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Perception of the social and built environment and physical activity among Northeastern Brazil adolescents
Preventive Medicine 52 (2011) 114–119
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Preventive Medicine j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / y p m e d
Perception of the social and built environment and physical activity among Northeastern Brazil adolescents José Cazuza de Farias Júnior a,⁎, Adair da Silva Lopes b, Jorge Mota c, Maria Paula Santos c, José Carlos Ribeiro c, Pedro Curi Hallal d a
Federal University of Paraiba – UFPB/CCS/DEF, Brazil Federal University of Santa Catarina – DEF/CDS/UFSC, Brazil Research Centre in Physical Activity Health and Leisure, University of Porto, Portugal d Federal University of Pelotas – UFPel, Brazil b c
a r t i c l e
i n f o
Available online 10 December 2010 Keywords: Physical activity Environmental Adolescent Perception Facilities
a b s t r a c t Objective. To evaluate the association between levels of physical activity and perception of the social and built environmental in adolescents from Northeastern Brazil. Methods. The sample comprised 2874 adolescents aged 14 to 19 years (57.8% females) enrolled in private or public secondary schools in the municipality of João Pessoa, Northeastern Brazil. Level of physical activity was measured by questionnaire. Perception of environmental characteristics was measured by means of fifteen questions rated on four-point Likert-type scales ranging from 1 (“strongly disagree”) to 4 (“strongly agree”). The association between physical activity and perception of environmental characteristics was investigated using multivariate binary logistic regression. Results. Multivariate analysis showed that adolescents living in neighborhoods where other adolescents were physically active (68.7% vs. 60.1%, OR = 1.20; 95%CI: 1.05–1.56, among boys only) or who lived close to places they liked to frequent (71.8% vs. 53.4%, OR = 1.96; 95%CI: 1.40–2.78 among boys; and 42.0% vs. 32.3% OR = 1.33; 95%CI: 1.10–1.74 among girls) were more likely to be physically active. Conclusions. Adolescents with positive perceptions of certain environmental characteristics were more likely to be physically active. Environmental characteristics may relate differently to levels of physical activity among boys and girls. Published by Elsevier Inc.
Introduction Increasing levels of physical activity among adolescents is regarded as a public health priority. Reasons for this include the high prevalence of insufficient physical activity among this population (Currie et al., 2008; Sisson and Katzmarzyk, 2008; Tenório et al., 2010), the health hazards associated with physical inactivity (Strong et al., 2005), and the possibility of tracking of physical activity habits adopted during adolescence to adult life (Gordon-Larsen et al., 2004). To identify and to better understand the factors that influence the adolescent's choices in terms of physical activity are considered to be essential prerequisites for planning and implementing intervention programs targeting physical activity, especially if these measures are to be effective and to promote long-term changes (Davison and Lawson, 2006; Deforche et al., 2010; Haerens et al., 2009).
⁎ Corresponding author. Universidade Federal da Paraíba, Departamento de Educação Física, Campus I, Cidade Universitária, CEP: 58059-900 – João Pessoa, PB, Brazil. E-mail address: [email protected] (J.C. de Farias Júnior). 0091-7435/$ – see front matter. Published by Elsevier Inc. doi:10.1016/j.ypmed.2010.12.002
Systematic reviews in the literature show that physical activity during adolescence is associated with factors pertaining to different analytical levels — the individual level, comprising subject-related variables (self-efficacy, attitudes, pleasure, beliefs); and the environmental level, comprising variables related to physical and social environment (presence of facilities, safety, esthetics and infrastructure, social support) (Biddle et al., 2005; Ferreira et al., 2006; van Der Horst et al., 2007). However, considering that subject-related variables (such as selfefficacy, and attitude) account for only a small fraction of the variance in levels of physical activity among adolescents (Haerens et al., 2009; Lee et al., 2009), that physical activity takes place in specific environments (Mota et al., 2009), and that studies have shown that attributes of the environment are associated physical activity among adolescents (Dowda et al., 2007; Norman et al., 2006; Pate et al., 2008), it is assumed that environmental variables will play an important role in modulating the levels of physical activity. Identifying environmental variables associated with physical activity is important given that changes in these variables may affect a large number of individuals for a long time, rather than having only a short-term impact (Giles-Corti et al., 2005; Mota et al., 2005; Davison
J.C. de Farias Júnior et al. / Preventive Medicine 52 (2011) 114–119
and Lawson, 2006; Ferreira et al., 2006). In spite of the increasing body of studies addressing the relationship between environment and physical activity levels, the number of such studies carried out in low and middle-income countries such as Brazil is still extremely limited. The studies available in the literature analyzed environmental characteristics associated with physical activity in parks (Reis et al., 2009) or barriers to the practice of physical activity (Santos et al., 2010), but none of them analyzed the different attributes of the neighborhood of residence and levels of physical activity among adolescents. This study investigates the association between levels of physical activity and perception of the social and built environmental in adolescents from Northeastern Brazil. Methods The target population comprised adolescents aged 14–19 years, enrolled in public and private secondary schools in the municipality of João Pessoa, Northeastern Brazil. Sampling was carried out using a clustered strategy in two stages (schools and classes), with probability proportional to size (number of students enrolled). Initially, we allocated each of the 82 schools into the municipality's four regions (North, South, East, and West), separately by type (public and private). We then systematically selected 30 schools (16 public and 14 private), distributed proportionally among the four regions (North, South, East, and West). In the second stage, we randomly selected secondary education classes (n = 135), distributed proportionally by shift (day [morning or afternoon] and night) and grade (1st, 2nd, and 3rd grades of secondary school). In both stages, distributions were proportional to those of the target population. The number of classes to be drawn in each school was determined by dividing the number of students to be recruited from each grade by 20 (the mean number of students we expected to obtain in each class). Adolescents who failed to return the term of consent filled out and signed by a parent or caregiver (b 18 years old), refused to take part in the study, or were absent from class at the day of collection were considered as losses. Replacement was not allowed in order to prevent selection bias. Initially, 3477 adolescents were selected to take part in the survey. Of these, 70 either refused or were not authorized by their parents/caregivers to participate in the survey, and 187 were absent from school on the day of data collection. Of the 3220 adolescents who responded to the questionnaire, 271 were excluded for being b 14 or N 19 years of age, 65 did not report their age, 5 had some form of handicap, and 5 left several questions unanswered. The final sample included 2874 subjects. Data collection took place between May and September 2009 (mean temperature 26 °C, tropical humid climate) and was carried out by a previously trained team, supervised by the head researcher. Questionnaires were filled out anonymously by the adolescents themselves, while in the classroom, according to instructions provided by one of the interviewers. Adolescents answered questions on sociodemographic characteristics (sex, age, skin color [black, white, mixed, Asian, Amerindian], occupation [working, not working], time of residence in the neighborhood [years:months], type of school, [public and private] schooling of mother and father [illiterate, up to 3rd grade elementary, 4th grade elementary, incomplete elementary, complete elementary, incomplete secondary, complete secondary, incomplete tertiary, complete tertiary], and economic class — determined according to the criterion of the Brazilian Association of Research Companies (ABEP, 2009) which group subjects into the following economic classes: A1 [richest], A2, B1, B2, C1, C2, D, and E [poorest], based on a score combining ownership of assets, schooling of head of household, and number of employees in the household). Adolescents also answered questions on the physical activities they practiced and on their perception of the environment/neighborhood. All measures of independent variables showed satisfactory levels of reproducibility, with kappa values ranging from 0.89 (economic class) to 0.93 (mother's and father's schooling) in replicate administrations of the questionnaire with a one-week interval. Physical activity was measured by questionnaire using an instrument previously tested on a sample of subjects that did not take part in the main survey (reproducibility — ICC = 0.88; 95% CI: 0.84–0.91; validity: Spearman's rho = 0.62; p b 0.01; kappa = 0.59, comparing the results of four 24-hour physical activity recalls). Adolescents informed the frequency (days/week) and duration (h:min/day) of physical activities performed in the week
