Construct validity and test-retest reliability of a free mobile application for spatio-temporal gait analysis in Parkinson’s disease patients

BackgroundMobile applications may be used to assess gait pattern deviation through mobile smartphones in people with Parkinson’s disease (PD). However, few studies have investigated their psychometrics properties.Research questionTo study the construct validity and test-retest reliability of the RUNZI® free mobile application in people with mild to moderate PD.MethodsThirty individuals were evaluated with the RUNZI® app and with the 10-meter walking test (10 MW), simultaneously. In addition, the Timed Up & Go test (TUG), Tinetti scale, and the Berg Balance Scale (BBS) were used to study the construct validity. Also, test-retest reliability of the mobile for spatio-temporal gait parameters was explored.ResultsThe correlation indices of the 10 MW test with the RUNZI® app at fast speeds was moderate to excellent (r = .588–.957). At a comfortable speed, the correlation was excellent for walking speed (r = 0.944), moderate for steps (r = 0.780) and stride length (r = 0.760), and poor for cadence (r = .424). Results showed significant correlations between TUG and spatio-temporal gait parameters at fast and comfortable speeds. There were no significant correlations or consistent associations between Tinetti and BBS and RUNZI®. The test-retest reliability was good to excellent for parameters measured with the RUNZI®.SignificanceOur findings highlight specific opportunities for a free smartphone-based spatio-temporal gait analysis to serve as a complement to conventional gait analysis methods in clinical practice with a moderate to excellent construct validity with the 10 MW test and good to excellent test-retest reliability in PD patients.     

The association between gait variability with the energy cost of walking depends on the fall status in people with multiple sclerosis without mobility aids

BackgroundFalls, gait variability and increased energy cost of walking are common in people with multiple sclerosis (PwMS). However, no studies have as yet examined this triple association in PwMS or in other neurological populations.Research questionDoes a relationship exist between gait variability, falls and the energy cost of gait in PwMS?MethodsThis cross sectional study included 88 PwMS (50 women), mean age 39.8 (S.D = 13.0) and mean disease duration of 6.2 (SD = 8.2) years since diagnosis. Energy expenditure during walking was collected via a portable metabolic device (COSMED K5, COSMED Srl, Roma, Italy). Gait variability was measured by an electronic walkway (GAITRite™). Participants were divided into groups based on fall history (fallers and non-fallers). Differences between groups in terms of energy expenditure measures and gait variability metrics were determined by the analysis of variance test. The relationship between gait variability and energy cost of walking was examined by the Pearson's correlation coefficient test.ResultsThirty-three PwMS were classified as fallers and 55 as non-fallers. Non-significant differences between groups were observed in the energy expenditure measures, including cost of walking. Fallers demonstrated higher step length variability compared with non-fallers (4.58 (S.D. = 2.42 vs. 3.40 (S.D. = 1.40); p-value = 0.005). According to the Pearson's correlation coefficient analysis, a significant relationship was found between step length variability and energy cost of walking in the non-fallers group (Rho = 0.372, P-value = 0.006) and the total group (Rho = 0.296, p-value = 0.005), but not in those PwMS with a history of falls.SignificanceWe demonstrated a significant relationship between increased gait variability and energy expenditure while walking only in MS patients without a history of falls. This is important as there is evidence of the clinical relevance of increased gait variability, poor fitness level and high risk of falling in the MS population.     

Gait stability at early stages of multiple sclerosis using different data sources

BackgroundPeople at early stages of multiple sclerosis have subtle balance problems that may affect gait stability. However, differences in methods of determining stability such as sensor type and placements, may lead to different results and affect their interpretation when comparing to controls and other studies.QuestionsDo people with multiple sclerosis (PwMS) exhibit lower gait stability? Do location and type of data used to calculate stability metrics affect comparisons?Methods30 PwMS with no walking impairments as clinically measured and 15 healthy controls walked on a treadmill at 1.2 ms⁻¹ while 3D acceleration data was obtained from sacrum, shoulder and cervical markers and from an accelerometer placed at the sacrum. The local divergence exponent was calculated for the four data sources. An ANOVA with group (multiple sclerosis and control) and data source as main factors was used to determine the effect of disease, data source and their interaction on stability metrics.ResultsPwMS walked with significantly less stability according to all sensors (no interaction). A significant effect of data source on stability was also found, indicating that the local divergence exponent derived from sacrum accelerometer was lower than that derived from the other 3 sensor locations.SignificancePwMS with no evident gait impairments are less stable than healthy controls when walking on a treadmill. Although different data sources can be used to determine MS-related stability deterioration, a consensus about location and data source is needed. The local divergence exponent can be a useful measure of progression of gait instability at early stages of MS.     

