Gait & Posture

BackgroundTo step over an unexpected obstacle, individuals adapt gait; they adjust step length in the anterior-posterior direction prior to the obstacle and minimum toe clearance height in the vertical direction. Inability to adapt gait may lead to falls in older adults with diabetes. Therefore, this study aimed to investigate gait adaptability in older adults with diabetes. Research questionDoes diabetes impair gait adaptability and increase sagittal foot adjustment errors? MethodsThree cohorts of 16 people were recruited: young adults (Group I), healthy older adults (Group II), and older adults with diabetes (Group III). Participants walked in baseline at their comfortable speeds. They then walked and responded to what was presented in gait adaptability tests which included 40 trials with four random conditions: step shortening, step lengthening, obstacle avoiding, and walking through. Virtual step length targets were 40% of the baseline step length longer or shorter than the mean baseline step length; the actual obstacle was a 5-cm height across the walkway. A Vicon three-dimensional motion capture system and four A.M.T.I force plates were used to quantify spatiotemporal parameters of a gait cycle and sagittal foot adjustment errors (differences between desired and actual responses in the second step of the gait cycle). Analyses of variance (ANOVA) repeated measured tests were used to investigate group and condition effects on dependent gait parameters at a significance level of 0.05. ResultsStatistical analyses of Group I (n = 16), Group II (n = 14) and Group III (n = 13) revealed that gait parameters did not differ between groups in baseline. However, they were significantly different in adaptability tests. Group III significantly increased their stance and double support times in adaptability tests, but these adaptations did not improve their foot adjustments. They had the greatest step length errors and the lowest toe-obstacle clearance which might cause them to touch the obstacle the most. SignificanceThe presented gait adaptability tests may serve as entry tests for falls prevention programs.

BackgroundThere is evidence that ambulatory people with incomplete spinal cord injury (iSCI) have an impaired ability to control lateral motion of their whole-body center of mass (COM) during walking. This impairment is believed to contribute to functional deficits in gait and balance, however that relationship is unclear. Thus, this cross-sectional study examines the relationship between the ability to control lateral COM motion during walking and functional measures of gait and balance in people with iSCI. MethodsWe assessed the ability to control lateral COM motion during walking and conducted clinical gait and balance outcome measures on twenty ambulatory adults with chronic iSCI (C1-T10 injury, American Spinal Injury Association Impairment Scale C or D). To assess their ability to control lateral COM motion, participants performed three treadmill walking trials. During each trial, real-time lateral COM position and a target lane were projected on the treadmill. Participants were instructed to keep their lateral COM position within the lane. If successful, an automated control algorithm progressively reduced the lane width, making the task more challenging. If unsuccessful, the lane width increased. The adaptive lane width was designed to challenge each participants maximum capacity to control lateral COM motion during walking. To quantify control of lateral COM motion, we calculated lateral COM excursion during each gait cycle and then identified the minimum lateral COM excursion occurring during five consecutive gait cycles. Our clinical outcome measures were Berg Balance Scale (BBS), Timed Up and Go test (TUG), 10-Meter Walk Test (10MWT) and Functional Gait Assessment (FGA). We used a Spearman correlation analysis ({rho}) to examine the relationship between minimum lateral COM excursion and clinical measures. ResultsMinimum lateral COM excursion had significant moderate correlations with BBS ({rho}=-0.54, p=0.014), TUG ({rho}=0.59, p=0.007), 10MWT-preferred ({rho}=-0.59, p=0.006), and FGA ({rho}=-0.59, p=0.007) and a significant strong correlation with 10MWT-fast ({rho}=-0.68, p=0.001). ConclusionControl of lateral COM motion during walking predicts a wide range of clinical gait and balance measures in people with iSCI. This finding suggests the ability to control lateral COM motion during walking could be a contributing factor to gait and balance in people with iSCI.