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preceding the interview based on a list of 24 moderate to vigorous physical activities (sports, dance, martial arts, walking, jogging, cycling, strength training, active commuting, and outdoor games). The level of physical activity was calculated as the sum of the products of time spent on each physical activity (min/day) by their respective frequencies (days/week). Adolescents displaying levels of physical activity equal to or greater than 300 min/week were classified as “sufficiently active,” whereas the remainder were classified as “insufficiently active” (Biddle et al., 1998). Environmental characteristics were measured subjectively using a 15item questionnaire that including questions on: i) accessibility of destinations and facilities, 7 items; ii) infrastructure/esthetics, 4 items; and iii) safety, 4 items, extracted and adapted from other instruments (Saelens et al., 2003; Evenson and McGinn, 2005; Hume et al., 2006). The instruments were previously tested and showed satisfactory reproducibility (intra-class correlation coefficients (ICC) for different items ranging from 0.56 to 0.82, with a one-week interval between measurements) and internal consistency (α = 0.72, neighborhood scale). When responding to questions on the characteristics of the environment, adolescents were oriented to consider as close to their residences any place within a ten-minute walking range (Hume et al., 2006). All items were measured using a four-point Likert-type scale anchored at 1 “strongly disagree” and 4 “strongly agree.” For analysis purposes, responses were dichotomized into disagree (strongly disagree, disagree = “negative perception”) and agree (strongly agree, agree = “positive perception”). To compare the proportion of adolescents showing sufficient levels of physical activity in groups with positive or negative perception of the environment, we used chi-squared tests. Logistic regression was used to evaluate the unadjusted association between level of physical activity (dependent variable: b 300 min/week = 0 and ¡ N 300 min/week = 1) and each attribute of the perceived environment (independent variable(s): “negative perception” = 0 and “positive perception” = 1). In adjusted analysis, all variables were included in the model, and those with a p value b 0.20 were retained in the final model. The following potential confounders were included in the adjusted model: age, time of residence in the neighborhood, economic class, type of school (public or private), and father's and mother's schooling. Backward selection was employed. All analyses were stratified by sex. Before performing the adjusted analyses we ran tests for collinearity among the potential confounders, but none of them suggested high levels of multicollinearity. It is worth mentioning that although type of school and economic class are associated, they do not mean the same thing, which is why collinearity between these two variables is not a problem in these models. In Northeastern Brazil, there are many adolescents who belong to middle and low socioeconomic levels and study in private schools. Furthermore, the variables associated with physical activity were the same in the analyses with and without adjustment for type of school. Statistical analyses were carried out using Stata 10.1 software, and took into account the sampling strategy (cluster sampling). We adopted a 5% significance level. The study protocol was approved by the Research Ethics Committee of the Federal Univeristy of Paraíba.
Results The final sample comprised 2874 adolescents (mean age = 16.5; SD = 1.2; 57.8% female). The majority of adolescents were aged between 16 and 19 years (89.3%), did not work (86.9%), and came from the intermediate (46.1%) or lower (8.1%) economic classes (Table 1). Roughly half of the adolescents fulfilled the recommended 60 min per day of moderate or vigorous physical activity (50.2%; 95% CI: 47.3– 53.1). Boys were more physically active than girls (66.3% vs. 38.5%; p b 0.01; data not shown in tables). The proportion of adolescents fulfilling current physical activity recommendations was greater among those with positive perception of certain environmental characteristics (boys: places where I can practice of physical activities are well maintained, 69.8% vs. 63.3%; I frequently see other adolescents practicing physical activities, 68.7% vs. 60.1%; the neighborhood offers many opportunities for practicing physical activities, 70.0% vs. 62.7%; there are several places I like to frequent near my home, 71.8% vs. 53.7%; girls: there are bicycle lanes
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Table 1 Characteristics of the sample, João Pessoa, Northeastern Brazil, 2009. Variable
Age (years) 14–15 16–17 18–19 Skin color Mixed Black White Other Working Yes No Type of school Public Private Economic classa A (best) B C D,E (worst) Father's schooling Incomplete elementary Complete elementary Complete secondary Complete tertiary Mother's schooling Incomplete elementary Complete elementary Complete secondary Complete tertiary a
Male
Female
n
%
453 612 141
37.6 50.8 11.6
636 87 368 107
n
All %
n
%
671 817 165
40.6 49.4 10.0
1128 1438 308
10.7 50.0 39.3
53.1 7.3 30.7 8.9
846 74 561 165
51.4 4.5 34.1 10.0
1491 163 930 275
52.2 5.7 32.5 9.6
194 981
16.5 83.5
170 1443
10.5 89.5
366 2436
13.1 86.9
822 384
68.2 31.8
1189 464
71.9 28.1
2011 848
70.3 29.7
119 416 446 76
11.3 39.4 42.1 7.2
117 506 717 127
8.0 34.4 48.9 8.7
237 924 1167 205
9.3 36.5 46.1 8.1
309 233 402 229
26.3 19.9 34.3 19.5
563 279 491 266
35.2 17.5 30.7 16.6
877 514 895 497
31.5 18.5 32.2 17.8
309 221 399 266
25.9 18.5 33.4 22.2
538 315 502 283
32.8 19.2 30.6 17.4
853 538 906 550
30.0 18.9 31.8 19.3
istics associated with the outcome were exclusive to either boys or girls (Table 2). Tables 3 and 4 present the results of crude and adjusted analysis of the association of environmental characteristics with physical activity among male and female adolescents. Among boys, in crude analysis, there was a significant association between level of physical activity and the following environmental characteristics: places for physical activity are well maintained (OR = 1.34; 95%CI: 1.03–1.75), I frequently see other adolescents practicing physical activities (OR = 1.46; 95%CI: 1.13–1.88), environment offers many opportunities to practice physical activities (OR = 1.39; 95% CI: 1.05–1.85), there are several different places I like to frequent near my house (OR = 2.19; 95% CI: 1.58–3.03). Among girls the environmental characteristics associated with physical activity levels were: I frequently see other adolescents practicing physical activities (OR = 1.25; 95% CI: 1.02–1.53), I see interesting things when I walk or ride a bicycle on the streets (OR = 1.40; 95% CI: 1.15–1.70), there are several different places I like to frequent near my house (OR = 1.52; 95% CI: 1.20–1.91), it is safe to ride a bicycle on the streets around my house (OR = 1.29; 95% CI: 1.01–1.65). In adjusted analysis (for age, economic class, father's and mother's schooling, time at present address, type of school), the perceived characteristics of the environment that remained associated with levels of physical activity were: seeing other adolescents practicing physical activities, among boys (OR = 1.20; 95% CI: 1.05–1.56), and presence of places the adolescent liked to frequent near home, for both sexes (boys: OR = 1.96; 95% CI: 1.40–2.78; girls: OR = 1.33; 95% CI: 1.10–1.74).
Variable with the highest number of nonresponders, n = 341 (11.9%).
Discussion or places where I can ride a bicycle, 42.4% vs. 37.0%; I frequently see other adolescents practicing physical activities, 40.3% vs. 35.1%; There are places for practicing physical activities, 40.4% vs. 36.0%; I see many interesting things while I walk or ride a bicycle, 41.8% vs. 33.9%; There are several places I like to frequent near my home, 42.0 vs. 32.3%; Riding a bicycle in the streets around my house is not safe because of street traffic, 40.1% vs. 35.6%). Almost all environmental character-
Our results indicate that adolescents with positive perception of certain environmental characteristics (presence of places they liked to frequent near home and frequently seeing other adolescents being physically active) were more likely to be physically active. Environmental characteristics may relate differently to levels of physical activity among boys and girls.