Local dynamic stability during long-fatiguing walks in people with multiple sclerosis

BackgroundAltered balance/stability during walking is common in people with multiple sclerosis (PwMS). While dynamic gait stability has been related to falling and localized muscle fatigue, it has rarely been studied in MS. Specifically, the effects of walking-related fatigue on dynamic stability are unclear in PwMS. Research questions: 1) Are temporal changes in dynamic stability during long-walks different among PwMS and healthy controls (HC)? 2) Is there a relationship between stability and walking performance changes in PwMS?MethodsTwenty-five PwMS and ten HC participated in the six-minute walk test (6MWT) wearing six-wireless inertial sensors. Local dynamic stability (LDS) during gait was quantified by maximum-finite-time Lyapunov exponents (λS), where larger λS indicates less stable dynamics. Linear mixed models were fit to compare changes in LDS and walking performance over time among two groups. Additionally, the percent changes in λS and distance from minute 1 to 6 were recorded as Dynamic Stability Index (DSI6-1) and Distance-Walked Index (DWI6-1) respectively. Finally, Pearson correlation compared the association between DSI6-1 and DWI6-1.ResultsA significant group*time interaction was found for LDS. PwMS did not have different LDS than HC until minute-4 of walking, and differences persisted at minute-6. Further, PwMS walked significantly shorter distances and demonstrated a greater decline in walking performance (DWI6-1) during the 6MWT. Finally, DSI6-1 and DWI6-1 were significantly correlated in PwMS. Significance The dynamic stability differences among PwMS and HC were only apparent after 3-minutes of walking and ∼60% of PwMS became less stable over time, supporting the use of long walks in MS to capture stability changes during the motor task performance. A significant relationship between the decline in stability and poor walking performance over time during the 6MWT suggested a possible role of walking-related fatigue in the worsening of balance during long walks in PwMS.     

Rhythmic interlimb coordination of the lower limbs in multiple sclerosis during auditory pacing to three different frequencies

BackgroundMultiple sclerosis (MS) is a demyelinating disorder of the central nervous system with heterogeneous symptoms. Persons with MS (PwMS) show reduced walking capacity with changes in their gait pattern. It is unknown to which extent coordination deficits are present in PwMS, which can be measured by seated lower leg interlimb coordination tasks, and to which extent they are related to motor and cognitive function.Research questionHow is the control of interlimb coordination of the lower limbs characterized in PwMS compared to healthy controls (HC) during a seated rhythmical coordination task and what is the relationship between interlimb coordination, motor or cognitive function?MethodsRhythmical interlimb coordination was assessed during a single session in 38 PwMS and 13 HC, using a seated rhythmical coordination task, comprising of antiphase flexion-extension of the lower limbs, to metronomes at 0.75 Hz, 1.00 Hz, 1.50 Hz. Outcomes were phase coordination index (PCI), movement amplitude and movement frequency. Correlations between interlimb coordination, motor, and cognitive function were examined.ResultsPwMS showed impaired walking capacity but preserved cognitive function. Mixed model analysis revealed a significant effect of group and metronome frequency for PCI, attenuated by the variability in generating knee (antiphase flexion-extension) movements. Movement amplitude was highest at metronome frequency 1.00 Hz. In PwMS significant correlations were found between PCI and cognitive function when performing the task at metronome frequencies 0.75 Hz and 1.50 Hz, as well as motor function at 1.50 Hz.SignificancePwMS had a higher variability in interlimb coordination compared to HC. The most stable interlimb antiphase coordination mode was performed at 1.00 Hz. Significant correlations support the existence of a relationship between information processing speed, as well as walking impairment, with interlimb coordination. While cognitive and motor control are always needed for interlimb coordination movements, associations are strongest in the deviant higher and lower metronome rhythms.     

