The associations between asymmetries in quadriceps strength and gait in individuals with unilateral transtibial amputation

BackgroundIndividuals with unilateral transtibial amputations (ITTAs) are asymmetrical in quadriceps strength. It is unknown if this is associated with gait performance characteristics such as walking speed and limb symmetry.Research questionAre quadriceps strength asymmetries related to walking speed and/ or gait asymmetries in ITTAs?MethodsKnee-extensor isometric maximum voluntary torque (MVT) and rate of torque development (RTD) were measured in eight ITTAs. Gait data were captured as the ITTAs walked at self-selected habitual and fast speeds. Step length and single support time, peak knee extension moments and their impulse and peak vertical ground reaction force (vGRF) in the braking and propulsive phases of stance were extracted. Bilateral Asymmetry Index (BAI) and, for gait variables only, difference in BAI between walking speeds (ΔBAI) were calculated. Correlation analyses assessed the relationships between MVT and RTD asymmetry and (1) walking speed; (2) gait asymmetries.ResultsAssociations between strength and gait BAIs generally became more apparent at faster walking speeds, and when the difference in BAI between fast and habitual walking speed was considered. BAI RTD was strongly negatively correlated with habitual and fast walking speeds (r=∼0.83). Larger BAI RTD was strongly correlated with propulsive vGRF BAI in fast walking, and larger ΔBAIs in vGRF during both the braking and propulsion phases of gait (r = 0.74–0.92). ITTAs who exhibited greater BAI MVT showed greater ΔBAI in single support time (r = 0.83).SignificanceWhile MVT and RTD BAI appear to be associated with gait asymmetries in ITTAs, the magnitude of the asymmetry in RTD appears to be a more sensitive marker of walking speed. Based on these results, it’s possible that strengthening the knee-extensors of the amputated limb to improve both MVT and RTD symmetry may benefit walking speed, and reduce asymmetrical loading in gait.     

Adaptive treadmill walking encourages persistent propulsion

BackgroundAdaptive treadmills allow real-time changes in walking speed by responding to changes in step length, propulsion, or position on the treadmill. The stride-to-stride variability, or persistence, of stride time during overground, fixed-speed, and adaptive treadmill walking has been studied, but persistence of propulsion during adaptive treadmill walking remains unknown. Because increased propulsion is often a goal of post-stroke rehabilitation, knowledge of the stride-to-stride variability may aid rehabilitation protocol design.Research questionHow do spatiotemporal and propulsive gait variables vary from stride to stride during adaptive treadmill walking, and how do they compare to fixed-speed treadmill walking?MethodsEighteen young healthy subjects walked on an instrumented split-belt treadmill in the adaptive and fixed-speed modes for 10 minutes at their comfortable speed. Kinetic data was collected from the treadmill. Detrended fluctuation analysis was applied to the time series data. Shapiro-Wilk tests assessed normality and one-way repeated measures ANOVAs compared between adaptive, fixed-speed, and randomly shuffled conditions at a Bonferroni-corrected significance level of 0.0055.ResultsStride time, stride length, step length, and braking impulse were persistent (α > 0.5) in the adaptive and fixed-speed conditions. Adaptive and fixed-speed were different from each other. Stride speed was persistent in the adaptive condition and anti-persistent (α < 0.5) in the fixed-speed condition. Peak propulsive force, peak braking force, and propulsive impulse were persistent in the adaptive condition but not the fixed-speed condition (α ≈ 0.5). Net impulse was non-persistent in the adaptive and fixed-speed conditions. All variables were non-persistent in the shuffled condition.SignificanceDuring adaptive treadmill walking, increases in propulsive force and impulse persist for multiple strides. Persistence was stronger on the adaptive treadmill, where increased propulsion translates into increased walking speed. For post-stroke gait rehabilitation where increasing propulsion and speed are goals, the stronger persistence of adaptive treadmill walking may be beneficial.     

How to compare knee kinetics at different walking speeds?

