Curitiba is the capital of Parana State, located in the
Southern region of Brazil and with a population of more
than 3 million people. The City has increased the green
space area per inhabitant providing public parks and
squares and also has improved the public transport
system by offering bus commuting and bike lanes. As
result, Curitiba has been recognized by the United
Nations as example for good practices related to environmental
sustainability (http://www.un.org/Conferences/
habitat/). The study was carried out with a representative
sample of high school students from the public
schools of Curitiba (N = 42.563). Sample size calculation
was based on the following parameters: sampling
error 3%; estimated prevalence (of physical inactivity)
50%; design effect 1.5; 95% confidence interval; plus
10% for nonresponse, resulting in a sample of 1,718 students
(response rate = 93.2%). To assure representativeness,
a two-stage clustered-proportional sampling strategy
was employed: a) first, the proportion of students
was established according to the number of registered
students in each of the 9 studied geographic areas of the
city; b) then, the proportion of students for each grade