Validation of reaching in a virtual environment in typically developing children and children with mild unilateral cerebral palsy

There is a lack of consistency among researchers and clinicians in the use of terminology that describes changes in motor ability following neurological injury. Specifically, the terms and definitions of motor compensation and motor recovery have been used in different ways, which is a potential barrier to interdisciplinary communication. This Point of View describes the problem and offers a solution in the form of definitions of compensation and recovery at the neuronal, motor performance, and functional levels within the framework of the International Classification of Functioning model.

Unrestrained human arm trajectories between point targets have been investigated using a three-dimensional tracking apparatus, the Selspot system. Movements were executed between different points in a vertical plane under varying conditions of speed and hand-held load. In contrast to past results which emphasized the straightness of hand paths, movement regions were discovered in which the hand paths were curved. All movements, whether curved or straight, showed an invariant tangential velocity profile when normalized for speed and distance. The velocity profile invariance with speed and load is interpreted in terms of simplification of the underlying arm dynamics, extending the results of Hollerbach and Flash (Hollerbach, J. M., and T. Flash (1982) Biol. Cybern. 44: 67-77).

Children with cerebral palsy (CP) have difficulty controlling and coordinating voluntary muscle, which results in poor selective control of muscle activity. Children with spastic CP completed ankle selective motor control exercises using a virtual reality (VR) exercise system and conventional (Conv) exercises. Ankle movements were recorded with an electrogoniometer. Children and their parents were asked to comment on their interest in the exercise programs. Greater fun and enjoyment were expressed during the VR exercises. Children completed more repetitions of the Conv exercises, but the range of motion and hold time in the stretched position were greater during VR exercises. These data suggest that using VR to elicit or guide exercise may improve exercise compliance and enhance exercise effectiveness.