Relative fascicle excursion effects on dynamic strength generation during gait in children with cerebral palsy

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.

Comparison of calf muscle architecture between Asian children with spastic cerebral palsy and typically developing peers

“…Based on the clinical experience, motor dysfunctions may be influenced more by limitations related to mechanical factors in soft tissues than to neurological factors in central command disorders as children with CP have grown up to be youths and adults. Fascicle length is especially important when analyzing muscle architecture because it is highly related to secondary musculoskeletal contracture development, which can severely limit the initial length of muscle contraction and excursion[ 9 , 28 , 40 , 46 , 47 ]. In this study, we show that the fascicle length in the affected calf was shorter than that observed in both TD peers and the unaffected side of children with hemiplegic CP.…”

Alterations in neuromuscular function in girls with generalized joint hypermobility

“…An alternative theory to explain the higher RTD is that girls with GJH use a more optimal joint position for rapid force generation in the isometric knee flexion test compared to NGJH girls, or in other words girls with GJH operate closer to the optimal region of the length-tension curve than NGJH girls. An association between relative muscle length and rate of force development in children with cerebral palsy was suggested recently as a possible underlying mechanism for understanding why these children have a reduced range of motion and reduced rate of force development compared to typically developing children [ 24 ].…”

Does patella lowering as part of multilevel surgery improve knee kinematics in children with cerebral palsy and crouch gait? A meta-analysis of comparative studies

“…23 While acknowledging the complex, multifactorial nature of crouch gait pathogenesis, an attempt should be made to treat as many of the existing causes as possible as part of a tailored approach. 20 Even for reducible deformities and in the absence of transverse or frontal plane abnormalities, nonsurgical treatments, such as physiotherapy and antigravity muscle strengthening, 24,25 together with spasticity management and orthotic adjustment 26 seem insufficient. 27,28 Among the surgical procedures used to correct crouch gait, distal hamstring lengthening (HSL) has traditionally been used to improve KE.…”