Table 2 Proportion of adolescent students that reached current recommended levels of physical activity according to perceived environment, João Pessoa, Northeastern Brazil, 2009. Characteristics of the social and built environment (neighborhood)
There are sidewalks on most streets Sidewalks are narrow and full of holes/obstaclesc Places where I can practice of physical activities are well maintained The neighborhood is polluted, with open sewage, garbage and debris on the streetsc There are bicycle lanes or places where I can ride a bicycle I frequently see other adolescents practicing physical activities. There are places for practicing physical activities (parks, squares, courts, fields, etc.) The neighborhood offers many opportunities for practicing physical activities Places proper for physical activity are close to my home I see many interesting things while I walk or ride a bicycle There are several places I like to frequent near my home Walking or jogging in the streets around my house is not safe because of street trafficc Riding a bicycle in the streets around my house is not safe because of street trafficc Places where I can practice physical activities are not safec The neighborhood is violent, with a lot of muggings, crime, and drugsc ⁎⁎⁎ Chi-squared test for heterogeneity. a Negative perception (strongly disagree, disagree). b Positive perception (strongly agree, agree). c Variables with inverted response scales.
p⁎⁎⁎
Males Negative perceptiona
Positive perceptionb
70.1 66.3 63.3 68.4
65.0 66.3 69.8 65.4
66.6 60.1 65.0
p⁎⁎⁎
Females Negative perceptiona
Positive perceptionb
0.28 0.10 0.03 0.26
37.6 36.7 37.1 37.8
38.9 39.8 40.3 38.7
0.60 0.14 0.30 0.73
65.4 68.7 66.9
0.72 0.01 0.48
37.0 35.1 36.0
42.4 40.3 40.4
0.05 0.03 0.01
62.7
70.0
0.02
36.3
41.2
0.07
64.4 63.8 53.7 64.3
67.0 67.8 71.8 67.5
0.45 0.13 b0.01 0.32
36.8 33.9 32.3 35.8
39.4 41.8 42.0 40.3
0.26 b 0.01 b 0.01 0.10
63.6
67.8
0.20
35.6
40.1
0.04
64.7 68.2
67.8 65.6
0.19 0.30
36.8 37.0
40.3 39.8
0.22 0.25
J.C. de Farias Júnior et al. / Preventive Medicine 52 (2011) 114–119 Table 3 Crude and adjusteda analysis of the association between measures of perceived environment and level of physical activity among adolescent students, João Pessoa, Northeastern Brazil, 2009 — males. Characteristics of the social and built environment (neighborhood)b
There are sidewalks on most streets Sidewalks are narrow and full of holes/obstaclesc Places where I can practice of physical activities are well maintained The neighborhood is polluted, with open sewage, garbage and debris on the streetsc There are bicycle lanes or places where I can ride a bicycle I frequently see other adolescents practicing physical activities. There are places for practicing physical activities (parks, squares, courts, fields, etc.) The neighborhood offers many opportunities for practicing physical activities Places proper for physical activity are close to my home I see many interesting things while I walk or ride a bicycle There are several places I like to frequent near my home Walking or jogging in the streets around my house is not safe because of street trafficc Riding a bicycle in the streets around my house is not safe because of street trafficc Places where I can practice physical activities are not safec The neighborhood is violent, with a lot of muggings, crime, and drugsc
Level of physical activity (b 300 min/ week = 0 and ≥ 300 min/week = 1) n
ORc
95% CI
1205 1186
0.79 1.00
0.52–1.21 0.78–1.28
1202
1.34
1.03–1.75
1194
0.87
0.69–1.11
1195
0.95
0.69–1.29
1199
1.46
1.13–1.88
1197
1.09
0.85–1.39
1199
1.39
1.05–1.85
1197
1.09
0.85–1.39
1197
1.19
0.95–1.51
1197
2.19
1.58–3.03
1199
1.15
0.86–1.54
1196
1.21
0.90–1.62
1194
1.15
0.95–1.39
1191
0.89
0.72–1.11
ORa
1.20
1.26
1.96
Table 4 Crude and adjusteda analysis of the association between measures of perceived environment and level of physical activity among adolescent students, João Pessoa, Northeastern Brazil, 2009 — females. Characteristics of the social and built environment (neighborhood)b
95% CI
1.05–1.56
0.95–1.70
1.40–2.78
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There are sidewalks on most streets Sidewalks are narrow and full of holes/obstaclesc Places where I can practice of physical activities are well maintained The neighborhood is polluted, with open sewage, garbage and debris on the streetsc There are bicycle lanes or places where I can ride a bicycle I frequently see other adolescents practicing physical activities. There are places for practicing physical activities (parks, squares, courts, fields, etc.) The neighborhood offers many opportunities for practicing physical activities Places proper for physical activity are close to my home I see many interesting things while I walk or ride a bicycle There are several places I like to frequent near my home Walking or jogging in the streets around my house is not safe because of street trafficc Riding a bicycle in the streets around my house is not safe because of street trafficc Places where I can practice physical activities are not safec The neighborhood is violent, with a lot of muggings, crime, and drugsc
Level of physical activity (b 300 min/ week = 0 and ≥ 300 min/week = 1) n
ORc
95%CI
1650 1630
1.05 1.14
0.86–1.30 0.96–1.36
ORa
95%CI
1646
1.14
0.88–1.48
1622
1.04
0.83–1.31
1627
1.25
1.00–1.57
1636
1.25
1.02–1.53
1.18
0.93–1.51
1615
1.20
0.96–1.51
1638
1.23
0.98–1.55
1644
1.12
0.92–1.35
1637
1.40
1.15–1.70
1.20
0.99–1.46
1629
1.52
1.20–1.91
1.33
1.10–1.74
1645
1.21
0.96–1.52
1637
1.29
1.01–1.65
1.22
0.93–1.60
1636
1.16
0.91–1.46
1622
1.12
0.92–1.38
c: crude analysis. a: adjusted analysis — adjusted for the other variables in the model and for potential confounders (age, time of residence in the neighborhood, economic class, student membership in public or private school, and father's and mother's schooling). a Non-response rates ranged from 0.08% (presence of sidewalk, n = 1) to 1.7% (sidewalks are narrow, n = 20) among environmental variables, and 2.7% (father's schooling, n = 33) to 12.4% (economic class, n = 149) among confunders. b Reference category: negative perception of the environment. c Variables with inverted response scales.
c: crude analysis. a: adjusted analysis — adjusted for the other variables in the model and for potential confounders (age, time of residence in the neighborhood, economic class, student membership in public or private school, and father's and mother's schooling). a Non-response rates ranged from 0.2% (presence of sidewalk, n = 3) to 2.3% (sidewalks are narrow, n = 38) among environmental variables, and 3.3% (father's economic class, n = 54) to 11.1% (economic condition, n = 183) among confunders. b Reference category (1): negative perception of the environment. c Variables with inverted response scales.
