Lower extremity joint stiffness during walking distinguishes children with and without autism

Lower extremity joint stiffness of autistic adolescents during running at dual speeds

Running is one of the most common forms of physical activity for autistic adolescents. However, research examining their lower extremity dynamics is sparse. In particular, no information exists regarding lower extremity joint stiffness in autistic adolescents. This study compared knee and ankle joint stiffness during the absorption phase of running between autistic adolescents and non-autistic controls. Motion capture and ground reaction forces were recorded for 22 autistic adolescents and 17 non-autistic age, sex, and BMI matched peers who ran at self-selected and standardized (3.0 m/s) speeds. Group × speed knee and ankle joint stiffness, change in moment, and range of motion were compared using mixed-model ANOVAs. There were no group × speed interactions for any variable. Autistic adolescents presented with significant (12 % and 19 %) reduced knee and ankle joint stiffness, respectively. In addition, autistic adolescents had significant reduced changes in knee and ankle joint moments by 11 % and 21 %, respectively, compared to their non-autistic peers. Only knee joint stiffness and knee joint moments were sensitive to running speed, each significantly increasing with speed by 6 %. Current literature suggests joint stiffness is an important mechanism for stability and usage of the stretch shortening cycle (or elastic recoil); as such, it is possible that the reduced ankle plantar flexor and knee extensor stiffness found in autistic adolescents in this study could be indicative of reduced efficiency during running. As group differences existed across both speeds, autistic adolescents may benefit from therapeutic and/or educational interventions targeting efficient running mechanics.

[Motor impairments in children with autism spectrum disorders: causes and possibilities for correction]

Autism spectrum disorder (ASD) is characterized by triad of abnormalities in the form of developmental distortion with a lack of communicative abilities, behavioral and motor stereotypies. Etiology and pathogenesis of disease currently are unknown, but multifactorial causes of this pathology have been suggested. Although social disorders are considered a defining characteristic, motor disorders are a key feature of ASD. They are based on a postural control impairment, which is accompanied by delayed psychomotor development, reduced ability to motor synchronism in early childhood, modified arrangement of muscles, problems with balance and gait, postural instability, coordination deficiency, presence of motor dyspraxia and other abnormalities.

OBJECTIVE

To analyze current scientific data about motor disorders in ASD and their correction possibilities in children with this pathology.

MATERIAL AND METHODS

Analysis of publications, contained in PubMed and Google Scholar databases, which give consideration to motor disorders in children with ASD, was carried out. The search was done by keywords: motor disorders, children, autism spectrum disorder, causes, correction.

RESULTS AND CONCLUSION

Adaptive physical culture during individual training is one of the available and effective methods of physical rehabilitation in patients with ASD. Children with ASD need three levels of psychological support, each of which offers individual exercises, depending on the nature and severity of speech and cognitive impairment.

Children with autism display altered ankle strategies when changing speed during over-ground gait

BACKGROUND

Examining gait mechanics when altering speed has been used in various clinical populations to understand the pervasiveness of neurological impairments. Few studies have examined whether different gait mechanics exist when altering speed in children with Autism Spectrum Disorder, although autism may present as a movement disorder due to abnormalities in the central nervous system. Most autism gait-related research has used preferred walking speed, while different speeds may yield discernible patterns that can be used for future interventions. The purpose of this study was to examine kinematic strategies used by children with autism in preferred, fast, and slow walking speeds.

METHODS

Three-dimensional kinematic data were obtained on 14 children (aged 8-17 years) during preferred, fast, and slow walking. Hip, knee, and ankle angular joint positions were examined at loading response, pre-swing, and terminal swing sub-phases due to their importance on forward propulsion and weight transfer. Repeated measures analyses of variance (α = 0.05) were used to test for statistical differences and effect sizes were interpreted with Cohen's d.

FINDINGS

Although significant differences were observed for each joint and sub-phase, the left and right ankle joints during pre-swing displayed the most consistent differences among conditions (p < 0.001, and p < 0.001), respectively. Additionally, the left ankle displayed a moderate effect size (η² = 0.71) and the right ankle displayed a large effect size (η² = 0.80).

INTERPRETATIONS

These findings reveal that the ankle joint, during pre-swing, is the primary kinematic strategy used by children with autism when altering gait speed, whereas previous evidence suggests that the hip joint was the primary strategy.

Weighted Vest Loads Do Not Elicit Changes in Spatial-Temporal Gait Parameters in Children and Adolescents With Autism

Weighted vests have been used primarily as behavioral interventions for children and adolescents with autism. Contemporary research has begun to examine weighted vest effects on movement. Previous research in children with neurotypical development revealed 15% body mass loads modified spatial-temporal gait characteristics; however, a value applicable to children and adolescents with autism has not been established. The purpose of this study was to establish an appropriate mass value by examining spatial-temporal gait parameters in children and adolescents with autism with various loads in a weighted vest. Nine children and adolescents with autism, aged 8–17, walked without a weighted vest, with 5%, 10%, 15%, and 20% body mass while spatial-temporal data were captured. Repeated-measures analysis of variance (α = .05) were conducted among conditions for each variable, with a Holm–Bonferroni method correction. Analysis revealed significant decreases in right step length, but no differences in stride width, left step length, double-limb support time, or stride velocity were observed. Due to insignificant findings, an appropriate mass value could not be determined for weighted vests for children with autism. However, unchanged spatial-temporal gait parameters with increasing loads could be clinically relevant as weighted vest loads of 10% are typically used for behavioral interventions.

