Multivariate physical activity association patterns for fundamental motor skills and physical fitness in preschool children aged 3-5 years.

Physical activity (PA) is important for children's development of fundamental motor skills (FMS) and physical fitness (FIT) but evidence regarding which intensities are associated with these outcomes in early childhood is limited. The aim of this study was to determine the cross-sectional multivariate PA intensity signatures associated with FMS and FIT in children aged 3-5 years. We used a sample of 952 Norwegian preschoolers (4.3 years, 51% boys) who provided data on PA (ActiGraph GT3X+), at least one FMS (locomotor, object control and/or balance skills) or FIT (speed agility, standing long jump, and/or handgrip strength) outcome, body mass index, and socioeconomic status in 2019-2020. We created 17 PA intensity variables (0-99 to ≥15000 counts per minute) from the vertical axis and used multivariate pattern analysis for analyses. The PA intensity spectrum (including sedentary time) was significantly associated with all outcomes. Associations for PA intensities were positive (negative for sedentary time), strongest for moderate and vigorous intensities, and were significant across sex and age groups. Our findings show that the PA intensity spectrum is associated with FMS and FIT in young children and that promotion of PA, in particular moderate- and vigorous-intensity activity, from an early age benefits children's physical development.

The influence of reliability and variability of objectively measured physical activity on associations with lower body muscle strength in young children.

It is not known how extended or multiple monitoring periods affect associations between accelerometer-measured physical activity and outcomes. The aim of this study was to examine how accelerometer monitoring length influenced cross-sectional and prospective associations for physical activity with lower body muscle strength in young children. 176 Norwegian 2-6-year-old children had 3 valid 14-day periods of accelerometer monitoring (ActiGraph GT3×+) between September 2015 and May 2016 (baseline) as well as baseline and 4-year follow-up measurements of standing long jump. We analysed physical activity using a descriptor with 4 intensities using 6 different monitoring lengths both within and across monitoring periods (1 day, 3 days, 1 week, 2 weeks, 3 weeks, 6 weeks) and determined associations with lower body muscle strength using multivariate pattern analysis. We found that the strength of cross-sectional associations with lower body muscle strength improved for longer monitoring periods (explained variances = 7.7%, 9.8%, 11.8%, 15.8%, 18.4% and 22.9% for 1 day, 3 days, 1 week, 2 weeks, 3 weeks and 6 weeks of measurement). Longitudinal associations were weaker and less clear. Our findings suggest that multiple extended physical activity monitoring periods improve the validity of the study findings regarding associations between physical activity and relevant outcomes.

Prospective Association Patterns for the Physical Activity Intensity Spectrum With Body Mass Index and Lower Body Muscle Strength in Norwegian Children Aged 3-9 Years.

BACKGROUND: Limited evidence exists regarding prospective associations for physical activity (PA) and sedentary time (SED) with body mass index (BMI) and muscle strength in young children. We aimed to determine prospective associations for PA and SED with change in BMI and standing long jump over 2 and 4 years in children aged 3-5 years at baseline. METHODS: A sample of 262 Norwegian children (50% girls) was followed from 2015 to 2017 and/or 2019. PA and SED (hip-worn ActiGraph GT3X+) were measured at baseline and BMI and standing long jump at baseline and at follow-ups. Multivariate pattern analysis was used to determine prospective associations between the triaxial PA intensity spectrum (0-99 to ≥15,000 counts per minute) and the change in outcomes. RESULTS: We found significant prospective associations between the PA intensity spectrum and standing long jump at 2- (explained variance = 5.8%-7.7%) and 4-year (explained variance = 4.8%-5.6%) follow-ups. Associations were negative for SED and positive for all PA intensities. We found no associations between PA/SED and BMI. CONCLUSIONS: Our findings suggest that PA and SED can predict future lower body muscle strength but not BMI in early childhood.

The multivariate physical activity signatures associated with body mass index and waist-to-height ratio in 3-5-year-old Norwegian children.