One of the major strengths of the present survey is that it investigates the relationship between environmental variables and physical activity in a representative sample of secondary school students. Other strengths include the number of subjects and the sample selection process. The sampling procedure favored the participation of adolescents living in neighborhoods with very different environmental and socioeconomic characteristics. Finally, all instruments were previously tested and showed satisfactory reproducibility and validity. Among the environmental characteristics analyzed in the present study, after adjustment for variables that remained in the model and for potential confounders, seeing other adolescents being physically active in the neighborhood, among boys, and living close to places they liked to frequent, among both sexes, were directly associated with levels of physical activity. Santos et al. (2009), in a survey of Portuguese adolescents aged 12–18 years, found that seeing other adolescents being physically active was the only perceived characteristic of the environment out of the 16 measured that was associated with levels of physical activity among male adolescents (OR = 1.59; 95% CI: 1.05–2.40). These results agree with those of the present survey, which shows an increase of up to 20% in the chance of being sufficiently physically active among
adolescents who reported seeing other adolescents being physically active in the neighborhood in which they lived (OR = 1.20; 95%CI: 1.05–1.56). A probable explanation for these results is that seeing other adolescents engaging in physical activities may act as a source of social support, acting through the modeling of another's behavior, and/or through psychological support (Plugliese and Tinsley, 2007). It is assumed that a number of health-related behaviors are established by influence of behaviors adopted by others, including friends (Plugliese and Tinsley, 2007). According to this notion, seeing other adolescents being physically active would act as a form of learning from the successful experiences of other adolescents or as motivation for practicing physical activity (Plugliese and Tinsley, 2007; van Der Horst et al., 2007). Social support has been shown to be consistently and positively associated with physical activity among adolescents (Biddle et al., 2005; Ferreira et al., 2006; van Der Horst et al., 2007). Adolescents who reported greater social support, especially from their peers, showed higher levels of physical activity (Plugliese and Tinsley, 2007). Living at walking distance from places they liked to frequent was directly associated with physical activity levels (boys: OR = 1.96; 95% CI: 1.40–2.78; girls: OR = 1.33; 95% CI: 1.10–1.74). A possible explanation for this finding is that this variable may be a measure of
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the presence of facilities such as schools, shopping centers, gyms, and clubs near the subject's home. It may also reflect greater accessibility of these destinations. These factors are believed to stimulate walking and bicycling as forms of travel, favoring an increase in global physical activity levels. In the present study, walking as a form of travel was the physical activity most frequently performed by adolescents (whole sample = 51.4%; boys = 55.6% vs. girls = 48.3%; p b 0.001). Deforche et al. (2010), found a positive association between street connectivity and presence of facilities (stores, shopping centers, schools, libraries) near the subject's home and physical activity for travel purposes. Similar results have been described in other studies (Davison and Lawson, 2006; Rosenberg et al., 2009). However, other studies have failed to provide support for this hypothesis (Mota et al., 2005; Santos et al., 2009; Tucker et al., 2009). Another possibility is that the places near home frequented by adolescents may include recreational facilities proper for the practice of physical activities, such as gyms, dance schools, and social clubs. Studies with adolescents have shown a positive correlation between presence and proximity of such facilities and physical activity levels (Norman et al., 2006; Dowda et al., 2007; Pate et al., 2008; Tucker et al., 2009). In the present study, both the presence of places proper for physical activity and their infrastructure, safety, and distance from the subject's home were not associated with physical activity levels among adolescents. These results confirm the findings of other studies, which failed to detect significant associations between such variables, measured either objectively (Trost et al., 1999; Sallis et al., 2002; Haerens et al., 2009) or subjectively (Sallis et al., 2002; Bruijn et al., 2006; Haerens et al., 2009; Lee et al., 2009; Santos et al., 2009; Deforche et al., 2010), and physical activity levels. On the other hand, other studies have shown significant positive associations between presence of facilities proper for physical activities (gyms, clubs, tennis courts, swimming pools, and recreational centers) near the subject's home and levels of physical activity, especially in leisure time (Hume et al., 2005; Norman et al., 2006; Huang et al., 2010). Tucker et al. (2009), in a study of Canadian adolescents, found that subjects living in neighborhoods with two or more commercial sports facilities close to home were 1.7 times more likely (95% CI 1.09–2.50) to be physically active compared to those living in neighborhoods with a smaller number of such facilities. Studies that found positive associations between presence of facilities and levels of physical activity measured the former objectively or using a list of facilities. Moreover, most of these studies focused on private facilities, and measured leisure-time physical activity (Panter and Jones, 2008; Pate et al., 2008; Tucker et al., 2009). Both factors may contribute to the discrepancies found between these and the present results. Adolescents are usually involved in different types of physical activities and have different preferences, especially when comparing boys and girls (Kuo et al., 2009). Another issue is that private facilities usually provide structured activities, which result in higher levels of physical activity. Likewise, this may explain the lack of association observed in this and other studies that also used global measures to assess the presence of physical activity facilities. Another aspect to be considered is that environmental characteristics may differ in terms of degree of influence depending on the outcome or measure of physical activity (Mota et al., 2009; Rosenberg et al., 2009). It may be possible that the lack of correspondence between outcome and predictor variables and insufficient consideration of the scale of the environment to be studied might all contribute to the lower levels of explanatory power achieved in this study. For example, correlates of active transport are likely to be different from those of leisure physical activity or structured physical activity. Finally, one must consider the possibility that most of the influence of physical environment on physical activity levels among adolescents
is not direct, and is instead mediated by individual or subject variables, such as self-efficacy. Motl et al. (2007) found no direct relationship between environmental characteristics and physical activity levels among adolescents. The “effects” of environmental variables were fully mediated by the perception of self-efficacy. Similar results have been described in other studies (Motl et al., 2005; Bruijn et al., 2006; Deforche et al., 2010). The present study has limitations that should be considered. One of these is the fact that the characteristics of the environment were measured subjectively. Subjective measures have shown low to moderate agreement with objective measures (Scott et al., 2007). Moreover, it is possible that subjective measures reflect motivational behaviors or characteristics of the subject, rather than an actual characteristic of the environment (Huang et al., 2010). Measuring levels of physical activity using a questionnaire is another limitation, because such instruments may be subject to response bias and may have accuracy problems (Dollman et al., 2009). The cross-sectional nature is another limitation of this study, therefore the direction of the associations cannot be evaluated. We found that the influence of perceived environment on physical activity levels among adolescents was small, with only two out of fifteen environment characteristics being associated with levels of physical activity. Our results suggest that important, environmental characteristics by themselves seem not to “determine” the levels of physical activity among adolescents, and therefore other variables, related to the subject, must be considered, as proposed by the ecological model. However, we found that presence of a variety of adolescent-friendly destinations in the neighborhood can favor an increase in physical activity among this population, possibly by stimulating and favoring walking and cycling as forms of active transport. Social environment (seeing other adolescents performing physical activities) was also found to be an important factor in physical activity, especially among boys.
Conflict of interest statement The authors declare that there are no conflicts of interest.
Acknowledgments We would like to thank Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES), for study and research grants, and Fundação para Ciência e a Tecnologia — FCT, Portugal, for supporting the participation of Prof. Jorge Mota in the present study (FCT:SFRH/ BSAB/1025/2010). References ABEP (Associação Brasileira das Empresas de Pesquisa), 2009. Critério de Classificação Econômica Brasil. www.abep.org/mural/abep. Acessed: 26/11/2009. Biddle, S., Sallis, J.F., Cavill, N.A., 1998. Young and Active? Young People and Health Enhancing Physical Activity. Evidence and Implication. Health Education Authority, London. Biddle, S.J.H., Whitehead, S.H., O'Donovan, T.M., Nevill, M.E., 2005. Correlates of participation in physical activity for adolescent girls: a systematic review of recent literature. J. Phys. Act. Health 2, 423–434. Bruijn, G.-J., Kremers, S.P.J., lensvelt-Mulders, G., Vries, H., van Mechelen, W., Brug, J., 2006. Modeling individual and physical environmental factors with adolescent physical activity. Am. J. Prev. Med. 30, 507–512. Currie, C., Gabhainn, S., Godeau, E., Roberts, C., Smith, R., Currie, D., Picket, W., Richter, M., Morgan, M., Barnekow, V., 2008. Inequalities in young peoples health behaviour in school-aged children. International report from the 2005/2006 survey, Denmark. Davison, K.K., Lawson, C.T., 2006. Do atributes in the physical activity environmental influences children's physical activity? A review of the literature. Int. J. Behav. Med. 3, 19. doi:10.1186/1479-5868-3-19. Deforche, B., van Dyck, D., Verloigne, M., De Bourdeaudhuij, I., 2010. Perceived social and physical environmental correlates of physical activity in older adolescents and the moderating effect of self-efficacy. Prev. Med. 50, S24–S29. Dollman, J., Okely, A.D., Hardy, L., Timperio, A., Salmon, J., Hills, A.P., 2009. A hitchhiker's guide to assessing young people's physical activity: deciding what method to use. J. Sci. Med. Sport 12, 518–525.
