Introduction
Health-related quality of life (HRQoL) is a multidimensional concept that encompasses the physical, mental, and social aspects of health [
1]. Lower HRQoL levels, closely associated with increased risks of conditions like obesity/overweight, dental caries, and neurodevelopmental disorders (e.g., ASD) [
2‐
4], may potentially impact the future physical development of preschool children [
5], highlighting HRQoL's crucial role as a robust predictor of morbidity and mortality. Limited evidence on preschool children indicates that HRQoL significantly impacts their early development. A cross-sectional study revealed markedly lower physical, school performance, and overall HRQoL scores in preschoolers with developmental coordination disorder compared to typically developing children of the same age [
6]. It is important to note that the HRQoL of preschool children decreases with age [
1,
7]. Therefore, it is necessary to understand the HRQoL of preschool children, its influencing factors, and to explore effective means of improving their quality of life.
It is widely acknowledged that HRQoL is influenced not only by immutable factors, such as age, but also to a large extent by environmental factors, such as daily movement behaviors. Twenty-four-hour (24-h) movement behaviors include sleep, sedentary behavior (SB), light physical activity (LPA), and moderate-to-vigorous physical activity (MVPA) [
1]. Previous research has consistently shown a positive correlation between sleep duration and HRQoL scores in preschool children [
8,
9]. However, there are conflicting findings regarding the association between physical activity (PA), SB, and HRQoL scores. While one cross-sectional study identified a link between PA, SB, and HRQoL scores [
10], another found no association [
11]. Limited research exists on the relationship between PA, SB, and HRQoL in preschool children, and current findings remain inconclusive.
Previous studies, previous studies, limited by analyzing movement behaviors separately in assessing the correlation between 24-h movement behaviors and HRQoL, often employed questionnaire methods to qualitatively assess physical activity [
10], potentially contributing to uncertain association results [
1]. The analyzing movement behaviors separately method overlooks the time constraint (i.e., 24-h) and the interdependence of 24-h movement behaviors data [
12], where a change in the time of one activity will inevitably cause a change in the time of one or more remaining activities [
12]. Therefore, exploring the relationship between the reallocation of activity time and HRQoL is particularly important. Twenty-four-hour movement behaviors constitute a set of component data, exhibiting significant multicollinearity among activity behavior times. Consequently, conventional statistical methods like multiple linear regression are not directly applicable for related research. Compositional data analysis (CoDA) recognizes the compositional nature of daily 24-h movement behaviors data and has been widely employed in investigating the correlation between daily 24-h movement behaviors and health indicators [
13]. Additionally, the isometric log-ratio models can be utilized to explore the relationship between the reallocation of activity behavior time and HRQoL [
13,
14].
Previous studies have demonstrated the widespread application of CoDA in examining the correlation between 24-h movement behaviors and HRQoL across children and adults, indicating that reallocating time from other behaviors to MVPA/sleep can enhance HRQoL scores [
1,
15]. However, it remains uncertain whether this association extends to the preschool population. While only one compositional data analysis has shown a link between preschool children's 24-h movement behaviors and HRQoL [
14], caution must be taken when generalizing the results of this study due to variations in policies, cultures, and activity patterns across countries, which may influence the association between 24-h movement behaviors and HRQoL [
1]. Furthermore, studies have demonstrated that 24-h movement behavior patterns [
16‐
18] and HRQoL [
19,
20] differ between boys and girls. Considering these gender differences, previous research has emphasized the importance of employing CoDA to examine the association between daily time-use composition and HRQoL across genders [
21]. To the best of the authors' knowledge, evidence of gender-related differences among preschoolers remains limited or unsubstantiated.
Therefore, to address this gap in the literature, the present study aims to investigate the association between preschool children's 24-h movement behaviors and HRQoL, while also examining the impact of reallocating time among these daily movement behaviors on HRQoL and exploring potential gender differences in these effects.
Discussion
To our knowledge, this study represents the first endeavor to scrutinize the cross-sectional associations between 24-h movement behaviors and the comprehensive HRQoL scores, along with its sub-dimensions, among Chinese preschoolers. The results underscore a robust linkage among SB, sleep patterns, and HRQoL in preschoolers. Employing a composition approach through the application of the component isochronous substitution model, the investigation unveiled a noteworthy enhancement in the overall HRQoL score subsequent to equitably redistributing time originally allocated to SB towards sleep activities. In the gender subgroup analyses, this correlation was notably accentuated within the cohort of boys, exhibiting substantial increments primarily in psychosocial health scores. This observation implies the vulnerability of boys' HRQoL to daily fluctuations in 24-h movement behaviors.
