Lauren A. Luginsland, Hunter J. Bennett, Justin A. Haegele. Old Dominion University, Norfolk, VA.

BACKGROUND: Autism spectrum disorder (ASD) remains on the rise in the United States. While previous research has investigated walking mechanics in adolescents, limited research on running mechanics in autistic persons exist. Running, like walking, is a highly popularized form of physical activity. Lower limb asymmetries in running provides a snapshot of overall lower limb motor control. The purpose of our study was to investigate running limb asymmetries in autistic youth compared to neurotypical controls. METHODS: Seventeen individuals (aged 14.7±1.5yrs, BMI 20.1±3.9kg/m2) clinically diagnosed with ASD and seventeen age, sex, and BMI matched controls (aged 14.5±1.4yrs, BMI 20.3±3.6kg/m2) ran shod over-ground at a standardized speed (3.0m/s) and a self-selected (SS) speed (2.63±0.33m/s & 2.74±0.39m/s, respectively). 3D kinematics (VICON Motion Systems) and ground reaction forces (GRFs) (Bertec Corporation) were collected and analyzed using Visual3D Biomechanical Software. Limb comparison symmetry index was calculated for step width and step length at 3.0m/s and SS speeds. Two-way (group x speed) mixed model analysis of variances (alpha = 0.05) were used to determine differences in asymmetry. RESULTS: The step width of ASD at SS and 3.0m/s were 0.16±0.03m and 0.15±0.03m and in CON 0.15±0.06 and 0.15±0.02m, respectively. The step length of ASD at SS and 3.0m/s were 1.08±0.16m and 1.13±0.13m and in CON were 1.22±0.11m and 1.13±0.14m, respectively. Limb asymmetries calculated for step width in ASD were 31.3±13.5% and 41.2±25.7% in CON. The step length asymmetry values calculated for individuals with ASD were 22.9±27.9% and 22.9±15.1% in CON. There were no significant interactions or speed/group main effects for step width asymmetry (F=4.39, p=0.05; F=0.21, p=0.68, & F=1.32, p=0.33) or step length asymmetry (F=0.22, p=0.89; F=1.18, p=0.31; F=2.46, p=0.13). CONCLUSION: Understanding lower limb asymmetries in running provides a snapshot of motor control function during this popular form of physical activity. The results here demonstrate autistic youth do not run with greater spatiotemporal asymmetries when running at similar speeds. However, it is important to note ASD is an umbrella term for a variety of social, physiological, and/or behavioral features; thus, our results may not be generalizable to portions of the ASD population that may (those requiring significant support) have motor control issues.

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