BACKGROUND AND PURPOSE
Concerns about declining participation in physical activity (PA) among youths continue to be expressed1; however, for a certain subpopulation, additional barriers to participation may be present. For children and adolescents with motor coordination problems such as developmental coordination disorder (DCD),2 a wide range of skills including athletic, academic, and vocational and social pursuits are often affected.3 Many of these children withdraw from or avoid PA, tending to be less physically active4 and less physically fit than their peers,5,6 with increased body fat and low cardiorespiratory fitness.7,8 Given the association between aerobic fitness, obesity, and cardiovascular disease, children with DCD are potentially at risk of long-term health conditions that may in fact be mediated by the effect of the disorder on PA participation.8–10
Self-Efficacy for PA and Participation
Several underlying factors are thought to contribute to lower PA participation levels in children with DCD. These include lower levels of self-worth and self-perceived social acceptance,3 exclusion from physical games,10 and poor self-efficacy for PA.11–13 Self-efficacy, the belief in one’s personal competence to perform a specific task or behavior, is a strong predictor of health behaviors and maintenance of those behaviors over time.14,15 More specifically, self-efficacy for PA has been shown to affect motor performance and PA participation rates, with lower levels of perceived adequacy being correlated with lower levels of PA participation in children with DCD.16,17 Interventions that successfully promote self-efficacy for physical tasks may, therefore, enhance PA participation.4,16,17
“Core” Problems in DCD
It has been suggested that temporal processing and execution difficulties contribute to the motor coordination difficulties experienced by children with DCD.18 Further evidence suggests that these children use altered core or trunk muscle recruitment patterns, which is associated with deficient feedforward (anticipatory) control mechanisms.19 For some, this lack of proximal stability is associated with the compensatory use of stronger muscular contractions and cocontractions across more distal joints to control the degrees of freedom during movement or in response to external perturbations.20 This type of movement pattern, however, is inefficient, and deficiencies in anticipatory postural control mechanisms are likely to impair the child’s ability to attain a state of postural readiness to move.21 Therefore, activities requiring coordinated force output, proprioception, and timing or sequencing of muscle activity may be affected. Altered activation of postural muscles in particular may interfere with the initiation, execution, and completion of coordinated movement and may help to explain why tasks requiring timely activation of muscles are often so challenging for children with DCD.19
These primary motor impairments common in DCD suggest a role for core stability training in improving coordination, strength, and balance. Although core stability training is a generic term, it is used here to refer to training of the superficial and deep intrinsic muscles of the lumbopelvic and abdominal regions,22 which are involved with trunk motion and the maintenance of segmental stability of the lumbar spine during motion and postural adjustments.23 Although several studies of adults have demonstrated that muscles such as transversus abdominis are activated in advance of limb motion,24 this anticipatory activation seems to be impaired in children with DCD.19
Core stability training is frequently used by athletes and the general population to improve strength, balance, extremity function, and endurance, as well as to manage back pain.23,25,26 This type of training is thought to improve trunk stability through the promotion of muscular capacity (strength and endurance) and improved recruitment at the level of neural control.26 Because children with DCD often have deficits in strength, coordination, balance,27 and proximal stability,20 it would seem that core training could potentially affect these impairments. To date, however, we are not aware of any research that addresses the use of core stability training in pediatric or DCD populations.
Task-Specific Intervention in DCD
For children with DCD, a growing body of evidence supports the use of “top-down” function-, and task-based approaches, such as task-specific intervention.9,28,29 Task-specific intervention is an individualized approach that focuses on problem solving and direct teaching of specific functional, meaningful skills, with the goal of optimizing movement efficiency and performance, given the individual’s abilities.30 Other characteristics of successful motor skill intervention for children with DCD include its applicability to children older than 5 years, a group setting or home program format, and a frequency of 3 to 5 times per week.29
A PA intervention program was, therefore, designed to use task-specific training as a method of teaching motor skills and, by using an adapted core stability training program, as a means to positively affect motor skills in children with DCD. It was anticipated that such an intervention program would lead to (1) improved self-perceived adequacy for PA, (2) improved motor proficiency, and (3) incremental gains in strength- and balance-related exercises. This type of programming has the potential to increase lifelong participation in PA in this population, with concomitant benefits related to health, development, and quality of life.