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 ability of the instrumented tandem walking tests to discriminate fully ambulatory people with MS from healthy adults

BackgroundPeople with multiple sclerosis (PwMS) experience walking and balance deficits at the initial phases of the disease, even when classified as only minimally disabled. Complex balance tasks, such as tandem walking, are probably more sensitive in detecting mild balance difficulties compared to the standard traditional tests in this population.Research questionThe aim was to investigate different types of 3-meter tandem walking tests in fully ambulatory PwMS.MethodsThis observational case-control study included 50 participants; 25 PwMS, 17 women and 8 men, aged 35.2 (S.D = 8.6) and 25 healthy subjects, 18 women and 7 men, aged 34.3 (S.D = 6.1). The 3-meter tandem walk tests were performed during a single session. Each subject completed a sequence of 3 consecutive tests under 3 different task conditions: normal tandem walking, backward tandem walking and cognitive tandem walking. Tandem walking tests were evaluated via three small, lightweight axial wearable accelerometers (APDM, Oregon, USA).ResultsThe mean EDSS for the MS group was 1.6 (S.D = 0.6) indicating minimal disability. PwMS walked slower and at a slower pace, with a prolonged double support and decreased swing phase compared to healthy subjects in normal and backward conditions. In contrast, during the cognitive task, non-significant differences were found in gait measures between the PwMS and the healthy controls. Significant differences were found between task conditions for all participants. All reduced their walking speed and walked at a slower pace in both the cognitive and backward conditions compared to the normal tandem walk condition. However, non-significant scores were found for the condition X group factor.SignificanceThe study provides new insights into the 3-meter tandem walk test. Findings should improve evaluation and training of dynamic balance in fully ambulatory PwMS.     

Test-retest reliability and minimal detectable change of ankle kinematics and spatiotemporal parameters in MS population

BackgroundMany people with multiple sclerosis (pwMS) experience walking impairments often including foot drop, evident as either reduced dorsiflexion at initial contact and/or at the swing phase of the gait cycle. To measure even subtle differences in ankle kinematics, 3D gait analysis is considered a ‘gold’ standard. However, the psychometric properties of ankle kinematics in the MS population have not yet been examined.ObjectiveThe aim of the study was to examine test-retest relative and absolute reliability of sagittal ankle kinematics and spatiotemporal parameters in two groups of pwMS with different levels of walking impairment.MethodsTwo groups of pwMS underwent 3D gait analysis on two occasions 7–14 days apart. Group A consisted of 21 (14 female) people with Expanded Disability Status Scale (EDSS) 1–3.5 and group B consisted of 28 participants (14 female) with EDSS 4-6. The Intraclass Correlation Coefficient (ICC_2,2), standard error of measurement (SEM) and minimal detectable change (MDC_95%) were calculated for peak dorsiflexion (DF) in swing, ankle angle at initial contact (IC), gait profile score (GPS), walking speed, cadence and step length.ResultsBoth groups presented ‘excellent’ ICC values (>0.75) for DF in swing, IC and step length of most and least affected limbs, walking speed and cadence, with GPS for both limbs exhibiting ‘fair’ to ‘good’ ICCs (0.489–0.698). The MDC_95% values for all ankle kinematic parameters in group A were lower (1.9°–4.2°) than those in group B (2.2°–7.7°).ConclusionThe present results suggest that ankle kinematic and spatiotemporal parameters derived from 3D gait analysis are reliable outcome measures to be used in the MS population. Further, this study provides indices of reliability that can be applied to both clinical decision making and in the design of studies aimed at treating foot drop in people with MS.     

The relationship between energy cost of walking,ankle push-off and walking speed in persons with multiple sclerosis

BackgroundThe energy cost of walking (ECw) is an important indicator of walking dysfunction in persons with multiple sclerosis (PwMS). However, its underlying causes and its relation with ankle push-off and walking speed are not well understood.Research questionWhat is the contribution of ankle push-off and walking speed to increased ECw in PwMS?MethodsTen PwMS with walking limitations and 10 individually gender- and age-matched healthy controls (HC) were included. All participants performed two 6-min walking trials on a treadmill at comfortable walking speed (CWS of PwMS) and fast walking speed (FWS, 130 % of CWS of PwMS). Kinetics and metabolic cost were evaluated. Generalized estimating equations were performed to investigate effects of group and walking speed, and their interaction. Spearman correlations were conducted to examine whether ECw was related to ankle push-off in PwMS, controlling for differences in walking speed in PwMS.ResultsECw at matched walking speed was significantly higher in PwMS compared to HC. Kinetic parameters were not different between the most impaired leg in PwMS and HC at matched walking speed, but asymmetry between both legs of PwMS was observed. At FWS, ECw reduced and ankle push-off increased similarly in both groups. ECw was inversely related to peak ankle power of the most impaired leg in PwMS at CWS.SignificanceSlow walking speed is one factor that contributes to increased ECw in PwMS. Furthermore, PwMS who had a higher ECw showed a lower peak ankle power, independent of walking speed. This indicates that ankle push-off could be a contributor to increased ECw.     