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Contents lists available at ScienceDirect
Preventive Medicine j o u r n a l h o m e p a g e : w w w. e l s e v i e r. c o m / l o c a t e / y p m e d
Perception of the social and built environment and physical activity among Northeastern Brazil adolescents José Cazuza de Farias Júnior a,⁎, Adair da Silva Lopes b, Jorge Mota c, Maria Paula Santos c, José Carlos Ribeiro c, Pedro Curi Hallal d a
Federal University of Paraiba – UFPB/CCS/DEF, Brazil Federal University of Santa Catarina – DEF/CDS/UFSC, Brazil Research Centre in Physical Activity Health and Leisure, University of Porto, Portugal d Federal University of Pelotas – UFPel, Brazil b c
a r t i c l e
i n f o
Available online 10 December 2010 Keywords: Physical activity Environmental Adolescent Perception Facilities
a b s t r a c t Objective. To evaluate the association between levels of physical activity and perception of the social and built environmental in adolescents from Northeastern Brazil. Methods. The sample comprised 2874 adolescents aged 14 to 19 years (57.8% females) enrolled in private or public secondary schools in the municipality of João Pessoa, Northeastern Brazil. Level of physical activity was measured by questionnaire. Perception of environmental characteristics was measured by means of fifteen questions rated on four-point Likert-type scales ranging from 1 (“strongly disagree”) to 4 (“strongly agree”). The association between physical activity and perception of environmental characteristics was investigated using multivariate binary logistic regression. Results. Multivariate analysis showed that adolescents living in neighborhoods where other adolescents were physically active (68.7% vs. 60.1%, OR = 1.20; 95%CI: 1.05–1.56, among boys only) or who lived close to places they liked to frequent (71.8% vs. 53.4%, OR = 1.96; 95%CI: 1.40–2.78 among boys; and 42.0% vs. 32.3% OR = 1.33; 95%CI: 1.10–1.74 among girls) were more likely to be physically active. Conclusions. Adolescents with positive perceptions of certain environmental characteristics were more likely to be physically active. Environmental characteristics may relate differently to levels of physical activity among boys and girls. Published by Elsevier Inc.
Introduction Increasing levels of physical activity among adolescents is regarded as a public health priority. Reasons for this include the high prevalence of insufficient physical activity among this population (Currie et al., 2008; Sisson and Katzmarzyk, 2008; Tenório et al., 2010), the health hazards associated with physical inactivity (Strong et al., 2005), and the possibility of tracking of physical activity habits adopted during adolescence to adult life (Gordon-Larsen et al., 2004). To identify and to better understand the factors that influence the adolescent's choices in terms of physical activity are considered to be essential prerequisites for planning and implementing intervention programs targeting physical activity, especially if these measures are to be effective and to promote long-term changes (Davison and Lawson, 2006; Deforche et al., 2010; Haerens et al., 2009).
⁎ Corresponding author. Universidade Federal da Paraíba, Departamento de Educação Física, Campus I, Cidade Universitária, CEP: 58059-900 – João Pessoa, PB, Brazil. E-mail address: [email protected] (J.C. de Farias Júnior). 0091-7435/$ – see front matter. Published by Elsevier Inc. doi:10.1016/j.ypmed.2010.12.002
Systematic reviews in the literature show that physical activity during adolescence is associated with factors pertaining to different analytical levels — the individual level, comprising subject-related variables (self-efficacy, attitudes, pleasure, beliefs); and the environmental level, comprising variables related to physical and social environment (presence of facilities, safety, esthetics and infrastructure, social support) (Biddle et al., 2005; Ferreira et al., 2006; van Der Horst et al., 2007). However, considering that subject-related variables (such as selfefficacy, and attitude) account for only a small fraction of the variance in levels of physical activity among adolescents (Haerens et al., 2009; Lee et al., 2009), that physical activity takes place in specific environments (Mota et al., 2009), and that studies have shown that attributes of the environment are associated physical activity among adolescents (Dowda et al., 2007; Norman et al., 2006; Pate et al., 2008), it is assumed that environmental variables will play an important role in modulating the levels of physical activity. Identifying environmental variables associated with physical activity is important given that changes in these variables may affect a large number of individuals for a long time, rather than having only a short-term impact (Giles-Corti et al., 2005; Mota et al., 2005; Davison
J.C. de Farias Júnior et al. / Preventive Medicine 52 (2011) 114–119
and Lawson, 2006; Ferreira et al., 2006). In spite of the increasing body of studies addressing the relationship between environment and physical activity levels, the number of such studies carried out in low and middle-income countries such as Brazil is still extremely limited. The studies available in the literature analyzed environmental characteristics associated with physical activity in parks (Reis et al., 2009) or barriers to the practice of physical activity (Santos et al., 2010), but none of them analyzed the different attributes of the neighborhood of residence and levels of physical activity among adolescents. This study investigates the association between levels of physical activity and perception of the social and built environmental in adolescents from Northeastern Brazil. Methods The target population comprised adolescents aged 14–19 years, enrolled in public and private secondary schools in the municipality of João Pessoa, Northeastern Brazil. Sampling was carried out using a clustered strategy in two stages (schools and classes), with probability proportional to size (number of students enrolled). Initially, we allocated each of the 82 schools into the municipality's four regions (North, South, East, and West), separately by type (public and private). We then systematically selected 30 schools (16 public and 14 private), distributed proportionally among the four regions (North, South, East, and West). In the second stage, we randomly selected secondary education classes (n = 135), distributed proportionally by shift (day [morning or afternoon] and night) and grade (1st, 2nd, and 3rd grades of secondary school). In both stages, distributions were proportional to those of the target population. The number of classes to be drawn in each school was determined by dividing the number of students to be recruited from each grade by 20 (the mean number of students we expected to obtain in each class). Adolescents who failed to return the term of consent filled out and signed by a parent or caregiver (b 18 years old), refused to take part in the study, or were absent from class at the day of collection were considered as losses. Replacement was not allowed in order to prevent selection bias. Initially, 3477 adolescents were selected to take part in the survey. Of these, 70 either refused or were not authorized by their parents/caregivers to participate in the survey, and 187 were absent from school on the day of data collection. Of the 3220 adolescents who responded to the questionnaire, 271 were excluded for being b 14 or N 19 years of age, 65 did not report their age, 5 had some form of handicap, and 5 left several questions unanswered. The final sample included 2874 subjects. Data collection took place between May and September 2009 (mean temperature 26 °C, tropical humid climate) and was carried out by a previously trained team, supervised by the head researcher. Questionnaires were filled out anonymously by the adolescents themselves, while in the classroom, according to instructions provided by one of the interviewers. Adolescents answered questions on sociodemographic characteristics (sex, age, skin color [black, white, mixed, Asian, Amerindian], occupation [working, not working], time of residence in the neighborhood [years:months], type of school, [public and private] schooling of mother and father [illiterate, up to 3rd grade elementary, 4th grade elementary, incomplete elementary, complete elementary, incomplete secondary, complete secondary, incomplete tertiary, complete tertiary], and economic class — determined according to the criterion of the Brazilian Association of Research Companies (ABEP, 2009) which group subjects into the following economic classes: A1 [richest], A2, B1, B2, C1, C2, D, and E [poorest], based on a score combining ownership of assets, schooling of head of household, and number of employees in the household). Adolescents also answered questions on the physical activities they practiced and on their perception of the environment/neighborhood. All measures of independent variables showed satisfactory levels of reproducibility, with kappa values ranging from 0.89 (economic class) to 0.93 (mother's and father's schooling) in replicate administrations of the questionnaire with a one-week interval. Physical activity was measured by questionnaire using an instrument previously tested on a sample of subjects that did not take part in the main survey (reproducibility — ICC = 0.88; 95% CI: 0.84–0.91; validity: Spearman's rho = 0.62; p b 0.01; kappa = 0.59, comparing the results of four 24-hour physical activity recalls). Adolescents informed the frequency (days/week) and duration (h:min/day) of physical activities performed in the week
