An abundant body of literature has demonstrated the positive impact of moderate-to-vigorous physical activity (MVPA) for fitness, motor and cognitive development as well as psychosocial, skeletal and cardiometabolic health in early childhood (1). However, much of this work has failed to take into account that other movement behaviors—such as sleep, sedentary time and light physical activity (LPA)—also play an important role (2). This constrained approach has sparked a push for the adoption and application of the 24-h movement paradigm to better understand how interrelationships among movement behaviors across the whole day affect healthy development during the early years (3, 4). Previous work has shown that increasingly sedentary patterns of movement behaviors begin to emerge as early as the preschool years (5–8), resulting in less favorable health outcomes (5), which can track into adulthood (9). Therefore, it is imperative that we improve our current understanding of the interactive nature of movement behaviors and their relationship with mental health so that we can design effective interventions moving forward.

Certain populations such as children with neurodevelopmental disorders experience a variety of barriers and limitations to daily activities that may cause them to engage in less active and more sedentary lifestyles than their typically developing (TD) peers (10, 11). This is of particular concern given that this population is at an increased risk of physical comorbidities (12). Developmental Coordination Disorder (DCD) is a neurodevelopmental disorder that affects ~2–6% of children (13, 14) and has received considerable attention regarding patterns of movement behaviors during childhood, but work in this area has focused largely on MVPA. For instance, a systematic review of the literature found children with DCD engage in lower levels of MVPA than TD children and these differences persist as they age into adolescence (15). While there has been little research on the early years, recent work using accelerometry suggests that preschool-aged children at risk for DCD (rDCD) engage in similar amounts of MVPA, LPA and sedentary time compared to their TD peers (16). However, studies taking a more comprehensive approach that moves beyond considering absolute amounts of time engaging in each behavior to instead focus on the relative proportion of time spent engaging in each behavior within a finite window have yet to be conducted.

To date, very few studies have taken an integrative approach to investigate associations between movement behaviors and health outcomes among preschool children. Even fewer studies have adopted compositional data analysis methods to examine how time spent engaging in one movement behavior relative to the others or reallocation of time between movement behaviors is related to healthy development. Recent work using accelerometry has shown that 24-h movement compositions significantly predict fundamental motor skills (17, 18) and cognitive development (17, 19) in preschool-age children. Although evidence has demonstrated beneficial associations between different intensities of physical activity and indicators of mental health within samples of children and youth between the ages of 6–17 years (20–22), the only study to examine these relationships among preschool-age children observed null relationships (17). Combined with the fact that children at risk for DCD experience higher rates of mental health problems beginning as early as the preschool years (23), this dearth of research highlights the need for additional work—particularly among larger and more diverse samples—to better understand whether movement behaviors influence mental health in the early years. Although existing literature has examined different pathways by which physical activity and sedentary time influence indicators of mental health among children classified as rDCD (24, 25), studies adopting novel techniques to investigate how the interplay between these movement behaviors affects their mental health have yet to be conducted.

Therefore, the purpose of the present study is two fold: (1) to examine whether differences in wake-time movement compositions (i.e., sedentary time, LPA, MVPA) exist between preschool children classified as TD and rDCD; and (2) to investigate associations between the movement composition of preschool children and indicators of mental health.

This study was the first to examine whether wake-time movement compositions differ between preschool children classified as TD and rDCD, and represents the largest study to investigate the impact of wake-time movement behaviors on indicators of mental health among preschool children using accelerometry. Our results indicated that movement compositions were relatively similar for TD preschool-age children and those classified as rDCD; with both groups, on average, engaging in nearly 5 h of activity of varying intensities during a 12-h wake period. Given the similarity in movement compositions between TD children and those classified as rDCD, we pooled the sample and adjusted for rDCD status when investigating associations between sedentary time, LPA and MVPA with indicators of mental health. Findings demonstrated a significant negative relationship for sedentary time (relative to time in LPA and MVPA) and externalizing problems, whereas null associations were observed for each of the other relationships. Collectively, these findings suggest preschool children engage in a considerable amount of activity across the course of a day, but their movement behavior patterns explain very little variance in parent-reported measures of internalizing and externalizing problems.

Previous research has generally suggested that as children and adolescents with DCD grow older, they engage in increasingly less active and more sedentary lifestyles than their TD peers (15). This study was the first to use compositional data analysis techniques to determine whether these traditionally observed differences in movement behaviors are apparent as early as the preschool years. Using accelerometry, our findings showed that the relative amount of time spent engaging in sedentary time, LPA and MVPA across the course of an average day was roughly equivalent for TD children and those classified as rDCD. These movement compositions involved a smaller portion of time spent engaging in physical activity and more time in sedentary behavior compared to previous work investigating Canadian preschool children (17), but were similar to movement compositions that have been reported by two studies conducted in Brazil (18, 19). Although the present study focused on general patterns of movement behaviors, other work using the baseline CATCH cohort suggests that there may be subtle differences in how preschool children classified as rDCD accumulate their MVPA (16). Given that the CATCH study will track this sample into late childhood, future work will provide a better understanding of when differences in movement compositions begin to manifest. For instance, it is reasonable to hypothesize that children classified as rDCD will become less active and more sedentary when they reach middle childhood, as this period represents when many children begin playing organized sports and engaging in other active pursuits that require greater motor demands. For children with DCD, their poor motor skills may affect their confidence to participate (54), thus leading them to engage in more sedentary pursuits. Fortunately, multiple waves of data from the CATCH study will be able to answer many of the outstanding questions in this area.

