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

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

Concurrent validity of the GAITRite electronic walkway and the 10-m walk test for measurement of walking speed after stroke

Background: Walking speed is used to assess functional status, predict recovery, prescribe exercise, and track functional progress after stroke. Determining concurrent validity ensures that results from different tests of walking speed can be compared or used interchangeably. The GAITRite electronic walkway and the 10-m walk test (10MWT) are popular measurement tools of walking speed in the laboratory and in clinical settings, respectively.Research question: Do walking speeds in chronic stroke survivors measured with the 10-m walk test and GAITRite electronic walkway demonstrate concurrent validity?Methods: 77 participants with chronic stroke performed four trials of 10MWT and four trials of GAITRite—two trials at comfortable walking speed and two trials at maximal walking speed. Intraclass correlations [ICC (3,1), absolute agreement] and Bland-Altman plots were used to assess the relationship between gait speed from these two measures.Results: Walking speed showed poor to good absolute agreement between 10MWT and GAITRite for comfortable walking speed [ICC: 0.77 (95% CI: 0.46, 0.89; P < 0.001)] and excellent absolute agreement for maximal walking speed [ICC: 0.94 (95% CI: 0.91, 0.96; P < 0.001)]. Mean difference value (systematic bias) was different from 0 for comfortable walking [10MWT was faster; P < 0.001 (95% CI: 0.05, 0.10)] but not for maximal walking [P = 0.16 (95% CI: −0.01, 0.04)]. Limits of agreement were broad (comfortable walking speed, 0.43; maximal walking speed, 0.37), and there was proportional bias at both speeds whereby participants who walked faster tended to have a faster walking speed during 10MWT vs. GAITRite (comfortable walking speed, R² = 0.22, P < 0.001; maximal walking speed, R² = 0.08, P = 0.01).Significance: Systematic bias, proportional bias, and broad limits of agreement suggest that caution should be used when comparing walking speeds from 10MWT and GAITRite. It may not be appropriate to use them interchangeably. Conducting 10MWT and GAITRite tests at maximal walking speeds may allow more accurate comparisons between measures.     

Residual limb strength and functional performance measures in individuals with unilateral transtibial amputation

BackgroundIndividuals with lower limb amputation exhibit lower residual limb strength compared to their sound limb. Deficits in residual limb knee flexion and extension strength may impact functional performance during tasks relevant to daily living.Research questionDoes knee flexor and extensor strength in the residual limb impact functional outcome measures, such as walking energetics and performance metrics, in individuals with unilateral transtibial amputation?MethodsFourteen individuals with traumatic unilateral transtibial amputation were recruited for this observational study. Participants completed metabolic testing at three standardized speeds based on leg length, as well maximum isokinetic knee flexion and extension strength for both residual and sound limbs. Participants also completed a series of functional outcome tests, including a two-minute walk test, timed stair ascent test, and four-square step test. Walking energetics (metabolic cost, heart rate, and rating of perceived exertion) and performance metrics were compared to percent deficit of residual limb to sound limb knee flexion and extension muscle strength. A linear regression assessed significant relationships (p < 0.05).ResultsA significant relationship was observed between percent deficit of knee extension strength and heart rate (p = 0.024) at a fast walking speed. Additionally, percent deficit knee flexion strength related to rating of perceived exertion at slow and moderate walking speeds (p = 0.038, p = 0.024). Percent deficit knee extension strength related to two-minute walk time performance (p = 0.035) and percent deficit knee flexion strength related to timed stair ascent time (p = 0.025).SignificanceThese findings suggest the importance of strength retention of the residual limb knee flexion and extension musculature to improve certain functional outcomes in individuals with unilateral transtibial amputation.     

