Muscle architecture predicts lower extremity power generation during a power leg press test in individuals with cerebral palsy.

Abstract

The purpose of this cross-sectional study was to examine relationships between power and muscle architecture in individuals with cerebral palsy (CP). Participants (n = 26; 19.3 ± 7.8 years; range 10-37 years; Gross Motor Function Classification System level I-III) performed 5 power leg presses with the concentric performed at a high velocity. Peak Power was calculated as the highest power value across the 5 presses. Architectural outcomes were muscle thickness, cross-sectional area, and fascicle length of the vastus lateralis, medial gastrocnemius, and rectus femoris. Simple linear and multiple regression were used to examine associations between architecture and Peak Power. Peak Power was positively associated with all architectural variables (p < 0.05) except for rectus femoris fascicle length (p = 0.058). Rectus femoris thickness alone explained the greatest variance in Peak Power (50.8%). Rectus femoris and medial gastrocnemius cross-sectional area combined with fascicle length of each muscle explained between 68.5%-69.2% of the variance in Peak Power (p < 0.001). Rectus femoris cross-sectional area, age, and Gross Motor Function level together explained 71.6% of the variance in Peak Power (p < 0.001). Muscle architecture is a significant predictor of lower extremity muscle power in individuals with CP. Muscle size was a stronger predictor of power than fascicle length; however, combining these variables substantially increased model strength, explaining 69% of the variance in power. The addition of age and Gross Motor Function level provided additional explanatory power. These findings highlight the key role of muscle architecture in muscle performance in individuals with CP.