BackgroundGiven the rapid development during the early years (0-4 years), an understanding of the health implications of physical activity is needed. The purpose of this systematic review was to examine the relationships between objectively and subjectively measured physical activity and health indicators in the early years.MethodsElectronic databases were originally searched in April, 2016. Included studies needed to be peer-reviewed, written in English or French, and meet a priori study criteria. The population was apparently healthy children aged 1 month to 59.99 months/4.99 years. The intervention/exposure was objectively and subjectively measured physical activity. The comparator was various volumes, durations, frequencies, patterns, types, and intensities of physical activity. The outcomes were health indicators ranked as critical (adiposity, motor development, psychosocial health, cognitive development, fitness) and important (bone and skeletal health, cardiometabolic health, and risks/harm). The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) framework was used to assess the quality of evidence for each health indicator by each study design.ResultsNinety-six studies representing 71,291 unique participants from 36 countries were included. Physical activity interventions were consistently (>60% of studies) associated with improved motor and cognitive development, and psychosocial and cardiometabolic health. Across observational studies, physical activity was consistently associated with favourable motor development, fitness, and bone and skeletal health. For intensity, light- and moderate-intensity physical activity were not consistently associated with any health indicators, whereas moderate- to vigorous-intensity, vigorous-intensity, and total physical activity were consistently favourably associated with multiple health indicators. Across study designs, consistent favourable associations with health indicators were observed for a variety of types of physical activity, including active play, aerobic, dance, prone position (infants; ≤1 year), and structured/organized. Apart from ≥30 min/day of the prone position for infants, the most favourable frequency and duration of physical activity was unclear. However, more physical activity appeared better for health. Evidence ranged from “very low” to “high” quality.ConclusionsSpecific types of physical activity, total physical activity, and physical activity of at least moderate- to vigorous-intensity were consistently favourably associated with multiple health indicators. The majority of evidence was in preschool-aged children (3-4 years). Findings will inform evidence-based guidelines.Electronic supplementary materialThe online version of this article (10.1186/s12889-017-4860-0) contains supplementary material, which is available to authorized users.

CONTEXT: The World Health Organization recommends tummy time for infants because of the benefits of improved motor development and reduced likelihood of plagiocephaly. Because of poor uptake of these recommendations, the association of tummy time with other health outcomes requires further investigation.OBJECTIVE: To review existing evidence regarding the association of tummy time with a broad and specific range of infant health outcomes.

Background The World Health Organization recommends 30 min of tummy time daily for improved motor development and reduced likelihood of plagiocephaly. As only 30% of infants meet this recommendation, parents require strategies and support to increase this proportion. Methods The aim of this study was to determine the feasibility, acceptability, and potential efficacy of a group intervention to promote tummy time. The design is a cluster randomized controlled trial with concealed allocation, assessor blinding, and intention-to-treat analysis. Five groups of healthy infants (N = 35, baseline mean (SD) age 5.9 (2.8) weeks) and their mothers attending local mother’s groups (Australia) were randomly allocated to the intervention or control group. The intervention group received group tummy time classes in addition to usual care. The control group received usual care with their child and family health nurse. Primary outcomes were intervention feasibility and acceptability. Secondary outcomes were tummy time duration (accelerometry), adherence to physical activity guidelines, head shape, and motor development. Measures were taken at baseline, post-intervention, and when infants were 6 months of age. Analyses were by linear mixed models and Cohen’s d statistic. Results Recruitment, retention, and collection of objective data met feasibility targets. Acceptability was also met with intervention mothers reporting the information, goal planning, and handouts significantly more useful and relevant than control group mothers (p < 0.01). Moderate effect sizes were also found at post-intervention for tummy time duration, adherence to physical activity guidelines and infant ability in prone and supine favoring the intervention group (intervention infants had a mean of 30 min and 30% adherence to guidelines (95% CI 0 to 60.6 min) compared to the control infants who had a mean of 16.6 min and 13% adherence to the guidelines (95% CI 0 to 42.1 min, Cohen’s d = 0.5). Limitations were the small sample size, 4-week intervention, limited accelerometer use, and a homogenous sample of participants. Conclusion Group tummy time classes delivered in a mother’s group setting were shown to be feasible and acceptable. A larger randomized controlled trial is warranted. Trial registration ANZCTR, ACTRN12617001298303p. Registered 11 September 2017