Background
An ever-growing evidence-base documents relationships between levels of land use mix, street connectivity, and density where people live and self-reported levels of walking in the general population. Research also documents relationships between these same measures of urban form and self-reported and objectively measured levels of physical activity in the general population. However, to date, little evidence exists on the relationships between the built environment and activity patterns among youth.
Methods
Data from 3,161 youth collected by the SMARTRAQ household travel survey in the Atlanta region in 2001 were analyzed. Self-reported travel data was captured in a diary over a two-day period for youth between five- and 20-years of age. Socio-demographic and attitudinal information was provided by a head of household in a recruitment call through the use of a computer aided telephone interview protocol. A legal guardian filled out surveys for youth aged 14-years and younger. Data collection was stratified across four ranges of income and household size and five levels of residential density to ensure a variation in socio-demographics and urban form across observations. A representative sample was achieved through focused recruitment in ethnic minority locations.
Urban form measures of mixed use, street connectivity and density were developed within a one-kilometer street network distance from the place of residence for each of the households in the survey using parcel level land use, census, and street network data. Three dichotomous dependent variables were created. Daily walking versus not at all, distance walked of half a mile or more and of a mile or more. Each environmental variable – intersection density (tertiles), household density (tertiles), land use mix (greater than zero), presence of commercial sites (greater than zero), vacant sites (greater than zero), and recreation and open spaces (greater than zero) – was explored in a separate logistic regression model controlling for age, gender, ethnicity, income, household size and car ownership.
Results
Half of the sample was female, 38% was non-white, 20% had a household income less than $30,000, 36% were in a household with less than four inhabitants and 4.8% had no car. Fourteen percent of the sample walked at least once a day and 6% walked at least half a mile per day. Odds ratios (ORs) and 95% confidence intervals (CIs) are presented for the strongest dependent variable; walked a half a mile or more. Children aged 12 to 15 (OR 1.79, 95% CI 1.15-2.79) and aged 16 to 20 (OR 1.81, 95% CI 1.15-2.83) were significantly (p=.01) more likely to walk half a mile than children aged five- to eight-years old. Non whites (OR 1.88, 95% CI 1.38-2.56) were significantly (p=.001) more likely to walk a half a mile, as were those in households of less than four people (OR 1.72, 95% CI 1.27-2.35), and those with household incomes of less than $30,000 compared to those with household incomes of $60,000 or more (OR 2.97, 95% CI 2.08-4.25). Those with no car (OR 6.77, 95% CI 4.01-11.4) or one car (OR 2.17, 95% CI 1.37-3.45) were significantly more likely to walk than those with three cars per household. After adjustment for these socio-demographic variables the most important urban form predictor of walking was household density, with those in the top tertile more likely to walk than those in the bottom tertile (OR 2.68, 95% CI 1.65-4.34). Land use mix was also a significant predictor (OR 1.92, 95% CI 1.30-2.82), followed by intersection density; those in the top tertile walking more than those in the bottom tertile (OR 1.83, 95% CI 1.22-2.74). Having recreation facilities and open space was also significantly related to walking (OR 2.17, 95% CI 1.57-2.99), as was presence of commercial land use (OR 1.82, 95% CI 1.24-2.66).
Conclusions
Both socio-demographic and urban form factors play an important role in predicting the likelihood that youth will walk a half a mile per day on average. Relationships between urban form and physical activity behavior seen in adults are also apparent in youth aged five to 20. Household density was particularly important, as was availability of recreational space; however land use mix and street connectivity were also significant. Walking a distance of a half a mile was more closely related to urban form than whether or not youth walked at all or walked more than one mile. Further analyses should explore the strengths of these associations across the different sub-age groups in youth and across income, ethnicity, vehicle ownership and household size. The results presented offer some insight into how both urban form and demographic characteristics associate with walking for youth.
