Longitudinal examination of objectively-measured physical activity and sedentary time among children with and without significant movement impairments

Human Movement Science 47 (2016) 159–165

Contents lists available at ScienceDirect

Human Movement Science journal homepage: www.elsevier.com/locate/humov

Full Length Article

Longitudinal examination of objectively-measured physical activity and sedentary time among children with and without significant movement impairments Matthew Y.W. Kwan a,b,⇑, Sara King-Dowling c, John A. Hay d, Brent E. Faught d, John Cairney a,c,e a

Department of Family Medicine, McMaster University, Hamilton, ON, Canada Michael G. DeGroote School of Medicine, Niagara Regional Campus, McMaster University, St. Catharines, ON, Canada c Department of Kinesiology, McMaster University, Hamilton, ON, Canada d Department of Health Sciences, Brock University, St. Catharines, ON, Canada e Department of Psychiatry and Behavioural Neurosciences and Clinical Epidemiology and Biostatistics, CanChild Centre for Childhood Disability Research, and Offord Centre for Child Studies, McMaster University, Hamilton, ON, Canada b

a r t i c l e

i n f o

Article history: Received 16 April 2015 Revised 2 February 2016 Accepted 4 March 2016 Available online 18 March 2016 Keywords: DCD Physical activity MVPA Sedentary Accelerometry Movement impairments

a b s t r a c t Background: Children with Developmental Coordination Disorder (DCD) tend to be less active than typically-developing (TD) children. Current evidence, however, is based on cross-sectional and self-reported activity, and little is known about sedentary time among children with significant movement impairments such as DCD. The current study examines the longitudinal patterns of objectively measured physical activity and sedentary time in children with and without possible DCD (pDCD). Methods: Data is from a longitudinal nested case-control study, with 103 participants (n = 60 males ages = 12 and 13 at baseline). Participants averaging 616th percentile on the Movement Assessment Battery for Children were considered having significant movement impairments and pDCD (n = 49). All participants wore accelerometers for seven days. Results: There were significant main effects for time (Estimate = 23.98, p < .01) and gender (Estimate = 59.86, p < .05) on total physical activity, and time spent being sedentary (Estimate = 15.58, p < .05). Significant main effects for pDCD (Estimate = 5.38, p < .05) and gender (Estimate = 26.89, p < .01), and time by gender interaction (Estimate = 7.50, p < .05) were found for moderate-to-vigorous physical activity (MVPA). Sedentary time did not differ between children with and without DCD. Conclusions: Results suggest children with pDCD engaged in less MVPA compared to TD children. Consistent patterns of MVPA over time, however, suggest that the divergence in MVPA occurs earlier in childhood. Further longitudinal research following a younger cohort is necessary to identify the specific point that differences in MVPA emerge. Ó 2016 Elsevier B.V. All rights reserved.

1. Introduction Childhood and adolescence are considered critical periods for establishing active lifestyles, yet population-level statistics indicate that only 7% of children and youth are meeting current physical activity recommendations (Colley et al., 2013). It is well established that physical activity itself is linked to various health outcomes such as increased bone mineral ⇑ Corresponding author at: Department of Family Medicine, 100 Main St. W, DBHSC 5th floor, Hamilton, ON L8P 1H6, Canada. E-mail address: [email protected] (M.Y.W. Kwan). http://dx.doi.org/10.1016/j.humov.2016.03.004 0167-9457/Ó 2016 Elsevier B.V. All rights reserved.