BackgroundWalking speed is a confounding factor in biomechanical analyses of gait, but still many studies compare gait biomechanics at comfortable walking speed (CWS) that is likely to differ between groups or conditions. To identify gait deviation unrelated to walking speed, methods are needed to correct biomechanical data over the gait cycle for walking speed.Research questionHow to compare knee kinetics over the gait cycle at different walking speeds?Methods22 asymptomatic subjects walked on a dual-belt treadmill at CWS and 4 fixed speeds. Knee moments in sagittal (KFM) and frontal plane (KAM) were calculated via inverse dynamics. The net moment differences between CWS and fixed speed were expressed as a root-mean-square error (RMSE) normalized to the range of the variable. Two methods to correct for walking speed were compared. In method 1, KFM and KAM values were estimated based on interpolation between speeds at each percentage of the gait cycle. In method 2, principal component analysis was used to extract speed related features to reconstruct KFM and KAM at the speed of interest. The accuracy of both methods was tested using a leave-one-out cross validation.ResultsWalking speed influenced the magnitude and shape of KFM and KAM. To account for these speed influences using both methods, leave-one-out cross validation showed low normalized RMSE (< 5 %), with little difference between the two methods. RMSE for both reconstruction methods were up to 60 % lower than the RMSE between CWS and fixed speed.SignificanceBoth methods could accurately correct knee kinetics over the gait cycle for the effects of walking speed. Walking speed dependency should be incorporated in each gait laboratory’s reference dataset to be able to identify gait deviations unrelated to gait speed.     

Characterizing intersection variability of butterfly diagram in post-stroke gait using Kernel Density Estimation

BackgroundCenter of pressure (COP) trajectory during treadmill walking have been commonly presented using the butterfly diagram to describe gait characteristics in neurologically intact and impaired individuals. However, due to the large amount of displayed information, the butterfly diagram is not an efficient solution to visualize locomotor variability.PurposeThe purpose of this study was to evaluate post-stroke locomotor variability by applying Kernel density estimation (KDE) on the intersections of the butterfly diagram, and to compare KDE derived metrics with conventional metrics of gait symmetry and variability.MethodsBilateral toe-off (TO) and initial contact (IC) points of the butterfly diagram were determined to calculate the COP symmetry index and the intersections of bilateral TOIC. Subsequently, the intersections during the walking window were used to evaluate its density and variability by Kernel density estimation. Standard deviations of step width and step length were compared between groups.ResultsUsing the KDE surface plots we observed 4 characteristically different patterns with individuals post-stroke, which were associated with functional status quantified using walking speed and lower extremity Fugl-Meyer scores. However, locomotor variability quantified using standard deviations of step width and lengths did not differ between groups.Significance & Novelty: This paper presents a novel approach of using KDE analysis as a better and more sensitive method to characterize locomotor COP variability in individuals with post-stroke hemiparesis, compared to conventional metrics of gait symmetry and variability.     

Analysis of sloped gait: How many steps are needed to reach steady-state walking speed after gait initiation?

BackgroundGait initiation in level walking is suggested to take three steps before reaching steady-state walking speed. In sloped gait, it is not clear if the general recommendation of level gait can be used.Research questionThe aim of this study was to investigate (1) if steady-state walking speed is reached within four steps in sloped gait, and (2) to what extent the number of initial steps cause differences in step length, cadence and ground reaction force (GRF).MethodsFourteen healthy participants walked on an instrumented ramp at inclinations of 0°, ±6°, ±12°, and ±18°, covering slight (clinical application) to steep (hiking and mountaineering) slopes. The starting position on the ramp was adjusted to collect each of the first to fourth step using a 12 infrared-camera motion capture system and two force plates. For each slope condition steady-state walking speed was determined using the ratio of the braking and propulsion impulse (ratio p_ap; $\frac{p_{braking}}{p_{propulsion}}$) and the resultant Centre of Mass (CoM) speed (vel_CoM). Statistical differences between steps were calculated by using a Friedman ANOVA and pairwise post-hoc Wilcoxon tests.ResultsIn all inclinations, ≥90 % (uphill) and ≥95 % (downhill) of steady-state speed regarding ratio p_ap and maximum vel_CoM was reached with the 3rd step. In the level and uphill condition the 4th step showed a slight decrease in vel_CoM. In uphill and downhill condition, the acceleration was mainly generated due to the increase in cadence with significant increases between the 1st and 2nd step as well as between the 2nd and 3rd step. A significant increase in step length was only observed in the uphill conditions.SignificanceSteady-state walking speed was reached with the 3rd step and thus, walkways which allow for two initial steps seem to be appropriate for uphill and downhill gait analysis for inclinations up to ±18°.     