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.

Coordination variability during running in adolescents with autism spectrum disorder

LAY ABSTRACT

Walking and running are popular forms of physical activity that involve the whole body (pelvis/legs and arms/torso) and are coordinated by the neuromuscular system, generally without much conscious effort. However, autistic persons tend not to engage in sufficient amounts of these activities to enjoy their health benefits. Recent reports indicate that autistic individuals tend to experience altered coordination patterns and increased variability during walking tasks when compared to non-autistic controls. Greater stride-to-stride coordination variability, when the task has not changed (i.e. walking at same speed and on same surface), is likely indicative of motor control issues and is more metabolically wasteful. To date, although, research examining running is unavailable in any form for this population. This study aimed to determine if coordination variability during running differs between autistic adolescents and age, sex, and body mass index matched non-autistic controls. This study found that increased variability exists throughout the many different areas of the body (foot-leg, left/right thighs, and opposite arm-opposite thigh) for autistic adolescents compared to controls. Along with previous research, these findings indicate autistic persons exhibit motor control issues across both forms of locomotion (walking and running) and at multiple speeds. These findings highlight issues with motor control that can be addressed by therapeutic/rehabilitative programming. Reducing coordination variability, inherently lessening metabolic inefficiency, may be an important step toward encouraging autistic youth to engage in sufficient physical activity (i.e. running) to enjoy physiological and psychological benefits.

Walking lower extremity biomechanics of adolescents with autism spectrum disorder

Although the literature indicates children with autism spectrum disorder (ASD) walk at slower speeds and altered kinematics compared to neurotypical controls, no research has examined walking at matched speeds. This study examined biomechanical differences between adolescents with ASD and matched (age, sex, and body mass index) neurotypical controls. Lower extremity biomechanics of seventeen adolescents with ASD and seventeen controls were compared at matched speeds: self-selected and a standardized 1.3 m/s. Controls exhibited greater eversion angles and hip abduction moments compared to those with ASD. This study found adolescents, which may have a more mature gait than young children, walk with a similar pattern in the propulsive plane (i.e. sagittal) as neurotypical controls, but with alterations in the supportive plane (i.e. frontal).

Age-related gait development in children with autism spectrum disorder

BACKGROUND

A better understanding of gait development and asymmetries in children with autism spectrum disorder (ASD) may improve the development of treatment programs and thus, patient outcomes.

RESEARCH QUESTION

Does age affect walking kinematics and symmetry in children with ASD?

METHOD

Twenty-nine children (aged 6-14 years old) with mild ASD (level one) were recruited and assigned to one of the three groups based on their ages: 6-8 years (U8), 9-11 years (U11) and 12-14 years (U14). Walking kinematics were captured using an inertia measurement unit system placed bilaterally on participants' foot, lower leg, upper leg, upper arm, pelvis, and thoracic spine. Joint angles were computed and compared among the age groups. Symmetry angles were used to assess the gait symmetry and were compared among the age groups.

RESULTS

Older children exhibited less ankle dorsiflexion and knee flexion angles at heel-strike and greater plantarflexion angles at toe-off compared with younger children. In addition, a decreased pelvis and thorax axial rotation range of motion and increased shoulder flexion/extension range of motion were observed for older children. However, no age-related difference in gait symmetry was observed.

SIGNIFICANCE

These findings could suggest that older children with ASD may develop gait kinematics to a more energy-efficient walking pattern.

Relationship between tip-toe behavior and soleus - gastrocnemius muscle lengths in individuals with autism spectrum disorders

BACKGROUND

About 20% of individuals with autism spectrum disorders (ASD) showed tip-toe behavior (TTB). This behavior may be related to a decreased ankle joint range of motion (ROM) in dorsiflexion. Physiologically, gastrocnemius (GM) and soleus (SM) muscles influence ankle ROM independently. However, no studies investigated the relationship between the amount of time individuals with ASD spend in TTB and GM and SM muscle lengths.

OBJECTIVE

To evaluate the relationship between three mutually exclusive clinical patterns of TTB i.e., during standing, walking and running (TTB Class 1), or during walking and running (TTB Class 2), or only when running (TTB Class 3), and GM and SM muscle lengths.

METHODS

Sixty-nine individuals with ASD (average age: 14.1 ± 3.6 years, 56 males) were enrolled. In a clinical setting, SM and GM muscle lengths of both legs were assessed through a manual goniometer. Measurements were performed by two trained assessors blinded to TTB classifications.

RESULTS

Individuals with ASD classified as TTB Class 1 demonstrated a shortening of both GM and SM compared with NO-TTB and TTB Class 3 individuals.

CONCLUSIONS

Our results support the relationship between TTB severity and GM and SM shortening assessed by a decreased ankle joint ROM in dorsiflexion. Further studies are needed to determine the factors associated with TTB and decreased ankle ROM.

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.