Influência da atividade física e do tempo de tela no desenvolvimento na primeira infância

Abstract

Early childhood is one of the main phases of human development. World estimates suggest that about 80 million children in preschool age did not achieve basic goals related to their development. Considering the influence of movement behaviors on children’s health, some studies indicate that physical activity and screen time may be important predictors of early development. Thus, the objective of the present thesis was to evaluate the association of physical activity and screen time with child development at 48 months of age. To address the aims of the thesis, different methods were used, including a systematic review and secondary data analyses of participants in the 2004 and 2015 Pelotas Birth Cohorts were used. Those studies are part of the Pelotas Birth Cohorts, which are longitudinal studies that have been investigating health outcomes using a life course approach in individuals who were born in Pelotas, Rio Grande do Sul in 1982, 1993, 2004 and 2015. First, a systematic review of the literature about the association between physical activity measured by accelerometers and child development was conducted. This review has shown that physical activity is likely to benefit motor development. However due to the limited number of studies, the evidence of the association between physical activity and for other domains, like cognitive, the associations was inconclusive. Beyond the systematic review, two original articles were developed using secondary da a analyses. The first study investigated the longitudinal associations between device-measured physical activity and childhood neurodevelopment. Accelerometer-based measures of physical activity were collected when children were 12, 24 and 48 months old. Trajectories and cumulative effect analyses indicated a positive dose-response association, indicating that children who engage in more physical activity throughout early childhood present higher neurodevelopment scores at 48 months of age. Lastly, the third study of the thesis had the objective of evaluating the crosssactional and longitudinal associations between different types of screen time and neurodevelopment at 4 years. This paper used data from two Pelotas Birth Cohorts, 2004 and 2015. The results of the study suggest that the mean screen time rose from 3h30min in the 2004 Cohort to 4h30min in the 2015. All associations found were small in magnitude, suggesting that screen time may not be as harmful to childhood neurodevelopment as suggested in previous studies. In conclusion, this thesis has advanced knowledge in two main directions. First, despite the increase in mean screen time at 4 years in the last decade, the magnitude of the associations we found suggest that this effect was very small, indicating that such behavior may not be as harmful as previous hypothesis suggested. The second point is that the physical activity throughout early childhood has positive and consistent effects on neurodevelopment at 4 years. Therefore, policies that stimulate physical activity in this age group are highly recommended.