Gait & Posture

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.

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.

Purposeto characterize the dynamic postural control during weight load shifting with and without support surface reduction with temporal metrics commonly used in linear control systems identification. MethodsFrom the COP coordinates temporal, global and structural parameters were calculated. Reliability of derived parameters were determined using Bland-Altman analysis. ResultsFor the observed population, temporal variables tend to decrease when the complexity of the task is increased with the reduction in the support surface and the non dominance. ConclusionDelay and rise times were significantly shorter for the non-dominant limb in the anteroposterior direction when volunteers performed the same task with different limbs. In the mediolateral direction, delay and rise times were shorter in both unipodal stances with respect to their bipodal homologues. An increase in COP path length, velocity and sample entropy was observed when the support area was reduced. All parameters showed good reliability in both directions at all stances. This framework could be used in the clinical practice to assess dynamic postural control capabilities in patients whose balance is pathologically affected. The trial was evaluated and approved by the Central Committee of Bioethics in Biomedical Practice and Research of the province of Entre Rios.

BACKGROUND: Dual task walking requires simultaneous management of cognitive and motor demands and is associated with changes in gait and cortical activation. However, the relationship between task related cortical recruitment and dual task related gait adjustments in healthy young adults remains unclear. This study aimed to investigate the effects of dual tasking on gait performance and cortical activation, and to examine the association between changes in cortical activity and dual-task costs. METHODS: This cross sectional study included 33 healthy young adults. Participants performed three conditions: single task walking, cognitive single task (verbal fluency), and dual task walking. Each condition was repeated 10 times using a repeated short block design with randomized trial presentation. Gait performance was assessed using an instrumented walkway, and cortical activation was measured using functional near infrared spectroscopy. Dual task costs were calculated for gait and cognitive outcomes. Statistical analysis included repeated measures analysis of variance (ANOVA) and Wilcoxon signed rank tests, with false discovery rate correction for multiple comparisons. Associations between changes in cortical activation and dual task costs were examined using correlation analyses. RESULTS: Dual task walking resulted in significant changes in gait, including reduced speed, step and stride length, and increased base of support, stance, and double support (all p < 0.05), while cognitive performance remained unchanged. Dual tasking was associated with increased cortical activation in left prefrontal and motor related regions. Greater increases in cortical activation were associated with lower dual task costs across most gait parameters, with significant correlations observed in the left dorsolateral prefrontal cortex (r {approx} 0.42 to 0.47 for speed and stride length; p < 0.05). Double support showed a distinct pattern, suggesting a specific temporal adjustment within the gait cycle. CONCLUSIONS: Dual task walking in young adults is associated with coordinated behavioral and cortical adaptations. Increased cortical recruitment is linked to reduced motor interference, suggesting that broader engagement of cortical networks may contribute to performance under cognitive motor load.

PurposeQuantification of walking function, including joint motions, ground reactions, and joint loads, outside the lab is a growing research area. Because only joint motions can currently be measured outside the lab, researchers are utilizing tracking optimizations of walking to estimate associated ground reactions and inverse dynamic joint loads. However, foot-ground contact models used in such optimizations have been generic rather than personalized, which may limit the accuracy of estimated ground reactions and joint loads. This study compares the predictive capabilities of generic versus personalized foot-ground contact models. MethodsGeneric and personalized foot-ground contact models were evaluated in calibration and tracking optimizations performed using experimental walking data collected from three subjects in varying states of health. Foot-only calibration optimizations evaluated how well both models could reproduce experimental ground reaction and foot motion data while tracking both types of data simultaneously, while whole-body tracking optimizations evaluated how well both models could reproduce experimental ground reactions, joint motion, and joint load data while tracking only experimental joint motion data and achieving dynamic consistency. ResultsFor all three subjects and both types of optimizations, personalized foot-ground contact models reproduced experimental ground reaction, joint motion, and joint load data more accurately than generic foot-ground contact models. ConclusionPersonalized foot-ground contact models can improve the accuracy with which ground reactions and joint loads can be estimated via tracking optimizations of walking using only experimental motion data as inputs. Personalized models require little time and effort to calibrate using freely available software tools and should improve the accuracy of predictive simulations of walking as well.

