Children With Developmental Coordination Disorder Play Active Virtual Reality Games Differently Than Children With Typical Development

Differences Between Children With DCD and Children With TD

Analysis of hand path variables revealed that children with DCD achieved a significantly slower maximum hand speed than TD children during backhand strokes (1.20 m/s less). Reduced movement speed has previously been reported as a motor impairment in children with DCD during real-life tasks such as reach-to-grasp⁴¹; our study showed this finding also is true for AVG play.

The IMD theory would explain these differences as a result of impaired feedforward and feedback mechanisms and sensory integration.² The IMD theory suggests that children with DCD do not plan movements adequately prior to movement execution and do not use sensory feedback to adjust movement patterns at the completion of the movement.⁸ Deficient feedback processes in children with DCD may be facilitated through the various feedback mechanisms that AVG offers.⁴² Cognitive feedback (through game success) along with auditory, visual, and tactile feedback (provided by the handheld wand on Move) may assist higher cortical functioning to aid motor learning in children with DCD.⁴² Additionally, Kinect features a motion replay function that may enhance feedback and could be prescribed in therapeutic home use of AVG.

Furthermore, it is possible that children with DCD chose to utilize slower speeds of movement to enhance task accuracy during AVG play. Despite the fact that accuracy was not specifically recorded in this study, Fitts' law suggests that slower speeds are utilized to achieve higher accuracy.^43,44 This speed-accuracy trade-off principle is applicable to the general population^43,44; however, movement accuracy may be compromised at an even slower speed in children with DCD given the numerous reported impairments of motor coordination.⁴⁵ As therapists, this principle may be strategically used during AVG intervention. For example, if achieving movement accuracy is a treatment goal, task speed may be reduced initially. As a progression, once task accuracy improves, movement speed may be increased under supervision.

Our findings revealed that children with DCD utilized only a wrist extension range to achieve forehand and backhand strokes. This finding was different from that of children with TD, who utilized ranges of wrist flexion and extension. Children with DCD also demonstrated a significantly larger degree of peak elbow flexion during forehand strokes. Although we are unable to state the exact cause of these differences, these results support previous evidence that children with DCD minimize the degrees of freedom associated with task execution in order to increase task outcome success.⁴⁶ Additionally, as suggested by previous studies, a reduced ability to integrate sensory information may have resulted in the use of abnormal movement patterns to achieve the functional goal.^2,12 Altered joint kinematics are associated with changes in muscle activation at the joint of interest and at joints proximally and distally.⁴⁷ For example, Yu et al⁴⁷ showed that elbow extension was predominantly associated with activation of the middle and anterior deltoid and supraspinatus muscles, whereas in a position of 90 degrees of elbow flexion, the anterior deltoid and subscapularis muscles were the dominant contributors to shoulder abduction. Therefore, if a treatment goal is to facilitate muscle activation, it is important to consider how joints distally and proximally could be implicated. These findings highlight the need for therapists to observe joint angles and movement strategies utilized by children with DCD, as this can affect muscle activation and overall movement quality.

Differences Between PlayStation Move and Xbox Kinect

The findings of our study indicated several key differences between Move and Kinect. Forehand and backhand strokes on Move were performed at a slower speed (up to 0.85 m/s less during backhand strokes) and utilized a smaller hand path distance (up to 0.50 m less during backhand strokes) compared with Kinect. These differences were consistent for children with DCD and children with TD and may stem from technical differences between AVG types. The hands-free play that Kinect offers de-weights the upper limb, potentially allowing for a faster speed and greater path of hand movement, compared with Move where the player grips a handheld wand, potentially constraining the movement.⁴⁸ Additionally, the representation of the table tennis task and characters on screen were different between Move and Kinect. One example of this difference was the use of first-person perspective during table tennis using the PlayStation Move Sports Champions game and third-person perspective during table tennis on Xbox Kinect Sports. The differences in player perspective and projection of images on screen may have influenced the visual feedback received from each table tennis AVG.⁴²

Our study revealed no significant differences for wrist angle variables between AVG types, which was surprising given the technical differences between Move and Kinect. We anticipated a difference given the weight of the handheld Move wand. It is possible that the wand weight was accounted for by compensations at the elbow joint rather than the wrist. The findings revealed 2 significant elbow angle differences between AVG types: greater minimum elbow flexion was utilized on Move during forehand strokes (12.1° greater), and a smaller elbow range of movement was utilized on Move during backhand strokes (13.7° less). Although our findings highlight that table tennis on Move and Kinect utilized different movement patterns, it is unclear at this stage whether this finding was due to software or display game differences (eg, images on screen) or input control hardware differences (eg, presence of a handheld wand on Move). Therefore, when choosing an AVG type to address a movement quality goal, clinicians should be aware that AVG types are not necessarily interchangeable.

Limitations

Although our study contributed several key findings to understanding the movement patterns of children with DCD during AVG play, it had a number of limitations. A methodological limitation of our study was the use of a consistent order of tasks on Move then Kinect to minimize participant burden, which may have introduced an order effect. In addition, the sample size for our current study was based on matching the sample size from the RCT study.²² The original RCT study had been powered to detect a 5-point difference on MABC-2 total impairment score for children with DCD (within-subjects design).²¹ Our current mixed-model study, therefore, had less power. Although the results presented in Tables 2 and 3 do not suggest any group × AVG type interaction, a small interaction may exist and may not have been detected in the analyses.

Differences also may have existed between children with more or less marked motor impairment; however, small subgroup numbers precluded such analysis in this study. Additionally, only the movement patterns of an upper limb game were analyzed. Further research on lower limb and full body AVG tasks is needed to be able to comment on the applicability of our findings to other body areas. Furthermore, as only simple joint kinematics were analyzed, future research should consider complex measures (such as acceleration and movement jerkiness) given the reported deficiencies in these areas for children with DCD.² No data regarding forehand and backhand stroke success were assessed; associations between movement quality and functional outcome during AVG play is an area that could be explored in further studies. Participant feedback was utilized during the warm-up period to discourage “cheating” that is possible by utilizing small rapid “shakes” of the Wii input device.²⁶ Therefore, these data might not be a true representation of how some players might adapt their technique to achieve game success. Finally, our study findings suggest several differences between the movement patterns utilized on both AVG types. However, it is unclear what design elements in the AVG types contributed to these differences. Further examination of spatial and temporal accuracy requirements of each system could be explored to identify if these components are key design elements that contribute to movement fidelity during play.

In conclusion, the results of this novel study show several key differences in the movement quality of children with DCD compared with children with TD during AVG play. Such differences have implications for the use of AVG for intervention purposes. One intervention goal may be to gain task engagement, thereby enhancing participation in physical activity for physical and mental health reasons. Alternatively, the goal of treatment may be to practice good-quality movements to facilitate neuroplastic changes and enhance motor learning. Under these circumstances, therapists need to assess each child individually and decide which aspects of the movement quality are deficient and whether AVG play can address these deficiencies. Consideration should be given to whether movement quality is adequate for unsupervised practice using AVG. Finally, as different AVG types elicit different movement qualities, clinical judgment is required to decide which AVG type and game are preferable for facilitating the desired motor learning.