Moreover, our study found that boys engage in greater PA, including more vigorous PA, than girls during the preschool period, consistent with previous research [
37]. This variation may be attributed to sociocultural factors, familial expectations and support, as well as peer interactions. Societal perceptions and gender stereotypes may shape the activity patterns of boys and girls, as traditional norms often prescribe boys to be stronger and more active, while girls are expected to be quieter and gentler, potentially resulting in boys being more active and girls more sedentary [
38]. Families may have disparate expectations and encouragements for boys' and girls' physical activity, as research indicates that parents are inclined to motivate boys more towards physical activity while less so for girls [
39], potentially leading to a gender difference in activity levels. It has been shown that preschool children's behavior was strongly influenced by their peers [
40], with the highest proportion of time being spent on physical activity when they were with active peers, and less time being spent on physical activity when they were with quiet peers.
The current study aligns with findings from the sole existing isochronous substitution modeling analysis conducted on preschoolers [
14], both indicating that reallocating time dedicated to SB to sleep yields a notable enhancement in total HRQoL scores among preschool-aged children. This finding is further supported by several previous component analysis studies in children and adolescents [
1,
41]. Regarding physiological mechanisms, this phenomenon could be attributed to the potential effect of increased sleep duration on maintaining or enhancing connectivity within the prefrontal control network and the limbic system, particularly the amygdala [
42‐
44]. Consequently, this connectivity enhancement may mitigate negative biases and emotional responses [
45], consequently leading to an increase in HRQoL among preschoolers. Viewed from a psychological perspective, the recognition exists that adequate sleep triggers positive responses in emotion regulation, potentially augmenting the levels of HRQoL among preschoolers [
44,
46], thereby contributing, to a certain extent, to the understanding of the findings in the present study. Notwithstanding, it is imperative to acknowledge the prevailing focus of current research on sleep behaviors and their implications for HRQoL, primarily emphasizing sleep duration [
1,
47], while neglecting other dimensions such as sleep quality, which similarly wield considerable impact on HRQoL. The integration of these overlooked dimensions presents an opportunity to enrich our comprehension of the intricate interplay between sleep and HRQoL [
9,
47,
48]. Consequently, it is imperative that future research endeavors delve more comprehensively into the intricate impact of sleep on HRQoL among preschool children.
The present study has not found an association between reallocating time from moderate-to-vigorous physical activity (MVPA) or light physical activity (LPA) and other active behaviors with HRQoL scores, which contradicts the findings of Chen et al. [
14]. The inconsistency observed may be attributed to several factors: (1) disparities may arise due to variations in aspects such as the magnitude and nature of daily activity behaviors exhibited by preschoolers across different nations; (2) different methods of measuring PA and SB, Chen et al. used a questionnaire method to subjectively assess PA and SB, which is different from the objective accelerometer-based assessment method in the present study, with a certain degree of subjective bias; (3) differences in the methods for partitioning time for daily 24-h movement behaviors, with Chen et al. employing a three-classification method (i.e., PA, SB, and sleep), contrasting the four-classification method utilized in the current study, may also contribute to the incongruity in findings, potentially impacting the consistency of the analysis results to some extent; and (4) the temporal contexts of the data collection are different, Chen et al. who collected their data prior to the COVID-19 outbreak, whereas the present study collected their data during the COVID-19 epidemic in which the data were collected. Previous studies have indicated a notable reduction in levels of PA, particularly MVPA, among preschool children during the epidemic compared to the pre-epidemic period [
49], potentially resulting in an inadequate allocation of 30 min insufficient to meet the minimum "threshold" for MVPA to exert a health effect [
50]. This notion finds support in a recently published study, which similarly discovered that reallocating 30 min from another behavior to MVPA did not lead to significant changes in HRQoL scores among preschool children [
1]. The results of this study do not contradict the guidelines for daily 24-h movement behaviors in preschool children, as the health effects of daily movement behaviors in the preschool years may manifest themselves in childhood and adolescence. In previous studies, it has been established that while one study demonstrated no association between MVPA and HRQoL during the preschool years [
51], another study uncovered a significant positive correlation between MVPA and HRQoL during the school-age years (7–9 years) [
41]. Although no association between MVPA and HRQoL was found in the preschool years, it is important to consider that MVPA has been shown to have a facilitating effect on executive functioning and HRQoL in preschoolers [
14,
34]. Therefore, despite the absence of a direct link in the current study, it remains advisable to decrease sedentary behavior time and enhance MVPA time in preschoolers.