Paretic propulsion as a measure of walking performance and functional motor recovery post-stroke: A review

BackgroundAlthough walking speed is the most common measure of gait performance post-stroke, improved walking speed following rehabilitation does not always indicate the recovery of paretic limb function. Over the last decade, the measure paretic propulsion (Pp, defined as the propulsive impulse generated by the paretic leg divided by the sum of the propulsive impulses of both legs) has been established as a measure of paretic limb output and recently targeted in post-stroke rehabilitation paradigms. However, the literature lacks a detailed synthesis of how paretic propulsion, walking speed, and other biomechanical and neuromuscular measures collectively relate to post-stroke walking performance and motor recovery.ObjectiveThe aim of this review was to assess factors associated with the ability to generate Pp and identify rehabilitation targets aimed at improving Pp and paretic limb function.MethodsRelevant literature was collected in which paretic propulsion was used to quantify and assess propulsion symmetry and function in hemiparetic gait.ResultsParetic leg extension during terminal stance is strongly associated with Pp. Both paretic leg extension and propulsion are related to step length asymmetry, revealing an interaction between spatiotemporal, kinematic and kinetic metrics that underlies hemiparetic walking performance. The importance of plantarflexor function in producing propulsion is highlighted by the association of an independent plantarflexor excitation module with increased Pp. Furthermore, the literature suggests that although current rehabilitation techniques can improve Pp, these improvements depend on the patient’s baseline plantarflexor function.SignificancePp provides a quantitative measure of propulsion symmetry and should be a primary target of post-stroke gait rehabilitation. The current literature suggests rehabilitation techniques that target both plantarflexor function and leg extension may restore paretic limb function and improve gait asymmetries in individuals post stroke.     

Slow and faster post-stroke walkers have a different trunk progression and braking impulse during gait

BackgroundBraking forces absorbed by the leading paretic limb are greater than expected with regard to gait speed and not correlated with propulsive forces generated by the non-paretic limb in individuals with severe hemiparesis. Altered foot placement due to poor sensorimotor capacities may explain excessive braking forces.Research questionThe main objective of this study was to determine whether paretic foot placement was related to paretic braking forces in post-stroke individuals with various self-selected walking speeds and motor deficits.MethodsIn this cross-sectional study, 34 chronic hemiparetic post-stroke individuals, divided into slow (< 0.7 m/s, n = 17) and faster (n = 17) subgroups, walked at their self-selected speed. Kinematic and kinetic parameters were measured. Braking impulses, peak braking forces, step characteristics and clinical status were compared between groups and limbs, and their correlations were tested using Pearson (or Spearman) correlation tests.ResultsOn the paretic side, braking impulses and step length were similar between groups despite the slower walking speed in the slow group. Paretic peak braking forces and step length were correlated in both groups (r = 0.5). Paretic braking forces were correlated with walking speed, foot placement ahead of the pelvis, trunk progression (TP) from non-paretic initial contact to paretic initial contact, and better motor function of the paretic limb for the faster walkers (0.6 < r < 0.7), but not for the slow walkers. Among the slow walkers, reduced TP ahead of the paretic foot was correlated with a higher paretic impulse (r = -0.6).SignificanceBetter motor function likely helped the faster walkers to decelerate their center of mass appropriately relative to their walking speed. In the slow hemiparetic walkers, TP ahead of the paretic foot was perturbed. Clinicians should therefore consider vasti and plantar flexor muscle tone and activity that likely restrict TP ahead of the paretic foot and increase braking forces.     

