Development of a training game to coordinate torques produced between arms

The ability of individuals to accurately judge the forces that they generate is integral to seamlessly controlling their movements during everyday life. Individuals with chronic hemiparetic stroke have been shown to be impaired when matching forces between arms; this impairment may make activities as simple as carrying a tray challenging. Our goal was to develop a training protocol that individuals with stroke could use to improve their accuracy in judging the torques that they generate between arms. We designed a torque coordination game for this goal and tested its feasibility in six individuals without neurological impairments. Participants interacted with an instrumented isometric device at each arm and received automated audiovisual cues in response to the torques that they generated about each elbow joint. During the game, the participant's task was to keep a launched ball on its planned course. The participant achieved this task by sequentially applying required elbow torques at the correct times to close a left flap using the left arm and a right flap using the right arm. Participants performed this task 20 times when initiating with their left arm and 20 times when initiating with their right arm. Results indicate that all participants had a success rate in the range of 60% to 80% regardless of the arm dominance of the leading arm. Additionally, all participants anecdotally reported the game to be intuitive, and they provided an average difficulty rating that indicated the task was relatively easy to learn (i.e., 3 out of 10). Based on these findings, we conclude that this game may be suitable, enjoyable, and motivational for training coordination of torques between arms in individuals with stroke.