Beyond examining potential differences in movement compositions among children classified as TD and rDCD during the preschool years, the present study also contributes to the dearth of literature investigating the impact of movement behaviors on mental health during the early years. For the most part, our findings align with previous research that has failed to demonstrate significant associations between wake-time movement behaviors and mental health problems (17). In fact, wake-time movement compositions appear to explain only a very small amount of the variance in internalizing (3%) and externalizing (8%) problems during this early life stage. This is despite the fact that parent reports indicate 13.1% of TD children and 21.3% of children classified as rDCD in the CATCH cohort score at or above subclinical thresholds for possible mental health problems (23), thus highlighting the importance of identifying effective strategies to mitigate risk beginning at a young age so that these problems do not develop into psychiatric diagnoses. Nevertheless, in light of the complete movement composition explaining minimal variance in indicators of mental health among this sample, it may not be surprising that we found replacing up to 25 min of sedentary time with either LPA or MVPA confers negligible benefits for mental health. Although recent cross-sectional studies have shown movement compositions are positively associated with important physical and cognitive developmental outcomes in the early years (17–19), the benefits for mental health and well-being may not manifest until children are of school age (22). Despite these findings, it is worth noting that accelerometry data does not provide context-specific information about the activities people are engaging in; and therefore, recent advances in machine learning approaches for classifying device-measured movement behaviors into specific activities (e.g., free play, organized sport, cycling) may provide novel insights about the complexity of these relationships (55).

Although five out of the six relationships between movement behaviors and indicators of mental health were not found to be significant, a significant negative association was observed for sedentary time and externalizing problems. One potential explanation for this finding relates to measurement, not only related to the CBCL, but also accelerometry. Within the attention problems subscale (which together with the aggressive behavior subscale make up the externalizing problems scale) are items that may have implications for classification of accelerometer-based movements. For example, one item asks about whether a child cannot sit still. Given that hip worn accelerometers cannot distinguish between sedentary postures (i.e., sitting vs. standing) (56), it is a distinct possibility that sedentary time is misclassified as LPA if a child is constantly fidgeting in their seat or while they stand. For children who score high on measures of attention problems and/or may be diagnosed with ADD/ADHD—a common co-morbidity for children diagnosed with DCD (57)—these instances would serve to strengthen negative associations between sedentary time and externalizing problems. Contrary to this argument, however, is that these children may be expending ≥1 MET and these movement are therefore accurately captured. Moving forward, postural data obtained from wearables that measure posture may help to improve the classification of lower intensity movement behaviors, particularly among individuals with inattention problems.

From a public health standpoint, our findings suggest that movement behavior-related interventions may have limited efficacy when seeking to reduce mental health problems among preschool children. This is not to say that interventions focused on improving movement compositions should be avoided, as they have the potential to provide important benefits for cardiometabolic health and cognitive function (17–19), but rather, that individuals involved in developing health promotion strategies and campaigns for preschool children should be aware that effects for emotional and behavioral outcomes may be negligible. Until researchers begin employing methodologies that provide contextual information about what types of activities preschool children engage in during their sedentary time [i.e., mentally active vs. passive; (58)] or while active, in addition to who they engage in these activities with, we will only have a gross understanding of associations between movement compositions and mental health. Implementing such methodologies with young children may be fraught with challenges though.

Although the present paper addresses gaps in the existing literature, it is not without limitations. First, movement behaviors are traditionally examined using the 24-h paradigm, which also includes sleep. However, data pertaining to sleep duration was not collected in the CATCH study; thus, some of the variance in mental health problems explained by sleep was not captured. Second, the sample consisted of primarily White children living in households with a total income above the poverty line, which may potentially limit the generalizability of our findings to the broader Canadian population, although time spent engaging in each movement behavior was similar to that observed among a nationally representative sample of Canadian preschool children (59). Third, indicators of children's mental health were parent reported given the age of the sample, but evidence indicates parents experiencing mental health problems—mothers in particular—may provide biased reports when asked to assess the mental health of their child (60–62). Future studies would benefit from collaborative partnerships with clinicians who can provide a comprehensive mental health screening for pediatric study participants. Finally, this study involved cross-sectional data, which limits our ability to make causal inferences about the directionality of the relationships between movement compositions and mental health.

In conclusion, we showed that wake-time movement compositions were similar among preschool children classified as TD and rDCD. These findings indicate that differences in sedentary time and physical activity typically observed between these groups likely develop later in childhood. Furthermore, findings revealed that at this young age, the overall composition of wake-time movement behaviors does not appear to play an influential role for children's mental health. While movement behavior-related interventions may have beneficial effects for other important developmental outcomes, interventionists should be aware that the impact on mental health may be trivial.

The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

The studies involving human participants were reviewed and approved by Hamilton Integrated Research Ethics Board. Written informed consent to participate in this study was provided by the participants' legal guardian/next of kin.

DB: conceptualization, methodology, writing—original draft, formal analysis, data curation, and visualization. MK: methodology, writing—review and editing, supervision, and funding acquisition. SK-D: writing—review and editing. JC: methodology, writing—review and editing, supervision, and funding acquisition. All authors contributed to the article and approved the submitted version.

The Coordination and Activity Tracking in Children (CATCH) study was funded by the Canadian Institutes of Health Research (CIHR Award #: MOP 126015).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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