BackgroundThree-dimensional gait analysis (3DGA) is widely used to support clinical decision-making in individuals with motor impairments. However, kinematic outputs depend strongly on the underlying biomechanical model. The open-source Conventional Gait Model II (CGM2) integrates updates to joint centre estimation (CGM2.1), inverse kinematics (CGM2.2), and cluster-based segment tracking (CGM2.3). While previous work demonstrated consistency among CGM2 variants in typically developing children, their effect in clinical populations remains unknown. This study quantified how CGM2 variants influence gait kinematics in individuals with cerebral palsy (CP). MethodsTwenty-one individuals with CP (GMFCS I-II) underwent 3DGA using a 12-camera motion capture system and a CGM2.3 marker set. Hip, knee, and ankle kinematics from 487 gait cycles were computed using pyCGM2. Differences between CGM2.1, CGM2.2, and CGM2.3 were evaluated using Mean Absolute Deviation (MAD) and the adjusted coefficient of determination (R2). ResultsOverall, small differences were observed between model variants. MAD values were typically below 5{degrees} for most joints and planes, with high correlation between curves (R2>0.7). Hip rotation showed the largest discrepancies, with maximum MAD up to 7.7{degrees} when comparing CGM2.2 and CGM2.3. Differences between CGM2.1 and CGM2.3 were greater in the transverse and frontal planes but remained within acceptable limits (<5{degrees}), except for hip rotation. ConclusionThe CGM2 variant selection has limited impact on gait kinematics in individuals with CP, and most differences fall within known repeatability error. However, transverse-plane kinematics, particularly hip rotation, should be interpreted with caution when comparing data across CGM2 variants.

BackgroundPeople with stroke often walk with temporal asymmetry; which is related to increased fall risk. The purpose of this study was to determine the relationship between temporal gait asymmetry and mechanical stability among people with sub-acute stroke. MethodsThirty-one people with sub-acute stroke (<6 months post-stroke) completed six walking trials in a biomechanics laboratory. Three-dimensional motion capture was recorded. Swing symmetry was calculated as a ratio of swing time on the more affected limb divided by swing time on the less affected limb. Mechanical stability was the minimum margin of stability, relative to the medial and lateral borders of the stance limb, during the single support phase of the gait cycle. Multiple linear regression was used to determine the relationship between swing symmetry and mechanical stability, controlling for step width and walking speed. ResultsThere was a significant negative relationship between swing symmetry and lateral margin of stability on the less affected side (p<0.0001) and medial margin of stability on the more affected side (p=0.023). That is, as swing symmetry increased, the extrapolated centre of mass tended to be closer to the lateral border of the less affected side and farther from the medial border of the more affected side. ConclusionGait asymmetry could, in part, result from a strategy to compensate for poor balance control on the more affected side. Alternatively, reduced lateral margin of stability on the less affected side among asymmetric participants indicates instability in this direction and could increase the risk for falling.

BackgroundMyotonic dystrophy type 1 (DM1) is a prevalent inherited muscular dystrophy in adults, affecting distal muscles such as the gastrocnemius, soleus, and tibialis anterior. This leads to significant gait deviations and reduced walking speed, impacting overall well-being and increasing fall risk. ObjectiveThis study aimed to assess how walking speed affects gait kinematics in individuals with DM1. MethodEighteen individuals with genetically confirmed DM1 (4 women, age: 41.0 [35.5; 47.8] years, mass: 76.8 [67.1; 94.6] kg, height: 166.0 [156.7; 173.3] cm) participated in this study. Each participant walked barefoot along a 13-meter walkway at comfortable and fast speeds. Subsequently, spatiotemporal parameters and joint kinematics were assessed. ResultsThe step length (p < 0.001), cycle speed (p < 0.001), and cadence (p < 0.001) increased significantly, leading to a higher walking speed. Moreover, the vertical amplitude of the center of mass (CoM) increased significantly (p = 0.015), while the mediolateral amplitude decreased (p = 0.001) at fast walking condition. In addition, significant kinematic changes included increased trunk tilt (p < 0.001), greater anterior pelvic tilt (p < 0.001), increased hip flexion at initial contact, and enhanced knee flexion during both stance and swing phases. Ankle dorsiflexion showed a trend towards increase during stance phase (p = 0.055) at fast walking condition. ConclusionsFast walking speed in individuals with DM1 lead to significant gait adaptations. These adaptations reflect compensatory mechanisms to manage muscle weakness. The present study revealed significant changes in spatiotemporal parameters related to walking speed. Fast walking also highlighted kinematic adaptations in trunk, pelvis and lower limb joints. These findings enhance our understanding of gait deviation in individuals with DM1 and suggest the potential benefits of targeted fast walking training in this population.

