Background/Purpose: Childhood obesity is now a global epidemic and it is unlikely that medical intervention alone can resolve this issue. A logical step in the reduction of childhood obesity prevalence is to prevent it in the first place. Once an infant become obese, there is a 40% risk of remaining obese throughout early childhood. One behavior consistently overlooked is infant physical activity (PA). To date, there is a paucity of PA research during infancy including whether the behavior is modifiable. Therefore, the purpose of this study was to determine the developmental trajectory of PA during the first six months of life.
Method: Twenty-seven infants aged 1-6 months participated in this longitudinal study. Infant PA was measured once monthly during a 24hr period using an accelerometer worn on the ankle. A comprehensive log was completed by the mother to assist with data reduction.
Analysis/Results: A linear mixed-effects modeling approach was used to examine the developmental trajectory of PA during infancy. There is a significant accelerating linear trend of PA from 1-6 months (R2=0.845). With every 1 month increase in time, the expected increase in PA is 23.4 counts per minute (p=0.020).
Conclusions: The developmental trajectory of PA during infancy increased steadily each month from 1-6 months of age. Future research should focus on determining if PA in infancy is modifiable. If so, this knowledge can be used to develop effective interventions for infants at risk for childhood obesity as well as generate healthy PA recommendations for infants.