Determining the utility of a smartphone-based gait evaluation for possible use in concussion management

ABSTRACT

Objectives: Our was objectives were to (1) assess the validity of a smartphone-based application to obtain spatiotemporal gait variables relative to an established movement monitoring system used previously to evaluate post-concussion gait, and (2) determine the test-retest reliability of gait variables obtained with a smartphone.

Methods: Twenty healthy participants (n = 14 females, mean age = 22.2, SD = 2.1 years) were assessed at two time points, approximately two weeks apart. Two measurement systems (inertial sensor system, smartphone application) acquired and analyzed single-task and dual-task spatio-temporal gait variables simultaneously. Our primary outcome measures were average walking speed (m/s), cadence (steps/min), and stride length (m) measured by the inertial sensor system and smartphone application.

Results: Correlations between the systems were high to very high (Pearson r = 0.77–0.98) at both time points, with the exception of dual-task stride length at time 2 (Pearson r = 0.55). Bland-Altman analysis for average gait speed and cadence indicated the average disagreement between systems was close to zero, suggesting little evidence for systematic bias between acquisition systems. Test-retest consistency measures using the smartphone revealed high to very high reliability for all measurements (ICC = 0.81–0.95).

Conclusions: Our results indicate that sensors within a smartphone are capable of measuring spatio-temporal gait variables similar to a validated three-sensor inertial sensor system in single-task and dual-task conditions, and that data are reliable across a two-week time interval. A smartphone-based application might allow clinicians to objectively evaluate gait in the management of concussion with high ease-of-use and a relatively low financial burden.     

Cortical activity and gait parameter characteristics in people with multiple sclerosis during unobstructed gait and obstacle avoidance

BackgroundPeople with Multiple Sclerosis (PwMS) present higher cortical activity during walking. However, the cortical activity during gait while avoiding an obstacle is still not clear.ObjectiveTo investigate cortical activity and gait spatial-temporal parameters in PwMS during two different gait tasks (i.e., unobstructed and obstacle avoidance).MethodFifteen PwMS and 15 healthy controls (CG) were recruited. Participants performed ten trials in each gait condition, wearing a 64-electrode cap electroencephalogram (EEG) at 1024 Hz. Kinematic data were obtained through 10 Vicon® cameras at 200 Hz. EEG was analyzed through four cortical areas (frontal, motor, parietal, and occipital cortex areas) and five frequency bands (delta, theta, alpha, beta, and gamma) obtained through the power spectral density. In addition, spatial-temporal gait parameters (e.g., step length and velocity) were measured. Two-way ANOVA (group x gait condition) and MANOVA (group x gait condition) were used to compare gait and EEG parameters, respectively. One-way ANOVA was used to compare groups in the crossing phase of the obstacle avoidance condition.ResultsPwMS presented lower step length and velocity, and higher cortical activity in frontal (beta and gamma) and parietal (gamma) cortical areas in both gait conditions compared to CG. Moreover, PwMS presented increased cortical activation (frontal and parietal) and decreased step length and velocity in obstacle avoidance compared with unobstructed gait. In addition, PwMS required more cortical resources (frontal and parietal) than CG to accomplish both gait conditions. During the obstacle avoidance task, it was further observed that PwMS positioned their feet closer to the obstacle, before and after the task, compared to CG.ConclusionPwMS demand higher cortical resources to accomplish gait tasks, mainly when it is necessary to negotiate an obstacle in the pathway. This higher cortical activity may be a compensatory mechanism to deal with damage in subcortical structures caused by multiple sclerosis.     

