Biology subjects

Cherni, Y.

Publications and source records attributed to Cherni, Y..

5 recordsLinked to original sources

bioRxiv2026

Maturation of Gait: Identification of Locomotor Profiles from Early Childhood to Adulthood

BackgroundHuman gait is a key marker of motor development. While walking on even surface is well-documented, responses to irregular surfaces, closer to real-world environments, remain understudied. This limitation is reinforced by the frequent use of univariate analyses, though locomotor control emerges from interactions of multiple features. Multivariate approaches are therefore essential to characterize developmental modulations to uneven surfaces. Objectives(i) To evaluate the combined effects of age and surface complexity on multiple gait domains in healthy individuals during development; (ii) To identify locomotor profiles across gait maturation. MethodsSixty-eight participants (2-35 years) walked at a self-selected speed on even, medium, and high irregularity surfaces. Gait kinematics were captured using a 3D motion system. Linear Mixed Models evaluated age and surface effects on 28 variables across five domains: pace, rhythm, dynamic stability, variability, and asymmetry. Moreover, principal component analysis followed by k-means clustering was performed on 15 normalized variables to identify gait profiles. ResultsAge and surface influenced most variables (p<0.05). Young children (2-5 years) exhibited the greatest modulation of asymmetry, base of support, smoothness, and dynamic stability with surface complexity. Conversely, adults and adolescents (12-35 years) showed higher variability modulation on irregular surface. PCA-assisted clustering identified two clusters: Cluster1 (15.2 years, smooth-regular) and Cluster2 (6.1 years, wide-base-variable). Across surfaces, five subgroups emerged: two consistent (15.8 years in Cluster1; 5.4 years in Cluster2) and three switchers (8.5 years [7.6-12.8]) showing context-dependent transitions as surface complexity increased. DiscussionDifferential maturation and surface sensitivity suggest that irregular surfaces act as functional stressors, revealing developmental gaps hidden on even ground. The surface-dependent transition at 7-13 years suggests that locomotor maturity is task-dependent rather than a fixed state, shifting from stable, regular to a variability-driven, balance-supportive strategy with complexity. These profiles delineate developmental stages and may help to identify atypical trajectories in pediatric rehabilitation.

bioengineering↗

bioRxiv2026

Impact of age and surface irregularities on intersegmental and inter-joint coordination during gait

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.

physiology↗

bioRxiv2025

Within- and Between-Assessor Reliability of Lower-Limb Inter-Joint Coordination During Gait in Individuals With and Without Cerebral Palsy

BackgroundInter-joint coordination plays a key role in walking, particularly in people with cerebral palsy (CP), who experience altered movement patterns. The Continuous Relative Phase (CRP) method quantifies lower-limb coordination by assessing the phase relationships between joints. However, the reliability of CRP measurements during walking in individuals with CP remains unexplored, and may be affected by measurement variability due to marker placement errors, soft tissue artifacts, and natural movement fluctuations. Quantifying this reliability is important for appropriate clinical comparisons. This study aimed to quantify within- and between-assessor reliability of lower-limb CRP measurements in individuals with CP and their non-impaired (NI) peers. MethodsCP (n=19, age=18.4{+/-}7.3 years, GMFCS I-III) and NI (n=19, age=18.3{+/-}11.2 years) individuals completed two gait assessment sessions, each including 3D motion capture of at least 10 walking trials. Two trained assessors independently placed reflective markers and conducted gait analyses. Standard error of measurement (SEM) and minimal detectable change (MDC) were computed for knee-hip and ankle-knee coordination across gait subphases. FindingsThe SEM and MDC were lower for knee-hip than ankle-knee coordination, suggesting higher measurement reliability for proximal joint coupling. For knee-hip coordination, MDC reached 15.1{+/-}0.7{degrees}(CP) and 9.3{+/-}0.6{degrees}(NI) between assessors, and 23.8{+/-}3.0{degrees}(CP) and 9.1{+/-}1.6{degrees}(NI) within assessors. For ankle-knee coordination, MDC reached 29.0{+/-}2.6{degrees}(CP) and 25.0{+/-}3.5{degrees}(NI) between assessors, peaking at 47.3{+/-}10.9{degrees}(CP) and 28.6{+/-}1.5{degrees}(NI) in mid-swing within assessors. InterpretationThis study provides the first metrological reference for reliability of CRP-based inter-joint coordination during gait in CP. Results showed poor reliability, emphazing that such measurements must be interpreted with caution. Highlights- Knee-hip showed greater reliability than ankle-knee coordination across gait phases - Cerebral palsy individuals showed higher variability than non-impaired peers The beginning and the end of gait cycle showed the poorest reliability Pre-post comparisons should account for MDC thresholds to avoid misinterpretation

