Obesity in both adults and children is a major public health problem (15). Obesity is influenced by both energy intake through diet and energy expenditure through physical activity and sedentary behaviors (1). The home setting may be an important location for physical activity as it is a convenient and safe environment for both adults and children. It is also an opportunity for parents to model activity to their children.
Home exercise equipment has been positively correlated with physical activity levels in adults, youth, and children (6,19,25). A randomized trial found that a home exercise equipment intervention aided weight loss in adults (7). In adolescents, home exercise equipment has not been found to be related to obesity (29), but in one study, it was related to low activity status (16). An experimental study also demonstrated that proximity of the exercise choice influenced behavior (18), suggesting that equipment at home may help prompt activity. Another study found that provision of equipment in a school environment increased children's physical activity (31), emphasizing the importance of the availability of equipment for children's play. It is also known that the time spent outside, around the home, contributes to physical activity levels (26), so providing exercise aids around the home may be important for children and adults activity levels. These studies have focused mostly on traditional exercise equipment, although work is now beginning to study the relationship between physical activity and home-based computerized active games such as Dance Dance Revolution (DDR) (10,30).
Home-based exercise may be particularly important for families who live in less-safe neighborhoods, but studies have not investigated this in adult or youth populations. In one study, children in urban environments had more exercise equipment in the home (11). Several studies indicate that perceptions of neighborhood safety are related to physical activity in children and adults (22). One study, for example, found that parent concerns were a stronger predictor of active commuting than neighborhood walkability (8). Weir et al. (32). found that inner city children were less active than suburban children and that inner city parents' greater anxiety partly explained this difference. Studies have not investigated whether availability of home-based equipment can change the relationship between neighborhood safety and physical activity.
The aim of this study was to determine whether physical activity levels of parents and their adolescent children were related to neighborhood safety and availability of personal exercise aids designed to be used either at home or outdoors. In addition, we investigated whether there was an interaction between safety and home exercise aids such that perceived neighborhood safety moderated the relation of home-use or outdoor-use equipment with physical activity levels. We hypothesized that home-use equipment may be more important for families living in neighborhoods perceived as less-safe by facilitating physical activity in the safety of the home.
Adolescents aged 11-15 yr were recruited through their primary care provider as part of a health promotion intervention randomized control trial (17). A total of 45 primary care providers from six clinic sites in San Diego County, CA, agreed to participate. Cross-sectional baseline data were used for the current analyses. Participants were representative of the ethnic profile of San Diego County. Participants were recruited over a 1-yr period, so that all seasons were included in the data to control for variation in physical activity by season.
A total of 878 adolescents were measured at baseline; 407 boys and 471 girls. The study was powered to allow separate analyses for boys and girls because gender is a consistent predictor of activity levels. The accompanying parent or guardian was asked to complete a survey while their child completed their assessments. A total of 853 parents (721 females and 132 males) agreed to complete the survey. All study procedures were approved by the participating university and health care organization's institutional review boards for research with human subjects. Parents signed consent forms, and adolescents signed assent forms before enrolling in the study. Adolescents received $10 for completing all measurements and were entered into a lottery drawing for one of 10 cash prizes ranging from $10 to $50. Parents received $10 for transportation costs to the research office. Adolescents were excluded if they had health conditions that would limit their ability to comply with the physical activity or diet recommendations.
The availability of exercise aids, such as fitness equipment, running shoes, balls, bats, and boards, for use in and around the home was assessed by parent self-report using a 16-item checklist previously shown to be reliable and valid (25). The equipment items included aerobic fitness equipment, weights, and sports equipment, most of which were appropriate for use by adolescents and adults. The items were further categorized into home-use or outdoor-use (see Table 1).
Adolescent physical activity was measured by the 7-d physical activity recall interview that has been repeatedly validated for adolescents (24). Interviewers were trained according to a validated protocol (28), and quality was monitored throughout data collection. Adolescents were categorized as being moderate and/or vigorously physically active (at least 60 min·d−1) on five or more days a week or not (23). Parents' physical activity was measured by the self-administered long version of the International Physical Activity Questionnaire, that has been validated in 12 countries (2). Adults were categorized as reporting 150 min or more of moderate and/or vigorous activity per week or not (5). The activity outcomes were chosen to comply with the national activity recommendations for both children and adults. Accelerometer data were also collected but only from the adolescent sample. For comparison, only the self-report outcomes were analyzed.
