Control of angular momentum during walking in children with cerebral palsy

Children with hemiparetic Cerebral Palsy (CP) walk with marked asymmetries. For instance, we have recently shown that they have less arm swing on the affected side, and more arm swing at the unaffected side. Such an increase in arm swing at the unaffected side may be aimed at controlling total body angular momentum about the vertical axis, although it was never investigated in this respect. In the current study, we thus investigated if participants with hemiparetic CP control angular momentum by compensatory movements of the unaffected arm. We measured gait kinematics of 11 CP children, and 24 age matched typically developing (TD) children, walking at both self-selected and fast walking speeds, and calculated angular momenta. We found that children with hemiparetic CP did not have a reduced angular momentum of the affected arm. However, they showed substantial increases in angular momentum generated by the legs, which were compensated by increased angular momentum of the unaffected arm. As a result, there were no differences in total body angular momentum between TD and CP children. Moreover, walking speed had no effect on total body angular momentum in both groups. These findings support the idea that angular momentum during walking is a controlled variable, even in children with hemiplegic CP.