Historically, society has thought that infants (0 to 1 year of age) are “active enough” and not in need of efforts to promote physical activity (PA). However, approximately 10% of infants in the U.S. are obese and research has shown low PA is one of the risk factors for obesity in toddlers. Little research has been done to systematically compare PA levels between normal weight infants and obese/overweight infants in the first year of life. PURPOSE: The purpose of this study was to determine the level of PA in normal weight and overweight infants. METHODS: Twenty-one normal weight infants (age = 3.0 ± 0.4 month, weight-for-length z-score 50.6 ± 25.0) and nine overweight infants (age = 3.0 ± 0.4 month, weight-for-length z-score 97.4 ± 2.1) were recruited to participate in the study. Anthropometric measurements (e.g., height, weight) were taken at three different time points to determine infant size: 3-months of age, the onset of sitting, and one month post onset of sitting. Additionally, infant PA was assessed using Actigraph GT9X Link accelerometers at each time point. Infants wore two accelerometers on the left wrist and ankle for 4 consecutive days (2 weekdays, 2 weekend days). Caregivers were asked to complete a time activity diary every day the accelerometer was worn to document infant activity (e.g., sleeping, eating, quiet/active play) and infant location (e.g., daycare, home). Combined average ankle and wrist vector magnitude count (VMC) values were used as PA indicator. Statistical analyses were performed using two factor repeated measures (group x time) ANOVA between normal weight and overweight/obese infant. RESULTS: VMC values for the visits were: 1st visit=5486574, 2nd visit=5726418, and 3rd visit=5432360 for normal weight infants and 1st visit=5628067, 2nd visit=5743573, and 3rd visit=5103728 for overweight infants. There was no significant main effects of weight (F(1, 28)=.004, p=.948) and time (F(2,28)=.271, p=.765) and no significant interaction (F(2,28)=.413, p=.665) was found between group x time. Conclusion: Efforts are needed to quantify infant activity level in order to identify infants who may be at risk for developmental delay. Further research should employ larger samples in order to acquire more variation in PA level and other interested outcomes such as breastfed and formula-fed infants.
Available at: http://works.bepress.com/danae-dinkel/16/