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

Background: Human 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. Methods: Sixty-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. Results: Age 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. Discussion: Differential 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.