Virtual reality (VR) systems provide simulated environments where users manipulate virtual objects in a way that evokes behaviors that are similar to those occurring in real life.1 Performance within a virtual environment enables interaction in life-like situations that can be used for assessment and intervention.2 Thus, VR can be used as a purposeful, meaningful, and motivating intervention that provides opportunities to practice functional motor and cognitive skills in a safe environment. Indeed, VR games and functional environments are an emerging therapeutic tool used to improve movement abilities in children with motor impairments such as cerebral palsy.3–5 Several low-cost VR systems have been shown to be easy to set up, both in the clinic and at home, and to provide various games that are motivating when played by 1 or more children with developmental disorders.2 , 6 However, their use with children with developmental coordination disorder (DCD) is underexplored.
Children with DCD form a heterogeneous group generally characterized by a marked impairment in the development of motor coordination that interferes with their academic achievement and/or activities of daily living.7 In addition to slow motor development and limitations in fine and/or gross motor abilities, children with DCD present with deficits in balance and postural control, which are demonstrated by less efficient anticipatory postural reactions.8 They also demonstrate difficulties in engaging simultaneously in postural and cognitive tasks,9 , 10 which affect their performance in daily living activities. Problems in the processing of visual, proprioceptive, or tactile information, difficulties in visual–motor integration, and in motor programming, are often considered to be the underlying causes of these problems.11–13 In the absence of intervention, children with DCD may suffer from psychosocial problems and decreased social participation, which may continue to affect their lives throughout adolescence and adulthood.14
Interest is growing in recent years in determining the effective intervention approaches for children with DCD.15–17 Physical and occupational therapy treatment for this population is designed to enhance fine motor as well as gross motor and balance performance, and to prevent secondary impairments resulting from inactivity such as the loss of strength and fitness. Improvement in these impairments may ultimately lead to better performance in daily life activities and increased social participation. In a recent systematic review and meta-analysis, Smits-Engelsman et al17 have concluded that motor performance of children with DCD can be improved by different intervention approaches, with task-oriented approaches yielding greater gains than process-oriented approaches. Task-oriented approaches are based on current motor control, motor learning, and ecological principles, with the relative contributions of these principles varying between methods.18 However, for all approaches, frequent practice in different settings and consistent feedback seem to be key elements of successful interventions for children with DCD.15 , 17
VR-based intervention is, therefore, potentially highly suitable for children with DCD, providing environments in which both cognitive and motor control processes may be explicitly harnessed.19 Similar to more conventional task-oriented approaches, VR incorporates effective elements of motor learning, including multiple movement repetitions, augmented feedback, and practice variability.20 Furthermore, VR interventions are ecologically valid as they simulate real-life situations in an environment that can be graded to the individual's abilities although being both challenging and fun. To the best of our knowledge, only 1 publication suggests the application of VR-based interventions for children with DCD, which included 10- to 12-year-old children diagnosed with DCD.21 However, with the growing awareness of the ramifications of DCD, children demonstrating difficulties in motor coordination are now being referred to physical and occupational therapy at much younger ages, and examining whether they can also benefit from a VR-based intervention becomes important.15
Therefore, the aim of this pilot study was to investigate the feasibility and the effectiveness of a VR-based intervention program for young children with DCD. The study hypothesis was that an intervention program on the basis of the low-cost, off-the-shelf PlayStation®2 EyeToy game system would be well tolerated by young children with DCD and would improve their motor performance.
Approval of the study was received from the Institutional Review Board of the Helsinki Ethical Committee of the Meir Medical Center, Kfar-Saba, and a written informed consent was obtained from a parent of each participant.
A convenience sample of 9 children (2 girls and 7 boys), aged 4 to 6 years (mean = 5.6 ± 0.5 years) was recruited to participate in the study. Participants were referred by a pediatrician specializing in developmental disorders to a pediatric developmental center. The reasons for referral included complaints of gross and/or fine motor delay, clumsiness, balance problems, or difficulties in participating in classroom or playground activities. Each child demonstrated difficulties with activities of daily living and a score at or below the 15th percentile on the Movement Assessment Battery for Children (M-ABC-2).22 In addition, all the children attended a mainstream preschool program and had no known autism spectrum disorder or attention-deficit hyperactivity disorder, no uncorrected visual or auditory limitations, and no behavioral problems. Because the children were under the 15th percentile on the M-ABC-2, they were considered at risk for DCD or with probable DCD,15 with the final diagnosis deferred until age 6 years because of the young age of the children.
