The health benefits of physical activity (PA) are well established and supported by extensive observational and clinical trial evidence.(1–4) PA is a recommended behavioral strategy for preventing and controlling many chronic diseases, including diabetes, cardiovascular disease, and cancer,(5–8) and expert recommendations have been set to encourage people to engage in the minimum amount of activity to acquire the associated health benefits of PA.(9) However, self-reported estimates from the 2007 Behavioral Risk Factor Surveillance System (BRFSS) show that only 48.8% of adults meet the minimum recommendation of PA in a typical week.(10) Concerned with the low levels of PA in the US population, the Healthy People 2020 report calls for increased PA for all age groups, and underscores the importance of environmental supports for PA (e.g., sidewalks, bike lanes, trails, parks).(11)

Availability and quality of outdoor recreation areas, such as parks and green spaces are correlates of PA in community-dwelling adults.(12, 13) Parks can serve as important areas for gatherings of families, sports and recreation for children, and safe spaces for adults to utilize walking tracks.(14–16) A growing body of evidence demonstrates that the presence of parks, quality of park equipment, ease of access to parks, and perceived safety of parks are strong predictors of park use.(17–19) Parks offer convenient community locations for PA, and are associated with leisure-time PA in adults.(20, 21) Additionally, a recent review found exercising outdoors (versus indoors) to be associated with a range of emotional benefits such as decreased tension and depression and increased energy.(22)

Outdoor recreation areas are a prime target for public health attention as they are located in a broad range of neighborhoods throughout the US, offering access to PA resources for residents of all races/ethnicities and socioeconomic levels.(23) An analysis of the distribution of neighborhood-level PA resources in a diverse sample of neighborhoods found that while there was a higher density of recreations facilities (such as gyms) in White, high socioeconomic status neighborhoods, there was a fairly equitable distribution of parks across neighborhoods.(23)

Leaders from PA promotion groups such as Active Living Research are champions for the advancement of outdoor recreation areas to increase community-level PA, and suggest steps to achieve this goal beginning with work to make parks available, upgrade their features and safety, and finally promote their use.(24, 25) Additionally, there is support at the level of the US federal government to outdoor recreation areas and the integration of human, environmental, and ecological health, including a current campaign by The National Park Service (NPS), a division of the US Department of the Interior.(26) Through the 2011 NPS Healthy Parks Healthy People Strategic Action Plan, the initiative, the NPS works with organizations across the country at all levels (local, state, and national) as well as experts from business, healthcare, science, and the nonprofit sector, to create a network for engaging the public in a using outdoor recreation areas for health improvement.(26) The NPS is committed to promoting health in a wide sense (physical, mental, spiritual) as well as social well being, all through linking people with nature, both within and beyond parks.(26)

Despite the growing evidence about the benefits of outdoor recreation area use and the availability of these spaces across a range of neighborhoods, less is known about individual-level factors that predict outdoor recreation area use within a community with a variety of parks and trails available for use. (12, 13, 22) Targeted campaigns to raise awareness for parks and other outdoor recreation areas as well as interventions directed at low users of these resources could help to increase use and ultimately PA in adults.(21) Factors associated with lower PA levels include older age, gender (female), overweight/obesity, low socioeconomic status, and low education (e.g., did not complete high school).(27, 28) Targeted campaigns might be an effective means to encourage increased PA in generally sedentary populations,(29, 30) and highlighting outdoor recreation areas that are free and open to the public may increase awareness of avenues for being active regardless of financial status. Thus, it would be helpful to understand more about the individual-level correlates of outdoor recreation area use among a diverse group of community-dwelling adults.

Although the impact of environmental interventions on individual behavior has received increased study, several limitations in this literature exist, including the lack of diversity of participants.(31) A report by the President’s Council on Physical Fitness and Sports recommends that research into park use and active transport needs to focus on more diverse groups of people, including older adults and racial/ethnic minorities.(31)

The purpose of our study was to examine behavioral, attitudinal, sociodemographic, and health-related correlates of outdoor recreation area use in a county in the Southeastern US, representing a diverse area in terms of land use (rural and urban) as well as socioeconomic status and race. Using signal detection analysis, a novel method of analyzing data on outdoor recreation area use, we aimed to explain higher-order relationships between predictors of outdoor recreation area use for PA, and to identify subgroups of potential priority populations for future outdoor recreation area use campaigns.

