Short communicationP 143 - Plantarflexor strength in relation to vertical ground reaction force in terminal stance in children and adolescents with spastic cerebral palsy
Introduction
Muscle weakness, most pronounced around the ankle [1], is an important cause of gait deviations in cerebral palsy (CP) [2]. Many children with CP experience significant problems supporting their bodyweight and decelerating the downward velocity of the center of mass in terminal stance [3]. This is reflected in a decreased second peak (FZ2) of the vertical ground reaction force (GRF) to less than 100% of bodyweight. The contribution of weak plantarflexor muscles has not been explored previously. A better understanding of which factors reduce FZ2 may help to use FZ2 for clinical decision making.
Section snippets
Research question
Is vertical ground reaction force in terminal stance during gait related to plantarflexor strength in children and adolescents with CP?
Methods
Sixteen children/adolescents with spastic CP aged 7–19 years, and 16 typically developed (TD) controls aged 6–15 years were studied. All subjects conducted a 3D gait analysis on a 12-meter walkway with 3 force plates. They performed at least six trials at preferred walking (PW) and fast walking (FW) speed. The trial with lowest FZ2 from each speed was used for analysis as having the “greatest potential for collapse”. Isometric plantarflexor strength was measured, peak torque (Fmax) and rate of
Results
WL in CP was significantly weaker than SL and TD. WL in CP also had lower FZ2 and slower walking speed compared to TD in PW and FW. For the total study sample, there was a significant moderate positive correlation between FZ2 and both Fmax and RFD during PW (r = 0.36, 0.48, respectively), but not FW. In PW, Fmax and RFD did not correlate with FZ2 in WL in CP, but had a positive correlation in SL (r = 0.43, 0.28) and TD (r = 0.10, 0.37). In FW, these variables had a small negative correlation in
Discussion
Plantarflexor weakness in WL in CP was not related to the ability to support bodyweight in terminal stance in PW (FZ2). In FW it appears that stronger plantarflexors were related to a reduction in FZ2, maybe because the weaker they are, the more they use compensatory mechanisms, and therefore achieve a greater FZ2. Low variation in FZ2 and a small number of subjects could be the reason for the lack of correlation during PW.
References (3)
- et al.
Gait Posture
(2008)