115
preceding the interview based on a list of 24 moderate to vigorous physical activities (sports, dance, martial arts, walking, jogging, cycling, strength training, active commuting, and outdoor games). The level of physical activity was calculated as the sum of the products of time spent on each physical activity (min/day) by their respective frequencies (days/week). Adolescents displaying levels of physical activity equal to or greater than 300 min/week were classified as “sufficiently active,” whereas the remainder were classified as “insufficiently active” (Biddle et al., 1998). Environmental characteristics were measured subjectively using a 15item questionnaire that including questions on: i) accessibility of destinations and facilities, 7 items; ii) infrastructure/esthetics, 4 items; and iii) safety, 4 items, extracted and adapted from other instruments (Saelens et al., 2003; Evenson and McGinn, 2005; Hume et al., 2006). The instruments were previously tested and showed satisfactory reproducibility (intra-class correlation coefficients (ICC) for different items ranging from 0.56 to 0.82, with a one-week interval between measurements) and internal consistency (α = 0.72, neighborhood scale). When responding to questions on the characteristics of the environment, adolescents were oriented to consider as close to their residences any place within a ten-minute walking range (Hume et al., 2006). All items were measured using a four-point Likert-type scale anchored at 1 “strongly disagree” and 4 “strongly agree.” For analysis purposes, responses were dichotomized into disagree (strongly disagree, disagree = “negative perception”) and agree (strongly agree, agree = “positive perception”). To compare the proportion of adolescents showing sufficient levels of physical activity in groups with positive or negative perception of the environment, we used chi-squared tests. Logistic regression was used to evaluate the unadjusted association between level of physical activity (dependent variable: b 300 min/week = 0 and ¡ N 300 min/week = 1) and each attribute of the perceived environment (independent variable(s): “negative perception” = 0 and “positive perception” = 1). In adjusted analysis, all variables were included in the model, and those with a p value b 0.20 were retained in the final model. The following potential confounders were included in the adjusted model: age, time of residence in the neighborhood, economic class, type of school (public or private), and father's and mother's schooling. Backward selection was employed. All analyses were stratified by sex. Before performing the adjusted analyses we ran tests for collinearity among the potential confounders, but none of them suggested high levels of multicollinearity. It is worth mentioning that although type of school and economic class are associated, they do not mean the same thing, which is why collinearity between these two variables is not a problem in these models. In Northeastern Brazil, there are many adolescents who belong to middle and low socioeconomic levels and study in private schools. Furthermore, the variables associated with physical activity were the same in the analyses with and without adjustment for type of school. Statistical analyses were carried out using Stata 10.1 software, and took into account the sampling strategy (cluster sampling). We adopted a 5% significance level. The study protocol was approved by the Research Ethics Committee of the Federal Univeristy of Paraíba.
Results The final sample comprised 2874 adolescents (mean age = 16.5; SD = 1.2; 57.8% female). The majority of adolescents were aged between 16 and 19 years (89.3%), did not work (86.9%), and came from the intermediate (46.1%) or lower (8.1%) economic classes (Table 1). Roughly half of the adolescents fulfilled the recommended 60 min per day of moderate or vigorous physical activity (50.2%; 95% CI: 47.3– 53.1). Boys were more physically active than girls (66.3% vs. 38.5%; p b 0.01; data not shown in tables). The proportion of adolescents fulfilling current physical activity recommendations was greater among those with positive perception of certain environmental characteristics (boys: places where I can practice of physical activities are well maintained, 69.8% vs. 63.3%; I frequently see other adolescents practicing physical activities, 68.7% vs. 60.1%; the neighborhood offers many opportunities for practicing physical activities, 70.0% vs. 62.7%; there are several places I like to frequent near my home, 71.8% vs. 53.7%; girls: there are bicycle lanes
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Table 1 Characteristics of the sample, João Pessoa, Northeastern Brazil, 2009. Variable
Age (years) 14–15 16–17 18–19 Skin color Mixed Black White Other Working Yes No Type of school Public Private Economic classa A (best) B C D,E (worst) Father's schooling Incomplete elementary Complete elementary Complete secondary Complete tertiary Mother's schooling Incomplete elementary Complete elementary Complete secondary Complete tertiary a
Male
Female
n
%
453 612 141
37.6 50.8 11.6
636 87 368 107
n
All %
n
%
671 817 165
40.6 49.4 10.0
1128 1438 308
10.7 50.0 39.3
53.1 7.3 30.7 8.9
846 74 561 165
51.4 4.5 34.1 10.0
1491 163 930 275
52.2 5.7 32.5 9.6
194 981
16.5 83.5
170 1443
10.5 89.5
366 2436
13.1 86.9
822 384
68.2 31.8
1189 464
71.9 28.1
2011 848
70.3 29.7
119 416 446 76
11.3 39.4 42.1 7.2
117 506 717 127
8.0 34.4 48.9 8.7
237 924 1167 205
9.3 36.5 46.1 8.1
309 233 402 229
26.3 19.9 34.3 19.5
563 279 491 266
35.2 17.5 30.7 16.6
877 514 895 497
31.5 18.5 32.2 17.8
309 221 399 266
25.9 18.5 33.4 22.2
538 315 502 283
32.8 19.2 30.6 17.4
853 538 906 550
30.0 18.9 31.8 19.3
istics associated with the outcome were exclusive to either boys or girls (Table 2). Tables 3 and 4 present the results of crude and adjusted analysis of the association of environmental characteristics with physical activity among male and female adolescents. Among boys, in crude analysis, there was a significant association between level of physical activity and the following environmental characteristics: places for physical activity are well maintained (OR = 1.34; 95%CI: 1.03–1.75), I frequently see other adolescents practicing physical activities (OR = 1.46; 95%CI: 1.13–1.88), environment offers many opportunities to practice physical activities (OR = 1.39; 95% CI: 1.05–1.85), there are several different places I like to frequent near my house (OR = 2.19; 95% CI: 1.58–3.03). Among girls the environmental characteristics associated with physical activity levels were: I frequently see other adolescents practicing physical activities (OR = 1.25; 95% CI: 1.02–1.53), I see interesting things when I walk or ride a bicycle on the streets (OR = 1.40; 95% CI: 1.15–1.70), there are several different places I like to frequent near my house (OR = 1.52; 95% CI: 1.20–1.91), it is safe to ride a bicycle on the streets around my house (OR = 1.29; 95% CI: 1.01–1.65). In adjusted analysis (for age, economic class, father's and mother's schooling, time at present address, type of school), the perceived characteristics of the environment that remained associated with levels of physical activity were: seeing other adolescents practicing physical activities, among boys (OR = 1.20; 95% CI: 1.05–1.56), and presence of places the adolescent liked to frequent near home, for both sexes (boys: OR = 1.96; 95% CI: 1.40–2.78; girls: OR = 1.33; 95% CI: 1.10–1.74).
