Aim  The goal of this study was to contribute evidence towards the effectiveness of task-oriented training with and without restriction of trunk movement (trunk restraint) on the quality of upper limb movement in children with cerebral palsy (CP).

Method  We used a prospective, single-subject research design in 12 children (three males, nine females; aged 6–11y; median 9y) with di-, hemi-, or quadriplegia. Movements of the most affected arm were assessed five times: three times before training, immediately after training, and 3 months after training. The main outcome measures were the Melbourne Assessment of Unilateral Upper Limb Function (Melbourne) and upper limb movement kinematics during a functional reaching task. Children were randomly allocated to one of two groups: task-oriented training with or without trunk restraint. Treatment consisted of three 1-hour sessions per week for 5 weeks (total training duration 15h). Treatment effects were determined using single-subject research design analysis – regression through baseline data and standard mean differences.

Results  Although the Melbourne scores were largely unchanged after training, some children in each group improved arm trajectory smoothness (effect size 0.55–1.87), and most children improved elbow extension range (effect size 0.55–4.79). However, more children in the trunk restraint group than in the no restraint group demonstrated reduced trunk displacement (effect size 0.94–2.25) and longer-term improvements in elbow extension and trunk use. Among the group who underwent training without trunk restraint, trunk displacement was unchanged or increased, and fewer carry-over effects were apparent at follow-up.

Interpretation  This proof-of-principle study showed that greater improvement in the quality of upper limb movement in children with CP, including less compensatory trunk use and better carry-over effects, was achieved by training with trunk restraint.