# Kinematic analysis of autistic children during beam walking

Adrien Péneaud, Nasser Rezzoug, Aurélie Benchekri, Christel Bidet-Ildei,
Laetitia Fradet

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Adrien Péneaud, Nasser Rezzoug, Aurélie Benchekri, Christel Bidet-Ildei, Laetitia Fradet. Kinematic analysis of autistic children during beam walking. Multidisciplinary Biomechanics Journal, 2025, 50th congress of the.., 10.46298/mbj.16189. hal-05191741v2

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# Kinematic analysis of autistic children during beam walking

Adrien Péneaud<sup>a, b*</sup>, Nasser Rezzoug<sup>a</sup>,

Aurélie Benchekri<sup>a, b</sup>, Christel Bidet-Ildei<sup>b</sup>, Laetitia Fradet<sup>c</sup>

<sup>a</sup> Institut Pprime (Université de Poitiers, CNRS, ISAE-ENSMA), UPR 3346, Poitiers, France

<sup>b</sup> Centre de Recherches sur la Cognition et l'Apprentissage, Université de Poitiers, Université de Tours, CNRS -Poitiers, France

<sup>c</sup> Laboratoire Lab-STICC, UMR 6285, CNRS - Université de Bretagne-Sud, Lorient, France

* Corresponding author: adrien.peneaud@univ-poitiers.fr

Received date: 05/04/2025

Accepted date: 27/06/2025

Publication date: 27/10/2025

**Keywords:** autism, balance, gait, beam, kinematics

© 2025 The Authors

Licence CC-BY 4.0

Published by Société de Biomécanique

## 1. Introduction

Autism Spectrum Disorder (ASD) is a neurodevelop-
mental psychiatric condition whose first signs appear in
childhood, before the age of three, and persist through-
out life. The main features of ASD include persistent
deficits in communication and social interaction, and
restricted and repetitive patterns of behavior (DSM-
5-TR, 2022). However, motor deficits, particularly in
postural control and gait initiation have been identified
(Fournier et al. 2010) suggesting that balance mecha-
nisms are impacted by ASD.

Beam walking is an interesting task that further chal-
lenges balance in dynamic situations because the base
of support (BoS) is reduced along the medio-lateral
(ML) axis, thus limiting the strategies available to ensure
balance. A recent study showed differences in angular
momentum (AM) between ASD and neurotypical chil-
dren (NT) when walking on a narrow beam (Carron
et al. 2025), with AM being of critical importance for
ensuring balance. This AM was greater for ASD chil-
dren than for NT children in the frontal plane during
the swing phase. This study reinforced thus the idea
of specific balance characteristics in ASD. However,
joint kinematics were not presented in this study, raising
questions about the origin of the observed differences.

The aim of the present study was then to comple-
ment this previous study on balance of children with
ASD by examining joint kinematics during walking on
a narrow beam.

## 2. Methods

### 2.1 Participants & Procedure

For this experiment, 24 ASD children (9 females, 9.4 ± 1.8 years old, 136 ± 13 cm, 30.5 ± 10.9) were recruited at the Limoges University Hospital and La Rochelle Hospital, and 24 age- and size-matched TD children (13 females, 9.1 ± 1.6 years old, 137 ± 11 cm, 29.9 ± 5.8 kg) were recruited in Poitiers.

All children completed five walking trials at self-
selected speed on a 4 m long and 8 cm wide beam. A
Vicon 3D motion-capture system with 15 cameras sam-
pled at 100 Hz recorded the trajectories of 36 reflective
markers placed on anatomical landmarks according to
the Conventional Gait Model version 2.1.

### 2.2 Data analysis

Marker trajectories were Butterworth low-pass filtered at a 10 Hz cut-off frequency. Joint kinematics in sagittal and frontal planes were computed using the Conventional Gait Model version 2.1. Kinematics were normalized from 0 to 100% of the gait cycle (101 data points). For this analysis, for each subject, the data from the six cycles having the lowest AM were retained in accordance with (Carron et al. 2025).

The data did not follow a normal distribution, so a
Statistical Non-Parametric Mapping test was used to
compare the lower limb joint kinematics between the
two groups (ASD and NT children), with a p-value
< .05 considered statistically significant.
<figure><img src="image_2.png" /><figcaption>**Figure 1.** Average and standard deviation of hip, knee, and ankle joint angles in sagittal plane, hip and ankle joint angles in frontal plane (blue for ASD children and red for NT children).</figcaption></figure>

Additionally, the range of motion (RoM) during the gait cycles was computed for the upper limbs and trunk and compared between the two groups using an independent t-test with the same p-value (< .05).