Neighborhood safety was rated by the parents using the safety subscale from the Neighborhood Environment Walkability Scale (21). Fifteen questions assessed the perceived safety of the local environment from traffic (e.g., "There is so much traffic along the street I live on that it makes it difficult or unpleasant to walk in my neighborhood"). and from crime (e.g., "The crime rate in my neighborhood makes it unsafe to go on walks during the day"). Parents rated the statements on a 1-4 scale from strongly disagree to strongly agree. The scale had a high test-retest reliability and was validated against physical activity levels in neighborhoods varying in walkability (21). Scores for negative questions were reversed so higher scores indicate perceptions of greater safety.
The parents were asked to indicate the highest level of education completed for "Myself," "Other adult female," and "Other adult male" in the household. Nine education levels were included that ranged from "High school or less" to "Doctorate degree." Household education was calculated as the maximum value from the adult education levels and collapsed into two categories, namely "lower than high school through associates degree" and "bachelor's degree, graduate or professional school." Parents and adolescent also reported their gender and race/ethnicity (coded as non-Hispanic white vs others).
Logistic regression analyses were performed separately on the dichotomous outcome "meeting physical activity guidelines or not" for parents and adolescents. The logistic regression approach was performed to facilitate the interpretation of the interaction effects from a public health perspective and because physical activity outcomes are often skewed. In the adolescent sample, the analyses were stratified by gender as differences in boys and girls' physical activity patterns are to be expected (17). Age, race/ethnicity, and parent education were entered in all models as covariates. In the analyses for adolescents, parents' physical activity was also entered. In the parents' models, gender was entered. The parent data were not stratified by gender as there were few male respondents. Neighborhood safety and the reported number of home-use or outdoor-use exercise aids were entered into the models as continuous variables, and an interaction between equipment and safety was specified. Odds ratios (OR) and 95% confidence intervals (CI) are presented from the logistic regression analyses. OR express the likelihood of being active with an OR above 1 indicating a positive relationship between the independent variable and the outcome. The 95% CI confirm significance at the P = 0.05 level; if the CI includes the value 1.0, then it is not significant.
Table 1 presents the availability of exercise aids at home for the sample, indicating which items may be used for home-use versus activities outside of the home. Running shoes, balls, bats, bicycles, and skateboards were the most commonly reported item. The sample characteristics are presented in Table 2. The average age of adolescent participants was 12.8 yr, and 42% of the participants were nonwhite or Hispanic. Only 33% of the boys and 22% of the girls met the activity guidelines.
Adolescent's activity results.
The logistic regression analyses found that the presence of more home-use exercise equipment was related to physical activity in adolescent girls (OR = 1.27, 95% CI = 1.1-1.5). There was also a significant interaction between perceived safety and equipment (P < 0.01) such that equipment was not related to physical activity in safe neighborhoods (OR = 1.07) but was strongly related to physical activity in less-safe neighborhoods (OR = 4.40). That is, for girls living in a neighborhood perceived to be less-safe by their parents, having more home-use exercise equipment was strongly related to meeting physical activity guidelines. Reported outdoor-use exercise aids were also related to physical activity in adolescent girls (OR = 1.24, 95% CI = 1.1-1.4) but there was no interaction with safety (P > 0.05). Neither home (P = 0.61) or outdoor-use (P = 0.27) exercise aids nor neighborhood safety (P > 0.05) was related to the adolescent boys' activity levels.
Parent's activity results.
In the parent sample, home-use equipment was related to their physical activity levels (OR = 1.23, 95% CI = 1.1-1.3). There was no interaction with perceived safety (P > 0.05). Outside exercise aids were also related to physical activity in the parents (OR = 1.16, 95% CI = 1.0-1.3). There was an interaction between perceived safety and outside exercise aids (P < 0.01) such that outside equipment and supports were not related to physical activity in less-safe neighborhoods (OR = 0.91) but were strongly related to physical activity of those living in safe neighborhoods (OR = 2.43). That is, only among parents living in neighborhoods perceived to be safe were outdoor-oriented exercise aids related to meeting physical activity guidelines.