A characterisation of established unilateral transfemoral amputee gait using 3D kinematics,kinetics and oxygen consumption measures

BackgroundPersons with unilateral transfemoral (UTF) amputation are known to walk with less efficiency than able-bodied individuals, therefore understanding the gait deviations that drive this inefficiency was considered to be important.Research questionsWhat are the differences in gait outcomes between persons with UTF amputation and able-bodied persons? What is the prevalence of specific gait deviations within this group?MethodsUsing a cross-sectional study design, the level over ground gait of established prosthetics service users with UTF amputation using mechanical knee joints (n=60) were compared with able-bodied persons (n=10). Gait profile score, walking velocity, step length, step length symmetry ratio, step time symmetry ratio, vertical ground reaction force symmetry index, base of support, centre of mass deviation and metabolic energy expenditure were measured. All data were captured during walking on level ground at a self-selected speed. Prevalence of gait deviations for each UTF participant were assessed by inspection, using a predefined list of lower limb kinematic, upper body kinematic, ground reaction force and lower limb kinetic gait deviations.ResultsStatistically significant between-groups differences across all outcome measures were found, with all p-values <0.005, and effect sizes ranging from 'large' to 'huge'. The most prevalent gait deviations included: lack of prosthetic knee flexion in early stance (98%); lack of hip extension on the prosthetic side in late stance (82%): increased trunk side flexion range of motion across the gait cycle (92%); reduced anterior propulsion force on the prosthetic side in late stance (100%) and reduced prosthetic hip adduction moment in early stance (96%).SignificanceThe results of this study indicate that the magnitude of the differences between UTF amputees and able-bodied persons, across a comprehensive range of gait measures, are such that significant research into all aspects of prosthetic rehabilitation to reduce these differences is clearly justified.     

Hallux rigidus affects lower limb kinematics assessed with the Gait Profile Score

BackgroundPrevious research showed that hallux rigidus (HR) affects foot and ankle kinematics during gait. It is unclear if HR affects lower limb kinematics as well.Research questionDoes HR affect lower limb kinematics, and if so, is gait deviation correlated with patient-reported outcome?MethodsThis was a retrospective case-control study, including 15 HR patients and 15 healthy controls who underwent three-dimensional gait analysis by using the Plug-in Gait lower body model. The Gait Profile Score (GPS), a gait index score describing gait deviation and composed out of nine Gait Variable Scores (GVS), and intersegmental range of motion of lower limb joints were assessed. Patient-reported outcome was assessed with the Foot Function Index (FFI) and Manchester-Oxford Foot Questionnaire (MOXFQ). Data were analysed with Student t-tests and Spearman rank correlations.ResultsHR significantly affects gait, reflected by a higher GPS in HR subjects as compared to healthy controls. Gait deviation was seen in ankle flexion (GVS_{ankle flexion}) and to a lesser extent in pelvic rotation (GVS_{pelvic rotation}). Interestingly, these differences were not detected when lower limb kinematics were evaluated by comparing the intersegmental ranges of motion of these joints. Positive correlations were present between patient-reported outcomes and GPS, especially functional subdomains, were positively correlated with GPS and GVS_{ankle flexion}.SignificanceThis study demonstrated that HR, next to foot kinematics, additionally affects lower limb kinematics evaluated with an objective gait index score, i.e. GPS. The positive correlation between the GPS and patient-reported outcome can be seen as the first step in defining whether objectively measured gait indices can be used in considering surgery since most of the benefit of surgery will be expected in the patients with most gait deviation.     

Evolution of gait parameters in individuals with a lower-limb amputation during a six-minute walk test

BackgroundA recent amputation leads to decreased functional capacities in the lower limb amputees (LLA), especially during walking. Assessments of LLA’s gait in clinical settings are used to provide feedback on their evolution without quantifying gait parameters distinctly, unlike new technologies, such as inertial sensors (IMUs), which have demonstrated their effectiveness in different environments and populations.Research questionHow do the spatial-temporal gait parameters and kinematics of the LLA evolve quantitatively over a six-minute walk test (6MWT) and is the use of inertial sensors relevant in clinical practice to quantify those parameters?MethodsFifteen LLA from a study cohort performed a 6MWT post-rehabilitation, wearing inertial sensors on both feet to provide gait parameters (i.e., minimum toe clearance (minTC), speed, cadence, stance time and foot flat ratio (FFr)) over this test. A non-parametric ANOVA was conducted comparing the evolution of each parameter over the 6MWT (12 intervals of 30 s). Significance level was set at P ≤ 0.05. Post-hoc Wilcoxon signed-rank tests were performed if a main effect was detected.ResultsMinTC and stance phase variability along the 6MWT were significantly different over time. Cadence variability and speed variation were significantly different between both feet (amputated and non-amputated leg).SignificanceThe increased variability in gait parameters along the 6MWT suggests a greater risk of future mobility problems following a return in community. The data provided by the IMUs reflect the potential of the clinical rehabilitation programme and could, therefore, help clinicians to refine their interventions.     

