In conclusion , very little is known about sedentary behaviors other than screen time in this age group .
Although highly variable , findings suggest that children are already engaging in high levels of screen time by age 2 and the majority exceed current recommendations
Sedentary behavior has negative health outcomes , evident even in young children .
Identifying the prevalence of sedentary behavior in children < 2years is important for determining the necessity for intervention strategies .
The aim of this systematic review was to determine the prevalence of sedentary behavior in children < 2years .
Calibration and validation of the ActiGraph GT3X+ in 2-3 year olds.
OBJECTIVES To calibrate and vali date the ActiGraph GT3X+ to measure sedentary behaviour and physical activity in 2 - 3 year olds , using 5-s epochs ; and to compare the predictive validity of the result ing cut-points with that of NHANES ' , Trost 's , and Pate 's 15-s cut-points . DESIGN Cross-sectional study . METHODS Eighteen children ( 2.86 ± 0.60 years ) wore an ActiGraph GT3X+ during video-recorded semi-structured calibration activity sessions . Activity was coded following Children 's Activity Rating Scale . Receiver Operating Characteristic analysis was used to derive Axis1 and vector magnitude cut-points for sedentary behaviour and moderate-to-vigorous physical activity at 5-s epochs . Agreement with Children 's Activity Rating Scale was assessed with Cohen 's kappa , Lin 's concordance , and Bl and -Altman plots . Predictive validity of all cut-points was assessed in an independent sample of 20 children ( 2.99 ± 0.48 years ) video-recorded during free-play , using the same procedures as the calibration phase . RESULTS During calibration , vector magnitude cut-points ( sedentary behaviour ≤ 96.12 counts ; moderate-to-vigorous physical activity ≥ 361.94 counts ) showed slightly better classification agreement with Children 's Activity Rating Scale than Axis1 cut-points ( sedentary behaviour ≤ 5 counts ; moderate-to-vigorous physical activity ≥ 165 counts ) , but the latter showed the lowest bias in estimated sedentary behaviour and moderate-to-vigorous physical activity time . In the validation sample , 5-s Axis1 cut-points showed the best predictive validity and lowest mean differences of all cut-points between predicted and observed sedentary behaviour ( -2.31 % ) , light physical activity ( -24.40 % ) , and total physical activity time ( -0.95 % ) . Moderate-to-vigorous physical activity time was significantly overestimated by all cut-points ( 128.33 - 184.17 % ) . CONCLUSIONS Because moderate-to-vigorous physical activity was highly overestimated , using only the 5-s Axis1 sedentary behaviour cut-point to distinguish sedentary behaviour from total physical activity is advised . The high accuracy indicates that these cut-points are useful for epidemiological studies involving the sedentary behaviour and physical activity of 2 - 3 year olds
In conclusion , very little is known about sedentary behaviors other than screen time in this age group .
Although highly variable , findings suggest that children are already engaging in high levels of screen time by age 2 and the majority exceed current recommendations
Sedentary behavior has negative health outcomes , evident even in young children .
Identifying the prevalence of sedentary behavior in children < 2years is important for determining the necessity for intervention strategies .
The aim of this systematic review was to determine the prevalence of sedentary behavior in children < 2years .