The children were evaluated before the intervention as an indicator of baseline performance and again within 1 week of completion of the intervention period. The intervention consisted of ten 60-minute treatment sessions conducted weekly, with a total of 12 weeks allowed to accommodate missed appointments. Children had an individual intervention plan that took into account personal priorities related to their specific motor skill abilities and limitations (detail provided later).
Tests and Outcome Measures
All pre- and postintervention assessments were carried out by the same physical therapist who was not aware of the type of intervention. Treatments were carried out by another therapist who was unaware of the assessment results. The following measures were used to assess pre- and postintervention performance:
- Movement Assessment Battery for Children (M-ABC-2).22 The M-ABC-2 is used to identify and describe the impairments in motor performance of children aged 3 to 17 years. Norms are provided for 3 age bands (3-7 years, 7-11 years, and 11-16 years). All children perform a series of age-specific motor tasks divided into 3 major categories: manual dexterity, aiming and catching, and balance. Scores below the 5th percentile are considered to be indicative of a definite motor problem; scores between the 5th and 15th percentiles suggest a degree of difficulty; and scores above the 15th percentile indicate no problem. Ellinoudis et al23 found the first age band (3-7 years) of the test to be a reliable tool for assessing the effectiveness of motor intervention programs, and a valid tool for initial assessment.
- Developmental Coordination Disorder Questionnaire (DCD-Q).24 The DCD-Q queries parents about the performance of their children on tasks of daily living and motor skills. The questionnaire contains 17 items categorized into 3 domains: control during movement, fine motor/hand writing, and gross motor/planning and general coordination. Items are scored from 1 to 5, with higher scores indicating a more positive perception of the child's motor ability on the part of the parent.24
- Parents' subjective report. At the end of the intervention program, each accompanying parent was requested to describe his/her overall impression of the intervention and the child's response to the intervention. The number of parents who expressed overall satisfaction, changes in the children's motor performance, and changes in social participation were tallied.
- Walking and talking test. This test included 3 conditions: (1) a walking condition—wherein participants walked a distance of 10 m as quickly as they could while unencumbered; (2) walking with tray condition—wherein participants walked a distance of 10 m as quickly as they could while carrying a tray with a cup two thirds filled with water; and (3) walking while holding a tray and talking condition—wherein the child performed the same task as in the previous condition while answering 5 simple questions (eg, name of the teacher and name of siblings), which were familiar to all children. Each condition was performed 3 times, with the first trial used as a practice trial. The mean walking speed scores of the 2 remaining trials were used for analysis. The test was based on a similar multitasking test previously reported for children with DCD.25
- Six-minute walk test (6MWT).26 The 6MWT is a safe, easy-to-perform test that determines the distance a child can walk at a constant, uninterrupted, and unhurried pace in 6 minutes. It is an established measure of functional capacity, with psychometric properties that have been examined in various populations, including children who are typically developing as well as those with cerebral palsy, cystic fibrosis, and obesity.26–28 Lammers et al28 established normative values for children aged 4 to 11 years; the distance walked correlated with age (r = 0.64; P < .0001) and had very good test–retest reliability (ICC = 0.94).29 To date, this test has not been used for children with DCD.
The intervention consisted of 2 parts:
- VR-based intervention. The VR-based intervention was conducted using the commercially available gaming system, Sony's PlayStation®2 EyeToy. The system is based on a web camera video capture interface that uses 2-dimensional gesture recognition to allow the user to interact directly with virtual objects displayed on an 80-cm television monitor. Sound and visual feedback indicate the success or failure of the user's movements to accomplish the game tasks. These tasks require the user to make relatively accurate, target-based upper extremity movements that entail motor planning, standing balance, eye–hand coordination, and multitasking of varying complexity, mostly at a high level of intensity.
- The children played up to 4 single-player games during each of the first four 45-minute VR sessions. During sessions 5 to 10, the children also played multiplayer games with a parent. Each game included several levels of difficulty, concluding when the child either completed the highest level of difficulty or was unable to meet the game's accuracy requirements. The games were all time-limited, requiring a preset pace of performance. With the exception of 1 game (music game), which entailed rhythmic movements, all the games encouraged fast response times and rapid movement. A brief description of each game is presented in Table 1.
- All games were performed with the children standing upright at a 2-m distance from the monitor and involved forward and/or sideward reaching movements. To challenge the children's balance and encourage trunk activity, they were taught to reach toward the target with both hands as quickly and as accurately as possible, while flexing and abducting their shoulders as far away from their body as possible and keeping their elbows extended. To challenge the children's stability during the intervention, the games were performed on different surfaces, which either reduced proprioceptive input and/or increased instability. Thus, the children stood on stable surfaces, such as the floor or stools, and on unstable surfaces, such as rocker boards, wobble boards, or balance cushions that differed in height, width, and surface compliance.