BackgroundTreadmill walking is often employed for tightly controlled gait and energetics research, but growing evidence suggests that treadmill-based metabolic and biomechanical measurements may not directly reflect the ecologically valid mode of overground walking. While many previous studies focused on older adults, much less is known about how treadmill walking influences gait energetics and spatiotemporal parameters in young healthy adults across matched speeds. Aims and ObjectivesWe investigated energy expenditure, metabolic cost of walking and spatiotemporal gait parameters in healthy young adults walking overground and on a treadmill at three speeds (slow-1.0, comfortable-1.3, fast-1.5 m/s). Our hypothesis was that at the comfortable speed, treadmill and overground energetics and gait parameters would be comparable. However, at slow and fast speeds, there would be a significant energetic penalty, accompanied by significant differences in spatiotemporal parameters. MethodsTwenty young participants (10 males and 10 females) completed a randomized cross-over walking protocol with a minimum of ten minutes treadmill familiarization at 1.3 m/s. Breath-by-breath oxygen consumption [Formula] and Respiratory Exchange Ratio were measured using a portable indirect calorimetry system and gait parameters were calculated from Inertial Measurement Units. Gross and net energy expenditures, costs of walking, cadence, average step and stride lengths were calculated. A three-way mixed ANOVA was used for primary statistical analyses. ResultsTreadmill walking was characterized by higher gross and net energy expenditures and metabolic costs (p<0.001, p2 = 0.6) across all speeds compared to overground. It was also characterized by faster cadence and shorter average step and stride lengths (p<0.001, p2 = 0.9). Additionally, there was an effect of sex (p = 0.01, p2 = 0.3) on the gait parameters, with females exhibiting a faster cadence and shorter average step and stride lengths than males. Discussion and ConclusionsOur findings show that treadmill walking imposes a medium-to-large metabolic penalty even in healthy young adults, with compensatory gait adaptations, possibly reflecting increased stabilization demands and altered neuromuscular control strategies. These results underscore the limits of generalizing treadmill derived gait data to overground walking and we caution against the uncritical use of treadmills, especially while trying to understand ecologically relevant human walking mechanics and energetics.

Freezing of gait is a disabling episodic symptom of Parkinson's disease, typically emerging during complex locomotor tasks such as turning, obstacle negotiation, and gait initiation. These tasks require effective motor planning and proactive visual search of the intended walking route. Current evidence suggests that people with Parkinson's disease and freezing of gait show different patterns of visual search compared to those without freezing of gait and healthy older adults. However, existing reports are based on relatively simple tasks that lack common triggers for freezing of gait and do not adequately control for other factors likely to influence visual search, such as motor symptom severity and balance ability. This study examined visual search behaviour in 24 healthy older adults and 37 people with Parkinson's disease (21 with freezing of gait, 16 without) during a complex walking task requiring repeated turning and navigation through narrow spaces. Visual search characteristics were compared between people with Parkinson's disease and healthy controls, and relationships between visual search, freezing of gait, motor symptom severity, and balance ability were explored within the Parkinson's disease group. Compared with healthy controls, people with Parkinson's disease showed significantly fewer fixations toward areas outside the walking path, longer average fixation durations, and reduced saccade amplitudes, with no differences in proactive visual planning of the intended route. No relationship was found between visual search outcomes and freezing of gait. Reduced fixations to outside-path areas were associated with poorer functional balance independently of motor symptom severity. These findings indicate that restricted visual sampling in Parkinson's disease is primarily associated with balance impairment rather than freezing of gait or motor symptom severity.

