Combined Gait and Grasping in Autistic and Non-Autistic Youths

This study was designed to extend research on motor skill development in autism spectrum disorder using a dual-task skill. Nine autistic and 18 non-autistic youths walked without grasping or while reaching to grasp a small or large object. Step extremity ratio, percent time in double support, and normalized speed were quantified. We hypothesized that gait would differ between autistic and non-autistic youth and that differences would be moderated by the phase (approach and grasp) and the complexity of the task (walking and grasping versus walking alone). Although gait parameters were similar during the walking-only trials, the combined task resulted in slower speed and shorter steps in autistic youth, particularly during the grasp phase. These findings, while in a small sample, offer preliminary evidence that autistic youth who show typical gait during simple assessments of motor ability may have difficulties in more complex tasks that require the coordination of movements.

Inter and intra-limb coordination variability during walking in adolescents with autism spectrum disorder

BACKGROUND

Autism spectrum disorder, a neurodevelopmental disorder, is difficult to characterize from a gait biomechanics perspective, possibly due to increased inter and intra-individual variability. Previous research illustrates increased gait variability in young children with autism, but assessments in older adolescents or at varying speeds are unavailable. The purpose of this study was to determine if adolescents with autism demonstrate increased intra-limb and inter-limb coordination variability during walking compared to age, sex, and body mass index matched controls.

METHODS

Seventeen adolescents with autism (age 13-18 years) and seventeen matched controls performed walking at two matched speeds: self-selected of adolescents with autism and at 1.3 m/s. Modified vector coding was used to determine the patterns of movement for foot-shank, left/right thigh, and contralateral thigh-arm coupling. Coordination variability, a measure of cycle-to-cycle variability, was determined across the full stride. Mixed-model analyses of variance were used to determine if group by speed interactions and/or main effects existed for coordination variability.

FINDINGS

A significant interaction existed for foot-shank variability (p = 0.039). Adolescents with autism had greater variability at self-selected speeds (p = 0.018), but not at 1.3 m/s (p = 0.593) compared to controls. Thigh-thigh coordination was greater for adolescents with ASD compared to controls at both speeds (p = 0.021). Variability was decreased at 1.3 m/s for both foot-shank (p = 0.016) and thigh-thigh (p = 0.021) coupling.

INTERPRETATION

This study illustrates that adolescents with autism perform walking with increased coordination variability at both proximal and distal segments. Thus, it is likely intra-individual variability drives the disparity of movement patterns in this population.

Meta-Analysis Reveals Gait Anomalies in Autism

Gait abnormalities are frequently reported in autism. The empirical literature, however, is characterized by inconsistent findings concerning which aspects of gait are affected. We conducted a meta-analysis to summarize study findings that examined temporal and spatial (i.e., two-dimensional) gait parameters in pediatric and adult samples comprising individuals with autism and healthy controls. After searching electronic databases, a total of 18 studies were identified and included in this review. Results from the meta-analyses revealed autism is associated with a wider step width, slower walking speed, longer gait cycle, longer stance time and longer step time. Additionally, autism appears to be associated with greater intra-individual variability on measures of stride length, stride time and walking speed. Meta-regression analyses revealed cadence and gait cycle duration differences, between autism and control groups, become more pronounced with age. Overall, this review demonstrates that autism is associated with gait abnormalities. However, assessment of the methodological quality of the studies reveal, additional research is required to understand the extent that gait abnormalities are specifically linked to autism, or whether they may be secondary to other factors commonly found in this group, such as increased weight. LAY SUMMARY: It is often noted by clinicians that individuals with autism have an awkward or unusual walking style, which is also referred to as gait. In this report, we reviewed past studies that compared gait in individuals with and without autism. Our review indicates autism is associated with an abnormal gait. However, it is not yet clear whether gait abnormalities are caused by autism, or arise due to other factors such as heavier weight, which often co-occurs in this group.

Lesser magnitudes of lower extremity variability during terminal swing characterizes walking patterns in children with autism

BACKGROUND

Anecdotally, children with Autism Spectrum Disorder have highly variable lower extremity walking patterns, yet, this has not been sufficiently quantified. As such, the purpose of this study was to examine walking pattern variability by way of lower extremity coordination and spatio-temporal characteristics in children with autism compared with individuals with typical development during over-ground walking.

METHODS

Bilateral continuous relative phase variability was computed for the thigh-leg, leg-foot, and thigh-foot segment couples for 11 children with autism and 9 children with typical development at each gait sub-phase. Furthermore, left and right stride lengths and stride width were computed and compared. The Model Statistic was utilized to test for statistical differences in variability between each child with autism to an aggregate group with typical development. Effect sizes were computed to determine the meaningfulness between responses for children with autism and typical development. Coefficient of variation and effect sizes were computed for stride lengths and stride width.

FINDINGS

Analysis revealed that children with autism exhibited differences in variability in each gait sub-phase. Notably, all but two children with autism exhibited lesser variability in all segment couples during terminal swing. Differences in stride lengths were relatively minimal, however, greater coefficient of variation magnitudes in stride width were observed in children with autism.

INTERPRETATION

This finding reveals that children with autism may have limited or a preferred movement strategy when preparing the foot for ground contact. The findings from this study suggest variability may be an identifiable characteristic during movement in children with autism.

Gait Pattern and Motor Performance During Discrete Gait Perturbation in Children With Autism Spectrum Disorders

Quantitative evaluation of gait has been considered a useful tool with which to identify subtle signs of motor system peculiarities in autism spectrum disorder (ASD). However, there is a paucity of studies reporting gait data in ASD as well as investigating learning processes of locomotor activity. Novel advanced technologies that couple treadmills with virtual reality environments and motion capture systems allows the evaluation of gait patterns on multiple steps and the effects of induced gait perturbations, as well as the ability to manipulate visual and proprioceptive feedbacks. This study aims at describing the gait pattern and motor performance during discrete gait perturbation of drug-naïve, school-aged children with ASD compared to typically developing (TD) peers matched by gender and age. Gait analysis was carried out in an immersive virtual environment using a 3-D motion analysis system with a dual-belt, instrumented treadmill. After 6 min of walking, 20 steps were recorded as baseline. Then, each participant was exposed to 20 trials with a discrete gait perturbation applying a split-belt acceleration to the dominant side at toe-off. Single steps around perturbations were inspected. Finally, 20 steps were recorded during a post-perturbation session. At baseline, children with ASD had reduced ankle flexion moment, greater hip flexion at the initial contact, and greater pelvic anteversion. After the discrete gait perturbation, variations of peak of knee extension significantly differed between groups and correlated with the severity of autistic core symptoms. Throughout perturbation trials, more than 60% of parameters showed reliable adaptation with a decay rate comparable between groups. Overall, these findings depicted gait peculiarities in children with ASD, including both kinetic and kinematic features; a motor adaptation comparable to their TD peers, even though with an atypical pattern; and a motor adaptation rate comparable to TD children but involving different aspects of locomotion. The platform showed its usability with children with ASD and its reliability in the definition of paradigms for the study of motor learning while doing complex tasks, such as gait. The additional possibility to accurately manipulate visual and proprioceptive feedback will allow researchers to systematically investigate motor system features in people with ASD.