Children aged between 9 and 13 years who met the Diagnostic and Statistical Manual of Mental Disorders Fourth Edition criteria for DCD,2 were referred by a developmental pediatrician for the group program. Participants were excluded from the study if their score on the Wechsler Intelligence Scale for Children Third Edition was less than 70 or if they had any known neurological condition or other medical condition that would prevent them from participating in an exercise program. None of the children had known autism spectrum disorder. Parental consent and child assent were obtained for 5 children before the start of the program. Case reports for 3 of these children are presented later. These 3 children were selected from the group based on the diversity of their presentations and outcomes. The outcomes and presentations of the 2 children whose data are not presented were similar to the cases presented later.
Measures presented at baseline included the following: Developmental Coordination Disorder Questionnaire (DCDQ),30 used as a screening tool for DCD; the leisure section of the Canadian Occupational and Performance Model,9,31 used to identify the presence of difficulties in activities of daily living; the Short Form of the Bruininks-Oseretsy Test of Motor Proficiency (BOTMP-SF),32 used to measure changes in motor proficiency; the Children’s Self-Perceptions of Adequacy in and Predilection for Physical Activity (CSAPPA)16 used to measure changes in self-efficacy for PA; and a therapist-derived measure of core stability.
Child-chosen goals were also identified, and the child’s perceived competency was recorded for each goal. The DCDQ, Canadian occupational and performance model, and BOTMP-SF were used to verify approximation to the Diagnostic and Statistical Manual of Mental Disorders Fourth Edition criteria for DCD. All measures were repeated at completion of the 6-week program, with the exception of the DCDQ and Canadian Occupational and Performance Model.
The majority of these measures are described elsewhere in the research literature, so only the core stability screen and self-chosen goals measure are highlighted here.
Core Stability Screen.
The authors were not aware of any published clinical assessment of core stability, so after a review of the literature an assessment tool was created consisting of 6 items that were felt thought to adequately represent this function.33,34 On the basis of the examiners’ clinical experience, individuals were assessed on their ability to perform sit-ups and push-ups (maximum number of each in 20 seconds) and timed holds of plank, hip bridge, and “bird dog” positions (see the Appendix, exercises 1–3). Timed single-leg stance, which is a common element of many gross motor proficiency tests, was also included as a functional measure of postural stability and balance. These measures are routinely used in clinical practice to assess gross motor skills and strength and, as such, have established face and content validity within the field. Qualitative and quantitative ratings for these tasks were documented by at least 2 independent examiners experienced in clinical core stability assessment. Response categories were developed to reflect therapists’ judgments of the quality of the movement, providing further clarity with respect to movement proficiency and changes that may occur over time. These categories reflected the type of cuing required to allow the child to attain the position (visual, verbal, and tactile), the positions of the thoracic and lumbar spine (neutral, flexed, and extended) and pelvis (rotated and neutral), and the presence of scapular winging. Qualitative observations were also recorded (eg, the presence of “fixing” at joints and the degree of postural adjustments required to maintain balance).
Self-chosen Goals Scale.
To enhance motivation and assess changes in task-specific confidence, children were asked to select 2 activities in which they wished to improve and rate their ability to perform each of those tasks on a 5-point facial hedonic scale (Fig. 1). This scale allows children to rate whether they were “not good at all” through to “very good” at each of their self-chosen goals.
After ethical approval from the research ethics board of the institution, participants were individually assessed using the measures outlined earlier. These assessments were conducted jointly by 1 or 2 experienced physical therapists and an experienced exercise therapist.
One week after baseline data collection, the 6-week group program began. It was held twice weekly in a gymnasium at the rehabilitation center. Parents were encouraged to observe the group sessions to facilitate carry-over for the home program. Each session generally consisted of a 20-minute aerobic warm-up, 15 minutes of core stability exercises, and 20 minutes of task-specific intervention and sport skills training based on the child’s chosen goals.
Modified Core Stability Exercises.