Table 1 (first column) presents the demographic, health status, PA level, and park use and awareness data for all participants (N=829). Participants ranged in age from 18 to 99, with a mean age of 51.2±19.0 years. Respondents were mainly female (62.9%), Non-Hispanic (97.4%), and White (55.9%) or African American (41.7%); 27.6% of respondents were college graduates. The mean BMI was 28.5±6.2 kg/m², and similar to the overall prevalence in the U.S. population, 33.1% of respondents were obese.(40) Overall, most participants reported engaging in some PA—88.3% of respondents indicated that they do moderate PA for at least 10 minutes at a time at least once a week during a usual week (e.g., brisk walking, bicycling, vacuuming, gardening), though only 54.9% of respondents met PA recommendations.

The signal detection analysis identified seven subgroups of respondents with distinct rates of outdoor recreation area use, which are pictured in Figure 1. Overall, 53.6% of respondents reported having used an outdoor recreation area in the past 30 days; across the seven subgroups, outdoor recreation area use ranged from a low of 31.8% to a high of 77.2.4%. The dependent variable, independent variables, and descriptive variables for the seven subgroups are shown in Table 1.

Subgroups 1, 2, and 4 had the lowest percentages of outdoor recreation area use (range 31.8–38.7%). Subgroup 1 was the largest of the subgroups (n=239) and had the lowest level of outdoor recreation area use (31.8%). Respondents in this group were older than 55 years (mean age of 69 ± 11.8 years) and reported low perceived safety of outdoor recreation areas (0.0% selected “very safe”). They tended to be female (69.9%), White (63.6%), overweight (mean BMI of 28.5 ± 6.3 kg/m²), married or living with a steady partner (54.2%), and very few had children living in their household (8.4%). Subgroup 2 had low outdoor recreation area use (38.7%). Unlike Subgroup 1, characterized by older age and lower safety, participants in Subgroup 2 reported high perceived safety of outdoor recreation areas, and being over the age of 66 years (mean age of 77 ± 7.6 years). They also tended to be men (59.5%), White (59.7%), were well informed about parks (90.3%), and very few had children living in their household (3.2%). Subgroup 4 had low outdoor recreation area use (37.5%). These participants were <55 years of age (mean age of 40±10.0 years), reported that they did not hear a lot about places to be active, and had a BMI ≥ 27.5 (mean BMI of 33.5 ± 5.5 kg/m²). Many in this subgroup met PA recommendations (81.3%), and this subgroup had the highest percentage of households with a child in the household (54.7%), 45.3% of them were married.

Subgroups 3, 5, and 6 had more outdoor recreation area use (range 55.3%−64.2%) than the previous groups. Subgroup 3 had the most outdoor recreation area use of the older (> 55 years) groups (64.2%), and they reported high perceived safety of outdoor recreation areas. Subgroup 5 had moderate outdoor recreation area use (61.3%) and the subgroup was defined by age < 55 years (mean age of 36 ± 11.7 years), a BMI < 27.5 (mean BMI of 24.0 ± 2.4 kg/m²), and their reports of not hearing a lot about parks. This subgroup also reported lower perceived safety (17.5%), had the most people who lived with a spouse or serious partner (56.3%), and many had children living at home (43.8%). Subgroup 6 also had moderate outdoor recreation area use (55.3%) and were defined by age < 55 years (mean age 38 ± 11.6 years), reporting hearing a lot about parks, and not meeting PA recommendations. Many in this subgroup were also female (76.5%) and non-White (54.1%), and there were many married/serious partner households (50.6%) and households with children (44.7%).

Subgroup 7 had the highest percentage of outdoor recreation area users (77.2%). This group was defined by age < 55 years (mean age of 38 ± 11.1 years), reporting hearing a lot about parks, and meeting PA recommendations. They were also mostly White (57.7%), although they had the highest percentage of Hispanic respondents (5.3%). They tended to be female (56.5%), married or living with a partner (53.1%), and many had children < 18 years old (49.2%).