Manipulating walking path configuration influences gait variability and six-minute walk test outcomes in older and younger adults

This study determined whether manipulations to walking path configuration influenced six-minute walk test (6MWT) outcomes and assessed how gait variability changes over the duration of the 6MWT in different walking path configurations. Healthy older (ODR) and younger (YNG) (n = 24) adults completed familiarisation trials and five randomly ordered experimental trials of the 6MWT with walking configurations of; 5, 10 and 15 m straight lines, a 6 m by 3 m rectangle (RECT), and a figure of eight (FIG8). Six-minute walk distance (6MWD) and walking speed (m.s⁻¹) were recorded for all trials and the stride count recorded for experimental trials. Reflective markers were attached to the sacrum and feet with kinematic data recorded at 100 Hz by a nine-camera motion capture system for 5 m, 15 m and FIG8 trials, in order to calculate variability in stride and step length, stride width, stride and step time and double limb support time. Walking speeds and 6MWD were greatest in the 15 m and FIG8 experimental trials in both groups (p < 0.01). Step length and stride width variability were consistent over the 6MWT duration but greater in the 5 m trial vs. the 15 m and FIG8 trials (p < 0.05). Stride and step time and double limb support time variability all reduced between 10 and 30 strides (p < 0.01). Stride and step time variability were greater in the 5 m vs. 15 m and FIG8 trials (p < 0.01). Increasing uninterrupted gait and walking path length results in improved 6MWT outcomes and decreased gait variability in older and younger adults.     

A quantitative description of self-selected walking in adults with Achondroplasia using the gait profile score

BackgroundAchondroplasia is characterised by a shorter appendicular limb-to-torso ratio, compared to age matched individuals of average stature (controls). Previous work shows gait kinematics of individuals with Achondroplasia differing to controls, but no global quantification of gait has been made in adults with Achondroplasia.AimThe aim of this study was to quantify gait differences between a group of adult males with Achondroplasia and controls during self-selected walking (SSW) using the Gait Profile Score (GPS).DesignWhole body motion analysis of 10 adults with Achondroplasia (22 ± 3 yrs) who had not undergone leg lengthening and 17 adult controls (22 ± 2 yrs) was undertaken using a 14 camera VICON system (100 Hz). For each group, fifteen root mean squared Gait Variable Scores (GVS, units °) were computed from lower limb kinematic data and then summed to calculate GPS (°).ResultsThe group with Achondroplasia had higher GVSs than controls in 10 of the 15 measures (P < 0.05) with the largest differences found in ankle plantar/dorsiflexion (P < 0.001), knee flexion/extension (P < 0.001), and hip internal/external rotation (P < 0.001). The GPS value of the group with Achondroplasia was 64% higher than controls (11.4° (2.0) v 4.1° (1.8), P < 0.001).ConclusionGait is quantitatively different in adults with Achondroplasia compared to controls. The differences in GPS between groups are due to differences in joint kinematics, which are possibly manifested by maintaining toe-clearance during swing. Gait models derived from the anatomy of individuals with Achondroplasia may improve these data.     

Biomechanical correlates for recovering walking speed following a stroke. The potential of tibia to vertical angle as a therapy target