BACKGROUNDWith disease-modifying drugs on the horizon for degenerative ataxias, motor biomarkers are highly warranted. While ataxic gait and its treatment-induced improvements can be captured in laboratory-based assessments, quantitative markers of ataxic gait in real life will help to determine ecologically meaningful improvements.\n\nOBJECTIVESTo unravel and validate markers of ataxic gait in real life by using wearable sensors.\n\nMETHODSWe assessed gait characteristics of 43 patients with degenerative cerebellar disease (SARA:9.4{+/-}3.9) compared to 35 controls by 3 body-worn inertial sensors in three conditions: (1) laboratory-based walking; (2) supervised free walking; (3) real-life walking during everyday living (subgroup n=21). Movement analysis focussed on measures of movement smoothness and spatio-temporal step variability.\n\nRESULTSA set of gait variability measures was identified which allowed to consistently identify ataxic gait changes in all three conditions. Lateral step deviation and a compound measure of step length categorized patients against controls in real life with a discrimination accuracy of 0.86. Both were highly correlated with clinical ataxia severity (effect size {rho}=0.76). These measures allowed detecting group differences even for patients who differed only 1 point in the SARAp&g subscore, with highest effect sizes for real-life walking (d=0.67).\n\nCONCLUSIONSWe identified measures of ataxic gait that allowed not only to capture the gait variability inherent in ataxic gait in real life, but also demonstrate high sensitivity to small differences in disease severity - with highest effect sizes in real-life walking. They thus represent promising candidates for quantitative motor markers for natural history and treatment trials in ecologically valid contexts.

BackgroundBalance studies usually focus on quantities describing the global body motion, such as the position of the whole-body centre of mass (CoM), its associated extrapolated centre of mass (XCoM) and the whole-body angular momentum (WBAM). Assessing such quantities using classical marker-based approach can be tedious and modify the participants behaviour. The recent development of markerless motion capture methods could bypass the issues related to the use of markers. Research questionCan we use markerless motion capture systems to study quantities that are relevant for balance studies? MethodsSixteen young healthy participants performed four different motor tasks: walking at self-selected speed, balance loss, walking on a narrow beam and countermovement jumps. Their movements were recorded simultaneously by marker-based and markerless motion capture systems. Videos were processed using a commercial markerless pose estimation software, Theia3D. The position of their CoM was computed, and the associated XCoM and WBAM were derived. Bland-Altman analysis was performed and root mean square error and coefficient of determination were computed to compare the results obtained with marker-based and markerless methods across all participants and tasks. ResultsBias remained of the magnitude of a few mm for CoM and XCoM position, and RMSE of CoM and XCoM was around 1 cm. Confidence interval for CoM and XCoM was under 2 cm except for one task in one direction. RMSE of the WBAM was less than 8% of the total amplitude in any direction, and bias was less than 1%. SignificanceResults suggest that the markerless motion capture system can be used in balance studies as the measured errors are in the range of the differences found between different models or populations in the literature. Nevertheless, one should be careful when assessing dynamic movements such as jumping, as they displayed the biggest errors. HighlightsO_LIMarkerless motion capture could bypass issues from classical marker-based approaches C_LIO_LIWe compared balance related quantities computed from both approaches C_LIO_LIMean differences were about 1cm on the position of the whole-body center of mass C_LIO_LIObtained differences are acceptable for most applications C_LI

