Excluding unobserved areas like adjacent golf courses, FZ park size averaged 14.4 acres (range, 1-29 acres). Within a 1-mile radius around the parks, the average percentage of households in poverty was 29.3% (range, 6.8% to 61.5%); average population density was 40,964 persons (range, 7,581 to 72,292), percent Latino was 59% (range, 19.1% to 97.3%), and percent African American was 18.9% (range, 0.3% to 68.6%). (See .) The ten comparison parks averaged 12.4 acres (range 0.5-46 acres) and served an average of 33,226 individuals in a 1-mile radius including 46.3% Hispanic and 15.3% African American residents.
Observations of Park Users
Across the three observation periods, we counted 23,577 people in the 12 parks, including 2,570 in the FZ areas. Across all 12 parks at first follow-up one year after baseline, we counted 7,906 park users. After adjusting those observed at baseline (i.e, 6,906) for undercounts to 7,105, the difference over the year represents an 11% increase in users. These increases were concentrated in four City parks and two county parks, primarily those with a larger population density. Decreases in the overall number of park users were noted at the other six parks (see ). At the second follow-up in the spring, the number counted in the 12 parks (7,017) was similar to baseline.
Park Use before and after Fitness Zone Installation
After installation, we observed Fitness Zone equipment being used throughout the day, with peaks in number of users from 9:30-11:30AM and 3:30-5:30PM. At the first follow-up we counted an average of 2.9 people per Fitness Zone in each of the 10 hourly scans (27 per day), but the number varied substantially across parks, with one Fitness Zone serving 89 users during one day. This observed number of users, however, undercounts actual use, because people typically reported staying less than 60 minutes and we counted people only once per hour. The average number of Fitness Zone users did not vary between weekdays and weekends (24 vs. 29 per day, respectively). In contrast; during the two follow-up periods, overall mean park use was significantly higher on weekend days compared to weekdays (202 vs. 91 per day, respectively). Across the 12 parks, Fitness Zone users comprised 5.4% and 5.6% of total park visitors at the first and second follow-ups, respectively.
At baseline and at both follow-up periods, over 60% of observed park users were male; but in Fitness Zones fewer than 50% were male (p <.05). Fitness Zone users did not differ significantly by age group from other park areas. Because they were using the exercise equipment, people in Fitness Zones engaged in substantially more moderate to vigorous physical activity (MVPA) than those in other park activity areas (66% vs. 31% at first follow-up; 72% vs. 35% at second follow-up). Most (65.1% during the first follow-up; 71.1% during second follow-up) were using equipment items as recommended by the manufacturer.. The most frequently used equipment pieces were the dual pendulum, the ski machine, and the leg press; in contrast, the leg curl and the horizontal bars were used the least. A greater proportion of people in smaller parks used Fitness Zone equipment (and the Fitness Zone) than those in larger parks.
Considering observed users and their activity levels, the total estimated METs was 16,900 at baseline (including the imputed values for adjusted counts). Estimated METs at first and second follow-ups were 19,383 and 18,234, representing increases of 15% and 8% from baseline, respectively. Estimated METs expended in the parks by users outside the Fitness Zones was similar at baseline and the first follow-up, but increased by 12% at the second follow-up.
Fewer people used Fitness Zone parks than comparison parks at baseline; over time however, the number using Fitness Zone parks increased more than the number using comparison parks. At the first follow-up an average of 207 additional individuals used a FZ park and the average estimated energy expenditure increased by 685 METs, with neither increase being statistically significant ().
Difference of differences analysis for the observation data (with control parks) and Propensity score analysis for self-reported data (with control parks)
Self-reported park use
Across all 12 FZ parks we interviewed 742 adult visitors at baseline, 942 at the first follow-up, and 952 at the second. During both follow-ups, 52% and 48% of the respondents, respectively, were in Fitness Zone areas. Fitness Zone respondents did not differ demographically from the other park users interviewed: 80% Latino; 9% African American; 61% female; average age = 40 years, sd =12.5, p=0.94 (.)
Characteristics of Park Users and Survey Respondents at Baseline and Fitness Zone Users at First and Second Follow-ups
At both follow-ups, self-reported use of equipment pieces matched the observed data, with the dual pendulum and the ski machine being used most and the leg curl and horizontal bars used the least. Fitness Zone respondents reported visiting the park more frequently than those in other park areas (3.5 vs. 2.4 visits per week, p<.0001), and they reported engaging in more exercise sessions per week (3.9 vs. 2.7; p<.0001). Losing weight was the most common reason reported for using the fitness equipment. Compared to other area users, Fitness Zone users reported getting to the park more often by walking (56.3 vs. 34.9%, p=.002) () and visiting the park for the first time within the past six months (20.5% vs. 7.1%, p<.0001).
Survey Responses of Fitness Zone Users (1st & 2nd Follow-ups Combined), Weighted1
About 91% of survey respondents provided a valid intersection which they said was closest to their residence. Based upon this address, Fitness Zone users tended to live closer to the park than other park users (mean= 0.71 vs. 1.14 miles, p<.02). About 33% of Fitness Zone users lived within 1/4 mile of the park and 24% lived between 1/4 and 1/2 mile, compared to 28% and 20% of other park users, respectively.
After accounting for differences in respondent characteristics, comparing baseline and follow-up measures of FZ parks alone, the propensity score analysis showed a trend for the percentage of respondents visiting the park for the first time in the past six months to be higher at the first follow-up than at baseline (11.3% vs. 7.2% p=.09). The average number of reported exercise sessions (2.76 vs. 2.49; p=.03) was also significantly higher at the first follow-up than at baseline, but the proportion of respondents using the park at least once per week was no different, nor were the percentage of new users and number of exercise sessions at the second follow-up (data not shown). Comparing all respondents in intervention parks with those from comparison parks confirmed that more FZ park users reported being new users in both the past month (p<.007) and the past six months (p<.014) and that there was a trend for intervention park visitors to report increased frequency of park use (p<0.081) ().
Calculating cost effectiveness based on change in the Fitness Zone parks over time showed a net gain of 1,909 METs in the 12 parks or 159 METs per park. This is equivalent to 52,311 additional METs/year at a cost of 10.5 cents/MET. This estimate includes the declines in METs in five parks and the increases in METs in seven of the 12 parks. Using the increase of 685 METs per park calculated in comparison to energy changes at non-FZ parks, the cost effectiveness is 2.4 cents/MET; however, the increase in METs was not statistically significant.