BackgroundRecovering independent walking is a priority for stroke survivors. Community walking requires speeds exceeding the average values typically achieved at discharge (0.7 m/s). To improve outcomes there is a need to clarify the factors associated with recovery of functional walking speeds.Research questionWhich biomechanical variables correlate significantly with improved walking speed following rehabilitation in acute stroke patients.MethodsThe study was embedded in a larger clinical trial testing efficacy of a gait training splint. Participants, within 6 weeks of their stroke and exhibiting abnormal gait, were recruited. Using a valid and reliable video-based system, specific kinematic measures were recorded before randomisation (baseline), after a 6-week rehabilitation phase (outcome) and six months after stroke (follow-up). Measures of temporospatial symmetry, knee angular velocity and tibia to vertical angle were added to clinical measures and correlated with change in speed.Results23 participants were recruited, (mean age 67.7 ± 16.7 years, 19.2 ± 9.0 days after stroke and 73.9% male), with 20/23 assessed at outcome and 17/23 at follow-up. Drop out was due to withdrawal (3) and technical failure (3). Walking speed increased by 0.15 ± 0.21 m/s (outcome), and 0.21 ± 0.14 m/s (follow-up) from baseline (0.50 ± 0.20 m/s). This increase correlated with an increase in step length (r=0.88) and change in angle of tibia at initial contact (r=-0.59), foot flat (r=-0.61) and terminal contact (r=0.54).SignificanceThis study of gait recovery among acute stroke patients demonstrated modest improvements in walking speed. Walking speed by follow-up (0.71 m/s) classified the group as community walkers (>0.66 m/s) but still too slow to safely use a pedestrian road crossing. Change in step length and tibia to vertical angle significantly correlated with increased walking speed. This finding provides distinctive targets for therapy aimed at improving community walking among stroke survivors. This hypothesis should be tested prospectively in future studies.     

Joint power distribution does not change within the contralateral limb one year after unilateral limb loss

BackgroundTo assist with forward progression during gait, persons with unilateral lower-limb amputation typically perform more work within the unaffected versus affected limb. However, prior cross-sectional (>2years post-amputation) studies cannot necessarily elucidate the origin or evolution of these compensatory mechanics.Research questionDo lower limb joint kinetics change during the initial stages of independent ambulation among persons with lower-limb amputation?MethodsNine males with unilateral lower-limb amputation (6 transtibial; 3 transfemoral) completed instrumented gait analyses (speed = 1.2 m/s) at 2 and 12-months post-independent ambulation. Within the unaffected limb, sagittal and frontal plane total positive and negative work, peak power, average positive power, and percent contribution of each joint were compared between time points using paired t-tests.ResultsNo differences existed between time points in total positive or negative work, at any joint (p > 0.038) in either plane. Similarly, there were no differences in percent contribution by each joint to total average power by sagittal (p > 0.15) or frontal (p > 0.32) planes.SignificancePersons with unilateral lower-limb amputation do not alter power distribution among joints within the unaffected limb during initial independent ambulation. However, compared to previous cross-sectional reports, smaller peak powers in the unaffected hip and knee here suggest mechanical work increases with time since amputation. Future research should longitudinally monitor segment mechanics to determine when deleterious strategies develop, as these have implications for joint degeneration and pain.     

Variability of gait speed during six minutes walking test in COPD and cystic fibrosis patients

BackgroundRecently, gait speed reached an increasing importance in the management of respiratory patients. The aim of this retrospective study was to compare walking speed and physiological adaptations during the 6MWT in COPD and CF patients.Methods6MWT performed by COPD and CF patients were retrospectively reviewed. Global and sequential walking speeds were measured on six minutes and every sequence of two minutes respectively. Heart rate, oxygen saturation and dyspnea were analyzed.Results78 and 246 tests from CF and COPD patients were reviewed respectively. FEV1 (52.3 vs 56.2% pred) and FVC (72.5 vs 73.8% pred) were similar between both diseases. However, 6MWT in patients with CF were characterized by significantly higher heart rate, global walking speed and walking distance (+68%) while dyspnea evolutions and the proportions of patients presenting walking speed decline over the 6 min were significantly lower.ConclusionWalking speed and cardio-respiratory parameters evolution during 6MWT differ between COPD and CF patients.     

Step length symmetry adaptation to split-belt treadmill walking after acquired non-traumatic transtibial amputation