BackgroundMotion sensors are widely used for gait analysis. ORPHE ANALYTICS is a motion-sensor-based gait analysis system. The validity of commercial gait analysis systems is of great interest to clinicians because calculating position/angle-level gait parameters using motion sensor data potentially produces an error in the integration process; moreover, the validity of ORPHE ANALYTICS has not yet been examined. Research questionHow valid are the position/angle-level gait parameters calculated using ORPHE ANALYTICS relative to those calculated using conventional optical motion capture? MethodsNine young adults performed gait tasks on a treadmill at speeds of 2-12 km/h. The motion sensors were mounted on the shoe midsole (plantar-embedded) and shoe instep (instep-mounted). The three-dimensional marker position data of the foot as well as the acceleration and angular velocity data of the motion sensors were collected. The position/angle-level gait parameters were calculated from motion sensor data obtained using ORPHE ANALYTICS and optical motion capture data. Intraclass correlation coefficients [ICC(2,1)] were calculated for relative validities, and Bland-Altman plots were plotted. ResultsEight items, namely, stride duration, stride length, stride frequency, stride speed (plantar-embedded), vertical height (plantar-embedded), stance phase duration, swing phase duration, and sagittal angleIC, exhibited excellent relative validities [ICC(2,1) > 0.9]. In contrast, the sagittal angleTO demonstrated good relative validity [ICC(2,1) = 0.892-0.833], while the frontal angleIC exhibited moderate relative validity [ICC(2,1) = 0.566-0.627]. SignificanceORPHE ANALYTICS, a motion-sensor-based gait analysis system, was found to exhibit excellent relative validity for most gait parameters. This finding suggests its feasibility for gait analysis outside the laboratory setting. HighlightsO_LIGait-parameter validities were examined for treadmill-based gait tasks at 2-12 km/h. C_LIO_LIMost gait parameters showed excellent relative validity with optical motion capture. C_LIO_LIShoe midsole-embedded sensors had higher validities than instep-mounted sensors. C_LIO_LIORPHE ANALYTICS is potentially useful in clinical measurements. C_LI

BackgroundWith treatment trials on the horizon, this study aimed to identify candidate digital-motor gait outcomes for Autosomal Recessive Spastic Ataxia of Charlevoix-Saguenay (ARSACS), capturable by wearable sensors with multi-center validity, and ideally also ecological validity during free walking outside laboratory settings. MethodsCross-sectional multi-center study (4 centers), with gait assessments in 36 subjects (18 ARSACS patients; 18 controls) using three body-worn sensors (Opal, APDM) in laboratory settings and free walking in public space. Sensor gait measures were analyzed for discriminative validity from controls, and for convergent (i.e. clinical and patient-relevance) validity by correlations with SPRSmobility (primary outcome) and SARA, SPRS and FARS-ADL (exploratory outcomes). ResultsOf 30 hypothesis-based digital gait measures, 14 measures discriminated ARSACS patients from controls with large effect sizes (|Cliffs {delta}| > 0.8) in laboratory settings, with strongest discrimination by measures of spatiotemporal variability Lateral Step Deviation ({delta}=0.98), SPcmp ({delta}=0.94) and Swing CV ({delta}=0.93). Large correlations with the SPRSmobility were observed for Swing CV (Spearmans {rho} = 0.84), Speed ({rho}=-0.63) and Harmonic Ratio V ({rho}=-0.62). During supervised free walking in public space, 11/30 gait measures discriminated ARSACS from controls with large effect sizes. Large correlations with SPRSmobility were here observed for Swing CV ({rho}=0.78) and Speed ({rho}=-0.69), without reductions in effect sizes compared to lab settings. ConclusionWe identified a promising set of digital-motor candidate gait outcomes for ARSACS, applicable in multi-center settings, correlating with patient-relevant health aspects, and with high validity also outside lab settings, thus simulating real-life walking with higher ecological validity.