In order to delve deeper into the effects of SB and sleep on HRQoL and to consider potential gender differences, the present study employed component isochronous substitution models for separate analysis of boys and girls. While the HRQoL scores of boys exhibited a significant decrease when the time allotted for sleep was redistributed to SB, there was no notable alteration observed in the HRQoL scores of girls. Possible reasons for this phenomenon include the following: (1) it may stem from individual differences in HRQoL, which can vary among preschoolers of the same gender based on factors such as lifestyle, health status, and psychological characteristics; (2) it may arise from disparities in the initial timing of SB, as previous research has indicated significantly lower SB time in preschool boys compared to girls [
37,
52,
53], coupled with a noted correlation between SB time and HRQoL [
14], where preschoolers with prolonged sedentary behavior exhibited lower HRQoL scores; and (3) it may be attributed to variances in PA levels between boys and girls, supported by evidence indicating a positive correlation between PA and HRQoL [
10], alongside findings suggesting higher PA levels among boys than girls [
37], which could partly elucidate our observations. Additionally, it's essential to consider that disparities in activity preferences could also could also play a contribution role. Girls tend to favor indoor activities [
54], where they allocate more time engaging in static games, while boys exhibit a higher tendency towards outdoor activities [
55]. Although this study identified gender differences in the association between 24-h movement behaviors and HRQoL, its cross-sectional design limits causal interpretation. Future research, especially longitudinal and experimental studies, is essential to more thoroughly explore and confirm the presence of these gender differences.
Derived from the outcomes of this investigation, it is suggested that gender-specific strategies pertaining to activity behaviors be incorporated into public health policies and childcare practices. Specifically targeting girls, it is advisable to promote increased physical activity and reduced sedentary behavior to enhance their HRQoL. Through the implementation of these interventions, a more effective promotion of the overall health and well-being of preschool children can be achieved, thereby establishing a sturdy foundation for their future development.
The present study, characterized by numerous strengths, stands as a significant contribution to the realm of 24-h movement behaviors research in preschool children. Firstly, through the utilization of accelerometers for the measurement of preschoolers' PA and SB, the current study has effectively acquired high-quality data on children's daily movement behaviors. This methodology, distinguished by its objectivity and accuracy, surpasses traditional self-report or observational methods. Secondly, our study utilized compositional data analysis, an advanced statistical method, enabling the consideration of interdependencies among various movement behaviors in our analysis [
11,
51]. Employing this method enhances the precision and reliability of the analysis results, offering novel insights into comprehending the intricate interactions of 24-h movement behaviors in preschool children. Thirdly, this study provides a nuanced discussion of the respective benefits of LPA and MVPA to provide a more complete understanding of how different activity intensities affect preschoolers' HRQoL. More significantly, as far as we are aware, this study is the first to specifically investigate the relationship between preschool children's 24-h movement behaviors and their HRQoL as well as its sub-dimensions. This research fills a void in the current body of literature and offers robust evidence to confirm the validity of the link between 24-h movement behaviors and HRQoL. While this study offers novel insights into the relationships among SB, sleep, and HRQoL in preschool children, we acknowledge the intricate nature of these connections. Drawing generalizable conclusions from the sample in this study may prove challenging. Nonetheless, the present study undoubtedly furnishes crucial additional evidence for research on the correlation between 24-h movement behaviors and HRQoL in Chinese preschool children.
Certainly, it's important to acknowledge the limitations of this study. One notable limitation is that the correlation between MVPA and LPA with HRQoL was less pronounced, as indicated by the broader 95% confidence intervals. These findings could be attributed to the study's limited sample size and the inherent variability within the sample. Furthermore, the cross-sectional design restricts our ability to infer causality between movement behaviors and HRQoL. Future research efforts should focus on increasing the sample size to enhance the accuracy of predictions regarding HRQoL after redistributing movement behaviors, thus strengthening the reliability of the findings. Another limitation is the potential for subjective bias in the use of questionnaires to investigate sleep duration in preschool children. But, the reliability and validity of the questionnaire were validated [
31]. Future research could benefit from utilizing accelerometry to track both daytime and nighttime behaviors. Additionally, it's important to recognize that the data concerning sleep duration and HRQoL were obtained from parental reports, potentially introducing subjective biases. However, it's crucial to note that the survey methodology employed for sleep assessment and the validity and reliability of the PedsQL questionnaire, widely recognized for measuring quality of life in school-aged children, have been rigorously validated [
31,
32].
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