###### Abstract  
Background: Children with cerebral palsy (CP) have difficulty in managing postural control during functional reaching tasks, although children with different postural control ability are able to come up with different motor solutions to cope with different task demands. This study examined the effect of task constraint on postural control performance in children with cerebral palsy and typical development (TD) in terms of different postural control abilities. Methods: A cross-sectional research design was used. Twelve children with spastic diplegic cerebral palsy (mean age: 107.8 months) and 16 typically developing children (mean age: 110.9 months) participated in this study. Individually, all subjects were seated in a height-adjusted chair and were requested to reach for target(s) located at three different directions (medial, anterior, and lateral). A six-camera Qualisys Motion Capture System was used to capture motion data. Kinematic data in terms of body alignment and angular changes were analyzed. Results: Children with cerebral palsy demonstrated different postural control strategies to complete different reaching tasks compared to typically developing children by preparing postural alignment in advance, coordinating different body orientation movements during reaching after showing difficulty in managing reach medially. Conclusions: Children with cerebral palsy perceive their insufficient ability and prepare their alignment in advance to adapt to the task demanded and decrease the postural challenges of the task. Even though children with cerebral palsy self-generate different motor solutions to reach without falling, these alternative strategies might not be the most efficient adaptation. p 2021 22 November 2021 22 November 2021  
etc., as they perform functional tasks or deal with balance threats [8; 9; 10; 11; 12; 13; 14]. These motor problems could be affected by these multiple factors, and as children with CP have deficit in sensorimotor integration, anticipating control of force regulation could be impaired [15]. [PERSON] and [PERSON] found that children with CP encountered difficulty in recruiting motor units during force regulation [16]. Consequently, children with CP might use alternative motor strategies to complete functional tasks. Several studies have found that severity of involvement and biomechanical constraints play important roles in the motor control of children with CP [14; 17; 18]. Due to the specific characteristics of this group, it appears essential for PT clinicians to recognize how children with CP react to tasks considering their specific postural control ability. Such information would be very valuable in clinical settings when attempts are made to mediate their problems with performing tasks. The seated reaching task is commonly seen in daily activities, such as reaching for a book sitting in front of a table or passing over a report to the next person (rotating the trunk and reorienting the body in 3D space in order to let the upper arm reach for a specific location). Since children with CP may have more problems with standing; it could be easier for them to sit and manage tasks, as pointed out by [PERSON] and [PERSON] (2004) [13], although seated reaching tasks have not yet been thoroughly studied. Several studies regarding reaching tasks have been reported [11; 12; 19]. [PERSON] et al. (2004) found that most children (CP and TD groups, aged 2-11 years) demonstrated direction-specific postural control in reaching; however, they still observed that some children (aged 8-11) with CP demonstrated variable motor performance, and anticipatory postural control was seldom observed among them [20].