- Goal-directed task. In the first intervention session, the children and their parents were asked to define their personal specific intervention goals. During the last 15 minutes of every session, task-specific non-VR activities were carried out in accordance with each child's stated goals. The children were familiar with their chosen task and were not provided with specific instructions while practicing that task in the clinic. The tasks included activities such as riding their own bicycles, playing ball games (soccer, basketball), or putting on and taking off their clothes.
Descriptive statistics included the median, mean, range, and standard deviation of all outcome measures. Because the parametric assumptions of homogeneity and normality were not met, nonparametric tests were used. The Wilcoxon signed rank test was used to compare pre- and postintervention differences. The SPSS version 17 statistical program was used, and the level of significance was set at α = 0.05. The Cohen's effect sizes were determined using the G*Power program,30 which uses the standard effect size definition on the basis of means and standard deviations of difference scores, whether the statistic actually employed is parametric or nonparametric. An effect size of 0.2 was considered small; 0.5 medium; and 0.8 large.
Table 2 presents the pre- and postintervention descriptive and statistical results of the M-ABC-2, the DCD-Q, the walking and talking test, and the 6MWT of the entire group. Also included are the effect sizes of each outcome.
For the M-ABC-2, the Wilcoxon signed rank test indicated significant improvement in the total standard (P = .024) score after intervention. Similar results were obtained for the balance subcategory, where the standard score after intervention improved significantly (P = .012). Effect sizes for both the M-ABC-2 and the balance subcategory were large (0.91 and 1.26, respectively). No significant group changes were observed for the manual dexterity and the aiming and catching subcategories.
For the DCD-Q, the Wilcoxon signed rank test indicated significant improvement in the overall score after intervention (P = .05) and a medium effect size (0.68). A significant effect was also obtained for the “control during movement” subcategory (P = .036), with a large effect size (0.88). However, no significant differences were found in the “fine motor/handwriting,” and in the “gross motor/planning and general coordination subcategories.”
Only 5 children performed the walking and talking test as this measure was introduced at a later stage of the study. No statistical group differences were found in these tasks before and after intervention. However, 4 of the 5 children demonstrated improvements in the more complex task, which entailed talking while walking and carrying a tray with a cup of water, and the effect size was 0.74. Five of the children demonstrated at least some improvement on the 6MWT, although no statistically significant difference was observed.
An in-depth qualitative analysis of the subjective impressions of the parents and children regarding their experience with the VR intervention was not carried out. However, all the parents reported that their children truly enjoyed the intervention; 8 of the 9 parents expressed high satisfaction with the intervention; 6 reported improvements in ball activities during play time; and 5 reported increased self-confidence and generally improved performance on the playground. The parents also reported that their children accomplished their personal goals: 5 improved their ball skills, 2 improved their playground skills, and 2 improved their bicycle riding skills.
The results of this study demonstrated the feasibility of using VR game-based intervention with young children with DCD to improve their motor capabilities. Despite the small sample size, statistically significant changes were noted in some of the primary outcome measures, with medium to large effect sizes for the majority of the measures. Furthermore, the intervention was well accepted by the children as indicated both by their active enthusiastic participation and their parents' reports.
The overall motor ability of these very young children, as determined by the M-ABC-2, shifted from a mean percentile score indicative of probable DCD (ie, mean 5th percentile), to a higher performance level (ie, mean 27th percentile, with 6 children changing their performance level). These changes are further supported by the perceptions of the parents who reported a significant change in their children's daily motor performance as determined by the overall DCD-Q scores as well as by their comments. Although this pilot study did not include a control group, the changes in the total M-ABC-2 seem to be rather impressive as they represent a mean change of more than 50%. Comparable studies investigating the effects of various intervention protocols generally report smaller changes, ranging between 25% and 40%.31–33
Balance control, especially during activities that require multitasking, is an important aspect of motor control that has been shown to be affected in children with DCD.9 , 10 Because the ability to maintain one's balance is crucial for a very wide range of daily activities, this aspect of mobility was the focus of this intervention program. Indeed, the balance subcategory of the M-ABC-2 was the only subcategory that demonstrated a significant change, and had the strongest effect size (1.2). Thus, the positive intervention effect on balance performance demonstrates the specificity of practice principle, whereby best learning is hypothesized to occur when practice characteristics are the same as those of the task to be performed.34
In contrast, despite multiple, goal-directed movements practiced during treatment, no significant changes were observed in the aiming and catching subcategory of the M-ABC-2. This may be related to differences in real life versus virtual tasks; although motor sequencing in this virtual environment was quite similar to real-life movements, the absence of haptic input during reaching and catching movements may have inhibited skill transfer. Further studies are necessary to determine how to design practice protocols that will transfer more effectively to functional tasks in the real world.