Variable with the highest number of nonresponders, n = 341 (11.9%).
Discussion or places where I can ride a bicycle, 42.4% vs. 37.0%; I frequently see other adolescents practicing physical activities, 40.3% vs. 35.1%; There are places for practicing physical activities, 40.4% vs. 36.0%; I see many interesting things while I walk or ride a bicycle, 41.8% vs. 33.9%; There are several places I like to frequent near my home, 42.0 vs. 32.3%; Riding a bicycle in the streets around my house is not safe because of street traffic, 40.1% vs. 35.6%). Almost all environmental character-
Our results indicate that adolescents with positive perception of certain environmental characteristics (presence of places they liked to frequent near home and frequently seeing other adolescents being physically active) were more likely to be physically active. Environmental characteristics may relate differently to levels of physical activity among boys and girls.
Table 2 Proportion of adolescent students that reached current recommended levels of physical activity according to perceived environment, João Pessoa, Northeastern Brazil, 2009. Characteristics of the social and built environment (neighborhood)
There are sidewalks on most streets Sidewalks are narrow and full of holes/obstaclesc Places where I can practice of physical activities are well maintained The neighborhood is polluted, with open sewage, garbage and debris on the streetsc There are bicycle lanes or places where I can ride a bicycle I frequently see other adolescents practicing physical activities. There are places for practicing physical activities (parks, squares, courts, fields, etc.) The neighborhood offers many opportunities for practicing physical activities Places proper for physical activity are close to my home I see many interesting things while I walk or ride a bicycle There are several places I like to frequent near my home Walking or jogging in the streets around my house is not safe because of street trafficc Riding a bicycle in the streets around my house is not safe because of street trafficc Places where I can practice physical activities are not safec The neighborhood is violent, with a lot of muggings, crime, and drugsc ⁎⁎⁎ Chi-squared test for heterogeneity. a Negative perception (strongly disagree, disagree). b Positive perception (strongly agree, agree). c Variables with inverted response scales.
p⁎⁎⁎
Males Negative perceptiona
Positive perceptionb
70.1 66.3 63.3 68.4
65.0 66.3 69.8 65.4
66.6 60.1 65.0
p⁎⁎⁎
Females Negative perceptiona
Positive perceptionb
0.28 0.10 0.03 0.26
37.6 36.7 37.1 37.8
38.9 39.8 40.3 38.7
0.60 0.14 0.30 0.73
65.4 68.7 66.9
0.72 0.01 0.48
37.0 35.1 36.0
42.4 40.3 40.4
0.05 0.03 0.01
62.7
70.0
0.02
36.3
41.2
0.07
64.4 63.8 53.7 64.3
67.0 67.8 71.8 67.5
0.45 0.13 b0.01 0.32
36.8 33.9 32.3 35.8
39.4 41.8 42.0 40.3
0.26 b 0.01 b 0.01 0.10
63.6
67.8
0.20
35.6
40.1
0.04
64.7 68.2
67.8 65.6
0.19 0.30
36.8 37.0
40.3 39.8
0.22 0.25
J.C. de Farias Júnior et al. / Preventive Medicine 52 (2011) 114–119 Table 3 Crude and adjusteda analysis of the association between measures of perceived environment and level of physical activity among adolescent students, João Pessoa, Northeastern Brazil, 2009 — males. Characteristics of the social and built environment (neighborhood)b
There are sidewalks on most streets Sidewalks are narrow and full of holes/obstaclesc Places where I can practice of physical activities are well maintained The neighborhood is polluted, with open sewage, garbage and debris on the streetsc There are bicycle lanes or places where I can ride a bicycle I frequently see other adolescents practicing physical activities. There are places for practicing physical activities (parks, squares, courts, fields, etc.) The neighborhood offers many opportunities for practicing physical activities Places proper for physical activity are close to my home I see many interesting things while I walk or ride a bicycle There are several places I like to frequent near my home Walking or jogging in the streets around my house is not safe because of street trafficc Riding a bicycle in the streets around my house is not safe because of street trafficc Places where I can practice physical activities are not safec The neighborhood is violent, with a lot of muggings, crime, and drugsc
Level of physical activity (b 300 min/ week = 0 and ≥ 300 min/week = 1) n
ORc
95% CI
1205 1186
0.79 1.00
0.52–1.21 0.78–1.28
1202
1.34
1.03–1.75
1194
0.87
0.69–1.11
1195
0.95
0.69–1.29
1199
1.46
1.13–1.88
1197
1.09
0.85–1.39
1199
1.39
1.05–1.85
1197
1.09
0.85–1.39
1197
1.19
0.95–1.51
1197
2.19
1.58–3.03
1199
1.15
0.86–1.54
1196
1.21
0.90–1.62
1194
1.15
0.95–1.39
1191
0.89
0.72–1.11
ORa
1.20
1.26
1.96
Table 4 Crude and adjusteda analysis of the association between measures of perceived environment and level of physical activity among adolescent students, João Pessoa, Northeastern Brazil, 2009 — females. Characteristics of the social and built environment (neighborhood)b
95% CI
1.05–1.56
0.95–1.70
1.40–2.78
117
There are sidewalks on most streets Sidewalks are narrow and full of holes/obstaclesc Places where I can practice of physical activities are well maintained The neighborhood is polluted, with open sewage, garbage and debris on the streetsc There are bicycle lanes or places where I can ride a bicycle I frequently see other adolescents practicing physical activities. There are places for practicing physical activities (parks, squares, courts, fields, etc.) The neighborhood offers many opportunities for practicing physical activities Places proper for physical activity are close to my home I see many interesting things while I walk or ride a bicycle There are several places I like to frequent near my home Walking or jogging in the streets around my house is not safe because of street trafficc Riding a bicycle in the streets around my house is not safe because of street trafficc Places where I can practice physical activities are not safec The neighborhood is violent, with a lot of muggings, crime, and drugsc
Level of physical activity (b 300 min/ week = 0 and ≥ 300 min/week = 1) n
ORc
95%CI
1650 1630
1.05 1.14
0.86–1.30 0.96–1.36
ORa
95%CI
1646
1.14
0.88–1.48
1622
1.04
0.83–1.31
1627
1.25
1.00–1.57
1636
1.25
1.02–1.53
1.18
0.93–1.51
1615
1.20
0.96–1.51
1638
1.23
0.98–1.55
1644
1.12
0.92–1.35
1637
1.40
1.15–1.70
1.20
0.99–1.46
1629
1.52
1.20–1.91
1.33
1.10–1.74
1645
1.21
0.96–1.52
1637
1.29
1.01–1.65
1.22
0.93–1.60
1636
1.16
0.91–1.46
1622
1.12
0.92–1.38
c: crude analysis. a: adjusted analysis — adjusted for the other variables in the model and for potential confounders (age, time of residence in the neighborhood, economic class, student membership in public or private school, and father's and mother's schooling). a Non-response rates ranged from 0.08% (presence of sidewalk, n = 1) to 1.7% (sidewalks are narrow, n = 20) among environmental variables, and 2.7% (father's schooling, n = 33) to 12.4% (economic class, n = 149) among confunders. b Reference category: negative perception of the environment. c Variables with inverted response scales.
c: crude analysis. a: adjusted analysis — adjusted for the other variables in the model and for potential confounders (age, time of residence in the neighborhood, economic class, student membership in public or private school, and father's and mother's schooling). a Non-response rates ranged from 0.2% (presence of sidewalk, n = 3) to 2.3% (sidewalks are narrow, n = 38) among environmental variables, and 3.3% (father's economic class, n = 54) to 11.1% (economic condition, n = 183) among confunders. b Reference category (1): negative perception of the environment. c Variables with inverted response scales.