Background and Objectives Patients with peripheral neuropathies (PN) commonly exhibit balance impairment. In clinical practice, balance is typically assessed using the Rombergs test and ataxia scales, which rely on examiner interpretation, while objective biomarkers for quantifying balance remain lacking. Wearable sensors are valuable tools for objectively quantifying gait abnormalities in PN patients and may capture clinically meaningful changes over time. By integrating these parameters, artificial intelligence (AI) can assist in generating a digital score that enables easy, objective, and reproducible monitoring of patients postural balance. This study aims to generate and assess an AI-generated digital Rombergs test to quantify balance impairments in a cohort of PN patients. Methods PN patients were assessed in a longitudinal study using a wearable system composed of inertial sensors placed on the trunk and plantar pressure sensors integrated in insoles. Patients performed the Rombergs test under both eyes-open and eyes-closed conditions and were classified according to ataxia severity (mild, moderate, or severe) following the score obtained in item 1 of MICARS and SARA scales. Results We included 97 patients with PN (including autoimmune and hereditary polyneuropathies), and 117 healthy controls (HC). Significant differences in trunk sway and center of pressure (COP) were observed between groups, particularly with eyes closed. Using wearable sensor parameters, we developed an AI digital Rombergs test, which correlated with clinician-rated Rombergs test performance and distinguished patients with and without ataxia (AUC=0.632) and across different PN pathologies. Longitudinally, digital Rombergs test and iRODS showed concordant trajectories. Also, changes [&ge;]25% in the score were associated with clinical changes in ataxia severity measured by an increase in MICARS-SARA score (+1.42 points), whereas improvement was associated with a decrease (-0.20 points) in the scale. Discussion This study demonstrates that wearable sensors are useful to detect and quantify balance impairment. The AI-generated Rombergs test is an objective and reproducible tool for postural balance assessment, with robust discriminatory performance across clinical ataxia severity in PN. Scores longitudinal changes aligned with clinical severity, supporting its potential for monitoring disease progression and treatment response. Its strong association with balance measures reinforces its role as a quantitative biomarker of postural control in ataxia patients.

Uneven walking surfaces require adjustments in motor strategies and can thus provide insights into the neuromuscular changes underlying maturation. Also, coordination metrics and variability offer a richer description of motor control mechanisms than standard spatiotemporal parameters, constituting a more sensitive approach to characterize developmental changes. This study aimed to investigate the effects of uneven surfaces on intersegmental coordination, as well as inter-joint coordination and its variability, and to assess the differences in adaptation between age groups when walking on uneven surfaces. Seventy participants (2-29 years), divided into four age groups, completed gait trials on an even and two levels of uneven surfaces while equipped with reflective markers. Mean absolute relative phase and deviation phase of the knee-hip and ankle-knee joint pairs were computed to characterize lower limb inter-joint coordination and variability. In addition, the organization and density of whole-body intersegmental coordination were assessed using correlation networks built from marker acceleration data. Uneven surfaces induced more in-phase inter-joint coupling, reduced network density and increased variability across all age groups. While the organization of intersegmental coordination remained stable, older participants exhibited denser networks, reflecting refined segmental interactions. In contrast, younger participants showed more in-phase joint coordination and higher variability suggesting less mature motor control. The age-related inter-joint coordination differences were emphasized on uneven surfaces, likely reflecting the maturation-related ability to modulate spinal locomotor patterns via supraspinal control, thereby increasing adaptation to environmental perturbations. Highlights- Uneven surfaces induce more in-phase inter-joint coordination. - Uneven surfaces accentuate differences in locomotor strategies across development. - Kinectome density may be a promising indicator of locomotor maturation. - Coordinative variability decreased with neuromotor development.