160

M.Y.W. Kwan et al. / Human Movement Science 47 (2016) 159–165

density and decreased cardiovascular risk factors (Andersen et al., 2006; Bailey, Mckay, Mirwald, Crocker, & Faulkner, 1999). In addition to the high prevalence of inactivity and increasing cardiovascular risk factors observed in typicallydeveloping (TD) children and adolescents, those with poor motor ability, including children with Developmental Coordination Disorder (DCD), tend to experience additional challenges engaging in physical activity. DCD is a diagnosis characterized by motor skill impairment unrelated to other physical and/or intellectual disorders as defined in the ICD-10 (American Psychiatric Association, 2013; WHO, 1992), with prevalence estimated between 1.8% and 5% (Lingam, Hunt, Golding, Jongmans, & Emond, 2009). Specific manifestations of the disorder are varied and pervasive, affecting both gross and fine motor skills, thus making activities of daily living such as tying shoelaces and handwriting and participating in physical activities extremely difficult. Occurring early in the developmental period, children with DCD have been consistently found to be less active than their TD peers, and are not a result of a lack of opportunity (Cairney, Hay, Faught, Wade, et al., 2005; Cairney, Hay, Faught, Mandigo, et al., 2005; Rivilis et al., 2011). The evidence suggests that physical activity deficits tend to persist throughout childhood and youth, further increasing the risk of future negative health outcomes later in life (Visser, Geuze, & Kalverboer, 1998). Often undiagnosed, these children are typically viewed as unmotivated or lazy, and the common belief is that their motoric difficulties they exhibit are not serious enough to warrant intervention, or that children with coordination problems will out-grow their ‘clumsiness’ (Hay & Missiuna, 1998; Losse et al., 1991). While children and youth with DCD are at much greater risk for poorer health outcomes, it is recognized that it may be exacerbated by inactive lifestyles established during youth (Cantell, Smyth, & Ahonen, 1994; Hellgren, Gillberg, Gillberg, & Enerskog, 1993). The extant literature regarding the relationship between DCD and physical activity, however, has been limited in several ways, most notably a reliance on self-reported physical activity measures and cross-sectional designs. Much of our current knowledge has been based on children being observed at different ages, and assessed only at one point in time (Rivilis et al., 2011). Indeed, the studies have consistently found children with DCD being significantly less active than TD children. Yet, it is unclear if there are differences in the patterns of physical activity over time based on motor proficiency. The broader literature thus far supports a persistence model, whereby the differences in physical activity between DCD and TD children tend to be stable over time (Cairney, Hay, Veldhuizen, Missiuna, & Faught, 2010). However, some studies have found physical activity widening or diminishing over time, depending on the type of activity examined (Cairney et al., 2010; Visser et al., 1998). Like most cross-sectional studies, these longitudinal studies relied on self-reported physical activity measures, which are prone to social desirability biases and recall errors. To our knowledge, no longitudinal study has examined the effect of DCD on physical activity using objective measurements of physical activity. There is increasing recognition of the importance of sedentary behavior as a related, yet discrete behavior to physical activity. Evidence suggests that children and youth spend a large majority of their discretionary time in sedentary pursuits (e.g., watching television, playing video games). Studies have consistently found children spending on average 6–9 h of their waking day being sedentary (Colley et al., 2011; Matthews et al., 2008). There is accumulating evidence showing a positive relationship between sedentary time and a variety of negative health outcomes (Tremblay et al., 2011). It is unclear, however, how sedentary behaviors may be impacted by motor coordination difficulties in children. Given that children with DCD are presumed to be less active over time, it stands to reason that these children may be displacing their time in movement activities for more sedentary pursuits requiring little to no movement. To further the understanding of the health risks associated with children with significant motor impairments, research must examine sedentary time in addition to physical activity, identifying ways to get children to sit less and move more. The current study will further our knowledge on children with these significant motor impairments by examining patterns of objectively measured physical activity over time in children with and without possible DCD (pDCD). The term pDCD will be used in this study going forward, as not all criteria of the Leeds consensus (Sugden, 2006) were measured for a clinical DCD diagnosis. We will also examine whether there are gender differences, and if gender moderates the relationship between pDCD and physical activity levels. Furthermore, the study will examine sedentary time to determine whether there are differences in this health behavior over time between children with and without pDCD. 2. Methods 2.1. Participants and procedures The current study is a longitudinal investigation of a subset of children participating in a larger, 6-year prospective cohort study examining the healthy growth and development of children, called Physical Health and Activity Study Team (PHAST) (Cairney, Hay, Veldhuizen, Missiuna, & Faught, 2009). A group of children were selected from PHAST, and invited to participate in a longitudinal nested case-control study. Specifically, the current investigation is based on data collected in the final two years of the study, consisting of 126 participants selected from the PHAST study based on their motor proficiency scores. Children with the lowest motor proficiency scores were matched with a sample of children with higher motor proficiency scores. Included in the analyses were 103 of these participants (n = 60 males, 59%) that completed a minimum of one of the follow-ups.