Cerebral palsy (CP) is characterized by neuromusculoskeletal impairments, including reduced muscle fiber lengths, which alter muscle-tendon unit (MTU) lengths and contribute to gait deviations. Estimation of MTU length reliability using musculoskeletal modeling is essential for guiding interventions such as muscle lengthening. This study aims to assess within-assessor (WA) and between-assessor (BA) reliability of MTU length estimation during gait in CP and non-impaired (NI) individuals. 38 individuals (19CP,19TD) participated in 3 3DGA sessions (2 by the same assessor). Normalized MTU length, MTU lengthening, and maximum lengthening range of the rectus femoris, semitendinosus, and gastrocnemius medialis were reported. Reliability was quantified through the standard error of measurement (SEM) and minimal detectable change (MDC). The mean SEM (MDC) during the gait ranged from 1.0-2.1% (2.5-5.7%) for normalized MTU length, from 3.6-8.7 mm (10.1-24.1 mm) for MTU lengthening, and from 2.9-8.0 mm (8.0-22.1 mm) for MTU lengthening range in individuals with CP. In NI individuals, the mean SEM (MDC) during the cycle ranged from 0.6-1.3% (1.8-3.7%) for normalized MTU length, from 2.6-5.0 mm (7.3-13.9 mm) for MTU lengthening, and from 2.7-5.0 mm (7.5-12.4 mm) for MTU lengthening range. Results suggest reliable estimations by the same assessor, supporting therapeutic decision-making and patient progress monitoring.

Falls occur more often as we age. To identify people at risk of falling, balance analysis requires an accurate base-of-support model. We previously developed a functional base-of-support (fBOS) model for standing young adults and showed that its area is smaller than the footprint area. Our fBOS model is a polygon that contains centre-of-pressure (COP) trajectories recorded as standing participants move their COP in the largest possible loop while keeping their feet flat on the ground. Here we assess how the size of the fBOS changes with age by comparing 38 younger (YA), 14 middle-aged (MA), and 34 older adults (OA). The fBOS area is smaller in older adults: OA area is 58% of the YA area (p < 0.001), and 59% of the MA area (p = 0.001), with no difference between YA and MA. The reduction in fBOS area among the OA is primarily caused by a reduction in the length of the fBOS. In addition, among older adults smaller fBOS areas correlated with a lower score on the Short Physical Performance Battery ({tau}=0.28, p = 0.04), a reduced walking speed ({tau}=0.25, p = 0.04), and a higher frailty level (p = 0.09). So that others can extend our work, we have made our fBOS models available online.