Performance-based physical function correlates with walking speed and distance at 3 months post unilateral total knee arthroplasty

BackgroundAfter total knee arthroplasty (TKA), walking speed and distance are main concerns of patients.Research questionWhich physical functions affect walking speed and distance after TKA?MethodsCross-sectional data from 149 patients who underwent unilateral primary TKA and completed performance-based physical function tests. Instrumental gait evaluation for spatiotemporal parameters, isometric knee extensor and flexor strength of both knees, 6-minute walk test (6MWT), timed up-and-go (TUG) test, timed stair climbing test (SCT), and knee flexion and extension range of motion (ROM) of surgical knee were examined. Western Ontario McMaster Universities Osteoarthritis Index (WOMAC) and EuroQol five dimensions (EQ-5D) questionnaires were also performed.ResultsUnivariate analyses revealed that post-operative walking speed showed significant positive correlations with cadence, stride length, propulsion index of surgical and non-surgical knee, peak torque (PT) of the extensor of surgical and non-surgical knee and flexor of surgical and non-surgical knee, 6MWT, EQ-5D, and significant negative correlations with gait cycle duration, TUG, SCT-ascent and descent, and WOMAC-pain scores. Post-operative walking distance had significant positive correlations with walking speed, cadence, stride length, swing phase duration, propulsion index of surgical and non-surgical knee, PT of the extensor of surgical and non-surgical knee, EQ-5D, and significant negative correlation with gait cycle duration, double support duration, TUG, SCT-ascent and descent. In the multivariate linear regression analyses, TUG, cadence, stride length and propulsion index of non-surgical knee were factor correlated with post-operative walking speed. The SCT-ascent and descent, TUG and propulsion index of surgical knee were factor correlated with post-operative walking distance.SignificancePhysical performance factors correlated with walking speed and distance at 3 months after surgery. Based on these observations, rehabilitation of bilateral muscle strength and functional mobility would be important for functional recovery after unilateral TKA.     

Timing of propulsion-related biomechanical variables is impaired in individuals with post-stroke hemiparesis

BackgroundIn individuals with post-stroke hemiparesis, reduced paretic leg propulsion, measured through anterior ground reaction forces (AGRF), is a common and functionally-relevant gait impairment. Deficits in other biomechanical variables such as plantarflexor moment, ankle power, and ankle excursion contribute to reduced propulsion. While reduction in the magnitude of propulsion post-stroke is well studied, here, our objective was to compare the timing of propulsion-related biomechanical variables.Research questionAre there differences in the timing of propulsion and propulsion-related biomechanical variables between able-bodied individuals, the paretic leg, and non-paretic leg of post-stroke individuals?MethodsNine able-bodied and 13 post-stroke individuals completed a gait analysis session comprising treadmill walking trials at each participant’s self-selected speed. Two planned independent sample t-tests were conducted to detect differences in the timing of dependent variables between the paretic versus non-paretic leg post-stroke and paretic leg versus the dominant leg of able-bodied individuals.ResultsPost-stroke individuals demonstrated significantly earlier timing of peak AGRF of their paretic leg versus their non-paretic leg and able-bodied individuals. Post-stroke participants displayed earlier timing of peak power of their paretic leg versus their non-paretic leg and able-bodied individuals, and earlier timing of peak ankle moment of the paretic leg versus able-bodied. No significant differences were detected in the timing of peak ankle angle.SignificanceThe earlier onset of peak AGRF, peak ankle power, and peak ankle moment may be an important, under-studied biomechanical factor underlying stroke gait impairments, and a potential therapeutic target for stroke gait retraining. Future investigations can explore the use of interventions such as gait biofeedback to normalize the timing of these peaks, thereby improving propulsion and walking function post-stroke.     