M.Y.W. Kwan et al. / Human Movement Science 47 (2016) 159–165

161

Details of the initial selection process and response patterns for the PHAST cohort are described in a previous publication (Cairney, Hay, Veldhuizen, & Faught, 2010). Data collected for this study began in the spring semester of 2008, when children were in Grade 7 (mean age = 12.36 +/- .51), and were re-assessed annually 12- and 24-months later. Data collection took place between January and June of each of the data collection years. Trained research assistants first administered a brief questionnaire, an occupational therapist then assessed motor competence using the Movement Assessment Battery for Children Second Edition (MABC-2) (Henderson, Sugden, & Barnett, 2007) and cognitive functioning (verbal and non-verbal IQ) with the Kaufman Brief Intelligence Test – Second Edition (KBIT-2) (Kaufman & Kaufman, 2004). In total, each visit took approximately 90-to-120 min to complete. Following the lab assessments, children returned home with an accelerometer to wear for seven consecutive days, including an activity log to document when they wore the accelerometer. 2.2. Measures 2.2.1. Assessment of motor competence: Movement Assessment Battery for Children-2nd edition (MABC-2) All children were tested for motor competence using the MABC-2 at each assessment period. The MABC-2 is a widely accepted tool in DCD diagnosis that measures severity of motor impairment (Blank, Smits-Engelsman, Polatajko, & Wilson, 2012). In this study, the third age band of the MABC-2 (ages 11–16) was utilized to assess motor coordination difficulties. The tool itself is comprised of eight items under three motor skill categories of manual dexterity, aiming and catching, and balance (static and dynamic). It has demonstrated good reliability and validity (Brown & Lalor, 2009; Henderson et al., 2007). The 15th percentile is a commonly used threshold for case identification of DCD (Piek, 2000; Schott, Alof, Hultsch, & Meermann, 2007), however, normative scores from the MABC-2 are valued at the 9th and 16th percentiles. For the purpose of this study, children whose average total score was at or below the 16th percentile across the three assessments were considered to be pDCD. 2.2.2. Physical activity and sedentary behaviors The RT3 Triaxial Actical Accelerometer (Actical, Version 2.0, Mini Mitter, Respironics, 2006) was placed over the right hip of the child and worn for seven days during waking hours following the laboratory assessments. The accelerometers recorded data in 60s epochs. Participants were given a logbook to track when the accelerometer was worn, when they put the accelerometer on in the morning and when they took it off at night, and if they had taken it off during the day for any reason (e.g. swimming, bathing). To prevent the possible inclusion of activity counts not representative of the child’s activity (e.g., movement of the accelerometer in the mother’s purse), log books were used to ensure that only values corresponding to the times the child indicated that they were wearing the accelerometer were used for analysis. Time spent in each intensity level of physical activity was determined for each child. Sedentary activity was defined as less than 100 activity counts per minute, light activity was between 100 and less than 1500 activity counts per minute, moderate activity was from 1500 to less than 6500 activity counts per minute, and vigorous activity was defined as 6500 activity counts or greater per minute, based on the validation work of Puyau and colleagues (2004). The average time spent per day based on valid wear-time in moderate-to-vigorous physical activity (MVPA), total physical activity, and sedentary time were examined. 2.3. Statistical analysis Mixed effects modeling was used to estimate behavior change within individuals over time, adjusting for correlation of measures within children (repeated measures). A random intercept and slope for time was included, and an unstructured covariance matrix was chosen as it is considered the most flexible covariance structure. For each dependent variable, three models were specified. The first examined the effects of time on physical activity or sedentary time, adjusting for accelerometer wear time (Model 1). Next, pDCD status and gender were added (Model 2). To identify potential differences between boys and girls with respect to change in physical activity over time, a time by gender interaction was included. In the final model, the moderating effect of gender was tested by adding three interaction terms: time by pDCD status, gender by pDCD status, and time by gender by pDCD status (Model 3). This procedure allows for the possibility that the effect of pDCD on physical activity and sedentary behaviors may not be the same between genders across time. All analyses were conducted using SAS version 9.1. 3. Results Sample size and descriptive statistics for each wave for children with (n = 49) and without pDCD (n = 54) are shown in Table 1. Complete results of mixed-effects models predicting physical activity from pDCD, time, and gender, adjusting for accelerometer wear-time is shown in Table 2. The results found significant main effects for time (Estimate = 23.98, p < .01) and for gender (Estimate = 59.86, p < .05) on total physical activity. However, there were no significant effects, for pDCD or any of the interaction terms related to total physical activity. These results suggest that males tend to engage in more total physical activity than females, but total physical activity decreased over time regardless of gender or pDCD status. With respect to MVPA, no significant effect was found for time. Model 2 found a significant main effect for pDCD (Estimate = 5.38, p < .05). In model 3, we found a significant main effect for gender (Estimate = 26.89, p < .01), and a significant