The Appendix describes the exercises that were selected for the group and home programs. These were based on classic Pilates and core stability exercises and graded to match the abilities of the children in the group. These exercises have been shown to strengthen an array of key trunk and hip muscles such as transversus abdominis, internal oblique, and gluteus medius.34–36 During the exercises, the children were instructed to focus on keeping their trunk regions still, and the therapists provided individual physical and verbal cues to maximize recruitment of the local and global stabilizing muscles of the trunk. Instructions were not scripted but depended on the individual child’s abilities and the therapist’s clinical expertise.
This component of the program included individual, direct teaching of age-appropriate sport skills, such as floor hockey, basketball, and soccer, and the children’s self-selected goals. Group practice of these same skills focused on cooperative play, rather than competition. When teaching a specific task, a therapist observed the child performing the task, with the goal of identifying the inefficient component(s) of the movement pattern.29 The therapist then provided the child with verbal and/or visual feedback about the results of his or her actions to help the child make adjustments to the movement pattern and improve its efficiency.
A written home program consisting of 8 different exercises was provided to all children (Appendix). Parents and children were instructed in proper execution of the exercises during the first group session. A sticker chart for tracking progress was provided to each child with instructions to do the program at home at least once per week. This chart was used as an indication of home program compliance. In addition, because all the children missed some group sessions because of family holidays, a program that emulated the structure of the group sessions was provided for the children to perform twice per week while they were away.
Education about the importance of participation in PA and fitness was provided by an exercise therapist and a physical therapist during the group sessions. One session for parents was provided specifically to address the subject of promoting PA in children with DCD. Printed materials such as Canada’s PA Guides for Youth37 were provided.
One week after program completion, each child was individually reassessed by a minimum of 2 therapists. Repeat measures consisted of the CSAPPA, BOTMP-SF, core stability screen, and the self-chosen goal scale.
Changes over time on the BOTMP-SF, CSAPPA, core stability screen, and perceived ability for self-chosen goals were examined independently for each child. Table 1 outlines the scores on these outcome measures before and after the intervention program for all 3 children described in the following case reports.
Client 1 was a 10-year-old girl diagnosed with attention-deficit/hyperactivity disorder, combined type, nonverbal learning disability, “issues of difficult temperament,” and DCD. Her DCDQ score was 37/85, indicating DCD. Her motor proficiency score, according to the BOTMP-SF, was below the first percentile on both the pretest and post-test. Her CSAPPA score, which was used to assess changes in movement confidence, was initially 55 and improved to 73. Scores on the CSAPPA can range from 20 to 80, with those below 60 indicating adequacy and predilection that is expected to be less than moderate.17 In general, this girl’s improvements on the CSAPPA were noted on the questions pertaining to her enjoyment of games and sports. She attended 6 of 12 group sessions and reported that she did not perform the home program at all during the course of the group program.
On the core stability assessment, she demonstrated an increase in timed single-leg balance on the right leg (from 0 to 8 seconds). During the pretest, she was unable to maintain her balance while performing the hip bridge with 1 leg extended (Appendix, exercise 3). On the post-test, she held this bridge position for 12 seconds with her right leg extended and 53 seconds with her left leg extended. While maintaining her balance in a 4-point position, with a relatively neutral spine position, she was initially able to extend her left leg for 7 seconds and her right leg for 2 seconds (Appendix, exercise 1). On the post-test, she was able to hold either leg extended for 60 seconds while maintaining a relatively similar spine posture, but the therapists’ qualitative observations indicated less compensatory scapular elevation and elbow hyperextension.
This girl’s self-selected goals were to improve her performance of jumping rope and her running skills. Initially, she rated her jumping rope as “not good” and her running as “average.” On the post-test, both of her ratings improved, and she reported being average at jumping and “really good” at running. At the first group session, she jumped rope for 8 consecutive times, and she was not able to remain in the same spot while jumping. On the last day of the group sessions, she achieved 42 consecutive jumps with the skipping rope and was better able to jump in one place during the activity.
Client 2 was a 10-year-old boy diagnosed with nonverbal learning disability and DCD. His DCDQ score was 40/85, indicating DCD. Over the course of the group sessions, his BOTMP-SF score improved from below the first percentile to the first percentile, and his CSAPPA score remained at 68. His self-selected goals were to run faster and to play soccer better. Over the course of the program, his rating of his soccer skills stayed the same (average) and his running rating improved from not good to average. He performed the home program 4 times over the course of the program and attended 6 of 12 sessions.