Gait and cognitive abnormalities are associated with regional cerebellar atrophy in elderly fallers – A pilot study

ObjectivesTo investigate cerebellar lobule atrophy patterns in elderly fallers (EFs) and their association with gait and cognitive performance.BackgroundCognitive impairments, gait, and balance deficits are major risk factors for falls in older adults, however, their neural fingerprints remain poorly understood. Recent evidence from neuroimaging studies highlight the role of the cerebellum in both sensorimotor and cognitive networks, suggesting that it may contribute to fall risk.MethodsFourteen EFs (mean age ± SD = 78 ± 1.5 yrs.) and 20 healthy controls (HCs) (mean age ± SD = 69.6 ± 1.3 yrs.) underwent a 3 T MRI scan obtaining 3D T1-weighted images, cognitive, and gait assessments. Cerebellar lobule segmentation was performed, and the obtained cerebellar lobules volumes were adjusted for intracranial volume (ICV). The relationship between lobules volumes, gait, and cognitive performance scores was assessed using hierarchical multiple linear regression adjusted for age and gender.ResultsEFs exhibited lower cerebellar volumes in the posterior cerebellum, lobules V, VI, VIIB, VIIIA, VIIIB, and Crus II, and significantly higher volumes in the anterior cerebellum and lobule IV (p = 0.018 and p = 0.046) compared to HCs. In EFs, lobule V, VI, VIIB, VIIIA, VIIIB, and anterior cerebellum volumes were found to be independent predictors of usual walking (UW) gait speed, dual-task (DT) gait speed, mini Best, MOCA, CTTa, and CTTb (p < 0.05).ConclusionsThe observed patterns of cerebellar lobule atrophy and their associations with motor and cognitive performance scores suggest that cerebellar atrophy contributes to the pathophysiology of fall risk in EFs.     

Loaded forced-marching shifts mechanical contributions proximally and disrupts stride-to-stride joint work modulation in recruit aged women

BackgroundMilitary personnel in combat roles often perform gait tasks with additional load, which can affect the contributions of joint mechanical work (positive and negative). Furthermore, different locomotion patterns can also affect joint specific work contributions. While mean behavior of joint work is important to understanding gait, changes in joint kinetic modulation, or the regulation/control of stride-to-stride joint work variability is necessary to elucidate locomotor system function. Suboptimal modulation exhibited as a stochastic time-series (large fluctuation followed by an opposite smaller fluctuation) could potentially affect locomotion efficiency and portend injury risk. It remains unclear how the locomotor system responds to a combination of load perturbations and varying locomotion patterns.Research questionWhat are the interactive effects of load magnitude and locomotion pattern on joint positive/negative work and joint work modulation in healthy, active, recruit-aged women?MethodsEleven healthy, active, recruit-aged (18–33 years) women ran and forced-marched (walking at a velocity an individual would typically jog) in bodyweight (BW), an additional 25 % of BW (+25 %BW) and an additional 45 % of BW (+45 %BW) conditions at a velocity above their gait transition velocity. Joint work was calculated as the time integral of joint power. Joint work modulation was assessed with detrended fluctuation analysis (DFA) on consecutive joint work time-series.ResultsJoint work contributions shifted proximally for forced-marching demonstrated by lesser (p < .001) positive/negative ankle work but greater (p = .001) positive hip work contributions compared to running. Running exhibited optimal positive ankle work modulation compared to forced-marching (p = .040). Knee and ankle negative joint work modulation was adversely impacted compared to the hip during forced-marching (p < .001).SignificanceEmploying forced-marching gait while under loads of 25 and 45 % of BW reduces the ability of the plantar-flexors and knee extensors to optimally contribute to energy absorption and propulsion in recruit-aged women, potentially reducing metabolic efficiency and increasing injury risk.     

