Background Identifying how racial/ethnic residential segregation and mobility may impact health can guide innovative strategies for reducing youth disparities.

Methods This natural experiment examined the association between change in residential segregation and cardiovascular health outcomes across race/ethnicity and gender for youth (n=2250, mean age 9.1 years, 54% male; 51% Hispanic, 49% non-Hispanic black (NHB); 49% high area poverty) attending a multisite park-based afterschool fitness programme in Florida, USA. Two-level generalised linear mixed models with random intercepts for park effects were fit to test the change in segregation–cardiovascular health association over two school years.

Results After covariate adjustment (individual-level gender, race/ethnicity, age, time and park-area poverty), greater improvements in cardiovascular health including body mass index percentile, sum of skinfold thicknesses, systolic/diastolic blood pressure percentiles and 400 m run time were found for youth who attended the program in a less segregated area compared with their home area (p<0.05 for all outcomes). NHB girls showed the greatest cardiovascular health improvements. Specifically, compared with the reference group (no change in segregation), skinfold thicknesses and systolic blood pressure percentiles decreased 17% (incidence rate ratio (IRR) 95% CI 0.81 to 0.86) and 16% (IRR 95% CI 0.82 to 0.87), respectively, versus 1% increase for both outcomes (IRR 95% CI 0.98 to 1.05) and (IRR 95% CI 0.98 to 1.05), respectively, for movement to less versus more segregated areas.

Conclusion In light of a continually expanding youth obesity epidemic, the global effort to reduce health inequities may be supported through Parks and Recreation Departments given potential to expand geographic mobility for low resource subgroups.