Wearable exoskeletons are a promising tool for augmenting balance and reducing fall risk. Recent work suggests that active ankle exoskeletons need to act faster than the human to improve reactive balance control. However, the magnitude of exoskeleton torque that is best for improving reactive balance remains unknown. Drawing from the optimal torque for minimizing metabolic expenditure, we hypothesized that reactive balance would improve with increased exoskeleton torque. Participants wearing bilateral ankle exoskeletons were instructed to maintain standing balance during 15cm backward support-surface perturbations. Three exoskeleton plantarflexion torque conditions were tested: NO (Off), LOW (15Nm), or HIGH (30Nm). LOW torque improved balance performance compared to NO torque (p<0.001), with a 7{+/-}3% decrease in peak center of mass (CoM) displacement. Although HIGH torque caused a 9{+/-}11% decrease in peak CoM displacement compared to NO torque (p=0.12), it was not significant due to high intersubject variability. Whereas LOW torque decreased peak CoM displacement in all (range: -0.2 to -1.6cm), HIGH torque only decreased it in some (range = 1.2 to -2.6cm). The change in CoM displacement from LOW to HIGH torque was associated with balance ability, quantified by the narrowing beam test (R2=0.29, p=0.06), while this relationship didnt meet conventional statistical significance, likely due to the small sample size, it suggests that higher levels of exoskeleton torque may hinder balance performance in individuals with better balance ability. Taken together, more exoskeleton torque is not always better for balance, highlighting a potential need to personalize exoskeleton torque for balance augmentation.

Measuring neuromotor control after stroke is crucial for identifying the mechanisms underlying asymmetrical walking and guiding rehabilitation. The lower extremity portion of the Fugl-Meyer (FM-LE) and the number of muscle synergies are commonly used measures, but have important limitations. The dynamic motor control index has emerged as a complementary metric, yet its relationship to established clinical measures (i.e., FM-LE), muscle synergy number, and gait biomechanics remains unclear. This study evaluated the ability of the dynamic motor control index to quantify post-stroke neuromotor impairment relative to FM-LE and muscle synergy number and examined its relationship with propulsion asymmetry. Electromyography data from 22 individuals post-stroke and 31 neurotypical controls were analyzed using non-negative matrix factorization. The dynamic motor control index and not the muscle synergy number differentiated paretic, non-paretic, and neurotypical limbs ({chi}2(2) = 27.57, p < .001). It also differed significantly between less and more impaired individuals classified by FM-LE (p = .05) and demonstrated good discriminative performance between these groups (AUC: 0.777, p = .017). The index also moderated the relationship between FM-LE and propulsion asymmetry ({Delta}R2 = 0.223, p = .007). These findings support the dynamic motor control index as a clinically relevant msarker of post-stroke neuromotor impairment and recovery.

Background: Huntington ' s disease (HD) causes progressive postural control deficits, but how sensory reweighting mechanisms degrade across disease stages remains poorly understood. Objective: To determine whether objective markers of postural sway track disease severity and altered sensory reweighting across the HD spectrum. Methods: Ninety-seven adults (46 {+/-} 14 yrs) were categorized into four groups: 29 with HD, 27 pre-manifest (PM), 28 not at risk (AR-), and 13 age-matched healthy controls (HC). Participants performed three trials of quiet standing with eyes open and eyes closed on a force plate. Results: Manifest HD individuals exhibited greater AP, ML, and total COP sway displacement compared with the PM, AR-, and HC groups. HD and PM groups demonstrated greater instability with eyes closed. COP wavelet power was concentrated below 1 Hz across all groups. The eyes-open to eyes-closed change in 0-1 Hz power predicted total COP sway in HC (68%), AR- (45%), and PM (46%), but this relation was substantially weaker in HD. Conclusions: Progressive weakening of oscillatory-sway coupling distinguishes manifest HD from premanifest stages. PM individuals demonstrate early sensory reweighting deficits that manifest only when vision is removed, while HD individuals show decoupled oscillatory activity that fails to support stable postural regulation. This progressive decoupling may serve as a candidate marker of disease conversion prior to overt motor diagnosis.