Statistically significant improvements were not observed in any of the walking tests in this study, and most children did not demonstrate improvements in the less challenging conditions (ie, the simple task of walking 10 m or the walking and tray condition). However, 4 of 5 children improved their performance in the most complex walking condition (talking while walking and carrying a tray with a cup of water). The interactions within the gaming environment called for continuous multitasking as the children were required to pay attention to multiple visual and auditory stimuli while standing upright. While these activities did not translate into significant differences in the walking tests, the very small number of children performing the tests, combined with the moderate effect size (0.74) noted for the more complex walking tests, indicates a fair probability that the testing of a larger group may lead to significant results in time-sharing abilities.
Children generally tend to exert themselves more when they are involved in challenging, game-like activities. In fact, an intervention program with the same VR gaming system used in this study increased physical fitness in a group of adults with intellectual and developmental disabilities.35 The majority of the children perspired profusely during treatment and seemed to exert themselves throughout the intervention sessions. We chose to evaluate the effect of the intervention on functional capacity with the 6MWT, which is easily administrated in a clinical setting, has age norms for young children, and has been shown to be reliable.29
The pre- and postintervention comparison of walking distance was not significant, and the effect size was only 0.40. The mean walking distance of the children in this study before and after intervention was considerably lower than the distance reported in the literature for 5-year-old children that are typically developing.28 Although these group differences in walking endurance must be substantiated by full-scale studies, the results are supported by research demonstrating reduced fitness in children with DCD.36 Previous studies have demonstrated that children with cerebral palsy require longer periods of training to achieve physiological changes in endurance.37 , 38 Thus, longer intervention periods with a larger number of children may be necessary to determine the effect of VR interaction on fitness in children with DCD.
Enjoyment and motivation were not directly measured in this study. However, the children complied fully with the intervention and were willing to participate in activities that are often regarded as prolonged for such young children, while at the same time maintaining attention to the games' challenging requirements. Indeed, all the children completed the series of 10 intensive 45-minute VR intervention sessions, and their parents reported that the children were consistently excited about returning to treatment. Thus, as reported in similar VR interventions with children with other impairments,5 , 39 this intervention was viewed as highly enjoyable and very motivating by the children.
Starting at the fifth session, the therapist added VR games that involved parents playing with and competing against their children. It has been suggested that direct involvement of parents is likely to ensure that the learned skills will continue to be practiced and used after the formal intervention.17 , 40 , 41 In fact, these interactions between the child and the parent were reported as extremely pleasurable for both. As children are naturally competitive, playing with their parents seemed to motivate them to exert more effort and to perform better. In turn, the parents became just as involved as their children, probably because they witnessed their children's enjoyment and motivation. With the increasing economic limitations of public health care systems, high intervention frequency can rarely be met using conventional protocols. In contrast, low-cost game-based interventions, which can be used in the home environment with the active participation of the parents, are likely to extend the benefits observed in the clinical setting.
A number of limitations exist in this pilot study. First, only a small number of children were included in the sample, and there was no control group receiving either no intervention or an alternative intervention. Second, repeated pretests were not included in this pilot study. These were not performed because the primary outcome measure, the M-ABC, is reported to be susceptible to a learning effect if repeated within 20 days to 3 months.15 , 42 Furthermore, as in previous studies of children with DCD, the M-ABC was used here both as a screening test and as an outcome measure of motor impairment.15 , 22 Third, although training in this study involved multitasking, the tests used to determine multitasking abilities involved gait rather than static skills and did not include the calculation of dual task costs. The results, which demonstrated a positive effect on gait speed in 4 of the 5 children only in the more complex walking test, can only suggest the need to further examine the effect of VR interventions on multitasking abilities. Fourth, while the children appeared to exert themselves during the intervention, walking endurance was directly trained only in 2 of the games (boot and monkey games), thus specificity of training for walking endurance was limited. As indicated, longer training periods are necessary to determine the effect of these interventions on endurance. Finally, this pilot study did not include follow-up assessments and did not allow us to conclude whether the attained skills and abilities were, in fact, retained.
Despite its limitations, the results of this study indicate for the first time that a low-cost, off-the-shelf VR game system seems to be an effective, enjoyable, and motivating intervention tool when used by a trained therapist for children with DCD as young as 4 to 6 years. Given the possible benefits of a low-cost VR intervention program for young children with DCD, further research is necessary to compare its effectiveness with other treatment modalities and to determine its optimal application. In light of these pilot findings, a randomized controlled study is presently being conducted to compare the effects of a VR intervention program in comparison to a more conventional individual intervention program.
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