One of the major strengths of the present survey is that it investigates the relationship between environmental variables and physical activity in a representative sample of secondary school students. Other strengths include the number of subjects and the sample selection process. The sampling procedure favored the participation of adolescents living in neighborhoods with very different environmental and socioeconomic characteristics. Finally, all instruments were previously tested and showed satisfactory reproducibility and validity. Among the environmental characteristics analyzed in the present study, after adjustment for variables that remained in the model and for potential confounders, seeing other adolescents being physically active in the neighborhood, among boys, and living close to places they liked to frequent, among both sexes, were directly associated with levels of physical activity. Santos et al. (2009), in a survey of Portuguese adolescents aged 12–18 years, found that seeing other adolescents being physically active was the only perceived characteristic of the environment out of the 16 measured that was associated with levels of physical activity among male adolescents (OR = 1.59; 95% CI: 1.05–2.40). These results agree with those of the present survey, which shows an increase of up to 20% in the chance of being sufficiently physically active among
adolescents who reported seeing other adolescents being physically active in the neighborhood in which they lived (OR = 1.20; 95%CI: 1.05–1.56). A probable explanation for these results is that seeing other adolescents engaging in physical activities may act as a source of social support, acting through the modeling of another's behavior, and/or through psychological support (Plugliese and Tinsley, 2007). It is assumed that a number of health-related behaviors are established by influence of behaviors adopted by others, including friends (Plugliese and Tinsley, 2007). According to this notion, seeing other adolescents being physically active would act as a form of learning from the successful experiences of other adolescents or as motivation for practicing physical activity (Plugliese and Tinsley, 2007; van Der Horst et al., 2007). Social support has been shown to be consistently and positively associated with physical activity among adolescents (Biddle et al., 2005; Ferreira et al., 2006; van Der Horst et al., 2007). Adolescents who reported greater social support, especially from their peers, showed higher levels of physical activity (Plugliese and Tinsley, 2007). Living at walking distance from places they liked to frequent was directly associated with physical activity levels (boys: OR = 1.96; 95% CI: 1.40–2.78; girls: OR = 1.33; 95% CI: 1.10–1.74). A possible explanation for this finding is that this variable may be a measure of
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the presence of facilities such as schools, shopping centers, gyms, and clubs near the subject's home. It may also reflect greater accessibility of these destinations. These factors are believed to stimulate walking and bicycling as forms of travel, favoring an increase in global physical activity levels. In the present study, walking as a form of travel was the physical activity most frequently performed by adolescents (whole sample = 51.4%; boys = 55.6% vs. girls = 48.3%; p b 0.001). Deforche et al. (2010), found a positive association between street connectivity and presence of facilities (stores, shopping centers, schools, libraries) near the subject's home and physical activity for travel purposes. Similar results have been described in other studies (Davison and Lawson, 2006; Rosenberg et al., 2009). However, other studies have failed to provide support for this hypothesis (Mota et al., 2005; Santos et al., 2009; Tucker et al., 2009). Another possibility is that the places near home frequented by adolescents may include recreational facilities proper for the practice of physical activities, such as gyms, dance schools, and social clubs. Studies with adolescents have shown a positive correlation between presence and proximity of such facilities and physical activity levels (Norman et al., 2006; Dowda et al., 2007; Pate et al., 2008; Tucker et al., 2009). In the present study, both the presence of places proper for physical activity and their infrastructure, safety, and distance from the subject's home were not associated with physical activity levels among adolescents. These results confirm the findings of other studies, which failed to detect significant associations between such variables, measured either objectively (Trost et al., 1999; Sallis et al., 2002; Haerens et al., 2009) or subjectively (Sallis et al., 2002; Bruijn et al., 2006; Haerens et al., 2009; Lee et al., 2009; Santos et al., 2009; Deforche et al., 2010), and physical activity levels. On the other hand, other studies have shown significant positive associations between presence of facilities proper for physical activities (gyms, clubs, tennis courts, swimming pools, and recreational centers) near the subject's home and levels of physical activity, especially in leisure time (Hume et al., 2005; Norman et al., 2006; Huang et al., 2010). Tucker et al. (2009), in a study of Canadian adolescents, found that subjects living in neighborhoods with two or more commercial sports facilities close to home were 1.7 times more likely (95% CI 1.09–2.50) to be physically active compared to those living in neighborhoods with a smaller number of such facilities. Studies that found positive associations between presence of facilities and levels of physical activity measured the former objectively or using a list of facilities. Moreover, most of these studies focused on private facilities, and measured leisure-time physical activity (Panter and Jones, 2008; Pate et al., 2008; Tucker et al., 2009). Both factors may contribute to the discrepancies found between these and the present results. Adolescents are usually involved in different types of physical activities and have different preferences, especially when comparing boys and girls (Kuo et al., 2009). Another issue is that private facilities usually provide structured activities, which result in higher levels of physical activity. Likewise, this may explain the lack of association observed in this and other studies that also used global measures to assess the presence of physical activity facilities. Another aspect to be considered is that environmental characteristics may differ in terms of degree of influence depending on the outcome or measure of physical activity (Mota et al., 2009; Rosenberg et al., 2009). It may be possible that the lack of correspondence between outcome and predictor variables and insufficient consideration of the scale of the environment to be studied might all contribute to the lower levels of explanatory power achieved in this study. For example, correlates of active transport are likely to be different from those of leisure physical activity or structured physical activity. Finally, one must consider the possibility that most of the influence of physical environment on physical activity levels among adolescents
is not direct, and is instead mediated by individual or subject variables, such as self-efficacy. Motl et al. (2007) found no direct relationship between environmental characteristics and physical activity levels among adolescents. The “effects” of environmental variables were fully mediated by the perception of self-efficacy. Similar results have been described in other studies (Motl et al., 2005; Bruijn et al., 2006; Deforche et al., 2010). The present study has limitations that should be considered. One of these is the fact that the characteristics of the environment were measured subjectively. Subjective measures have shown low to moderate agreement with objective measures (Scott et al., 2007). Moreover, it is possible that subjective measures reflect motivational behaviors or characteristics of the subject, rather than an actual characteristic of the environment (Huang et al., 2010). Measuring levels of physical activity using a questionnaire is another limitation, because such instruments may be subject to response bias and may have accuracy problems (Dollman et al., 2009). The cross-sectional nature is another limitation of this study, therefore the direction of the associations cannot be evaluated. We found that the influence of perceived environment on physical activity levels among adolescents was small, with only two out of fifteen environment characteristics being associated with levels of physical activity. Our results suggest that important, environmental characteristics by themselves seem not to “determine” the levels of physical activity among adolescents, and therefore other variables, related to the subject, must be considered, as proposed by the ecological model. However, we found that presence of a variety of adolescent-friendly destinations in the neighborhood can favor an increase in physical activity among this population, possibly by stimulating and favoring walking and cycling as forms of active transport. Social environment (seeing other adolescents performing physical activities) was also found to be an important factor in physical activity, especially among boys.
Conflict of interest statement The authors declare that there are no conflicts of interest.
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