Gait asymmetry is a common manifestation of walking impairment among clinical populations. We recently developed a novel treadmill walking approach called dynamic treadmill walking that can provide asymmetric gait training by changing the treadmill speed between fast and slow speeds within a single stride. Here, we studied the energy expenditure associated with a variety of dynamic treadmill walking conditions. We hypothesized that the metabolic power required for dynamic treadmill walking in all conditions would approximate the metabolic power associated with conventional walking at the mean of the fast and slow speeds employed in the task. Eleven young adults without gait impairment walked on an instrumented treadmill and breathed into a metabolic measurement system. During dynamic treadmill walking, the treadmill fluctuated between 0.75m/s and 1.50m/s, each for 50% of an individuals stride time. We used a metronome to synchronize participants right heel-strikes with four different timing conditions. Net metabolic power during dynamic treadmill walking was significantly greater than normal walking at the mean speed of the task (1.125m/s) and generally lower than walking at the fast speed (1.5m/s). We did not observe any significant associations between net metabolic power and several measures of gait asymmetry during dynamic treadmill walking. These findings establish dynamic treadmill walking as a promising technique for improving gait symmetry in individuals who cannot tolerate fast treadmill walking, a common gait rehabilitation approach. Future work will assess the feasibility, metabolic demands, and clinical efficacy of using dynamic treadmill walking to improve gait symmetry in clinical populations. Key Points SummaryO_LIDynamic treadmill walking (i.e., walking with oscillating treadmill speeds) has previously been shown to drive gait asymmetries, but little is known about the energy expenditure required to complete the task. C_LIO_LIOur hypothesis was that dynamic treadmill walking would have similar metabolic power requirements to normal walking at a speed that is intermediate between the two dynamic treadmill walking speeds. C_LIO_LIWe found that dynamic treadmill walking actually requires metabolic power that is greater than the average of the two belt speeds, but less than that used for fast walking. C_LIO_LIDynamic treadmill walking is a promising and clinically translatable technique for rehabilitating populations with gait asymmetries that is not more energetically costly than fast treadmill walking, a common gait rehabilitation approach. C_LI

BACKGROUND: Aging and Parkinsons disease (PD) reduce gait automaticity and increase cognitive demand during walking. Although dual task (DT) paradigms investigate cognitive motor interference, evidence remains limited by heterogeneous tasks, predominant focus on prefrontal cortex (PFC) activity, and variability in functional near infrared spectroscopy (fNIRS) methods. This study investigates whether longitudinal changes in cortical activation during DT walking differ among young adults, older adults, and individuals with PD, and how these changes relate to DT costs over 5 years. METHODS: This longitudinal observational study follows STROBE and fNIRS guidelines and will be conducted in a controlled laboratory (Rede Amparo, CEPID NeuroMat, University of Sao Paulo). Participants will be evaluated annually under three randomized conditions: motor single-task walking, cognitive single task phonemic verbal fluency and DT walking with phonemic verbal fluency, each repeated 10 times. The primary outcome measure will be longitudinal changes in cortical activation during DT walking, quantified by oxygenated hemoglobin (HbO) signals measured with fNIRS in prefrontal and premotor cortical regions. The main predictors of interest will be motor and cognitive DT costs. Covariates will include age, sex, education, cognition, balance, mood, and disease severity in the PD group. Spatiotemporal gait parameters, including gait speed, step length, stride length, step time, base of support, double support, stance phase, and variability, will be recorded using the GAITRite system, and DT costs will be calculated for selected parameters. Cortical activation will be assessed using a 66 channel wearable fNIRS system with short separation channels. DISCUSSION: By combining randomized task blocks, separate motor and cognitive conditions, broader cortical coverage, and concurrent neural and gait assessment across three groups annually, this protocol is expected to provide a comprehensive characterization of cognitive motor interference during walking and its evolution, supporting interpretation of cortical and behavioral responses. The study may help distinguish age related adaptations from PD specific alterations and clarify whether increased cortical recruitment during DT gait reflects compensation, reduced neural efficiency, or ceiling effects, refining understanding of gait automaticity decline and informing rehabilitation and non invasive brain stimulation approaches.

