Relationship between lower limb strength and walking capacities in children with spastic bilateral cerebral palsy

Abstract

Purpose Evaluate the relationship between different walking capacities and muscle strength in children with bilateral cerebral palsy (BCP) and assess these relationships in stronger and weaker children. Materials and methods Thirty-two children with spastic BCP were included. All participants walked under three speed conditions: comfortable, fast, and for a longer period (6 min). Walking speeds, Energy Expenditure Index (EEI), and lower limb muscle strength were measured. A global strength index (GSI) was computed as the sum of each muscle group strength. Pearson’s coefficient and regression models were computed between walking capacities and the GSI. Results GSI was correlated with the EEI and all walking speeds. Logarithmic regressions models explained between 24 and 34% of the variance of walking capacities. Then, the group was divided in two subgroups (weaker and stronger children). GSI was correlated with comfortable and endurance waking speed in weaker children, but not in stronger children. Conclusion This study reports logarithmic relationship between muscle strength and walking capacities in children with BCP. The subgroup analysis implies that muscle strength has an impact on walking capacities solely in weaker children, suggesting that muscle strength must be preserved and reinforced in interventions targeting motor function in weaker children with BCP. Implications for rehabilitation In a sample of children with spastic bilateral cerebral palsy, this study shows that global muscle strength is associated with walking capacities and the relationship seems more complex than linear. Based on the results, interventions should focus on maintaining or improving muscle strength in weaker children as no association was observed between muscle strength and walking capacities in stronger children. In stronger children, intervention should focus on factors other than muscle strength as it does not influence walking capacities. Based on this study, a more accurate screening of children who could benefit from strength training could be completed by initial global muscle strength.