Background and objectivesSTXBP1-related disorder (STXBP1-RD), caused by pathogenic variants in the STXBP1 gene, is a rare neurodevelopmental condition, characterized by early-onset seizures, developmental delay, intellectual disability (ID), and prominent motor dysfunction. Despite the high prevalence of motor symptoms, systematic gait characterization remains limited. We therefore aimed to quantitively assess gait in individuals with STXBP1-RD. MethodsIn this cross-sectional study, we included ambulatory patients aged 6 years or older with genetically confirmed STXBP1-RD. Instrumented 3D Gait Analysis (i3DGA) was performed to objectively quantify gait. Functional mobility was assessed with the Functional mobility scale (FMS) and Mobility Questionnaire 28 (MobQues28). Caregiver health-related quality of life was evaluated using the PedsQL-Family Impact Module (PedsQL-FIM). We explored associations between gait, functional mobility, STXBP1-variant type and clinical features (ID, age at seizure onset, seizure frequency, age at onset of independent walking). Correspondence between i3DGA and the Edinburgh Visual Gait Score (EVGS), an observational gait assessment, was investigated. ResultsEighteen participants were included. Compared to typically developing peers, individuals with STXBP1-RD had significantly reduced walking speed, step and stride length. Gait patterns were highly variable, with the most frequent pattern being an externally rotated foot progression angle (FPA), present in 11/18 participants. At home, 93.75% of the participants (16/18) walked independently, yet community mobility was more variable: 11/16 (68.75%) walked independently, 2/16 (12.50%) with aid and 3/16 (18.75%) used a wheelchair, indicating increasing limitations with distance and environmental complexity. Earlier acquisition of independent walking strongly predicted later unassisted ambulation at community level (p<0.001). Median MobQues28 score was 57.14% and median PedsQL-FIM score was 60.42%, indicating a moderate level of mobility limitations and reduced health-related quality of life of caregivers. EVGS was highly positive correlated with i3DGA (p= 0.001). DiscussionQuantitative gait analysis in individuals with STXBP1-RD demonstrates heterogenous kinematic deviations, with an externally rotated FPA emerging as the most common pattern. Age at independent walking was a clinically relevant predictor of later functional mobility. EVGS showed strong correspondence with i3DGA and may offer a more practical, semi-quantitative assessment for broader use. These findings inform clinical decision-making and guide the selection of scalable outcome measures for natural history studies and interventional trials.

Background and PurposeWalking speed is the dominant clinical metric used to classify post-stroke hemiparetic gait severity. However, speed does not describe how mechanical energy is generated and redistributed. We tested whether whole-body center-of-mass (COM) work patterns provide a biomechanically grounded supplement to speed-based severity classification. MethodsLimb-specific COM power and work were computed from ground reaction forces using the individual-limbs method across five walking speeds (0.2-0.7 m/s). We quantified net COM work index of asymmetry (IA_Wnet), positive COM work asymmetry (IA_Wpos), and the Propulsion-Support Ratio (PSR = impFy/impFz). Piecewise and quadratic regressions were used to assess speed-dependent trends. ResultsIA_Wnet remained elevated across speeds and showed no significant high-speed association. IA_Wpos demonstrated a significant quadratic relationship with speed (p=0.023, R{superscript 2}=0.23), decreasing near 0.5 m/s before rising again. Paretic limb PSR remained constrained and exhibited a quadratic association (p=0.012, R{superscript 2}=0.14), while unaffected limb PSR declined significantly at higher speeds (p=0.019, R{superscript 2}=0.38). Below 0.5 m/s, COM power profiles collapsed to a two-phase pattern without paretic limb push-off; at [&ge;]0.5 m/s, a four-phase structure emerged. ConclusionIncreasing walking speed did not normalize interlimb mechanical imbalance. COM work organization revealed a biomechanical transition near 0.5 m/s and distinguished compensation from recovery-based restoration. Supplementing speed with COM work and propulsion-support metrics may refine severity stratification and guide mechanism-targeted rehabilitation.

1.Although the time a patient can stand on one leg is a common clinical test of balance in those prone to fall, a surprising knowledge gap is how much hip abduction muscle strength is required. This is important because hip abduction strength has been shown to be important for compensating for impairments in diabetic neuropathy, for example. As a start we tested the hypothesis that maximum hip abduction muscle endurance time at 50% effort would be longer than the time that 18 young and 17 older healthy adults can stand on one leg. First, maximum hip abduction endurance time at 50% effort as well as maximum abduction strength were measured in the gravity-free plane. Then subjects were asked to balance on their left foot for as long as they could while body segment kinematics and ground reaction data were measured. The results showed that the mean intensity of the hip abduction moment required to stand on one leg exceeded 50% of the maximum hip abduction strength for all four groups (young women and men 53% and 55%, and older women and men 94% and 72% respectively). However, unipedal stance times were not limited by hip abduction 50% effort endurance time (p = 0.9). Therefore a significant portion of the hip abduction moment required to stand on one leg must be carried by passive tissues. The underlying mechanism remains to be explained.

