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Knee muscle strength at varying angular velocities and associations with gross motor function in ambulatory children
Wei-Hsien Hong1, Hseih-Ching Chen, I-Hsuan Shen
1Department of Sports Medicine, China Medical University, 91 Hsueh-Shih Road, Taichung 40402, Taiwan.
Insights
Children with cerebral palsy (CP) exhibit knee flexor strength deficits impacting gross motor functions like balance and running. The hamstring-quadriceps ratio may serve as a biomarker for targeted muscle strengthening interventions.
Area of Science:
- Pediatrics
- Neurology
- Rehabilitation Medicine
Background:
- Cerebral palsy (CP) is a group of movement disorders affecting muscle tone and posture.
- Ambulatory children with CP often experience muscle weakness, particularly in the lower extremities, affecting gross motor function.
- Understanding the relationship between specific muscle group strength and functional abilities is crucial for effective rehabilitation.
Purpose of the Study:
- To investigate the association between muscle strength at various angular velocities and gross motor functions in ambulatory children with spastic cerebral palsy (CP).
- To compare muscle strength and gross motor function between different Gross Motor Function Classification System (GMFCS) levels in children with CP.
- To identify potential biomarkers for assessing therapeutic effectiveness in muscle strengthening programs for children with CP.
Main Methods:
- A cross-sectional study involving 33 ambulatory children with spastic CP (ages 6-15) and 15 typically developing children.
- Muscle strength was assessed using isokinetic tests for knee extensors and flexors at different angular velocities.
- Gross motor function was evaluated using the Gross Motor Function Measure (GMFM-66) and the Bruininks-Oseretsky Test of Motor Proficiency (BOTMP).
Main Results:
- Children with GMFCS level II demonstrated significantly lower scores in BOTMP, GMFM-66, curl-up tests, hamstring-quadriceps (HQ) ratio, and knee muscle strength compared to GMFCS level I.
- Regression analysis revealed that knee flexor strength at 60 and 90°/s correlated with balance and overall strength, respectively.
- Knee flexor strength at 120°/s was strongly associated with running speed and agility, indicating its importance for dynamic movements.
Conclusions:
- Ambulatory children with CP exhibit significant knee strength deficits, especially in knee flexors, which are critical for postural control and dynamic gross motor functions.
- Postural muscle strength (knee flexors) appears to play a more dominant role in gross motor function than antigravity muscle strength (knee extensors).
- The HQ ratio and knee flexor strength at specific velocities show potential as biomarkers for monitoring treatment efficacy and guiding personalized muscle strengthening strategies in children with CP.
Abstract:
The aim of this study was to evaluate the relationships of muscle strength at different angular velocities and gross motor functions in ambulatory children with cerebral palsy (CP). This study included 33 ambulatory children with spastic CP aged 6-15 years and 15 children with normal development. Children with CP were categorized into level I (n=17) or level II (n=16) according to Gross Motor Function Classification System (GMFCS) levels. All children underwent curl-up test and isokinetic tests of the knee extensor and flexor muscle. Children with CP underwent the gross motor function assessments, including the Gross Motor Function Measure (GMFM-66) and the gross motor subtests of Bruininks-Oseretsky Test of Motor Proficiency (BOTMP). The hamstring-quadriceps ratio (HQ ratio) was calculated as 100%×(isokinetic peak torque of hamstring (knee flexor)/isokinetic peak torque of quadriceps (knee extensor)). Children with GMFCS level II had lower BOTMP and GMFM-66 scores, curl-up scores, HQ ratio, and knee muscle strength, especially knee flexor, compared to those with GMFCS level I. The regression analysis showed that knee flexor torques at 60 and 90°/s are mainly related to balance (r(2)=0.167, p=0.011) and strength (r(2)=0.243, p=0.002) while knee flexor torques at 120°/s mainly contribute to running speed and agility (r(2)=0.372, p<0.001). These findings suggest that children with CP had knee strength deficits, especially knee flexor. Postural muscle (knee flexor) strength dominated gross motor function than antigravity muscle strength (knee extensor). The knee flexor strength at different angular velocities was associated with various gross motor tasks. The HQ ratio may be used as a potential biomarker to probe the therapeutic effectiveness for muscle strengthening in these children. These data may allow clinician for formulating effective muscle strengthening strategies for these children.