### 3. Results and discussion

According to Figure 1, the kinematics observed during this beam-walking task were similar to those found when walking on the ground.

AT and NT children presented similar kinematics patterns and amplitude for the hip and ankle joints in the sagittal plane. For the knee, during the loading and the swing phase, ASD children had a smaller knee flexion than the NT children (p< .05).

In the frontal plane, NT children had a larger hip adduction during a short period of the stance phase. The ankle angle showed also a difference but during the swing phase (70-100% of the gait cycle). NT children had a varus foot during the swing phase, as when walking on ground, whereas ASD children kept their ankle in a more neutral position.

Table 1 shows non-significant differences between ASD and NT children for the trunk and upper limb RoM.

Consistent with other studies (Calhoun et al. 2011), the results highlight a distinctive pattern in hip abduction/adduction among children with ASD. The reduced hip adduction in these children during the stance phase also raises questions about the positioning of the upper-body CoM relative to the beam during this phase.

Overall, the differences found in kinematics could be justified by the lower speed of the children with ASD (p<.03), as reduced walking speed reduces joint angle amplitudes (Schwartz et al. 2008). However, not all of the kinematic differences suggested by speed differences were observed.

<table><caption>**Table 1.** Upper limb and trunk RoM of ASD and TD children (FE: Flexion Extension, AA: Adduction Abduction), Mean RoM (in degrees).</caption><thead><tr><td>RoM</td><td>ASD</td><td>TD</td><td>p-value</td></tr></thead><tbody><tr><td>Shoulder FE</td><td>16.3</td><td>18.2</td><td>0.705</td></tr><tr><td>Shoulder AA</td><td>16.4</td><td>19.0</td><td>0.751</td></tr><tr><td>Elbow FE</td><td>18.2</td><td>17.7</td><td>0.705</td></tr><tr><td>Thorax AA</td><td>13.1</td><td>13.5</td><td>0.795</td></tr></tbody></table>
As the amplitudes of upper limb movements were almost identical between ASD and NT children, the main adaptations of strategies to achieve better balance on a beam would be in the lower limbs, as mentioned above. However, this conclusion should be taken with caution, as important inter-individual differences in the children's arm posture were observed, with the shoulder more or less abducted.

## 4. Conclusions

In conclusion, this study highlights notable differences in lower limb joint kinematics between children with ASD and NT children during a beam walking task. Some of these differences may be attributed to the slower walking speeds observed in children with ASD. Further research is needed to better understand the underlying factors contributing to these adaptations, which could also offer valuable insights into the unique balance characteristics of children with ASD.

## Conflict of Interest Statement

None of the authors have competing interests.

## Funding

This project has received financial support from the Region Nouvelle-Aquitaine and the CNRS through the MITI interdisciplinary programs.

## References

* American Psychiatric Association. 2022. DSM-5-TR. https://www.psychiatry.org:443/psychiatrists/practice/dsm

* Calhoun, M., Longworth, M., & Chester, V. L. (2011). Gait patterns in children with autism. *Clinical Biomechanics, 26*(2), 200–206. https://doi.org/10.1016/j.clinbiomech.2010.09.013

* Carron, T., Tisserand, R., Bechet, R., Benchekri, A., Bidet-Ildei, C., Fradet, L. (2025). Balance analysis of autistic children during beam walking. *Multidisciplinary Biomechanics Journal, 1*, 243–245. https://doi.org/10.46298/mbj.14516

* Fournier, K. A., Kimberg, C. I., Radonovich, K. J., Tillman, M. D., Chow, J. W., Lewis, M. H., Bodfish, J. W., Hass, C. J. (2010). Decreased static and dynamic postural control in children with autism spectrum disorders. *Gait & Posture, 32*(1), 6–9. https://doi.org/10.1016/j.gaitpost.2010.02.007

* Schwartz, M. H., Rozumalski, A., Trost, J. P. (2008). The effect of walking speed on the gait of typically developing children. *Journal of Biomechanics, 41*(8), 1639–1650. https://doi.org/10.1016/j.jbiomech.2008.03.015