162

M.Y.W. Kwan et al. / Human Movement Science 47 (2016) 159–165

Table 1 Descriptive statistics for probable developmental coordination disorder (pDCD) demographics over time. Total

Sample size (n) Baseline age Gender Male Female MABC-2 average percentiles Physical activity Total PA MVPA Sedentary

pDCD

TD

49 12.37 (.51)

54 12.36 (.52)

28 21 6.77 (4.94)

32 22 49.00 (17.56)

262.12 (64.99) 24.57 (16.78) 508.64 (77.32)

271.68 (67.51) 30.38 (19.66) 503.39 (74.34)

Grade 7 (Spring 2008)

Grade 8 (Spring 2009)

Grade 9 (Spring 2010)

pDCD

TD

pDCD

TD

pDCD

TD

292.01 (59.50) 25.83 (16.45) 470.93 (67.48)

303.62 (70.24) 32.62 (21.06) 485.00 (83.83)

252.01 (64.17) 23.92 (17.61) 533.85 (87.86)

263.27 (60.18) 29.40 (18.88) 516.64 (79.87)

229.66 (60.94) 23.53 (16.59) 534.51 (87.94)

240.32 (55.39) 27.69 (16.79) 516.84 (65.61)

Note: Mean scores and standard deviations (in parentheses) are reported. MABC-2 average percentiles range between .10 and 16 for pDCD and 25–91 for TD children. Physical activity and sedentary time reflect average mins/day for valid wear time.

Table 2 Mixed effects models of physical activity over time by gender, and DCD status.

Total PA Intercept Wear time Time DCD status pDCD Typically developing Gender Male Female Time  male Time by pDCD pDCD by male Time  pDCD by male MVPA Intercept Wear time Time DCD Status pDCD Typically developing Gender Male Female Time  male Time by pDCD pDCD by male Time  pDCD by male

Model 1 Estimate (SE)

Model 2 Estimate (SE)

Model 3 Estimate (SE)

157.22 (48.86)⁄⁄ 0.210 (0.06)⁄⁄ 30.587 (3.66)⁄⁄

149.21 (50.37)⁄⁄ 0.200 (0.06)⁄⁄ 25.527 (5.78)⁄⁄

129.83 (51.44)⁄ 0.204 (0.06)⁄⁄ 23.980 (7.83)⁄⁄

6.211 (9.20) –

1.226 (14.83) 0.038 (0.02)⁄ 1.204 (1.24)

24.888 (26.04) –

33.524 (17.27) – 9.146 (7.44)

59.857 (23.93)⁄ – 11.271 (10.09) 1.963 (11.57) 51.539 (34.28) 2.561 (14.92)

4.266 (15.03) 0.032 (0.02) 2.32 (1.93)

10.919 (16.58) 0.032 (0.02) 2.169 (2.60)

5.380 (2.58)⁄ – 18.853 (5.13)⁄⁄ – 6.347 (2.49)⁄

3.220 (2.89) – 26.889 (7.01)⁄⁄ – 7.496 (3.34)⁄ 0.699 (3.85) 12.480 (8.97) 1.859 (4.96)

Note: *p < .05; **p < .01.

time by gender interaction (Estimate = 7.50, p < .05). None of the interactions related to pDCD, however, were statistically significant. These results suggest that generally speaking, pDCD children and females were significantly less active than TD and male children, respectively. Unlike males, who had declining MVPA over the two years, there were no significant differences in the patterns of MVPA over time between pDCD and TD children. We have graphed the patterns of MVPA over time on the basis of gender and DCD status (see Fig. 1). Complete results from the mixed effects analyses of sedentary time are shown in Table 3. Results found a significant positive main effect for time (Estimate = 15.58, p < .05). None of the interactions entered into the models were significant. These results suggest that sedentary time increased across the broader sample, but that there were no differences on the basis of gender or pDCD.