Changes to gait speed when romantic partners walk together: Effect of age and obstructed pathway

BackgroundWalking at a brisk pace is widely recommended to promote health. When partners walk together, walking activity is increased and maintained due to enhanced social support and accountability, but at least one person must adjust their gait speed. Decreased gait speed could compromise health benefits, which may be especially relevant for the aging population.Research questionDo adults change gait speed when walking with their romantic partner, relative to walking alone, and is the change in speed affected by age or pathway conditions?MethodsParticipants were 141 individuals from 72 romantic couples; age range 25−79 years. The three couple conditions were walking alone, walking with their partner, and walking while holding hands with their partner. The two pathway conditions were clear pathway and pathway with obstacles. Gait speed was modeled as a function of the couple conditions, pathway conditions, and covariates (gender, age, relationship duration, and physical activity) using mixed-effects (3-level) regression.ResultsIn both pathway conditions, both partners reduced speed when walking together (p < 0.001), and reduced speed further while holding hands (p < 0.001), when compared to walking alone. These effects were unchanged when covariates were included in the model. Further, speed was slower on the obstructed pathway for all participants, but the magnitude of slowing was greater with increasing age (p < 0.001) and in females (p=0.03).SignificanceAcross the adult lifespan, when walking together, both partners decreased gait speed by a clinically meaningful amount (≥0.05 m/s). While walking with a partner may increase walking activity due to social support, reduced speed when walking together may unintentionally reduce health benefits and gait quality in both partners. Future research should identify how health is impacted by the trade-off between increased walking activity and reduced gait speed when romantic partners walk together.     

Altered gait mechanics are associated with severity of chondropathy after hip arthroscopy for femoroacetabular impingement syndrome

BackgroundSuboptimal patient-reported function and movement impairments often persist after hip arthroscopy for femoroacetabular impingement syndrome (FAIS). Individuals with FAIS with preoperative cartilage pathology (ie. chondropathy) demonstrate distinct movement patterns and have worse post-operative outcomes. It is unknown whether the presence of chondropathy after surgery negatively affects movement and function.Research questionDo sagittal plane gait mechanics differ based on chondropathy severity following arthroscopy for FAIS?MethodsA cross-sectional walking gait analysis was performed for 25 participants post-arthroscopy (2.48 ± 1.38y) and 12 healthy controls (HCs). Peak total support moment (TSM) and relative contributions of the hip, knee, and ankle were calculated during loading response. The Hip Osteoarthritis MRI Scoring System was used to categorize the FAIS group into no-mild or moderate-severe chondropathy groups based on 3 T magnetic resonance imaging of their surgical hip. The interactions of group by limb were evaluated for kinetic variables, covaried by gait speed.ResultsGroups did not differ based on age, BMI and sex distribution (P ≥ 0.14). 13 participants with FAIS presented with moderate-severe chondropathy and 12 presented with no-mild chondropathy. Participants with moderate-severe chondropathy walked significantly slower than both other groups (P = 0.006) and demonstrated lower peak TSM than those with no-mild chondropathy (P = 0.002). Participants with no-mild chondropathy demonstrated lower hip (61.5 %) and greater ankle (17.7 %) contributions to the TSM on the involved limb compared to the moderate-severe group (hip:73.4 %, P = 0.07; ankle:10.5 %, P = 0.007).SignificanceSlower gait speed alone did not explain the lower TSM strategy in participants with moderate-severe chondropathy. Interestingly, the joint contribution strategy of this group was not different than HCs. Participants with no-mild chondropathy demonstrated a TSM strategy that shifted the demand away from their hip and toward their ankle. Given the small sample size, and large variability in joint strategies, future work needs to examine whether these alterations in gait strategy, with or without advanced chondropathy, impact patient function.     