BackgroundBalance instability is a major contributor to disability and falls in people with Parkinsons disease (PwP) and is often insufficiently explained by motor impairment alone. Altered awareness of motor control has been suggested to contribute to sensorimotor dysfunction in PwP, but its relationship with balance performance is poorly understood. ObjectiveTo determine whether awareness of balance control, assessed using a control detection task (CDT), differs between healthy controls (HC) and PwP, and whether CDT performance is associated with balance-related measures. MethodsHealthy older adults (n=20) and PwP (n=22) performed a standing version of the CDT based on center-of-pressure (COP) control, using a force plate. CDT accuracy was used as the primary outcome measure. Static balance during quiet standing was assessed using the COP trajectory length and rectangular area. Dynamic standing balance was assessed using the Index of Postural Stability (IPS). Group differences were examined by independent-samples t-tests. Correlations between CDT accuracy and balance measures were analyzed. ResultsThe PwP group showed significantly lower CDT accuracy. Higher CDT accuracy was associated with better static balance in the HC group and the combined sample, and with higher IPS primarily in the PwP group. ConclusionsMotor awareness during postural tasks is altered in PwP and is associated with balance control. These findings suggest that balance instability in Parkinsons disease may involve altered balance-related action-outcome monitoring in addition to motor dysfunction.

Walking is an attentionally demanding process that draws from a limited pool of attentional resources. Dual-task assessments, where individuals perform a cognitive task while walking, often reveal changes in gait and balance due to competing attentional demands. As cognitive task difficulty increases, the attentional resources necessary to complete the task also increase, leading to greater interference with gait and balance. However, these interactions are typically examined using contrived lab-based tasks, leaving it unclear how the cognitive processes engaged during real-world movement impact walking. In the present study, we investigated whether increasing the attentional demand of spatial navigation, a cognitive process intrinsically linked to movement, interferes with gait and balance. Healthy adults completed an ambulatory virtual reality homing task in which they walked through a virtual environment and navigated to previously visited locations while wearing ankle and lumbar trackers. We increased the attentional demand of navigation by removing sensory cues during this homing phase: full cues, visual cues only, or self-motion cues only. Navigation performance declined as sensory cues were removed, but we observed no corresponding changes in their spatiotemporal gait and balance metrics. These results show that, in healthy adults, increasing the attentional demand of spatial navigation does not interfere with gait and balance during real-world movement. This finding suggests that locomotor control may be robust to navigation-related cognitive demands. Further research is needed to determine why navigation did not interfere with mobility and to clarify the relationship between these two interconnected processes.

Background: Freezing of gait (FOG) in Parkinson's disease (PD) is provoked by turning, doorways and dual-task walking. We evaluated WALK, a cadence-linked vibration neuromodulation combined with motor-learning training. Methods: Single-centre, sham-controlled pilot randomised trial. Adults with PD (Hoehn and Yahr 2 to 4) and neurologist-verified FOG were randomised 1:1 to intervention (WALK; vibration enabled) or sham (WALK; vibration disabled), alongside identical supervised home-based training for 6 weeks (3 sessions per week). OFF-medication assessments were performed at S0, S8 and S16. At S8 and S16, assessments were completed without a device and then with a device (fixed order). The primary endpoint was the mZ-FOG total (0 to 36). Results: Forty participants completed follow-up assessments (intervention n=24; sham n=16) with 100% session adherence and no serious device-related adverse events. In the intervention group, mZ-FOG total improved when assessed with the device at S8 ({Delta}=8.08) and S16 ({Delta}=9.21) relative to S0, with partial retention when assessed without the device at S16 ({Delta}=5.54). Conclusions: Cadence-linked, localised vibration neuromodulation plus motor-learning training was feasible and was associated with clinically meaningful within-intervention-group reductions in FOG. Taken together, the effect sizes and task-specific pattern support progression to a multicentre, assessor-blinded trial with an active sham, powered for between-group comparisons and durability and/or adherence endpoints.

