Poor Dual Task Gait in Retired National Football League Players.

ObjectiveSymptomatic head trauma associated with American‐style football (ASF) has been linked to brain pathology, along with physical and mental distress in later life. However, the longer‐term effects of such trauma on objective metrics of cognitive–motor function remain poorly understood. We hypothesized that ASF‐related symptomatic head trauma would predict worse gait performance, particularly during dual task conditions (ie, walking while performing an additional cognitive task), in later life.MethodsSixty‐six retired professional ASF players aged 29 to 75 years completed a health and wellness questionnaire. They also completed a validated smartphone‐based assessment in their own homes, during which gait was monitored while they walked normally and while they performed a verbalized serial‐subtraction cognitive task.ResultsParticipants who reported more symptomatic head trauma, defined as the total number of impacts to the head or neck followed by concussion‐related symptoms, exhibited greater dual task cost (ie, percentage increase) to stride time variability (ie, the coefficient of variation of mean stride time). Those who reported ≥1 hit followed by loss of consciousness, compared to those who did not, also exhibited greater dual task costs to this metric. Relationships between reported trauma and dual task costs were independent of age, body mass index, National Football League career duration, and history of musculoskeletal surgery. Symptomatic head trauma was not correlated with average stride times in either walking condition.InterpretationRemote, smartphone‐based assessments of dual task walking may be utilized to capture meaningful data sensitive to the long‐term impact of symptomatic head trauma in former professional ASF players and other contact sport athletes. ANN NEUROL 2020;87:75–83

Quantitative Gait Analysis and Cerebrospinal Fluid Tap Test for Idiopathic Normal-pressure Hydrocephalus

We investigated gait performance utilizing a quantitative gait analysis for 2 groups: (1) idiopathic normal-pressure hydrocephalus (INPH) patients who had a positive response to the cerebrospinal fluid tap test (CSFTT) and (2) healthy controls. The aims of the study were (1) to analyze the characteristics of gait features, (2) to characterize changes in gait parameters before and after the CSFTT, and (3) to determine whether there was any relationship between stride time and stride length variability and Frontal Assessment Battery (FAB) scores in INPH patients. Twenty-three INPH patients and 17 healthy controls were included in this study. Compared with healthy controls, the gait of INPH patients was characterized by lower velocity, shorter stride length, and more broad-based gait. Patients with INPH had a longer stance phase with increased double-limb support. Variability in stride time and stride length was increased in INPH patients. Stride time and stride length variability were correlated with FAB score. After the CSFTT, gait velocity, stride length, and step width significantly improved. There were significant decreases in stride time and stride length variability. These results suggest that the CSFTT for INPH patients might improve the so-called balance-related gait parameter (ie, step width) as well. Stride time and stride length variability also responded to the CSFTT. Association between FAB scores and both stride time and stride length variability suggests involvement of similar circuits producing gait variability and frontal lobe functions in INPH patients.

The influence of aging on the spatial and temporal variables of gait during usual and fast speeds in older adults aged 60 to 102 years

BackgroundWith increases in life expectancy, it is important to understand the influence of aging on gait, given that this activity is related to the independence of older adults and may help in the development of health strategies that encourage successful aging in all phases of this process. Research questionTo compare gait parameters with usual and fast speeds for independent and autonomous older adults throughout the aging process (60 to 102 years old), and also to identify which of the gait variables are best for identifying differences across the different age groups. MethodsTwo hundred older adults aged between 60 and 102 years were evaluated. The sample was divided into 3 age groups: 60 to 79 years, 80 to 89 years and 90 years and over. The analyzed gait variables were: speed (meters/s), cadence (steps/min), stride time (seconds), step length (centimeters), double support (percentage of the gait cycle), swing (percentage of the gait cycle), step length variability (CoV%) and stride time variability (CoV%). ResultsGroup comparison regarding usual gait and fast gait revealed a significant difference in all gait variables. In addition, it can be seen that variables such as gait speed and step length showed greater effect sizes in intergroup comparison (usual gait: 0.48 and 0.47; fast gait: 0.36 and 0.40; respectively), possibly showing that these variables can better detect the changes observed with increasing age. ConclusionThere are differences in the gait performance of older adults from different age groups for usual and fast gait speeds, which is more evident regarding gait speed and step length variables. We recommend the use of usual gait for the identification of the effects of aging because, besides showing a higher effect size values it is more comfortable and requires less effort from older subjects.

Effects of Mental and Physical Fatigue Inducing Tasks on Balance and Gait Characteristics

150-Word AbstractFatigue may reduce human performance and increase injury risk. This study investigated the effects of mental and physical fatigue inducing tasks (MF and PF) on balance and gait cha...

Wearable Sensor-Based Daily Life Walking Assessment of Gait for Distinguishing Individuals With Amnestic Mild Cognitive Impairment.

Objectives: To characterize gait disorders in patients with amnestic mild cognitive impairment (aMCIs) and determine the association between the performance of the gait function and cognition.Methodology: In this study, we enrolled 38 patients with aMCI and 30 cognitively normal individuals normal controls (NC). Neuropsychological assessments included tests of memory, executive function, language, and attention. Using an inertial-sensor-based wearable instrument, we collected the gait data dynamically for at least 1 h/day for 2 weeks. The gait parameters included walking velocity, stride length, stride time, cadence, and stride time variability.Results: The aMCI patients had reduced walking velocity and stride length and increased stride time variability compared with the NCs. The total number of steps, stride time, and cadence did not differ between the two groups. For all the subjects, walking velocity and stride length was positively associated with memory and executive function. Stride time variability was negatively correlated with the cognitive domains including memory, executive function and attention.Conclusion: This study suggested that cognitive impairment-related gait disorders occur (reduced gait speed, gait length, and gait stability) in daily life walking among the aMCI patients. A sensor-based wearable device for gait measurement may be an alternative and convenient tool for screening cognitive impairment.

Complexity, symmetry and variability of forward and backward walking at different speeds and transfer effects on forward walking: Implications for neural control

This study aimed to investigate effects of walking direction and speed on gait complexity, symmetry and variability as indicators of neural control mechanisms, and if a period of backward walking has acute effects on forward walking. Twenty-two young adults attended 2 visits. In each visit participants walked forwards at preferred walking speed (PWS) for 3-minutes (pre) followed by 5-minutes walking each at 80%, 100% and 120% of PWS of either forward or backward walking then a further 3-minutes walking forward at PWS (post). The order of walking speed in each visit was randomised and walking direction of each visit was randomised. An inertial measurement unit was placed over L5 vertebra to record tri-axial accelerations. From the trunk accelerations multiscale entropy, harmonic ratio and stride time variability were calculated to measure complexity, symmetry and variability for each walk. Complexity increased with increasing walking speed for all axes in forward and backward walking, and backward walking was less complex than forward walking. Stride time variability was also greater in backward than forward walking. Anterio-posterior and medio-lateral complexity increased following forward and backward walking but there was no difference between forward and backward walking post effects. No effects were found for harmonic ratio. These results suggest during backward walking trunk motion is rigidly controlled but central pattern generators responsible for temporal gait patterns are less refined for backward walking. However, in both directions complexity increased as speed increased suggesting additional constraint of trunk motion, normally characterised by reduced complexity, is not applied as speed increases.