Split-belt treadmill walking in patients with Parkinson’s disease: A systematic review

BackgroundWalking on a split-belt treadmill (SBT) can help to modulate an asymmetric gait, particularly for people with neurological conditions, such as Parkinson’s disease (PD), where asymmetry plays a role due to the laterality of the disease.Research questionThis systematic review critically evaluates the literature on SBT in PD. First, different SBT paradigms and methodological approaches were evaluated. Second, the review explored how people with PD adapt their gait to different SBT conditions compared to healthy controls (HC).MethodsWe conducted a systematic search of the PubMED, PsychINFO, and Web of Knowledge databases. Original research articles, published in English and investigating SBT walking in people with PD, were included.ResultsFrom the 925 studies originally identified, seven met the inclusion criteria and were selected for evaluation (n = 118 individuals with PD of whom 44 had freezing of gait (FOG)). The SBT paradigms varied across studies regarding the SBT settings, definitions of gait variables, and criteria for determining dominance of body side. Gait variability and bilateral coordination were found to adapt to the SBT condition similarly in people with PD and healthy controls (HC). Inconsistent results were found with respect to the adaptation of gait asymmetry, for the differences between PD and HC participants. The subgroup of people with PD and FOG showed reduced accuracy in detecting belt speed differences and slower adaptation to SBT conditions.ConclusionIndividuals with mild to moderately severe PD adapted similarly to HCs to SBT walking for gait variability and bilateral gait coordination. However, those with FOG had impaired perception of belt speed differences and did not adapt their gait so readily. Although SBT can be useful for modulating gait asymmetry in some people with PD, it was not beneficial for all. We recommend standardization of SBT protocols for clinical practice in future studies.     

Comparison of underwater gait training and overground gait training for improving the walking and balancing ability of patients with severe hemiplegic stroke: A randomized controlled pilot trial

BackgroundWalking training is an essential intervention to improve the function in stroke patients. However, only a limited number of gait training strategies are available for stroke patients with relatively severe disabilities.Research questionIs underwater gait training or overground gait training more effective in severe stroke patients?MethodsA total of 21 patients with severe hemiplegic stroke were randomly assigned to the experimental and control groups. All participants (n = 21) received 60-minute sessions of general physical therapy, 5 times a week for a period of 12 weeks. Additionally, the experimental and control groups underwent underwater and overground walking training, respectively, for 30 min twice times a week for 12 weeks. Postural assessment for stroke score, center of pressure path length and velocity, step time and step length difference, and walking velocity were measured before and after the 12-week training.ResultsBoth groups showed a significant decrease in the center of pressure path length and velocity after the intervention compared to the values before the intervention (p < .05). However, there was no significant difference in the center of pressure path length and velocity changes after training between the two groups (p > .05). In the walking variables, the step length difference changes after training between the two groups showed a significant difference (p < .05). In the experimental group, the step length difference increased after the intervention compared to that before the intervention (+4.55 cm), whereas that of the control group decreased (-1.25 cm).SignificanceIn severe stroke patients, underwater gait training can be effective for improving balancing ability, but it may be less effective on the improvement of gait function than overground walking.Clinical trial registration number: KCT0002587 (https://cris.nih.go.kr)     

Differential deficits in spatial and temporal interlimb coordination during walking in persons with incomplete spinal cord injury

BackgroundReturning to community walking remains a major challenge for persons with incomplete spinal cord injury (iSCI) due, in part, to impaired interlimb coordination. Here, we examined spatial and temporal features of interlimb coordination during walking and their associations to gait deficits in persons with chronic iSCI.Research QuestionDo deficits in spatial and temporal interlimb coordination correspond differentially to clinical indicators of walking performance in persons with iSCI?MethodsSixteen persons with chronic iSCI and eleven able-bodied individuals participated in this study. Participants walked at self-selected gait speeds along an instrumented walkway that recorded left and right step lengths and times. We quantified interlimb coordination in terms of normalized differences between left and right step lengths (spatial asymmetry index) and step times (temporal asymmetry index), as well as, gap and phase coordination indices. We then assessed the extent to which these indices independently associated with clinical measures of walking performance.ResultsParticipants with iSCI demonstrated greater spatial and temporal asymmetry, as well as, reduced gap and phase interlimb coordination as compared to age-matched controls (p < 0.001). We found no linear relationships between spatial and temporal asymmetry indices (p > 0.05) or between gap and phase coordination indices (p > 0.05). Spatial and temporal asymmetry indices weakly correlated with SCI-FAI composite scores (r² = 0.26; p = 0.04). However, only spatial asymmetry indices strongly correlated with slower walking speed (r² = 0.51; p < 0.002). We also found participants who used a hand-held assistive device (walker) demonstrated great spatial asymmetry as compared to those who did not (p < 0.03).SignificanceDifferential impairments in spatial and temporal interlimb coordination correspond to overground walking deficits in persons with chronic iSCI. Spatial asymmetry associated with decreased walking speed and increased reliance on hand-held assistive devices. Gait training methods that target well-defined space and time domains of interlimb coordination may enhance overground gait training in persons with iSCI.     