163

M.Y.W. Kwan et al. / Human Movement Science 47 (2016) 159–165

MVPA/day (min)

Fig. 1. Average daily MVPA over time.

Table 3 Mixed effects models of sedentary time by gender, and DCD status.

Intercept Wear time Time DCD status pDCD Typically developing Gender Male Female Time  male Time by pDCD pDCD by male Time  pDCD by male

Model 1 Estimate (SE)

Model 2 Estimate (SE)

Model 3 Estimate (SE)

63.234 (61.42) 0.682 (0.08)⁄⁄ 15.583 (4.72)⁄⁄

58.716 (63.09) 0.695 (0.08)⁄⁄ 12.82 (7.52)

33.760 (63.88) 0.691 (0.08)⁄⁄ 8.693 (10.05)

5.082 (10.34) –

–

31.039 (19.66) – 5.486 (9.66)

36.586 (29.81)

50.815 (27.20)⁄⁄ – 3.772 (12.91) 7.614 (14.88) 37.52 (39.13) 6.241 (19.15)

Note: *p < .05; **p < .01.

4. Discussion Despite consistent evidence to suggest that children and adolescents with significant motor impairments such as DCD are significantly less likely to be physically active than their TD peers, remarkably little published work has examined physical activity longitudinally, and none have used objective assessments of physical activity (i.e., accelerometers) across multiple time points. Moreover, although many studies have examined the associations between pDCD and physical activity, few studies have examined the associations of pDCD with sedentary time, and none that have examined the impact of pDCD on longitudinal changes in sedentary time. Interestingly, the results of the current study suggest that the patterns of physical activity and sedentary time were similar for school-aged children with and without motor coordination difficulties. While there were no differences in total physical activity and sedentary time, children with pDCD on a whole engaged in significantly less MVPA than typically-developing children. On average, children with pDCD spent approximately 25 min per day in MVPA, compared to 30 min for TD children. The differences in MVPA between pDCD and TD children were generally consistent across the two-years. These results are somewhat consistent with the broader literature. Findings from a recent systematic review found strong evidence to suggest children with pDCD are less active than TD children with respect to both MVPA and total physical activity (Rivilis et al., 2011). The effect of pDCD on MVPA was also evident in a large population-based cohort study by Green and colleagues (2011), but only among boys and not girls at age 12. Our findings indicate that children with significant motor difficulties tend to be consistently less active than TD children during early to mid adolescence. There have been inconsistent findings among the few studies examining physical activity over time. For example, a study by Visser and colleagues (1998) found self-reported physical activity being consistently lower among children with DCD, but that the differences diminished over time. Conversely, a study by Cairney and colleagues (2006) found no such diminishing effect over time in participation in both structured and unstructured physical activities; and consistent with the current findings, changes in both MVPA and total physical activity were equal for pDCD and TD children. Obviously, more longitudinal research examining the effect of pDCD on physical activity is necessary to further confirm these results. Specifically, more research using objective measures of physical activity with repeated assessments over a longer period of time beginning in younger children is required to more accurately understand patterns of physical activity behaviors among children with pDCD. Future research should also consider other factors such as opportunities to engage in physical activities, to more effectively capture the effect of significant motor impairments.