Quantifying gait abnormalities in persons with multiple sclerosis with minimal disability

Abnormalities in gait kinematics in persons with multiple sclerosis (PwMS) who have mild disability have been noted using motion capture systems. However, it is not clear if these abnormalities can be detected with clinically feasible technology. This investigation examined if the spatiotemporal markers of gait including variability metrics can distinguish between PwMS with minimal disability and controls with clinically feasible technology. 43 PwMS with minimal disability and 43 healthy controls completed four walking trials along a 26 foot long pressure sensitive pathway (GAITRite). Spatiotemporal markers of gait including variability metrics were determined. Statistical analysis revealed that PwMS walked slower, with fewer, shorter, wider steps and spent a greater percentage of a gait cycle in double support than controls. Additionally, PwMS had greater variability in the time between steps, single support percent and step width than controls. Collectively, the results highlight that PwMS, in the absence of clinical gait impairment, have subtle but detectable differences in gait and that these alterations can be detected with clinically feasible technology. The current results raise the possibility of targeting walking deviations earlier in disability progression in PwMS.     

Time-integrated propulsive and braking impulses do not depend on walking speed

BackgroundEnhancing propulsion during walking is often a focus in physical therapy for those with impaired gait. However, there is no consensus in the literature for assessing braking and propulsion. Both are typically measured from the anterior-posterior ground reaction force (AP-GRF). While normalization of AP-GRF force by bodyweight is commonly done in the analysis, different methods for AP-GRF time axis normalization are used.Research questionDoes walking speed affect propulsion and/or braking, and how do different methods for calculating propulsion and braking impact the conclusion, in both healthy adults and those with lower limb impairment?MethodsWe investigated three different analysis methods for assessing propulsion. 1. BW-TimeIntegration: Bodyweight (BW) normalized time integration of AP-GRF (units of BWs). 2. BW-%StanceIntegration: BW normalized AP-GRF is resampled to percent stance phase prior to integration (units of BW%Stance). 3. BW-Peak: BW normalized peak force (units of BW). We applied these methods to two data sets. One data set included AP-GRFs from trials of slow, self-selected, and fast walking speeds for 203 healthy controls (HCs); a second data set included subjects with lower limb orthopedic injuries.ResultsUsing the BW-TimeIntegration method, we found no effect of walking speed on propulsion for HCs. Time integration over the longer stance phase of slower walking balanced the lower magnitude AP-GRFs of slower walking, resulting in a time-integrated impulse that was the same regardless of walking speed. In contrast, the other two methods that are not time integration methods found that propulsion increased with walking speed. Similarly, in the gait pathology data set, differences in results were found depending on the analysis method used.SignificanceFor many gait studies concerning propulsion and/or braking, the impulse measure used should be related to the body’s change of momentum, necessitating an analysis method with a time integration of the AP-GRF.     

Does gait bout definition influence the ability to discriminate gait quality between people with and without multiple sclerosis during daily life?

BackgroundThere is currently no consensus about standardized gait bout definitions when passively monitoring walking during normal daily life activities. It is also not known how different definitions of a gait bout in daily life monitoring affects the ability to distinguish pathological gait quality. Specifically, how many seconds of a pause with no walking indicates an end to one gait bout and the start of another bout? In this study, we investigated the effect of 3 gait bout definitions on the discriminative ability to distinguish quality of walking in people with multiple sclerosis (MS) from healthy control subjects (HC) during a week of daily living.Methods15 subjects with MS and 16 HC wore instrumented socks on each foot and one Opal sensor over the lower lumbar area for a week of daily activities for at least 8 h/day. Three gait bout definitions were based on the length of the pause between the end of one gait bout and start of another bout (1.25 s, 2.50 s, and 5.0 s pause). Area under the curve (AUC) was used to compare gait quality measures in MS versus HC.ResultsTotal number of gait bouts over the week were statistically significantly different across bout definitions, as expected. However, AUCs of gait quality measures (such as gait speed, stride length, stride time) discriminating people with MS from HC were not different despite the 3 bout definitions.SignificanceQuality of gait measures that discriminate MS from HC during daily life are not influenced by the length of a gait bout, despite large differences in quantity of gait across bout definitions. Thus, gait quality measures in people with MS versus controls can be compared across studies using different gait bout definitions with pause lengths ≤5 s.     

Is the dynamic gait index a useful outcome to measure balance and ambulation in patients with cerebellar ataxia?