bioengineering↗

bioRxiv2024

Harmonization of Margin of Stability Calculations and Investigation of the Impact of Foot Length, Foot Width, Gait Speed, and Body Mass

The margin of stability (MoS), the minimum distance between the extrapolated center of mass and the edges of the base of support (BoS), is one of the most widely used metric to describe the mechanical stability during gait. In the current literature, the markers used to define the edges of the BoS are variable and the MoS model neglects the influence of anthropometric factors, such as foot length, foot width, and body mass. This study aimed to evaluate differences between anteroposterior (AP) and mediolateral (ML) MoS measures using various BoS edge definitions (AP: n = 3 methods, ML: n = 4 methods) and to investigate the impact of foot length, foot width, gait speed, and body mass on the MoS measures. Results show that the BoS edges definition affects the resulting MoS across the entire stance phase (AP: p<0.001 between the 3 methods; ML: p<0.001 between the 4 methods). Moreover, the AP MoS is influenced by foot length (p<0.029), as well as gait speed and body mass on both the AP (gait speed: p<0.001; body mass: p<0.038) and ML (gait speed: p<0.032; body mass: p<0.001) MoS. This study proposes a new approach based on optimal foot markers for defining the edges of the BoS, which may contribute to better assess mechanical stability during gait. Finally, the results suggest that normalizing the MoS (i.e., the AP MoS by foot length, gait speed, and body mass, and the ML MoS by gait speed and body mass) can facilitate comparisons between populations.

bioengineering↗

bioRxiv2024

Knee Biomechanics during Walking in Individuals with Anterior Cruciate Ligament Repair: The Role of a Custom 3D Printed Knee Brace

BackgroundAnterior cruciate ligament (ACL) injuries frequently lead to altered gait biomechanics and muscle activation patterns, increasing the risk of osteoarthritis. Knee braces are commonly used to address these issues although a lack of consensus remains regarding their clinical benefits. The recent emergence of 3D-printed braces, lighter and personalized, could improve rehabilitation. ObjectivesTo evaluate the effect of a novel custom-made 3D-printed knee brace (Provoke) in individuals after unilateral ACL reconstruction during walking. The brace incorporates an asymmetrical hinge system aimed at stabilizing the knee joint while minimizing compensatory movements. MethodsFourteen participants with unilateral ACL reconstruction wore the Provoke brace while walking at comfortable and fast paces. Knee kinematics and kinetics, and muscular activity (rectus femoris, vastus medialis, and semitendinosus) were assessed with and without the brace. Two-tailed non-parametric paired T-tests were used to assess the biomechanical effect of the brace. Results and conclusionsThe Provoke brace improved knee kinematics, facilitating a more neutral knee position by reducing valgus angles (-1.95{degrees}), and increasing flexion angles (+1.14{degrees}). Additionally, it enhanced muscle activation, particularly of the rectus femoris, suggesting improved quadriceps function. Overall, the Provoke brace effectively improves knee function and reduces muscle imbalances in individuals undergoing ACL reconstruction. It may help prevent further injury and reduce the risk of post-traumatic osteoarthritis development. The long-term effects of brace use in ACL rehabilitation must be investigated. Key PointsO_LIWalking while wearing Provoke brace allow to reduce knee valgus angles which could counteract the development of post-traumatic osteoarthritis. C_LIO_LIBraced walking may mitigate the stiffened knee gait strategy by increasing the peak knee flexion angle during the stance phase of the gait. C_LIO_LIIncreased rectus femoris activation during early stance phase could improve knee function and stability, acting against quadriceps weakness often observed after anterior cruciate ligament reconstruction. C_LI

bioengineering↗