Adaptation of postural responses to changing balance threats
Research has also shown that children with bilateral spastic CP have reduced ability to adapt
their postural responses to changing sizes and velocities of balance threat (Roncesvalles et
al. 2002). Those researchers hypothesised that balance problems of the children with CP
when recovering from large or fast platform displacements could be due to either (1) reduced
ability to increase contraction amplitudes of postural muscles when faced with larger or
faster compared to small or slow balance threats, (2) a delay in the onset of muscle
contractions, or (3) to simultaneous contraction of agonist and antagonist muscles, reducing
the efficiency of the agonist burst. They found that typically developing children showed
increased muscle response amplitudes when they were given larger or faster postural
perturbations, while children with cerebral palsy showed no significant increases under
these conditions. There was no difference in muscle contraction onset time or agonist–
antagonist co-contraction, supporting the hypothesis that problems with adaptation postural
response to increased balance threat magnitudes is due to an inability to increase muscleactivation
levels.