164

M.Y.W. Kwan et al. / Human Movement Science 47 (2016) 159–165

Current findings suggest that significant motor impairments did not impact sedentary behavior, as there were no differences in sedentary time between pDCD and TD children. However, it is important to note that, on average, sedentary time increased over time across the two-year period for all children. These results are fairly consistent with the limited literature examining the broader relationship between motor competence and sedentary behaviors, which for the most part has found no associations (Cliff, Okely, Smith, & Mckeen, 2009; Graf et al., 2003). A more recent study by Lopes, Santos, Pereira, and Lopes (2012) did find motor coordination being inversely related to sedentary activities. That is, better motor coordination was associated with significantly less sedentary activities. Importantly, it should be noted that the study dichotomized their sample to reflect only high and low motor coordination. In other words, did not specifically target pDCD children, although it is conceivable that some children in their sample could be classified as pDCD. Overall, this area of research has been very limited, and more longitudinal work is needed to better understand sedentary behaviors in children with pDCD. The negative effects associated with a sedentary lifestyle, as it relates to children’s health, are a cause for concern. Results from a recent systematic review found spending more than two hours per day being sedentary was associated with increased body fat, decreased fitness, and lower scores for self-esteem and pro-social behaviors (Tremblay et al., 2011). Sedentary time represented 61% at baseline and increased to 68%. This is broadly consistent with other studies that show children spending up to 80% of their time awake being sedentary (Colley et al., 2011; Lopes et al., 2012; Martinez-Gomez et al., 2011; Matthews et al., 2008). While the current study represents the first study to examine objectively-assessed physical activity and sedentary behaviors over time among children with and without pDCD, there are several limitations that should be noted. First, it should be noted that no official DCD diagnosis was confirmed in participants that we suspected had DCD. Although motor competence was assessed by an occupational therapist, not all criterions for the Leeds consensus and/or DSM 5 were examined (e.g., problems with activity of daily living were not documented). Second, the epoch length for the current study was 60 s, potentially underestimating the time that these children spent in MVPA and overestimating their sedentary time. With advances in technology, studies using shorter epoch lengths (e.g., 5s) are increasingly more common and recommended in childhood research (Trost, Loprinzi, Moore, & Pfeiffer, 2011) as it is more sensitive to the intermittent bouts of activity that are characteristic of children. However, it does not appear to be essential, especially for characterizing lower intensity activities (Reilly et al., 2008). Third, despite the inclusion of intellectual impairments as a covariate, other related factors potentially related to movement skills and physical activity behaviors such as the lack of opportunities or parenting styles were not examined. Finally, the current study included follow-up assessments at 12- and 24-months, which is a relatively short time frame within the broader child and youth developmental period. More studies with longer-term follow-up periods, with studies beginning earlier in childhood, are required to more accurately assess the potentially more complex patterns of physical activity for children with pDCD through the emerging childhood and adolescent period. 5. Conclusion Overall, this study is the first to examine physical activity and sedentary behaviors longitudinally among children with pDCD using objective measures. From a clinical or intervention perspective, our results suggest that children with pDCD are generally less active than typically-develop children with respect to MVPA, but not total physical activity. Although TPA seems unaffected by pDCD status, the deficit in MVPA seen in the pDCD group is of concern as it is the accumulation of MVPA that is considered most important for health benefits (Ekelund et al., 2012). Patterns of change in physical activity and sedentary behaviors are the same for both pDCD and TD children, showing slight decreases in total physical activity and MVPA in males, and slight increases in sedentary time and MVPA among females across the 2-year period from grade 7 to 9. Further longitudinal research following young children over time is necessary to identify the specific point in which differences in MVPA occur between children with and without DCD. Acknowledgements This study was supported by the Canadian Institutes of Health Research (Grant #: 66959). The Physical Health Activity Study Team (PHAST) appreciates the commitment by children, parents and teachers from the District School Board of Niagara. Dr. Cairney is supported by an endowed professorship in the Department of Family Medicine. References American Psychiatric Association (2013). DSM 5. American Psychiatric Association. Andersen, L. B., Harro, M., Sardinha, L. B., Froberg, K., Ekelund, U., Brage, S., et al (2006). Physical activity and clustered cardiovascular risk in children: A cross-sectional study (The European Youth Heart Study). The Lancet, 368(9532), 299–304. http://dx.doi.org/10.1016/S0140-6736(06)69075-2. Bailey, D. A., Mckay, H. A., Mirwald, R. L., Crocker, P. R. E., & Faulkner, R. A. (1999). A six-year longitudinal study of the relationship of physical activity to bone mineral accrual in growing children: The University of Saskatchewan bone mineral accrual study. Journal of Bone and Mineral Research, 14(10), 1672–1679. http://dx.doi.org/10.1359/jbmr.1999.14.10.1672. Blank, R., Smits-Engelsman, B., Polatajko, H., & Wilson, P. (2012). European Academy for Childhood Disability (EACD): Recommendations on the definition, diagnosis and intervention of developmental coordination disorder (long version). Developmental Medicine & Child Neurology, 54(1), 54–93. Brown, T., & Lalor, A. (2009). The movement assessment battery for children-(MABC-2): A review and critique. Physical & Occupational Therapy in Pediatrics, 29(1), 86–103.