On the core stability assessment, the quality of this boy’s movements and his ability to maintain a posture without excessive balance compensations changed slightly. On initial assessment, he held the plank” position (Appendix, exercise 2) for 19 seconds, and on the post-test, he held this position for 60 seconds. In 4-point kneeling, he could not initially extend his hip to lift his leg off the floor. On the post-test, he could hold either leg in this position for 40 seconds while maintaining a neutral position of his spine and arms. Therapists’ qualitative ratings also indicated that on the post-test, he no longer required tactile cuing to attain the starting positions for the test items, and he no longer leaned toward the weight-bearing leg in the single-leg balance.
This boy’s performance was noted to vary according to his motivation. His attitude toward PA was notably negative, and he required frequent and excessive encouragement to participate in the activities during the group session. This boy’s mother reported that he was struggling to accept his diagnosis. As a result, he had started to display more anger and “defiant behavior” in various settings. She stated that motivation to participate in PA was a significant challenge for him.
Client 3 was an 11-year-old girl who was diagnosed with nonverbal learning disability, panic attacks, anxiety disorder, fine and gross motor delays, social pragmatic language difficulties, a high degree of behavioral rigidity, and DCD. Her score on the DCDQ was 39/85, indicating DCD. Her BOTMP-SF score was in the 15th percentile on the pretest and in the 76th percentile after the program. Her CSAPPA score improved from 60 to 62 over the course of the program. On the core stability assessment measure, a ceiling effect was observed for the quantitative ratings of timed holds for each position. Qualitative observations indicated that on initial assessment, her lumbar spine was excessively extended, suggesting a lack of abdominal muscle activation; on the post-test, she was able to maintain a neutral position for the hip bridge with a single-leg extension, plank, push-ups, and bird dog.
Client 3 was noted to participate consistently and actively during group sessions. For instance, she was able to specifically identify a problem that she was having with jumping and asked for other exercises to address that problem. According to her home program chart, she completed the home program 38 times over the 12-week program.
This girl’s goals during the program were to improve her running and jumping skills. Facial hedonic scale ratings indicated that initially she felt she was not good at running and average at jumping. However, by the end of the program, she reported that she was really good at both running and jumping. She attended 6 of the 12 group sessions.
Our purpose was to pilot a group fitness program involving core stability exercises and task-specific training in a group of children with DCD. We attempted to address key components of DCD intervention as recommended in the literature, including promotion of self-efficacy for task-specific behaviors, education about modifying goals and expectations, and suggestions for encouraging PA in children with DCD. As these case reports describe, some emergent trends would suggest that further research is warranted. Of importance to clinical practice, several factors may have been associated with the variety of outcomes observed in these children.
Motivation, Self-Efficacy, and PA Participation
According to systems theory of motor control, movement production is dependent on the dynamic interplay of factors related to the individual, the task, and the environment.38 Client 3 seemed to make the largest motor gains; however, her CSAPPA score was not notably different from those of the other children and it improved very little (ie, 2 points) over the course of the program. In contrast, client 1 improved by 18 points on the CSAPPA, whereas her BOTMP-SF score remained below the first percentile. Both girls demonstrated gains in their self-chosen goals ratings. We would suggest that both motor performance and self-efficacy for PA are important outcomes to consider when designing and evaluating intervention programs for children with motor skills difficulties because they both are likely to affect PA participation.
The challenges of PA promotion are not entirely unique to children with DCD. Motivation has been identified as a key factor in improving PA participation in various populations, across developmental levels.39 Children aged 10 to 15 years old tend to be motivated more by competition and outperforming their peers than do younger children, who tend to be more motivated by simple task mastery, trying hard, and parental feedback.39 Therefore, as children with coordination problems experience this developmental shift in the relative contributions of social supports (ie, parents to peers), their self-esteem and perceived self-efficacy may be affected, especially if comparisons are made with peers without coordination difficulties. Lower feelings of self-worth have a demonstrable effect on the enjoyment of PA, and, in turn, motivation to participate or perform may decline.3,15,39
Although not overtly measured, enthusiastic participation in the home and group components of this program (as noted by parents and therapists, respectively) was more challenging for clients 1 and 2 compared with client 3. For children like clients 1 and 2, parental and therapist encouragement may not be sufficient to increase their motivation for the task at hand, a trend that may also be influenced by the accumulation of negative PA experiences over time. As young as 6 years of age, children with movement difficulties may already demonstrate social and affective characteristics such as anxiety, introversion, and awareness of decreased self-esteem associated with their physical limitations.40 The social and emotional implications of poor motor skills tend to worsen as these children get older,3 although age is clearly not the only factor. Early identification of children with DCD may potentially affect PA experiences and perceptions of competence in this domain.3,39 Further research is needed to examine whether implementing this type of model would in turn influence children’s decisions about PA participation.