Background and ObjectiveThe foot-ankle complex is a highly articulated and mechanically constrained system, often simplified as a chain of few rigid segments, neglecting many bone-to-bone motions and raising questions about the accurate representation of interaction with ground. This study proposes a new reduced-order multibody formulation that captures intrinsic kinematic constraints of the foot through motion synergies. MethodsBones kinematic coupling, or motion synergies, were experimentally derived from weight-bearing CT scans using principal component analysis. These couplings were embedded in a synergy-based multibody kinematic optimization framework describing the foot-ankle with five degrees of freedom: ankle flexion; foot adduction, pronation, and arching; and toe flexion. Model accuracy was evaluated against bone-level experimental kinematics. The model was applied to gait data from healthy, flat, and diabetic feet and compared with a standard multi-segment foot model, assessing robustness by progressively reducing the number of skin markers. ResultsAverage errors were about 1{degrees} and 0.5 mm when using subject-specific synergies and below 7{degrees} and 4 mm when scaling the generic model, matching or exceeding the accuracy of existing models. Reliable reconstruction was obtained using only four foot markers. In clinical gait analysis, the model showed superior discrimination between populations and enabled assessment of transverse arch deformation, not accessible with conventional models. ConclusionThe proposed synergy-based model provides an accurate, low-complexity framework for reconstructing bone-level foot and ankle kinematics, substantially simplifying gait analysis while improving biomechanical interpretability. This framework supports future integration with dynamic models aimed at studying load transmission in the foot.

Purpose: To identify, through iterative user-centered design, the auditory biofeedback requirements and sound preferences supporting gait training in children with cerebral palsy (CP), and to determine which feedback variables, sound mappings, and sound types yield clinically viable and movement-interpretable paradigms. Methods: The iterative process spanned two prototype phases. Prototype A comprised seven paradigms demonstrated to two experienced physiotherapists (Workshop 1A). Two of these were subsequently discarded owing to poor sound-movement interpretability and two were modified. Six paradigms were added to Prototype B, demonstrated to four children, five parents, and one therapist (Workshop 1B) and two therapists (Workshop 2B). Data were analyzed using systematic text condensation. Results: Within-child sound preferences varied with energy level and sensory state on a given day. Sound-movement interpretability tended to suffer for paradigms with greater acoustic complexity (e.g. computer-generated music). Therapists endorsed a repertoire spanning both movement quality and movement quantity targets. Participants independently proposed paradigms rewarding restrained and controlled movement, a feedback category absent from the current prototype. Conclusions: Session-level calibration is preferable to fixed sound profiles, requiring real-time interface support for paradigm adjustment. Acoustic complexity must remain subordinate to movement-sound interpretability. Paradigms targeting movement restraint are a development priority unaddressed in the literature.

Wearable digital health technologies may complement traditional gait assessments in amyotrophic lateral sclerosis (ALS) by sensitively capturing real-world mobility changes. In this study, we validated six digital gait metrics derived from ankle-worn sensors in a natural history cohort of 182 individuals with ALS. Investigated metrics correspond to various aspects of gait, including volume, speed, intensity, similarity, variability, and fragmentation. Longitudinal analyses showed significant declines in step count, peak cadence, stride intensity, and stride similarity, with increasing stride duration variability and walking fragmentation over 52 weeks. Many participants exhibited greater relative change in the gait metrics than the self-reported ALS Functional Rating Scale-Revised (ALSFRS-RSE). Stratified analyses revealed that digital metrics captured significant functional decline even in participants with stable walking scores on the ALSFRS-RSE. These findings support the potential utility of these metrics for disease monitoring in ALS clinical care and trials.