BackgroundAtaxia can adversely affect balance and gait and increase the incidence of falls, which puts individuals at greater risk for injury. Thus, interventions focused on balance and gait are integral in rehabilitation training. In order to determine if rehabilitation interventions are effective, we need an outcome measure to detect change. To our knowledge, no activity level outcome measures have been established for balance and gait in cerebellar ataxia.ObjectiveThe aim of the current study is to determine the reliability and validity of the Dynamic Gait Index (DGI) for ataxia.DesignTwenty adult participants (23–84 years) with ataxia were evaluated to assess construct validity, inter-rater reliability, and same day test-retest reliability of the DGI.MethodsParticipants completed ataxia-specific impairment level outcome measures, as well as the DGI. In addition to the in-person rater, three additional physical therapists scored video recordings of DGI test and retests. Construct validity was assessed via Spearman’s rank order correlation coefficient (Spearman’s rho) between the impairment measures (Scale for Assessment and Rating of Ataxia (SARA), International Cooperative of Ataxia Rating Scale (ICARS) and the DGI. Reliability was assessed by Spearman’s rho and Intraclass Correlation Coefficient ICC (2,1).ResultsIn terms of construct validity, we found significant correlations between the activity level DGI and impairment level outcome measures (-0.81 for SARA; -0.88 with ICARS). The interrater reliability of the DGI applied to participants with ataxia was high (Spearman rho: range 0.71−0.98; ICC (2,1) 0.98) as was test-retest reliability (Spearman rho: 0.95; ICC (2,1) 0.98).ConclusionWe showed that the DGI is a reliable and valid outcome measure to be used in the clinic for individuals with cerebellar ataxia. The DGI had excellent inter-rater and test-retest reliability for raters with varying years of clinical experience. Therefore, the DGI can be a useful clinical outcome measure for assessing balance and ambulation for individuals with cerebellar ataxia.     

Test-retest reliability and minimal detectable change for measures of balance and gait in adults with cerebral palsy

BackgroundWalking and balance often begin to deteriorate in ambulant adults with cerebral palsy (CP) in early adulthood. The decline in walking and balance imposes a more sedentary lifestyle, increases falls risk, negatively affects health, participation, and quality of life, and ultimately results in increased disability. Available research is not sufficient to guide interventions to improve walking and balance in this population. To advance research in this area, there is a need for measures of gait and balance with proven psychometrics for adults with CP.Research questionThe goal of this study was to determine test-retest reliability and minimal detectable change (MDC) values and to assess score distribution for the Balance Evaluation Systems Test (BESTest) and the Four Square Step Test (FSST) as measures of balance, for the Activities-specific Balance Confidence (ABC) Scale and the Modified Fall Efficacy Scale (MFES) as measures of balance confidence, and for over-ground spatiotemporal gait parameters at comfortable gait speed (CGS) and fast gait speed (FGS).MethodsTwenty ambulant adults with CP (mean age 32.7 years), GMFCS-E&R Levels I and II, were tested twice within an average of 10 days. Test–retest reliability was evaluated using intra-class correlation coefficients (ICC_2,1), and MDC₉₅ values were calculated using standard error of measurement values.ResultsThe test-retest reliability of most outcome measures was good to excellent. ICC values were: BESTest = 0.99, BESTest sections 0.88 to 0.98, FSST = 0.91, ABC=0.86, MFES = 0.9, CGS = 0.88, and FGS = 0.98. MDC values were: BESTest total = 4.9%, BESTest sections 8.7%–21.2%, FSST = 3.7 s, ABC = 18%, MFES = 1 point, CGS = 0.26 m/s, and FGS = 0.14 m/s. Most outcome scores were broadly distributed over scales ranges.SignificanceAdults with CP demonstrated stable test-retest performance on the selected measures. These measures could be useful to assess balance and gait of adults with CP. The MDC values can help evaluate whether observed changes exceed the expected random test-retest variations.     

Reliability and minimum detectable change of measures of gait in children during walking and running on an instrumented treadmill