M.Y.W. Kwan et al. / Human Movement Science 47 (2016) 159–165

165

Cairney, J., Hay, J. A., Faught, B. E., Corna, L., & Flouris, A. (2006). Developmental coordination disorder, age, and play: A test of the divergence in activity-deficit with age hypothesis. . Cairney, J., Hay, J. A., Faught, B. E., Wade, T. J., Corna, L., & Flouris, A. (2005a). Developmental coordination disorder, generalized self-efficacy toward physical activity, and participation in organized and free play activities. The Journal of Pediatrics, 147(4), 515–520. http://dx.doi.org/10.1016/j.jpeds.2005.05.013. Cairney, J., Hay, J., Faught, B., Mandigo, J., & Flouris, A. (2005b). Developmental coordination disorder, self-efficacy toward physical activity, and play: Does gender matter. Adapted Physical Activity Quarterly, 22(1), 67–82. Cairney, J., Hay, J. A., Veldhuizen, S., Missiuna, C., & Faught, B. E. (2010). Developmental coordination disorder, sex, and activity deficit over time: A longitudinal analysis of participation trajectories in children with and without coordination difficulties. Developmental Medicine and Child Neurology, 52 (3), e67–72. http://dx.doi.org/10.1111/j.1469-8749.2009.03520.x. Cairney, J., Hay, J., Veldhuizen, S., Missiuna, C., & Faught, B. (2009). Developmental coordination disorder, sex, and activity deficit over time: A longitudinal analysis of participation trajectories in children with and without coordination difficulties. Developmental Medicine and Child Neurology, 52(3), e67–e72. Cantell, M. H., Smyth, M. M., & Ahonen, T. P. (1994). Clumsiness in adolescence. Educational, motor, and social outcomes of motor delay detected at 5 years. Adapted Physical Activity Quarterly, 11, 115. Cliff, D., Okely, A., Smith, L., & Mckeen, K. (2009). Relationships between fundamental movement skills and objectively measured physical activity in preschool children. Faculty of Education – Papers (Archive), 436–439. Colley, R. C., Garriguet, D., Adamo, K. B., Carson, V., Janssen, I., Timmons, B. W., et al (2013). Physical activity and sedentary behavior during the early years in Canada: A cross-sectional study. International Journal of Behavioral Nutrition and Physical Activity, 10(1), 54. Colley, R. C., Garriguet, D., Janssen, I., Craig, C. L., Clarke, J., & Tremblay, M. S. (2011). Physical activity of Canadian children and youth: Accelerometer results from the 2007 to 2009 Canadian Health Measures Survey. Statistics Canada. . Ekelund, U., Luan, J., Sherar, L. B., Esliger, D. W., Griew, P., Cooper, A., et al (2012). Moderate to vigorous physical activity and sedentary time and cardiometabolic risk factors in children and adolescents. Journal of the American Medical Association, 307(7), 704–712. Graf, C., Koch, B., Kretschmann-Kandel, E., Falkowski, G., Christ, H., Coburger, S., et al (2003). Correlation between BMI, leisure habits and motor abilities in childhood (CHILT-Project). International Journal of Obesity, 28(1), 22–26. http://dx.doi.org/10.1038/sj.ijo.0802428. Green, D., Lingam, R., Mattocks, C., Riddoch, C., Ness, A., & Emond, A. (2011). The risk of reduced physical activity in children with probable Developmental Coordination Disorder: A prospective longitudinal study. Research in Developmental Disabilities, 32(4), 1332–1342. http://dx.doi.org/10.1016/j. ridd.2011.01.040. Hay, J., & Missiuna, C. (1998). Motor proficiency in children reporting low levels of participation in physical activity. Canadian Journal of Occupational Therapy, 65(2), 64–71. http://dx.doi.org/10.1177/000841749806500203. Hellgren, L., Gillberg, C., Gillberg, I. C., & Enerskog, I. (1993). Children with deficits in attention, motor control and perception (DAMP) almost grown up: General health at 16 years. Developmental Medicine & Child Neurology, 35(10), 881–892. Henderson Sugden, D. A, & Barnett, A. L (2007). Movement assessment battery for