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Postural problems play a central role in the motor dysfunction of children with cerebral palsy (CP). Therefore, they spend more time in sitting than in standing to perform vital tasks of daily life. The focus of this article is to describe the pathophysiology of postural control in sitting and outline some implications for management and treatment. In general, children with CP exhibit muscular activity counteracting forces that disturb equilibrium. Only ‘non-sitting’ children with severe CP lack such ‘direction-specific’ adjustments, possibly ruling out achievement of independent sitting. Most frequently, the children display dysfunctions in the adaptation of the adjustment. Typical characteristics of this adaptation in children with CP are a top-down recruitment of pos tural muscles, an excessive degree of antagonistic coactivation, and an incomplete adaptation of the EMG-amplitude to task specific constraints. Despite our knowledge on the pathophysiology underlying the postural problems in children with CP, little ’high-level’ evidence (according to Sackett) exists on how different interventions can affect these problems. Therapeutic attention to promote motor performance in sitting focuses on adaptive seating, tilting of the support surface, and ample, variable training in motivating settings. The challenge facing us now is to provide evidence about the efficacy of specific treatment approaches facilitating that children reach an optimal level of functioning in daily life.

The present paper gives an overview of the knowledge currently available on muscular dyscoordination underlying postural problems in children with cerebral palsy (CP). Such information is a prerequisite for developing successful therapeutic interventions in children with CP. Until now, three children with CP functioning at GMFCS (Gross Motor Function Classification System) level V have been documented. The children totally or partially lacked direction specificity in their postural adjustments and could not sit independently for more than 3 seconds. Some children functioning at GMFCS level IV have intact direction-specific adjustments, whereas others have problems in generating consistently direction-specific adjustments. Children at GMFCS levels I to III have an intact basic level of control but have difficulties in fine-tuning the degree of postural muscle contraction to the task-specific conditions, a dysfunction more prominently present in children with bilateral spastic CP than in children with spastic hemiplegia. The problems in the adaptation of the degree of muscle contraction might be the reason that children with CP, more often than typically developing children, show an excess of antagonistic coactivation during difficult balancing tasks and a preference for cranial-caudal recruitment during reaching. This might imply that both stereotypies might be regarded as functional strategies to compensate for the dysfunctional capacity to modulate subtly postural activity.