Test of two prediction methods for minimum and maximum values of gait kinematics and kinetics data over a range of speeds

BackgroundMinimum and maximum values of gait kinematics and kinetics data are commonly used to quantitatively describe a walking pattern.Research questionThe purposes of this study were to determine the effect of speed on the minimum and maximum values of gait kinematics and kinetics variables and to test two prediction methods for the estimation of these minimum and maximum values at different gait speeds.MethodsAn open dataset with the data of 24 healthy adults (age: 27.6 ± 4.4 years, height: 171.1 ± 10.5 cm, body mass: 68.4 ± 12.2 kg) walking on a treadmill at eight gait speeds was employed in this study. The minimum and maximum angles and moments of the hip, knee, and ankle joints were extracted from speed-dependent prediction curves solely for the minimum and maximum values (PEAK method) and from speed-dependent prediction curves for the entire gait cycle (CYCLE method). The overall error, computed as the root-mean-square error (RMSE), for the minimum and maximum values predicted by these two methods were compared with the experimental true values.ResultsThe RMSEs for the joint angles were PEAK: 3.86 ± 1.21°, CYCLE: 3.88 ± 1.18° and for the joint moments were PEAK: 0.129 ± 0.052 Nm/kg, CYCLE: 0.131 ± 0.052 Nm/kg.SignificanceThe two prediction methods tested can be used to estimate the minimum and maximum values of biomechanical gait variables at a certain speed.     

Gait variability is altered in cancer survivors with self-reported neuropathy

BackgroundFalls are prevalent among cancer survivors, and neuropathy, a side effect from chemotherapy treatment, is thought to contribute to falls. While falls commonly occur during walking, there is limited information about gait function in cancer survivors with neuropathy.Research Question: What is the difference between gait speed and gait variability in cancer survivors with and without self-reported neuropathy and healthy controls?MethodsSeventeen cancer survivors and 12 healthy individuals [age: 53.5 (11.8), gender: 10 females] participated in a single testing session. Cancer survivors were grouped into neuropathy [n = 9; age: 61.9 (6.1); gender: 8 females] and no neuropathy [n = 8; age: 50.75 (14.1); gender: 7 females] based on the self-reported FACT/GOG Neurotoxicity subscale questionnaire. All participants completed two walking trials at their comfortable pace across a 6 m pressure sensitive walkway. A one-way ANOVA with Tukey’s post-hoc analysis and effect sizes were used to detect differences in gait speed, step length variability, and step width variability between groups.ResultsAlthough there were no group differences in gait speed, a significant main effect was found for step length variability (p = 0.03, η² = 0.24) between groups. Step length variability was significantly less in cancer survivors with neuropathy than healthy controls (p = 0.05, d = 1.30). There was a significant main effect for step width variability between groups (p = 0.05, η² = 0.20). Cancer survivors with neuropathy had significantly greater step width variability than healthy controls (p = 0.04, d = 1.04).SignificanceCancer survivors with neuropathy display greater step width variability and less step length variability than healthy controls. Gait variability may be a more sensitive marker than gait speed to track mobility in cancer survivors with neuropathy symptoms. Assessing and treating gait function in cancer survivors with neuropathy symptoms may improve everyday ambulation.