Physical activity in early childhood: a five-year longitudinal analysis of patterns and correlates.

BACKGROUND: Knowledge on longitudinal patterns and related factors of young children's physical activity (PA) is still scarce. Therefore, the aim of this study was to examine patterns and changes of accelerometer-measured PA over time in two to six-year-old children. Furthermore, the aim was to investigate if parental PA, socioeconomic status, sex, weight status, and motor skills are related to child PA over time, using prospective cohort data from a clustered randomized controlled trial. METHODS: One hundred and six children (52% girls) and their parents had PA measured yearly from age two to six with an Actigraph GT3X. The actigraph was worn on the non-dominant wrist for one week; anthropometric data and motor skills, as well as background information, was collected simultaneously. The outcome was counts per minute from the vector magnitude, and linear mixed-effect models were used to answer the research questions. RESULTS: Among the children, accelerometer-measured PA increased on average by 11% per year from two years of age (mean 3170 cpm (3007-3334 95% CI)) onwards to six years of age (mean 4369 cpm (4207-4533 95% CI)). From three years of age, children were more active on weekdays than on weekend days. The rate of difference varied across low, medium, and highly active children (based on tertiles). No significant differences in weekdays/weekend PA among the lowest active children was found. Despite this, they were still significantly less active on weekend days than the most active children. Maternal, but not paternal PA was found to be significantly positively related to child PA over time, with a medium to large effect size. But no significant relationships were found between child PA and sex, weight status, or socioeconomic status. CONCLUSIONS: PA increased on average with 11% per year, similarly for boys and girls. From three years of age children were more active during weekdays than weekend days. These results indicate that child PA benefits from active stimulation by parents and care takers already from early ages. It is important to identify attributes of possible intervention designs for weekend days for families with young children as well as characterize the least active children. TRIAL REGISTRATION: Early STOPP was prospectively registered in the clinical trials registry: clinicaltrials.gov , ID NCT01198847.

Patterns and correlates of objectively measured physical activity in 3-year-old children.

BACKGROUND: To increase the knowledge about physical activity (PA) patterns and correlates among children under the age of 4, there is a need for study's using objective measurements. The aim of this study was therefore to investigate if objectively measured PA among 3-year-old children differed between day of week and time of day and whether it correlated to child weight status and sex as well as parental weight status and education. METHODS: Totally 61 children (51% girls) aged 3, participating in Early Stockholm Obesity Prevention Project were included. PA was measured with a tri-axial accelerometer (ActiGraph GT3X+) worn on the non-dominant wrist for one week. The main outcome was average PA expressed as counts per minute from the vector magnitude. PA and demographics/family-related factors were collected at baseline and at age 3. To analyze the results simple linear regression, ANOVA and paired t-tests were performed. RESULTS: The mean number of valid days was 6.7 per child. The children were more active on weekdays than weekends (p < 0.01) and the hourly pattern differed over the day with children being most active midmorning and midafternoon (p = 0.0001). Children to parents with low education were more active (p = 0.01) than those with highly educated parents. No differences in PA by child weight status, sex nor parental weight status were found. CONCLUSIONS: PA in 3-year-old children was lower during weekends than weekdays and varied over the day. Boys and girls had similar PA patterns, these patterns were independent of child or parental weight status. Children to parents with low education were more active than their counterparts. The fact that PA differed between weekdays and weekends indicates that PA might be affectable in 3-year-old children.

Sleep and Adiposity in Children From 2 to 6 Years of Age.

OBJECTIVES: To compare sleep in young children at different obesity risks, which were based on parental weight, as well as to explore the longitudinal associations of sleep characteristics with adiposity. METHODS: In total, 107 children from an obesity prevention project were included, of which 43 had normal-weight parents (low obesity risk) and 64 had overweight and/or obese parents (high obesity risk). Sleep was measured yearly from ages 2 to 6 years by using actigraphy. Five sleep characteristics, that of late sleep, long sleep latency, short sleep duration, low sleep efficiency, and irregular sleep onset, were defined and scored across ages, with a higher score indicating more frequent exposure. The outcome variables, also measured yearly, were BMI z score and waist circumference. RESULTS: There was no difference in sleep patterns among children at different risks. Higher short sleep duration score was associated with a greater increase in BMI z score (0.12; 95% confidence interval [CI] 0.01 to 0.25) across ages. Independently of sleep duration, higher late sleep score was associated with greater increases in BMI z score (0.16; 95% CI 0.05 to 0.27) and waist circumference (0.60 cm; 95% CI 0.23 to 0.98). Moreover, compared with children at low risk and without habitual late sleep, children at high risk and with habitual late sleep had greater increases in BMI z score (0.93; 95% CI 0.40 to 1.45) and waist circumference (3.45 cm; 95% CI 1.78 to 5.12). CONCLUSIONS: More frequent exposures to late sleep were associated with greater increases in adiposity measures from ages 2 to 6 years, particularly in children with obese parents.

Development of sleep patterns in children with obese and normal-weight parents.

AIM: To study the sleep development and sleep characteristics in children at different obesity risks, based on parental weight, and also to explore their weekday-weekend sleep variations and associated family factors. METHODS: A total of 145 children participating in a longitudinal obesity prevention project were included, of which 37 had normal-weight parents (low obesity risk), and 108 had overweight/obese parents (high obesity risk). Sleep diaries at ages 1 and 2 years were used to study sleep development in children at different obesity risks. Objectively assessed sleep using an accelerometer at 2 years of age was used to analyse weekday-weekend sleep variations. RESULTS: There was no difference in sleep development from age 1 to age 2 among children at different obesity risks, but more children in the high-risk group had prolonged sleep onset latency and low sleep efficiency. At 2 years of age, children in the high-risk group had more weekday-weekend variation in sleep offset (mean difference 18 min, 95% confidence interval (CI) 4-33 min), midpoint of sleep (mean difference 14 min, 95% CI 3-25 min) and nap onset (mean difference 42 min, 95% CI 10-74 min) than children in the low-risk group, after adjusting for other family factors. However, no difference could be detected between groups in weekday-weekend variation in sleep duration. CONCLUSIONS: Unfavourable sleep characteristics, as well as more variation in sleep schedules, have been observed in children at high obesity risk. While the differences were relatively small, they may reflect the unfavourable sleep hygiene in families at high obesity risk.