The evidence regarding associations between intensity-specific physical activity and adiposity in young children is inconclusive. The aim of this study was to determine the multivariate physical activity intensity signatures associated with body mass index and waist-to-height ratio in children aged 3-5 years. A sample of 1003 Norwegian preschool children (mean age 4.3 years, 51 % boys) from the Active Learning Norwegian Preschool(er)s study provided data on physical activity (ActiGraph GT3X+), body mass index, and waist-to-height ratio during 2019-2020. Multivariate pattern analysis was used to determine associations between the triaxial intensity spectrum (0-99 to ≥15,000 counts per minute) and the outcomes. We found significant associations for physical activity with body mass index and waist-to-height ratio (explained variances = 10.8 and 11.5 %, respectively). For the vertical axis, associations were negative for time spent sedentary (0-99 counts per minute) and positive for time spent in lower intensities (100-2999 counts per minute) for both outcomes, whereas associations for vigorous intensities (≥4000 counts per minute) differed for body mass index (no associations) and waist-to-height ratio (negative associations). Association patterns for body mass index and waist-to-height ratio were rather similar, but the stronger associations with vigorous physical activity intensities for waist-to-height ratio suggest that waist-to-height ratio might better capture adiposity resulting from inactivity than body mass index.

Structural validity of a test battery for assessment of fundamental movement skills in Norwegian 3-6-year-old children.

Fundamental movement skills (FMS) are building blocks of more advanced movements, including subdomains of locomotion, object control and balance skills, but limited evidence exists for this three-factor structure. The aim of this study was to examine the structural validity of a three-factor modified test battery of FMS across age and sex in two large samples of preschoolers aged 3-6 years (sample 1: n = 1213, mean age 4.8 (.09); sample 2: n = 1198, mean age 4.3 (.09)). We used a test battery of FMS consisting of movement tasks for locomotion (run, horizontal jump and hop) and object control (catch, overhand throw and kick) from the Test of Gross Motor Development and balance skills (single-leg standing, walking line backward and walking line forward) from the Preschoolers Gross Motor Quality Scale. Confirmatory factor analysis was used to analyse the data. We found support for both a three-factor and a two-factor structure. Measurement invariance testing showed invariance over age and partial scalar invariance over sex. We conclude that our modified test battery is an appropriate measure of young children's FMS across the domains of locomotion, object control and balance, but that locomotion and object control subdomains provide limited unique information.

Trajectories of physical activity and sedentary time in Norwegian children aged 3-9 years: a 5-year longitudinal study.

BACKGROUND: Limited evidence exists regarding the longitudinal development of physical activity during early to mid childhood. The aim of this study was to determine physical activity and sedentary time trajectories in children aged 3‒9 years from Western Norway. METHODS: A sample of 294 children (51% boys; aged 3‒5 years at baseline) from the Sogn og Fjordane Preschool Physical Activity Study was followed annually over 5 years (2015‒2019). Physical activity was measured every autumn during this period using hip-based accelerometry (ActiGraph GT3X+). Data was processed as counts. We used linear mixed models to analyse the data. Primary analyses included trajectories for total and intensity-specific physical activity (light, moderate, vigorous, and moderate to vigorous intensity) and sedentary time for boys and girls using 1-s epoch. Secondary analyses included trajectories for weekdays versus weekend days, preschool/school hours versus after school hours, and 1- versus 60-s epoch lengths. RESULTS: Over the total day, significant associations with age were found for boys and girls for all physical activity intensities and sedentary time (p < .001). Total physical activity peaked at age 5, whereas intensity-specific physical activity levels peaked at age 3 to 8 years (light intensity: 3-4 years; moderate intensity: 4-7 years; vigorous intensity: 7-8 years; moderate to vigorous intensity: 5-8 years). Boys had higher physical activity levels and more favourable trajectories than girls. Sedentary time increased from ages 3 to 9. Changes over time were larger for weekdays than for weekend days and larger for preschool/school hours than for after school hours. The use of a 60-s epoch resulted in larger changes over time than a 1-s epoch. CONCLUSIONS: Our findings suggest physical activity levels peaked between the ages of 3 and 8 years. Finding ways to prevent decline in physical activity during the transition from preschool to primary school is important, especially for girls. Standardising epoch length will help when comparing physical activity and sedentary behaviour across studies.

Accelerometer epoch length influence associations for physical activity intensities with body mass index and locomotor skills in young children.