Signal detection analyses identified meaningful subgroups that differed in their use of outdoor recreation areas, such that a group of younger, physically active adults who had heard of parks in the area had the highest use of the outdoor areas. Older adults (> 55 years old) had lower outdoor recreation area use, especially those with a lower perception of the safety of outdoor recreation areas. While some surveys of park usage have shown that older adults are the least likely group to use parks,(41) other research has shown that older adults are very likely to be active when their neighborhood facilitates activity.(42) Thus, the results of the signal detection indicate that park and other outdoor recreation area awareness campaigns and group events for older adults, where they can exercise together and increase their perceived safety at parks and trails, might be an effective way to engage this population.

As mentioned above, the group of people most likely to use outdoor recreation areas were younger, had heard a lot about parks, and were physically active (meeting recommendations). Adults in this group may not be the priority population for PA interventions, as they are already active, but our results suggest that these individuals are making use of the PA resources in their communities. Future research could also examine more about the location of PA in order to better understand how much these individuals are actually using outdoor recreation areas for their PA routines.

Signal detection was also able to discern more complicated higher order relationships than would have been possible in a regression model. For example, the signal detection showed that perceived safety in outdoor recreation areas operated differently for different groups. The younger respondents, who also tended to use more outdoor recreation areas, reported lower perceived safety, with only 17.5–33.7% of respondents in Subgroups 5–7 reporting high perceived safety. However, in the older respondents (Subgroups 1–3), perceived safety was an important defining criterion, where those respondents in Subgroup 3 had higher perceived safety in outdoor recreation areas as well as more outdoor recreation area use as compared to Subgroup 1.

Consistent with the community PA promotion literature(43) and recent research,(44) greater awareness of places to be active, like parks, emerged as an important predictor of outdoor recreation area use. For younger respondents, hearing about parks was also related to greater use of outdoor recreation areas. This finding indicates that future park promotion efforts might successfully increase park usage by increasing knowledge of parks, especially in younger community members (<55 years).

Interestingly, the signal detection analysis did not identify race, gender, or education level as important determinants of outdoor recreation area use. In general, White men tend to be the most active subgroup of adults, with women and racial/ethnic minority groups reporting lower levels of overall PA.(28) In the case of outdoor recreation area, it is worth noting that age, park awareness, and perceived outdoor recreation area safety were more important than the traditional demographic correlates of PA; this suggests that perhaps outdoor recreation area promotion efforts might be best served by targeting a general adult audience, with less emphasis on cultural or gender tailoring. Additionally, this supports the evidence that parks are widely available and present a somewhat universal method through which to promote PA regardless of the racial/ethnic or socioeconomic composition of the neighborhood.

BMI also played a relatively small role in the differentiation of subgroups, only emerging as a third-order variable for one subgroup. While estimates from the BRFSS indicate that adults of higher BMIs tend to have correspondingly lower levels of PA(45) and are more likely to report engaging in no PA in the past 30 days (33.0% of obese respondents vs. 21.4% of normal/underweight respondents),(45) some research indicates that BMI might play a larger role in the PA of obese adults as compared to normal weight adults.(46) Subgroup 4 had the highest mean BMI (33.5 ± 5.5 kg/m²), had low outdoor recreation area use (37.5%), and had the highest percentage of respondents with children <18 years in the household (54.7%). A recent study used GPS to track the joint PA of parent-child dyads and found that obese dyads did less PA together in open spaces such as outdoor recreation areas than did under/normal weight dyads.(47) Thus, while the results of the signal detection indicate that although BMI might have played only a small role in being associated with outdoor recreation area use, perhaps it was an important factor where it was related. Future campaigns for park promotion could target family PA, especially for obese parents and children.

Limitations of this study include the cross-sectional nature of the data analyzed, the descriptive and exploratory nature of the signal detection analysis, and the use of several single-item measures. The low response rates to the phone survey should also be noted in considering the limitations of the study. With data from a single time point, we are unable to address causation of park use. Likewise, signal detection provides a unique and objective perspective on correlates of park use, but it is meant for exploratory purposes and cannot posit causation either.

Despite these limitations, the current analysis offers a unique perspective on the combination of individual-level correlates of park use in a community environment that includes a number of PA resources for all residents, and used a sample of community-dwelling adults of diverse backgrounds. Our results suggest that gendered and ethnically-focused park promotion campaigns might be unnecessary, and instead efforts should be placed on increasing awareness of park facilities among older, less active community members.