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Relative fascicle excursion effects on dynamic strength generation during gait in children with cerebral palsy
T Martín Lorenzo1, S Lerma Lara2, I Martínez-Caballero3
1Laboratorio de Análisis del Movimiento, Hospital Infantil Universitario Niño Jesús, Avenida Menéndez Pelayo, 65, 28009 Madrid, Spain; Facultad de Ciencias de la Salud, Universidad Rey Juan Carlos, Madrid, Spain.
Insights
Muscle fascicle length is not well correlated with force development in children with cerebral palsy (CP). New research suggests focusing on relative muscle fascicle excursions may better predict outcomes for crouch gait prevention.
Area of Science:
- Biomechanics
- Pediatric Rehabilitation
- Neuromuscular Function
Background:
- Muscle structure significantly impacts force generation, particularly in children with cerebral palsy (CP).
- While many muscle parameters correlate with strength, muscle fascicle length shows conflicting results in children with CP compared to typically developing (TD) peers.
- Muscle fascicle length influences muscle excursion and velocity, yet its correlation with the rate of force development is inconsistent in children with CP.
Purpose of the Study:
- To investigate the relationship between muscle architecture parameters, sarcomere length, and dynamic power generation in children with CP.
- To understand the underlying mechanisms of weakness in children with CP for tailored interventions.
- To identify children at risk of developing crouch gait due to operating on the descending limb of the sarcomere length-tension curve.
Main Methods:
- Evaluation of muscle structure parameters, including muscle fascicle length and relative fascicle excursions.
- Assessment of dynamic power generation and its relationship to muscle architecture.
- Comparison of findings between children with CP and typically developing (TD) children.
Main Results:
- Conflicting results exist regarding the correlation between muscle fascicle length and strength development in children with CP.
- Potential reasons for the lack of correlation include non-optimal joint positioning during testing and the assumption that fascicle length represents sarcomere length.
- Relative muscle fascicle excursions show potential as a predictive variable for outcomes in crouch gait prevention treatments.
Conclusions:
- Understanding muscle architecture's role in weakness is crucial for individualized interventions in children with CP.
- Relative muscle fascicle excursions may serve as a valuable tool for predicting treatment outcomes and preventing crouch gait.
- Further research is needed to clarify the relationship between muscle architecture, sarcomere length, and dynamic function in pediatric populations with CP.
Abstract:
Evaluation of muscle structure gives us a better understanding of how muscles contribute to force generation which is significantly altered in children with cerebral palsy (CP). While most muscle structure parameters have shown to be significantly correlated to different expressions of strength development in children with CP and typically developing (TD) children, conflicting results are found for muscle fascicle length. Muscle fascicle length determines muscle excursion and velocity, and contrary to what might be expected, correlations of fascicle length to rate of force development have not been found for children with CP. The lack of correlation between muscle fascicle length and rate of force development in children with CP could be due, on the one hand, to the non-optimal joint position adopted for force generation on the isometric strength tests as compared to the position of TD children. On the other hand, the lack of correlation could be due to the erroneous assumption that muscle fascicle length is representative of sarcomere length. Thus, the relationship between muscle architecture parameters reflecting sarcomere length, such as relative fascicle excursions and dynamic power generation, should be assessed. Understanding of the underlying mechanisms of weakness in children with CP is key for individualized prescription and assessment of muscle-targeted interventions. Findings could imply the detection of children operating on the descending limb of the sarcomere length-tension curve, which in turn might be at greater risk of developing crouch gait. Furthermore, relative muscle fascicle excursions could be used as a predictive variable of outcomes related to crouch gait prevention treatments such as strength training.