The child in our study who made the largest motor proficiency gains according to the BOTMP-SF, client 3, was noted to demonstrate a more positive attitude toward PA and a greater motivation to actively participate in the group and home program compared with the other participants. It is interesting to note that client 3 entered the program with a much higher BOTMP-SF score than the other children. Some authors have classified children with motor proficiency scores below the 5th percentile as having DCD, while using a cutoff score of the 15th percentile to identify children with borderline DCD.43 The fact that the outcomes for client 3 were much different than that for clients 1 and 2, whose motor scores were at or below the first percentile, may allude to the clinical implications of this distinction. In our experience, group programs such as this one have the potential to be a motivating means of service delivery because children are provided the opportunity to participate in more typical age-appropriate peer interactions. In an appropriate and supportive setting, integration into community programs from an early age may facilitate the development of diverse skills and task-specific self-efficacy that contribute to participation in lifelong fitness pursuits. We believe that incorporating PA into a child’s daily activities is likely to be a key component of a successful intervention plan; however, the barriers to changing family lifestyle patterns present a challenge to implementation.
Measurement of Core Stability
As described earlier, an assessment protocol for core stability was designed for use in this study and at our center. It would seem that the quantitative portion of this core stability measure alone was not sensitive enough to measure change, requiring more reliance on qualitative observations, particularly in instances when a child reached the 60-second time limit and a ceiling effect was observed. The qualitative nature of clinical core stability assessment complicates its objective measurement in a naturalistic setting. Some authors have assessed lumbar stabilization using ultrasound, electromyography, and measurement of pressure changes using air-filled cells, as a reflection of neural and muscular control.42 However, for the current study, the authors believed that it was important to use measures consistent with current clinical practice, incorporating dynamic, functional movements, and involving muscle groups of the shoulder girdle, hip, pelvic girdle, and spine. As a result, the measure likely encompassed several elements of performance, including core stability, postural stability, and strength for several muscle groups.
Children with DCD are a heterogeneous group, and as such, the small number of children involved in the program allowed the investigators to make observations about the individual characteristics of the children, their abilities, and their responses to the program. Moreover, each of the children presented with a complex diagnostic picture and a variety of comorbidities.
Attendance in the group program was a limitation of this study. The group took place during the summer, which introduced conflicts with family vacations and other summer camps. A supplementary program similar to the group session was provided for the holiday period at the request of the families. Clinically significant changes in performance were still observed, although the extent to which other factors contributed to these gains, or whether the outcomes would have been different if the children had attended more sessions, is not known.
The definition and clinical evaluation of core stability are not standardized, and the use of core stability training has not been well documented in the context of neurological or developmental therapy. As such, there are no established norms to describe the core stability items used in the assessment procedure of the study. Future research is needed to validate a reliable tool for measuring core stability to describe what is, in fact, being measured and to link the measured data to functional implications and participation outcomes. For such a tool to be validated for pediatric populations, additional information is needed with regard to the developmental aspects of core stability. With respect to this group program, the extent to which the observed gains were related to core stability training or task-specific training or both is unknown. The design of this pilot work precludes any conclusions regarding the cause of observed gains, and the potential that these gains were associated with other factors (eg, increased comfort with the examiners or testing protocol) must be considered. The assessment of the efficacy of core stability training in this population is in its infancy, and as such, the current work focused on the clinical measurement of core stability and gross motor proficiency and not on the functional outcomes. As the ultimate goal for these children is arguably improved function and participation in PA, future research should use measures that specifically address these outcomes and use an experimental study design.