BackgroundBetween-limb step length asymmetry is common following transtibial amputation (TTA) and contributes to negative health consequences. There are limited evidence-based interventions targeting reduced gait asymmetry for people with TTA. Split-belt treadmill walking with asymmetrical belt speeds has successfully reduced gait asymmetry in other patient populations. However, individuals with non-traumatic TTA have critical health-related impairments that may influence the ability to respond to split-belt treadmill walking.Research QuestionDo people with acquired, non-traumatic TTA adapt and retain a more symmetrical gait pattern in response to split-belt treadmill walking?MethodsStep length asymmetry was measured during split-belt treadmill walking. Eight participants walked under two alternating belt speed conditions: symmetrical (3 sets; Baseline, TIED1, TIED2) and asymmetrical belt speeds (5 sets; SPLIT1–5). One-way repeated-measures ANOVA with post-hoc Tukey’s HSD tests were used to assess adaptation and short-term retention of step length symmetry. Adaptation was assessed as the level of asymmetry during TIED walking following repeated exposure to SPLIT walking. Retention was measured as the change in level of asymmetry during each set of SPLIT walking.ResultsSignificant adaptation to split-belt walking was observed from late Baseline to early TIED1 and early TIED2. Between-limb step length asymmetry decreased from late Baseline (5.3 ± 3.4) to early TIED1 (-9.4 ± 3.6) and this change was sustained between early TIED1 and early TIED2 (-11.2 ± 3.1) (ANOVA F = 73.043, p < .001). Adaptations were retained as step length asymmetry decreased from early SPLIT1 (48.5 ± 5.3) to early SPLIT3 (31.4 ± 3.5) to early SPLIT5 (23.9 ± 5.1) (ANOVA F = 35.284, p < .001).SignificanceIndividuals with non-traumatic TTA are capable of gait adaptation to split-belt walking and short-term retention of adaptations after removal of the asymmetrical belt speeds. Adaptability of step length symmetry is possible without modification to the prosthetic limb. Split-belt walking should be tested as a potential intervention to help people with acquired, non-traumatic TTA increase between-limb step symmetry.     

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.     

Quantitative characterization of walking on sand inecological conditions: Speed,temporal segmentation,and variability

BackgroundWalking on compliant surfaces, on sand in particular, is now recommended for training in both elderlies and injured subjects/individuals, allowing to perform high intensity exercises (i.e. augmented energy expenditure) in safe conditions (i.e. minimizing the impact on the joints and the risk of fall). Nevertheless, despite the assessment of energetics of walking on sand, the quantitative biomechanical characterization of walking on sand in ecological conditions is largely lacking.Research questionWhich is the effect of sand surface on gait speed, gait temporal segmentation and their variability as related to surface compliance in ecological condition?MethodsEighteen healthy adults were assessed while walking on solid ground, dry-, and wet sand in ecological conditions by means of wearable inertial sensors (Miniwave, Cometa s.r.l., Italy). The best performing algorithm for the segmentation of walking on sand was selected among 17 algorithms designed for solid ground. Gait timing (i.e. speed, temporal segmentation, variability) was analysed, for the first time, with respect to sand compliance, and compared to walking on solid ground.ResultsSelf-selected speed on a 60 m distance increased when walking on sand with respect to solid ground (Median 1.02 m/s), with the highest speed on wet sand (Median 1.15 m/s). A stabilizing strategy on the uneven surface provided by sand was highlighted by i) increased stance and double support durations with respect to speed on wet sand, and ii) increased short-term variability of stride, corresponding to continual adjustments of the lower limbs due to shifting surface provided by sand.SignificanceThis study represents the first step in the objective characterization of walking on compliant surfaces as sand, necessary for the definition of training and rehabilitative programs.     

High-frequency repetitive transcranial magnetic stimulation enhanced treadmill training effects on gait performance in individuals with chronic stroke: A double-blinded randomized controlled pilot trial

BackgroundRepetitive transcranial magnetic stimulation (rTMS) combined with treadmill training has been suggested to modulate corticomotor activity and improve gait performance in people with Parkinson’s disease.Research questionIt is unclear whether this combination therapy has a similar effect in people with stroke. The current study aimed to investigate whether high-frequency rTMS enhances the effects of subsequent treadmill training in individuals with chronic stroke.MethodsFourteen participants meeting the selection criteria were randomly assigned to either the experimental (n = 8) or control (n = 6) group. The experimental group received 5 Hz rTMS prior to treadmill training three times per week for 3 weeks. The control group received sham rTMS before treadmill training. Walking speed, gait symmetry, corticomotor excitability, motor function of the lower extremities, and muscle activity during walking were measured before intervention, after intervention, and at 1-month follow-up.ResultsThe walking speed, spatial asymmetry of gait, and motor function of the lower extremities improved significantly in the experimental group, and these improvements exhibited significant differences in between-group comparisons. However, there was no significant difference in corticomotor excitability or brain asymmetry ratio after the intervention in each group.SignificanceThe current results revealed that applying 5 Hz high-frequency rTMS over the leg motor cortex in the affected hemisphere enhanced the effects of subsequent treadmill training on gait speed and spatial asymmetry in individuals with chronic stroke. Improvement in gait speed persisted for at least 1 month in individuals with chronic stroke.     