The epoch length is decisive for the capture of physical activity intensities from accelerometry and possibly for associations between physical activity intensities and outcomes in children. The aim of the present study was to determine the multivariate physical activity intensity signatures related to body mass index and locomotor skills in preschool children using different epoch lengths. A sample of 1054 Norwegian children (mean age 4.8 years, 52% boys) from the Sogn og Fjordane Preschool Physical Activity Study provided data on physical activity (ActiGraph GT3X+), body mass index and locomotor skills in 2015-2016. Multivariate pattern analysis was used to determine associations between the physical activity intensity spectrum (0-99 to ≥15000 counts per minute) and the outcomes using files aggregated using 8 different epoch lengths from 1 to 60 seconds. We observed that associations across the intensity spectrum, from sedentary time to vigorous intensities, differed for data derived using different epoch lengths. For both outcomes, associations for moderate intensities became stronger and vigorous intensities became weaker for longer as compared to shorter epoch lengths. Aggregation of accelerometer data using different epoch lengths influences the capture of physical activity intensities and associations between physical activity intensities and related outcomes.

The role of weather conditions on time spent outdoors and in moderate-to-vigorous physical activity among Norwegian preschoolers.

The aim of this study was to determine associations between weather and playground surface conditions and time spent outdoors and in moderate-to-vigorous PA (MVPA) in preschool children aged 3-6 years. We included 1201 children (mean age 4.8 years, 51% boys) from 68 preschools in Norway who provided 12,030 days of observation during 2015-2016. Preschool MVPA was measured by accelerometry (ActiGraph GT3X+) for 10 consecutive weekdays. During this period, outdoor time and playground surface conditions were logged by staff and weather conditions were obtained from the Norwegian Meteorological Institute. Associations were determined using linear mixed models. Associations for MVPA depended on whether the analyses were adjusted for outdoor time or not. In unadjusted analyses, rainfall, wind, and wet, icy, and mixed playground conditions were negatively associated with MVPA, while temperature, snowfall, and dry playground conditions were positively associated with MVPA. In adjusted analyses, temperature and wet and mixed playground conditions were negatively associated with MVPA, while snowfall and dry and snowy playground conditions were positively associated with MVPA. Outdoor time and MVPA should be addressed simultaneously to inform interpretation of associations with weather characteristics and intervention development in early childhood education settings.

The multivariate physical activity signature associated with body mass index in young children.

The evidence regarding associations between intensity-specific physical activity and adiposity in young children is conflicting. Moreover, the evidence is limited by analytical approaches that cannot handle the multicollinearity among multiple variables across the entire intensity spectrum. We aimed to determine the multivariate physical activity intensity signature associated with body mass index in a large sample of preschool children aged 3-6 years. 1182 Norwegian preschool children (mean age 4.7 years, 51% boys) provided data on physical activity (ActiGraph GT3X+) and body mass index during 2015-2016. Multivariate pattern analysis was used to determine associations between the entire triaxial intensity spectra (time spent in intensities from 0-99 to ≥ 15000 counts per minute) and body mass index in the total sample and in subgroups split by sex and age (median split). The association patterns were comparable across the three axes. For the vertical axis, associations were negative for time spent sedentary (0-99 counts per minute), positive for time spent in lower intensities (100-2999 counts per minute), and negative for time spent in vigorous intensities (4000-12,999 counts per minute). Associations were stronger in older than in younger children and no associations were observed for vigorous intensities among younger children. Association patterns were comparable for boys and girls. In conclusion, we found clear associations with body mass index across the physical activity intensity spectrum in preschool children. However, the age-specific association patterns suggest negative (unfavorable) associations with vigorous physical activity intensities develop around 5-6 years of age.

A comparison of analytical approaches to investigate associations for accelerometry-derived physical activity spectra with health and developmental outcomes in children.

The use of high-resolution physical activity intensity spectra obtained from accelerometry can improve knowledge of associations with health and development beyond the use of traditional summary measures of intensity. The aim of the present study was to compare three different approaches for determining associations for spectrum descriptors of physical activity (the intensity gradient, principal component analysis, and multivariate pattern analysis) with relevant outcomes in children. We used two datasets including physical activity spectrum data (ActiGraph GT3X+) and 1) a cardiometabolic health outcome in 841 schoolchildren and 2) a motor skill outcome in 1081 preschool children. We compared variance explained (R2) and associations with the outcomes for the intensity gradient (slope) across the physical activity spectra, a two-component principal component model describing the physical activity variables, and multivariate pattern analysis using the intensity spectra as the explanatory data matrices. Results were broadly similar for all analytical approaches. Multivariate pattern analysis explained the most variance in both datasets, likely resulting from use of more of the information available from the intensity spectra. Yet, volume and intensity dimensions of physical activity are not easily disentangled and their relative importance may be interpreted differently using different methodology.