children-2: Movement ABC-2: Examiner’s manual. Pearson. Kaufman, A. S., & Kaufman, N. L. (2004). Kaufman Brief Intelligence Test (2nd ed.) Circle Pines, MN: AGS Publishing. Lingam, R., Hunt, L., Golding, J., Jongmans, M., & Emond, A. (2009). Prevalence of developmental coordination disorder using the DSM-IV at 7 years of age: A UK population-based study. Pediatrics, 123(4), e693–e700. http://dx.doi.org/10.1542/peds.2008-1770. Lopes, L., Santos, R., Pereira, B., & Lopes, V. P. (2012). Associations between sedentary behavior and motor coordination in children. American Journal of Human Biology, 24(6), 746–752. http://dx.doi.org/10.1002/ajhb.22310. Losse, A., Henderson, S. E., Elliman, D., Hall, D., Knight, E., & Jongmans, M. (1991). Clumsiness in children-do they grow out of it? A 10-year follow-up study. Developmental Medicine & Child Neurology, 33(1), 55–68. http://dx.doi.org/10.1111/j.1469-8749.1991.tb14785.x. Martinez-Gomez, D., Ortega, F. B., Ruiz, J. R., Vicente-Rodriguez, G., Veiga, O. L., Widhalm, K., ... Sjöström, M. (2011). Excessive sedentary time and low cardiorespiratory fitness in European adolescents: The HELENA study. Archives of Disease in Childhood. http://dx.doi.org/10.1136/adc.2010.187161. archdischild187161. Matthews, C. E., Chen, K. Y., Freedson, P. S., Buchowski, M. S., Beech, B. M., Pate, R. R., et al (2008). Amount of time spent in sedentary behaviors in the United States, 2003–2004. American Journal of Epidemiology, 167(7), 875–881. http://dx.doi.org/10.1093/aje/kwm390. Piek, J. P. (2000). Determinants of self-worth in children with and without Developmental Coordination Disorder, 47(3), 259–272. Puyau, M. R., Adolph, A. L., Vohra, F. A., Zakeri, I., & Butte, N. F. (2004). Prediction of activity energy expenditure using accelerometers in children. [Miscellaneous article]. Medicine & Science in Sports & Exercise, 36(9), 1625–1631. Reilly, J. J., Penpraze, V., Hislop, J., Davies, G., Grant, S., & Paton, J. Y. (2008). Objective measurement of physical activity and sedentary behaviour: Review with new data. Archives of Disease in Childhood, 93(7), 614–619. http://dx.doi.org/10.1136/adc.2007.133272. Rivilis, I., Hay, J., Cairney, J., Klentrou, P., Liu, J., & Faught, B. E. (2011). Physical activity and fitness in children with developmental coordination disorder: A systematic review. Research in Developmental Disabilities, 32(3), 894–910. http://dx.doi.org/10.1016/j.ridd.2011.01.017. Schott, N., Alof, V., Hultsch, D., & Meermann, D. (2007). Physical fitness in children with developmental coordination disorder. Research Quarterly for Exercise and Sport, 78(5), 438–450. http://dx.doi.org/10.1080/02701367.2007.10599444. Sugden, D. (2006). Leeds consensus statement: Developmental coordination disorder as a specific learning difficulty.Leeds: DCD-UK/Dyscovery Centre. Tremblay, M. S., LeBlanc, A. G., Kho, M. E., Saunders, T. J., Larouche, R., Colley, R. C., et al (2011). Systematic review of sedentary behaviour and health indicators in school-aged children and youth. International Journal of Behavioral Nutrition and Physical Activity, 8(1), 98. Trost, S. G., Loprinzi, P. D., Moore, R., & Pfeiffer, K. A. (2011). Comparison of accelerometer cut points for predicting activity intensity in youth. Medicine and Science in Sports and Exercise, 43(7), 1360–1368. http://dx.doi.org/10.1249/MSS.0b013e318206476e. Visser, J., Geuze, R. H., & Kalverboer, A. F. (1998). The relationship between physical growth, the level of activity and the development of motor skills in adolescence: Differences between children with DCD and controls. Human Movement Science, 17(4–5), 573–608. http://dx.doi.org/10.1016/S0167-9457 (98)00014-1. World Health Organization (1992). The ICD-10 classification of mental and behavioural disorders: Clinical descriptions and diagnostic guidelines. Geneva: World Health Organization.