Active commuting to elementary school and adiposity: an observational study.
BACKGROUND
Active commuting to school (ACS; walking or cycling to school) appears promising for decreasing children's obesity risk, although long-term studies are sparse. The aim was to examine whether kindergarten ACS was associated with fifth-grade adiposity.


METHODS
This study was a secondary analysis of the Early Childhood Longitudinal Study, Kindergarten (n=7938). Enrollment in kindergarten (1998-1999) was nationally representative of the United States and follow-up occurred in 2004. Kindergarten ACS was the main exposure variable and fifth-grade BMI z-score was the main outcome measure. Covariates included (1) neighborhood safety and BMI z-score in kindergarten and (2) demographics (i.e., age, gender, race/ethnicity, socioeconomic status, single- vs. two-parent households, region of country, and urbanicity in fifth grade). Three interactions were included: school travel*neighborhood safety; school travel*BMI z-score (kindergarten); and school travel*socioeconomic status. Analysis of covariance accounted for the complex sampling design.


RESULTS
Kindergarten ACS was associated with lower BMI z-score in fifth grade. The interaction of school travel*neighborhood safety indicated that children from less-safe neighborhoods who did ACS in kindergarten had a lower fifth-grade BMI z-score (p<0.05) than their peers who did not do ACS in kindergarten (i.e., in terms of BMI, this difference was -0.49 kg/m(2) for children of average height in less-safe neighborhoods).


CONCLUSIONS
Among children from less-safe neighborhoods, kindergarten ACS independently predicted lower BMI z-score in fifth grade among a national US cohort. Interventions and policies to increase ACS among young children, especially from unsafe neighborhoods, are warranted and should address parents' safety concerns.
1 USDA/ARS Children's Nutrition Research Center, Baylor College of Medicine , Houston, TX.
Jason A
JA
Mendoza
Yan
Y
Liu
D050154:Adiposity; D001642:Bicycling; D015992:Body Mass Index; D002648:Child; D002669:Child Welfare; D002675:Child, Preschool; D004779:Environment Design; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D010290:Parents / Q000523:psychology; D011050:Policy Making; D012111:Residence Characteristics; D012307:Risk Factors; D012449:Safety; D012574:Schools; D013997:Time Factors; D014186:Transportation / Q000379:methods*; D014481:United States; D016138:Walking