Active Learning Norwegian Preschool(er)s (ACTNOW) - Design of a Cluster Randomized Controlled Trial of Staff Professional Development to Promote Physical Activity, Motor Skills, and Cognition in Preschoolers.

INTRODUCTION: There is a dearth of high-quality evidence on effective, sustainable, and scalable interventions to increase physical activity (PA) and concomitant outcomes in preschoolers. Specifically, there is a need to better understand how the preschool context can be used to increase various types of physically active play to promote holistic child development. The implementation of such interventions requires highly competent preschool staffs, however, the competence in promoting PA is often low. The main aim of the ACTNOW study is therefore to investigate the effects of professional development for preschool staffs on child PA and developmental outcomes. METHODS: The study will be conducted in Norway 2019-2022 and is designed as a two-arm (intervention, control) cluster randomized controlled trial (RCT) with 7- and 18-months follow-ups. We aim to recruit 60 preschools and 1,200 3- to 5-years-old children to provide sufficient power to detect effect sizes (ESs) between 0.20 and 0.30. The intervention is nested within two levels: the preschool and the child. Central to the ACTNOW intervention are opportunities for children to engage in a variety of "enriched," meaningful, and enjoyable physically active play that supports the development of the whole child. To this end, the main intervention is a 7-month professional development/education module for preschool staff, aimed to provide them with the necessary capacity to deliver four core PA components to the children (moderate-to-vigorous PA, motor-challenging PA, cognitively engaging play, and physically active learning). We will include a range of child-level outcomes, including PA, physical fitness, adiposity, motor skills, socioemotional health, self-regulation, executive function, and learning. At the preschool level, we will describe implementation and adaptation processes using quantitative and qualitative data. DISCUSSION: Professional development of staff and a whole-child approach that integrates PA with cognitively engaging play and learning activities in the preschool setting may provide a feasible vehicle to enhance both physical and cognitive development in young children. ACTNOW is designed to test this hypothesis to provide a sustainable way to build human capital and provide an early solution to lifelong public health and developmental challenges. CLINICAL TRIAL REGISTRATION: www.ClinicalTrials.gov identifier NCT04048967.

Reproducibility of objectively measured physical activity: Reconsideration needed.

Reliability of accelerometer-determined physical activity (PA), and thus the required length of a monitoring period, appears to depend on the analytic approach used for its calculation. We compared reliability of objectively measured PA using different resolution of data in a sample of 221 Norwegian 2-6-year-old children providing 2-3 valid 14-day periods of accelerometer monitoring (ActiGraph GT3X+) during September-October, January-February, and May-June 2015-2016. Reliability (intra-class correlation [ICC]) was measured for 1-14 days of monitoring across the measurement periods using linear mixed effect modelling. These results were compared to reliability estimated using different resolution of data using the Spearman-Brown formula. The measured reliability improved only marginally with increased monitoring length and levelled off after 5-6 days. Estimated reliability differed substantially when derived from different resolution of data: 3.9-5.4, 6.7-9.2, 13.4-26.7 and 26.3-87.7 days of monitoring was required to achieve an ICC = 0.80 using an hour-by-hour, a day-by-day, a week-by-week and a period-by-period approach, respectively. Reliability could not be correctly estimated from any single resolution of data. We conclude that reconsideration is needed with regard to how reproducibility of objectively measured PA is analysed and interpreted.

Bi-directional prospective associations between objectively measured physical activity and fundamental motor skills in children: a two-year follow-up.