For all the children, qualitative observations made by the examiners reflected the overall improvement. On reassessment, it was observed for most exercises that the majority of children used fewer compensatory and substitution strategies such as muscular fixing, hyperextension to “lock” elbows, and holding their breath. They were able to maintain postures with fewer extraneous movements and displayed better body awareness and motor planning when assuming and maintaining the test postures. There is evidence to demonstrate that neuromuscular adaptations (eg, increased cortical level excitation, increased motor unit discharge rates, and decreased motor unit recruitment thresholds43) occur in the first weeks43 or days44 of a strengthening program and thus play a key role in early strength gains seen during such programs. Hence, although the length of time that these children participated may have been short, strength gains and new patterns of movement and muscle activation may have occurred. Future research is warranted to evaluate the implications of these changes in neural recruitment for functional performance.
This unique pilot program explored the use of a modified core stability program and task-specific training as a means to address motor performance in children with DCD. Case reports for 3 of the group’s participants illustrate 3 individual responses to the program, and some of the factors that may have contributed to the observed results. Self-efficacy for PA is acknowledged as a key contributor to participation in PA and should be considered as an important functional outcome. The results of this pilot work suggest that further exploration of the developmental aspects of core stability, its assessment, and the implementation of training in this population is warranted. Future research that explores the relationship between motor abilities, core stability training, and participation in PA has the potential to improve lifelong functional and health outcomes for pediatric populations with motor coordination difficulties.
1. Shields M, Tjepkema M. Canadian Community Health Survey—Nutrition
]. Ottawa, Ontario, Canada: Statistics Canada; 2005:1–32.
2. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders.
4th ed. Washington, DC: American Psychiatric Association; 1994.
3. Skinner RA, Piek JP. Psychosocial implications of poor motor coordination in children and adolescents. Hum Mov Sci.
4. Bouffard ME, Watkinson EJ, Thompson LP, et al. A test of the activity deficit hypothesis with children with movement difficulties. Adapt Phys Act Q.
5. O’Beirne C, Larkin D, Cable T. Coordination problems and anaerobic performance in children. Adapt Phys Act Q.
6. Hands B, Larkin D. Physical fitness and developmental coordination disorder. In: Cermak S, Larkin D, eds. Developmental Coordination Disorder.
Albany, NY: Delmar Thomson Learning; 2002.
7. Cairney J, Hay J, Faught B, et al. Developmental coordination disorder and overweight and obesity in children aged 9–14 y. Int J Obes.
8. Faught BE, Hay JA, Cairney J, et al. Increased risk for coronary vascular disease in children with developmental coordination disorder. J Adolesc Health.
9. Missiuna C, Rivard L, Bartlett D. Exploring assessment tools and the target of intervention for children with developmental coordination disorder. Phys Occup Ther Pediatr.
10. Smyth MM, Anderson HI. Coping with clumsiness in the school playground: social and physical play in children with coordination impairments. Br J Dev Psychol.
11. Hay J, Missiuna C. Motor proficiency in children reporting low levels of participation in physical activity. Can J Occup Ther.
12. Hay JA, Hawes R, Faught BE. Evaluation of a screening instrument for developmental coordination disorder. J Adolesc Health.
13. Klein S, Magill-Evans J. Perceptions of competence and peer acceptance in young children with motor and learning difficulties. Phys Occup Ther Pediatr.
14. Bandura A. Exercise of personal and collective efficacy in changing societies. In: Bandura A, ed. Self-Efficacy in Changing Societies.
London, England: Cambridge University Press; 1995.
15. Harter S. The determinants and mediational role of global self-worth in children. In: Eisenberg N, ed. Contemporary Topics in Developmental Psychology.
New York, NY: John Wiley and Sons, Inc.; 1987:219–242.
16. Hay JA. Adequacy in and predilection for physical activity in children. Clin J Sport Med.
17. Cairney J, Hay J, Faught BE, et al. Developmental coordination disorder, generalized self-efficacy toward physical activity and participation in organized and free-play activities. J Pediatr.
18. Jucaite A, Fernell E, Forssberg H, et al. Deficient coordination of associated postural adjustments during a lifting task in children with neurodevelopmental disorders. Dev Med Child Neurol.
19. Johnston LM, Burns YR, Brauer SG, et al. Differences in postural control and movement performance during goal directed reaching in children with developmental coordination disorder. Hum Mov Sci.