BackgroundInstrumented treadmills that incorporate pressure platforms are increasingly used to characterize gait in children. Although footprint size is known to influence the measurement performance of pressure platforms, published evidence on the reliability of such systems for children’s gait is lacking.Research questionThis study evaluated the test–retest reliability of temporospatial gait parameters and vertical ground reaction forces measured in healthy children during barefoot walking and running on a capacitance–based treadmill system.MethodsTemporospatial gait parameters, including cadence, stride length, stride duration, stance and swing phase durations and the magnitude and timing of conventional vertical ground reaction force peaks were determined on two occasions in 17 healthy children (mean age, 11 ± 2 years; height, 148.4 ± 9.3 cm; and mass, 43.3 ± 10 kg) during walking and running at preferred speed on an instrumented treadmill. Reliability was assessed using Intra Class Correlation Coefficients (ICC) and the standard error of measurement (SEM). The minimum detectable change (MDC95%) was also calculated.ResultsICC values ranged from 0.91–0.99 for all variables. When expressed as a percentage of the mean, the SEM was <5% for all gait parameters assessed during walking and running. The MDC95% values for gait parameters were typically higher during running than walking, and were ±4% of the gait cycle for temporal parameters, ±55 cm for stride length and ±0.1 bodyweights for peak vertical ground reaction force.SignificanceChildren’s gait parameters varied by <5% between test occasions and were more consistent during walking than running. These findings provide clinicians and researchers with an index of the reliability and sensitivity of the treadmill to detect changes in common spatiotemporal gait parameters and vertical ground reaction forces in children.     

Concurrent validity and reliability of wireless instrumented insoles measuring postural balance and temporal gait parameters

BackgroundThe OpenGo seems promising to take gait analysis out of laboratory settings due to its capability of long-term measurements and mobility. However, the OpenGo’s concurrent validity and reliability need to be assessed to determine if the instrument is suitable for validation in patient samples.MethodsTwenty healthy volunteers participated. Center of pressure data were collected under eyes open and closed conditions with participants performing unilateral stance trials on the gold standard (AMTI OR6-7 force plate) while wearing the OpenGo. Temporal gait data (stance time, gait cycle time, and cadence) were collected at a self-selected comfortable walking speed with participants performing test-retest trials on an instrumented treadmill while wearing the OpenGo. Validity was assessed using Bland-Altman plots. Reliability was assessed with Intraclass Correlation Coefficient (2,1) and smallest detectable changes were calculated.FindingsNegative means of differences were found in all measured parameters, illustrating lower scores for the OpenGo on average. The OpenGo showed negative upper limits of agreement in center of pressure parameters on the mediolateral axis. Temporal reliability ICCs ranged from 0.90–0.93. Smallest detectable changes for both stance times were 0.04 (left) and 0.05 (right) seconds, for gait cycle time 0.08 s, and for cadence 4.5 steps per minute.InterpretationThe OpenGo is valid and reliable for the measurement of temporal gait parameters during walking. Measurements of center of pressure parameters during unilateral stance are not considered valid. The OpenGo seems a promising instrument for clinically screening and monitoring temporal gait parameters in patients, however validation in patient populations is needed.     

Reliability and validity of knee angles and moments in patients with osteoarthritis using a treadmill-based gait analysis system

BackgroundAlthough commonly used to study knee osteoarthritis (OA), relatively little is known about the reliability and validity of three-dimensional (3D) gait biomechanics derived from treadmill-based systems.Research questionUsing a treadmill-based gait analysis system, our objectives were to: 1) estimate the test-retest reliability of frontal and sagittal plane knee angles and moments in knee OA patients; 2) examine concurrent validity by estimating the associations between treadmill-based and overground (gold standard) measures; and 3) examine known-groups validity by comparing measures between knee OA patients and matched healthy controls.Methods34 patients and 16 controls completed 3D gait analyses using treadmill-based and overground systems. Treadmill walking speed was matched to self-selected overground speed. Marker set, knee angle and moment calculations were consistent for both systems. Patients completed a second test session using the treadmill-based system <24 h later but within 1 week of the first test session. Variables calculated from knee angle and moment gait waveforms during stance were evaluated using Bland and Altman plots, Intraclass Correlation Coefficients (ICC), Pearson correlations (r) and t-tests.ResultsVisual inspection of the Bland and Altman plots did not reveal any systematic differences between test and retest sessions; however, limits of agreement (LoA) were larger for the sagittal plane than the frontal plane. Mean differences between sessions for knee angles were <0.25 degrees and <0.18 %BW*ht for knee moments. ICCs ranged from 0.57-to-0.93 for test-retest reliability. Pearson correlations between treadmill and overground systems ranged from 0.56-to-0.97. Although highly associated, there were substantial differences in the moments, emphasizing they cannot be used interchangeably. Patients had greater first peak knee adduction moments (KAM) than controls [mean difference (95 %CI): 0.55 (−1.07, −0.04), p = 0.03].SignificanceResults suggest frontal and sagittal plane knee angles and moments in patients with knee OA evaluated using a treadmill-based system are reliable and valid.