Differences of Biomechanical and Neuromotor Control Differences between Preschoolers with and without ASD

The purpose of this study is to compare the differences in biomechanics and muscle activities during running between preschoolers with and without ASD. This study further assesses the association between running biomechanics and clinical motor performance in both groups.

Twelve preschoolers with confirmed or suspected ASD (56.3±11.5 months old) and 12 age- and sex-matched typically developing (TD) preschoolers (56.2±11.5 months old) were recruited. Preschoolers in the ASD group were included only if they could follow simple directions to comply with experimental procedures. Kinematic, kinetic data, and muscle activation were collected using a motion capture system, force plates, and electromyographic (EMG) system during running tasks. Gross motor outcomes, including stationary, locomotion, and object manipulation subtests of the Peabody Developmental Motor Scales-Second Edition (PDMS-2), were used to evaluate gross motor performance and its association with biomechanical outcomes. The Mann-Whitney U tests and Spearman’s rank correlation coefficients were used for statistical analyses, with alpha level set at 0.05.

There is no significant difference in basic information between the two groups, and female-to-male ratio is 1:11. Preschoolers in the ASD group showed significantly smaller maximal knee flexion (p=0.04, effect size=1.18) during the stance phase of running than preschoolers in the TD group. They also reached the maximal hip flexion significantly earlier than the TD group (p=0.04, effect size=0.96). There was no significant difference on joint moments and co-contraction patterns between agonist and antagonist muscle pairs between the two groups. Preschoolers with ASD exhibited significantly lower quotient (p=0.006, effect size=1.68) and standard score (p=0.006, effect size=1.71) of overall gross motor performance and lower standard scores of object manipulation (p0.001, effect size=2.50) of the PDMS-2. There is no correlation between gross motor performance and biomechanical outcomes of running.  

Preschoolers with suspected or confirmed ASD may demonstrate poorer capacity of eccentric control of the hip flexor and extensor during running compared with preschoolers with TD. This may indicate reduced efficiency in the running task, which may further influence running speed and endurance in preschoolers with ASD. However, clinical tool for assessing running-related gross motor performance may not be sensitive enough to detect these differences. 

 This study showed biomechanical differences of running between preschoolers with and without ASD traits or diagnosis. This result may offer preliminary evidence to guide the direction of more comprehensive intervention programs to facilitate the overall health condition and development in preschoolers with ASD.