Atividade física mensurada por acelerometria em crianças de 12 meses: aspectos metodológicos e fatores associados

Abstract

The physical activity practice influences current and future health. Despite this knowledge, studies that address physical activity practice in younger children are still scarce, mainly because of the mistaken notion that very young children are naturally physically active. Thus, there is a growing need to measure young children’s physical activity through reliable methods that contemplate the complexity of this behavior, and accelerometers have been established as the most appropriate method for this purpose. In this context, a systematic review of the literature was carried out, gathering studies on physical activity measured by accelerometry in healthy children, aged up to three years, focusing on the methods applied and outcomes presented. Of the 4971 studies identified, 30 were included in the review. The descriptive results of the studies demonstrated that total physical activity ranged from 118 to 223.3 minutes per day, while light physical activity ranged from 17.5 to 411.8 minutes. Moderate to vigorous physical activity showed larger variability among the results, varying from 3.1 to 192 minutes per day. Further research is advocated to seek methodological comparability, and age-appropriate analysis is required to a better understanding of the physical activity behavior among infants and toddlers. Based on this knowledge, a protocol study was carried out among children from 9 to 15 months of age, aiming to determine the most appropriate physical activity measurement methods using accelerometry, including the minimum number of days of measurement required, best placement (wrist or ankle) and acceptance of the device. The results demonstrated that two and three days of measurement with the accelerometer placed on the wrist and ankle, respectively, can adequately represent a week of measurement. The qualitative evaluation indicated that the accelerometer placed on the wrist was better accepted by the children and mothers. Finally, based on the results of the protocol study, the 12-months follow-up of the 2015 birth cohort described the objectively assessed physical activity and its determinants in this population. The data were collected through a wrist mounted accelerometer (ActiGraph, wGT3X-BT), in a protocol of 24 hours for two days, with 15 seconds epoch length. The children spent an average of 19 hours per day below 50mg of acceleration, with girls spending an average of 10 minutes more than the boys in this intensity pattern, and on average 1.2 minutes less than the boys in the categories of greater intensity. Maternal physical activity during pregnancy, sex, motor development, and current paternal physical activity were associated with physical activity in children.