20. Wilson BN, Trombly CA. Proximal and distal function in children with and without sensory integrative dysfunction: an E.M.G. study. Can J Occup Ther.
21. Missiuna C, Rivard L, Bartlett D. Early identification and risk management of children with developmental coordination disorder. Pediatr Phys Ther.
22. Marshall PW, Murphy BA. Core stability exercises on and off a Swiss ball. Arch Phys Med Rehabil.
23. Hodges PW. Core stability in chronic low back pain. Orthop Clin North Am.
24. Hodges PW, Richardson CA. Feedforward contraction of transversus abdominis is not influenced by the direction of arm movement. Exp Brain Res.
25. Kibler WB, Press J, Sciascia A. The role of core stability in athletic function. Sports Med.
26. Revie G, Larkin D. Task-specific intervention with children reduces movement problems. Adapt Phys Act Q.
27. Geuze RH. Postural control in children with developmental coordination disorder. Neural Plast.
28. Pless M, Carlsson M. Effects of motor skill intervention on developmental coordination disorder: a meta-analysis. Adapt Phys Act Q.
29. Larkin D, Parker HE. Task-specific intervention for children with developmental coordination disorder: a systems view. In: Cermak S, Larkin D, eds. Developmental Coordination Disorder.
Albany, NY: Delmar Thomson Learning; 2002.
30. Wilson BN, Kaplan BJ, Crawford SG, et al. Reliability and validity of a parent questionnaire on childhood motor skills. Am J Occup Ther.
31. Law M, Baptiste S, Carswell A, et al. Canadian Occupational Performance Measure.
2nd ed. Toronto, Ontario, Canada: Canadian Association of Occupational Therapists; 1994.
32. Bruininks RH. Bruininks-Oseretsky Test of Motor Proficiency: Examiner’s Manual.
Circle Pines, MN: American Guidance Service; 1978.
33. Kavcic N, Grenier S, McGill S. Determining the stabilizing role of individual torso muscles during rehabilitation exercises. Spine.
34. Stevens VK, Vleeming A, Bouche KG, et al. Electromyographic activity of trunk and hip muscles during stabilization exercises in four-point kneeling in healthy subjects. Eur Spine J.
35. Endleman I, Critchley DJ. Transversus abdominis and obliquus internus activity during pilates exercises: measurement with ultrasound scanning. Arch Phys Med Rehabil.
36. Teyhen DS, Rieger JL, Westrick RB, et al. Changes in deep abdominal muscle thickness during common trunk-strengthening exercises using ultrasound imaging. J Orthop Sports Phys Ther.
37. Public Health Agency of Canada, The Canadian Society for Exercise Physiology. Canada’s Physical Activity Guide for Youth
. Ottawa, Ontario, Canada: Public Health Agency of Canada; 2002. Be more specific in the AQ. OK in what way?
38. Shumway-Cook A, Woollacott MH. Motor Control: Translating Research into Clinical Practice.
3rd ed. Philadelphia, PA: Lippincott Williams & Wilkins; 2007.
39. Weiss MR. Motivating kids in physical activity. Presidents Council Phys Fitn Sports Res Dig.
2000;3:1–7. Be more specific in the AQ. OK in what way?
40. Schoemaker MM, Kalverboer AF. School and affective problems of children who are clumsy: How early do they begin? Adapt Phys Act Q.
41. Geuze RH, Jongmanns MJ, Schoemaker MM, et al. Clinical and research diagnostic criteria for developmental coordination disorder: a review and discussion. Hum Mov Sci.
42. Richardson C, Jull G, Hides J, et al. Therapeutic Exercise for Spinal Segmental Stabilization in Low Back Pain: Scientific Basis and Clinical Approach
. London, England: Churchill Livingstone; 1999.
43. Cosio-Lima LM, Reynolds KL, Winter C, et al. Effects of physioball and conventional floor exercises on early phase adaptations in back and abdominal core stability and balance in women. J Strength Cond Res.
44. Del Balso C, Cafarell E. Adaptations in the activation of human skeletal muscle induced by short-term isometric resistance training. J Appl Physiol.
© 2009 Lippincott Williams & Wilkins, Inc.