Reliability of Isometric Knee Extensor Strength Measurement Using the Resistance Induction Method in Children with Autism Spectrum Disorder

Masahiro Kumagai, Mitsuhiro Ookura, Susumu Shimada, Koji Shigeshima, Fumiaki Iwasaki, Sho Yamamoto
Purpose:

This study aimed to verify the reliability measurements of isometric knee extensor muscle strength using the resistance induction method in children with ASD.

Methods:

This study measured isometric knee extensor muscle strength in 13 children with ASD (mean age 8.5 years) using a hand-held dynamometer. The posture was end-sitting with the feet grounded, and both arms crossed in front of the chest. During the measurement procedure, the examiner demonstrated the knee extension movement, and the child learned the movement through the resistance induction method. First, the examiner placed his hand on the front surface of the lower leg and practiced isotonic contraction of the knee in the direction of extension to overcome manual resistance, which then gradually induced isometric muscle contraction. Once the child understood the movement, two 5-second isometric knee extension exercises with maximal effort were performed, and the maximum value was taken as the knee extension muscle strength. When a movement was performed correctly, the examiner offered praise and muscle strength values to motivate the child. Two examiners conducted the measurements to examine inter-rater reliability, and the order in which the children were measured was randomized. Statistical analysis was used to examine reliability by calculating intraclass correlation coefficients and analyzing systematic errors using Bland-Altman plots.

Results:

The mean (standard deviation) isometric values of knee extension muscle strength were 17.2 (4.6) kgf and 18.3 (3.7) kgf for Examiners 1 and 2, in that order, with no significant differences. The intraclass correlation coefficient (2,1) showed good reliability with ICC = 0.77 (95% C.I = 0.43-0.92). No significant systematic errors were observed, and only chance errors occurred; the minimum detectable change was 5.4 kgf.

Conclusion(s):

Motion practice using the resistance induction method may have improved the understanding of the measured movements. Further, it increased the reliability of the measurements for the children with ASD in this study. Future studies should explore the relationship between knee extensor strength and gross motor and coordinated movements and activities of daily living in ASD.

Implications:

Suppose the significance of knee extensor strength measurement in ASD is clarified. In that case, it can be used as an indicator of improvement in motor skills and life situations.

Funding acknowledgements:
This study received no funding from any source.
Keywords:
Isometric knee extensor strength measurement
Reliability
Autism spectrum disorder
Primary topic:
Paediatrics
Did this work require ethics approval?:
Yes
Name the institution and ethics committee that approved your work:
This study was approved by the Ethics Committee of the Kochi Professional University of Rehabilitation.
Provide the ethics approval number:
KPUR2024E0009
Has any of this material been/due to be published or presented at another national or international conference prior to the World Physiotherapy Congress 2025?:
No

Back to the listing