BACKGROUND: The direction of the longitudinal relationship between physical activity (PA) and fundamental motor skills (FMS) remains unclear. We evaluated the bi-directional, prospective relationships between intensity-specific physical activity (PA) and domain-specific fundamental motor skills (FMS) over 2 years in children attending preschool at baseline. METHODS: A sample of 230 children (mean age at baseline 4.7 yr, 52% boys) from the 'Sogn og Fjordane Preschool Physical Activity Study' was measured 2 years apart. PA was assessed using ActiGraph accelerometers (GT3X+). FMS were evaluated by a test battery guided by the 'Test of Gross Motor Development 3' and the 'Preschooler Gross Motor Quality Scale'. PA outcomes were total PA (TPA [counts per minute]) and intensity specific PA and sedentary behaviour (SED) (min/day). FMS outcomes were locomotor, object control, and balance skills. Linear mixed model adjusting for potential co-variates was used to evaluate the bi-directional prospective associations between these variables, including the moderating effect of sex and age. RESULTS: Baseline total PA, moderate-to-vigorous PA (MVPA), and vigorous PA predicted higher locomotor, object control, and balance skills at follow-up (standardized regression coefficient (ß): 0.17 to 0.26, p = 0.002-0.017). Baseline SED predicted lower locomotor skills at follow-up (ß: - 0.27, p = 0.012). Baseline light PA did not predict FMS at follow-up. Baseline FMS were not associated with PA or SED at follow-up. CONCLUSIONS: MVPA was positively associated with development of FMS in young children. In contrast, FMS were not related to future PA levels. Our results suggest promotion of MVPA is important for FMS development in young children.

Boys, older children, and highly active children benefit most from the preschool arena regarding moderate-to-vigorous physical activity: A cross-sectional study of Norwegian preschoolers.

The preschool environment exerts an important influence on children's behaviour, including physical activity (PA). However, information is lacking regarding where and when most of children's PA is undertaken. This study aimed to describe PA and sedentary time (SED) during preschool hours and time out-of-care, and on weekdays and weekend days, and to investigate differences in PA patterns according to sex, age, and MVPA levels. From September 2015 to June 2016, we measured PA levels of 1109 children (age range, 2.7-6.5 years; mean age 4.7 years; boys, 52%) using ActiGraph GT3X+ accelerometers for up to 14 consecutive days. We applied a linear mixed model to analyse associations and interactions between total PA (counts per minute [cpm]), light PA (LPA), moderate-to-vigorous PA (MVPA), SED, sex, age, and overall MVPA regardless of setting, during preschool hours versus time out-of-care, and on weekdays versus weekend days. Children undertook more PA and less SED on weekdays compared to weekend days (p < 0.01). For boys, MVPA levels were higher during preschool hours than during time out-of-care (p < 0.05). Differences in total PA and MVPA between preschool hours versus time out-of-care, and between weekdays and weekend days, were greater in boys, older children, and highly active children than in girls, younger children, and children with lower overall MVPA levels (p < 0.01). The preschool arena is important for children's PA. Concerning MVPA, this study showed that boys, older children, and highly active children benefit more from this environment compared to girls, younger preschoolers, and children with lower MVPA levels.

Physical activity among Norwegian preschoolers varies by sex, age, and season.

BACKGROUND: Knowledge of physical activity (PA) in preschool populations is important for public health promotion. We investigated levels of PA in a large sample of Norwegian preschoolers and explored variations and development in PA by sex, age, and season. METHODS: Physical activity levels of 1154 children (mean age 4.7 years, 52% boys) were measured by accelerometry (ActiGraph GT3X+) for 14 consecutive days between autumn 2015 and summer 2016. Additionally, 330 children provided up to 3 repeated measurements of PA across seasons. A linear mixed model was applied to analyze associations and interactions of total PA (cpm), light PA (LPA), moderate PA (MPA), vigorous PA (VPA), moderate-to-vigorous PA (MVPA), sedentary time (SED), sex, age, and season. RESULTS: Boys and girls spent mean (standard deviation) 72 (21) and 59 (18) min/d in MVPA and had a total PA of 790 (202) and 714 (192) cpm/d, respectively. Boys had higher PA levels than girls, PA increased with age, and PA was higher during spring/summer than autumn/winter (P < 0.001). Boys had a greater increase in PA by age than girls (P < 0.05), mainly due to increased MVPA during spring/summer (p for sex × age × season=0.009). CONCLUSIONS: Boys were consistently more active and less sedentary than girls, and PA increased with age for both sexes. Boys exhibited a greater increase than girls in PA by age, and PA differed across seasons, with higher levels of MVPA during spring/summer. Differences in MVPA between boys and girls, among age groups, and among seasons seem to be interrelated, indicating that many factors influence preschoolers' PA.