Stiff-knee gait (SKG) after stroke is often accompanied by decreased knee flexion angle during the swing phase. The decreased knee flexion has been hypothesized to originate from excessive quadriceps activation. However, it is unclear whether this activation is due to poor timing or hyperreflexia, both common post-stroke impairments. The goal of this study was to investigate the relation between quadriceps hyperreflexia in post-stroke SKG with knee flexion angle during walking. The rectus femoris (RF) H-reflex was recorded in eleven participants with post-stroke SKG and ten healthy controls during standing and walking during toe-off. In order to separate the effects of poorly timed quadriceps muscle activation from hyperreflexia, healthy individuals voluntarily increased quadriceps activity using RF electromyographic (EMG) biofeedback during standing and pre-swing upon H-reflex stimulation. We observed a negative correlation (R = -0.92, p=0.001) between knee flexion angle and RF H-reflexes in post-stroke SKG. In contrast, H-reflex amplitude in healthy individuals in presence (R = 0.47, p = 0.23) or absence (R = -0.17, p = 0.46) of increased RF activity had no correlation with knee flexion angle. The RF H-reflex amplitude differed between standing and walking in healthy individuals, including when RF activity was increased voluntarily (d = 2.86, p = 0.007), but was not observed post-stroke (d =0.73, p = 0.296). Thus, RF reflex modulation is impaired in post-stroke SKG. Further, RF hyperreflexia, as opposed to overactivity, may play a role in knee flexion kinematics in post-stroke SKG. Interventions targeting self-regulated quadriceps hyperreflexia may be effective in promoting better neural control of the knee joint and thus better quality of walking post-stroke.

BackgroundClinical researchers are trying to unravel the impact of different training interventions on the kinematics of human gait. However, the effects of long-term training experience on the kinematics of a healthy gait pattern remains unclear. Here we assess the effect of long-term training experience on joint angle variability during walking. MethodsHip, knee, and ankle joint angles from fourteen soccer players and sixteen controls were acquired during treadmill and overground walking. Hip-knee coupling, knee-ankle coupling and coupling angle variability (CAV) of the right leg in the sagittal plane were assessed using a vector coding technique. ResultsSoccer players showed reduced hip-knee CAV during the mid-stance and terminal-stance phases and reduced knee-ankle CAV during the pre-swing phase of gait compared to the control group. In addition, soccer players less often used an ankle coordination pattern, in which only the ankle joint but not the knee joint rotates. InterpretationThese findings show that soccer players had more stability in the ankle joint during the stance phase of the gait compared to the control group. Future studies can test whether these differences in the coordination of the ankle joint reflect the effects of long-term training on normal gait by comparing knee-ankle coupling and variability before and after exercise training interventions.

PurposeGait parameters are altered and asymmetrical in individual with transtibial amputation. The purpose of this study was to evaluate and compare the effect of four different prosthetic feet on lower-limb biomechanics during gait. MethodsOne young adult with transtibial ampution performed four gait analysis sessions with four foot-ankle prosthesis (Variflex, Meridium, Echelon, Kinterra). Kinematic, kinetic parameters and gait symmetry were analyzed during different prosthesis conditions. ResultsThe type of prosthesis had little effect on amputee spatiotemporal parameters. Throughout the stance phase, an increase hip angle and a reduced knee flexion and ankle dorsiflexion were observed in the amputated leg. For kinetic parameters, a reduced propulsive force (SI=0.42-0.65), reduced knee extension moment (mainly during Echelon and Kinterra conditions, SI=0.17 and 0.32, respectively) and an increased knee abduction moment (mainly during the Variflex and Meridium, SI=5.74 and 8.93, respectively) in the amputated leg. Lower support moments were observed in the amputated leg compared to the unaffected leg, regardless of the type of prosthesis (SI=0.61-0.80). ConclusionsThe prostheses tested induced different lower-limb mechanical adaptations. If better gait symmetry between lower limbs is one of the clinical goals, an objective gait analysis could help clinicians to prescribe prosthetic feet based on quantitative measurement indicators.