Spring-mass behavioural adaptations to acute changes in prosthetic blade stiffness during submaximal running in unilateral transtibial prosthesis users

BackgroundIndividuals with lower-limb amputation can use running specific prostheses (RSP) that store and then return elastic energy during stance. However, it is unclear whether varying the stiffness category of the same RSP affects spring-mass behaviour during self-selected, submaximal speed running in individuals with unilateral transtibial amputation.Research questionThe current study investigates how varying RSP stiffness affects limb stiffness, running performance, and associated joint kinetics in individuals with a unilateral transtibial amputation.MethodsKinematic and ground reaction force data were collected from eight males with unilateral transtibial amputation who ran at self-selected submaximal speeds along a 15 m runway in three RSP stiffness conditions; recommended habitual stiffness (HAB) and, following 10-minutes of familiarisation, stiffness categories above (+1) and below (-1) the HAB. Stance-phase centre of mass velocity, contact time, limb stiffness’ and joint/RSP work were computed for each limb across RSP stiffness conditions.ResultsWith increased RSP stiffness, prosthetic limb stiffness increased, whilst intact limb stiffness decreased slightly (p<0.03). Centre of mass forward velocity during stance-phase (p<0.02) and contact time (p<0.04) were higher in the intact limb and lower in the prosthetic limb but were unaffected by RSP stiffness. Intact limb hip joint positive work increased for both the +1 and -1 conditions but remained unchanged across conditions in the prosthetic limb (p<0.02).SignificanceIn response to changes in RSP stiffness, there were acute increased mechanical demands on the intact limb, reflecting a reliance on the intact limb during running. However, overall running speed was unaffected, suggesting participants acutely adapted to an RSP of a non-prescribed stiffness.     

Gait Profile Score in able-bodied and post-stroke individuals adjusted for the effect of gait speed

Background: The Gait Profile Score (GPS) measures the quality of an individual’s walking by calculating the difference between the kinematic pattern and the average walking pattern of healthy individuals.Research questions: The purposes of this study were to quantify the effect of speed on the GPS and to determine whether the prediction of gait patterns at a specific speed would make the GPS outcome insensitive to gait speed in the evaluation of post-stroke individuals.Methods: The GPS was calculated for able-bodied individuals walking at different speeds and for the comparison of post-stroke individuals with able-bodied individuals using the original experimental data (standard GPS) and the predicted gait patterns at a given speed (GPS velocity, GPS^v). We employed standard gait analysis for data collection of the subjects. Sixteen participants with a stroke history were recruited for the post-stroke group, and 15 age-matched, able-bodied participants formed the control group.Results: Gait speed significantly affects the GPS and the method to predict the gait patterns at any speed is able to mitigate the effects of gait speed on the GPS. Overall, the gap between the GPS and GPS^v values across the post-stroke individuals was small (0.5° on average, range from 0.0° to 1.4°) and not statistically significant. However, there was a significant negative linear relationship in the absolute difference between the GPS and GPS^v values for the participants of the post-stroke group with gait speed, indicating that a larger difference between the speeds of the post-stroke participant and the reference dataset resulted in a larger difference between the GPS and GPS^v.Significance: The modified version of the GPS, the GPS^v, is effective in reducing the impact of gait speed on GPS; however, the observed difference between the two methods was only around 1° for the slowest individuals in comparison to the reference dataset.     