Availability of traditional fitness exercise equipment and aids, such as dogs or running shoes, for use in and around the home was found to be related to physical activity levels of parents and adolescent girls but not boys. However, perceived safety of the neighborhoods moderated associations between equipment and physical activity. Girls living in less-safe neighborhoods appeared to benefit from having exercise equipment they could use in the home. Parents living in neighborhoods they perceive as safe appeared to benefit from having exercise aids they could use outdoors. These findings highlight the need to develop and evaluate strategies for enhancing the perceived and actual safety of neighborhoods (12) and promoting physical activity specifically for those in less-safe neighborhoods.
Previous studies indicated that access to home exercise equipment was related to physical activity in adolescent girls (13,33). This pattern of findings suggests that home-based activity may be a particularly important option for girls and warrants further research as an element in interventions to promote physical activity. However, it was not possible to determine where the girls' physical activity took place, so future studies are needed to examine girls' participation in indoor activities. Although there are reasons to encourage outdoor activity in the appropriate environment (3,9), for girls in less-safe neighborhoods, the home may be considered a safe and convenient location for physical activity. Facilitating indoor physical activity is an even higher priority because adolescents are spending more time indoors in sedentary behaviors, often using electronic entertainment devices (20). Active video games such as the DDR may provide a good indoor activity for children (30), although active electronic games were not assessed in the current study. If opportunities for physical activity are available in the home, TV viewing time might also be reduced, but this relationship has rarely been studied (14).
In the present study, adolescent girls' activity seemed more sensitive to parental perceptions of neighborhood safety, confirming previous studies (4,13,33). However, the presence of opportunities for exercise at home appeared to help girls compensate for this. The type of home equipment and parental perceptions of neighborhood safety were not related to the boys' physical activity, perhaps because they engage in more organized team activities (27). The gender differences may partly be explained by the high number of Hispanic children in the sample, as parental neighborhood attitudes may vary by child gender and gender differences in activity may be heightened in Latino families (27,22).
Only among parents living in neighborhoods perceived as safe was availability of outdoor exercise aids related to overall physical activity levels. The sensitivity of parents to neighborhood safety may be because the adult sample was predominantly female. Perhaps having a variety of outdoor equipment and supplies provided parents with multiple options for physical activity, but this facilitating effect of equipment was not effective in helping them overcome the barrier of unsafe neighborhoods.
This study is limited by its cross-sectional design and the measure of equipment that only assessed availability and not use. The items may also appear outdated as the instrument was developed in 1997 and did not include active electronic games such as DDR. Improved measures of exercise equipment and supports are needed. Physical activity was measured by self-report, although the measures had strong evidence of reliability and validity. The direction of causality has not been established. It is also quite possible that those who are keen exercisers choose to live in neighborhoods that support activity and buy more exercise equipment to use in those environments. In addition, this was a convenience sample, and whereas the ethnic groups are representative of San Diego County, the variability in safety of the neighborhoods was not maximized by purposeful sampling and the relatively high activity and education levels of the parents may have influenced these results. Strengths of the study include statistical adjustment for important demographic variables, separate analyses for adolescents and parents, and recruitment of participants over a 1-yr period to control for seasonal differences in physical activity in the analyses.
Having exercise equipment may facilitate physical activity for adolescents and adults, but the potential for benefits appears to depend on the perceived safety of the neighborhood. Exercising in the home may be a viable alternative to private facilities or public places for adolescent girls living in less-safe neighborhoods. For adults living in safer neighborhoods, outdoor exercise equipment may help them meet weekly activity guidelines. This study indicates that physical activity in the home may be an important contributor to overall activity in adolescent girls, which warrants further research. Individuals living in less-safe environments may also be less able to afford exercise equipment, so it is important to establish safe neighborhoods where physical activity is possible for adults and children without expecting individuals to invest in equipment that allows them to exercise within the safety of their home.
This project was supported by the National Cancer Institute (R01 CA81495 and R01 CA113828)
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