Centre of mass (COM) is a key measurement used to assess balance and mobility. Marker-based motion capture systems have traditionally been used to measure COM, but they are time-consuming and prone to marker error. Markerless motion capture systems offer a potential alternative, reducing setup time while maintaining accuracy. The ease of collecting markerless data may be particularly beneficial when study participants have limited mobility, such as those with stroke. This study aimed to determine the differences in COM measurements between marker-based and markerless motion capture systems during balance and mobility tasks in individuals with sub-acute stroke. Seventeen participants completed the following tasks: walking, quiet standing, sit-to-stand, rise on toes, and backward reactive stepping. COM data were analyzed using two markerless models, a default with 17 segments and a fit model with 11 segments to match the marker-based model to be compared as the reference. The results showed high correlations (R2 = 0.75 to 0.999) and low root-mean-square differences (< 2 cm) in the anterior-posterior and medial-lateral directions. Larger differences (> 4 cm) were observed in the superior-inferior direction, particularly with the default model. These findings suggest that markerless motion capture can be used to measure COM in people with stroke, and that model selection plays an important role in COM estimates.

ObjectivesThe assessment of gait impairments requires a normative reference for comparison. For a fair assessment, comparisons must be made against a reference standing after controlling for sex, anthropometry, and walking characteristics. This study aimed to develop statistical models that predict the lower-limb kinematics and kinetics of walking across the lifespan of healthy participants, using seven simple covariates. Sixteen statistical models predicted 16 joint kinematics and kinetics during walking using the covariates of sex, age, height, mass, side (laterality), walking speed, and cadence, which were developed based on 301 participants between three to 91 years old. The root mean squared error (RMSE) ranged from 4.71{degrees} to 7.97{degrees} for joint angles, within 0.07N/kg for ground reaction forces, 0.09 to 0.15 Nm/kg for joint moments, and 0.33 to 0.39 W/kg for joint powers. We provide both online and local apps which can be easily used by clinicians and scientists to generate normative walking data with uncertainty values, which can be used for movement impairment analysis (https://github.com/EmanuelSommer/ShinyFOSR).

Gait asymmetry is present in several pathological populations, including those with Parkinsons disease, Huntingtons disease, and stroke survivors. Previous studies suggest that commonly used discrete symmetry metrics, which compare single bilateral variables, may not be equally sensitive to underlying effects of asymmetry, and the use of a metric with low sensitivity could result in unnecessarily low statistical power. The purpose of this study was to provide a comprehensive assessment of the sensitivity of commonly used discrete symmetry metrics to better inform design of future studies. Monte Carlo simulations were used to estimate the statistical power of each symmetry metric at a range of asymmetry magnitudes, group/condition variabilities, and sample sizes. Power was estimated by repeated comparison of simulated symmetric and asymmetric data with a paired t-test, where the proportion of significant results is equivalent to the power. Simulation results confirmed that not all common discrete symmetry metrics are equally sensitive to reference effects of asymmetry. Multiple symmetry metrics exhibit equivalent sensitivities, but the most sensitive discrete symmetry metric in all cases is a bilateral difference (e.g. left - right). A ratio (e.g. left/right) has poor sensitivity when group/condition variability is not small, but a log-transformation produces increased sensitivity. Additionally, two metrics which included an absolute value in their definitions showed increased sensitivity when the absolute value was removed. Future studies should consider metric sensitivity when designing analyses to reduce the possibility of underpowered research. Summary statementStatistical power is an important factor in study design. Our results show that not all discrete symmetry metrics have similar or sufficient sensitivity to detect effects of asymmetry.