The effect of various arm and walking conditions on postural dynamic stability when recovering from a trip perturbation

BackgroundAppropriately responding to unexpected perturbations, such as a trip, is critical to sustain balance and avoid falling during walking.Research questionHow do arm motion and walking asymmetry affect postural stability when recovering from a trip perturbation?MethodsFifteen healthy young individuals, who had no experience with treadmill induced perturbations, participated in this study. The Computer-Assisted Rehabilitation Environment system (CAREN-Extended) was used to simulate unexpected perturbations while walking symmetrically and asymmetrically with various arm swings (normal, bound, released). Whole-body angular momentum (WBAM), peak trunk angular velocities, Center of Mass (COM), step width and stance time were analyzed before and when recovering from trip perturbations.ResultsParticipants were able to recover their postural stability within three strides following the sudden anterior-posterior trip perturbation. The perturbation increased peak trunk angular velocity, the COM excursion and WBAM but did not affect stance time and step width. The arm conditions had significant effects on peak trunk angular velocity, WBAM and step width during pre-perturbation. Walking conditions had a significant effect on all variables during pre-perturbation; however, post-perturbation showed significant effects only for peak trunk angular velocity, WBAM, and COM.SignificanceUnexpected perturbation had effects on most of gait variables; nevertheless, participants fully recovered and adapted their gait pattern to sudden perturbations even without using their arms while walking symmetrically and asymmetrically. Arm movements could help young individuals recover after a perturbation but are not essential for perturbations of moderate magnitude. The effect of medial-lateral perturbations on gait still need to be investigated.     

Effects of arm swing on spatiotemporal characteristics of gait in unilateral transhumeral amputees

BackgroundGait is an autonomic process consisting of coordinated movements of the upper extremities, lower extremities, trunk and pelvis. However, researches regarding effects of upper extremity problems on gait parameters are limited.Research questionThe aim of this study was to investigate the effects of arm swing on spatiotemporal characteristics of gait in individuals with unilateral transhumeral amputations.MethodsA total of 25 unilateral transhumeral amputees and 25 healthy subjects were included. Information on the demographic features of individuals, amputations, and prosthetic devices were recorded. Spatiotemporal characteristics of gait were obtained using the GAITRite electronic walkway, and the arm swing was evaluated with the two video-cameras and analyzed using the Dartfish Pro Suite 7 software.ResultsThe groups were similar regarding their age, height and weight. Mean duration from the amputation was 14.91 ± 10.90 years, and the mean weight of the prostheses was 1.44 ± 0.39 kg. Amputees had a less ambulatory arm swing on their amputated sides compared to their intact arms and healthy individuals. When the amputee group was compared to the healthy individuals, their step and stride lengths were shorter and their foot progression angle was higher, their gait velocity and cadence were lower than the healthy group.SignificanceThe reduction of arm swing on the amputated side in unilateral transhumeral amputees is thought to be due to (1) use of the contralateral side in functional activities, (2) restriction of shoulder joint movement of socket boundaries and (3) fixed mechanical elbow joint. It has been thought that a decrease in the arm swing during walking may lead to a decrease in step length, stride length, and gait velocity.     

Physical activity does not impact mediolateral margin of stability across a range of postural-perturbing conditions in young adults

BackgroundThe maintenance of stability during walking is critical for successful locomotion. While targeted balance training can improve stability, it is unclear how simply meeting recommended physical activity guidelines may impact dynamic stability in healthy young adults.Research questionExamining the differences in the mediolateral margin of stability (ML-MOS) and the variability of the ML-MOS in physically active and inactive young adults across a range of stability-challenging walking tasksMethodTwenty-one physically active and twenty inactive young adults completed four experimental walking conditions: (1) Overground Walking, (2) Tandem Walking, (3) Beam Walking, and (4) Stepping-Stones. The ML-MOS and coefficient of variation of the ML-MOS were calculated at each heel strike while participants walked at their preferred walking speed. A two-way mixed-effects ANOVA was conducted to examine the effects of group and condition and their interaction on ML-MOS and ML-MOS variabilityResultsNeither the ML-MOS nor the variability of the ML-MOS was significantly different between physically active and physically inactive young adults during any experimental walking conditions. A significant main effect of the experimental walking condition was observed, with the ML-MOS decreasing from overground walking to the tandem and beam walking conditions. The ML-MOS also became more variable in the tandem, beam, and stepping-stones conditions than in overground gait.SignificancePhysical activity status did not influence frontal plane dynamic balance in healthy young adults, even in stability-challenging environments. Conditions that constrain step width, such as tandem and beam walking, are adequate for challenging frontal plane dynamic balance and indicate that trunk kinematics may be adjusted when step width is constrained.