Background The WHO calls for affordable population-based prevention strategies for reducing the global burden of cardiovascular disease (CVD) on morbidity and mortality; however, effective, sustainable and accessible community-based approaches for CVD prevention in at-risk youth have yet to be identified. We examined the effects of implementing a daily park-based afterschool fitness programme on youth CVD risk profiles over 5 years and across area poverty subgroups.

Methods The study included 2264 youth (mean age 9.4 years, 54% male, 50% Hispanic, 47% non-Hispanic black, 70% high/very high area poverty) in Miami, Florida, USA. We used three-level repeated measures mixed models to determine the longitudinal effects of programme participation on modifiable CVD outcomes (2010–2016).

Results Duration of programme participation was significantly associated with CVD risk profile improvements, including body mass index (BMI) z-score, diastolic/systolic blood pressure, skinfold thicknesses, waist–hip ratio, sit-ups, push-ups, Progressive Aerobic Cardiovascular Endurance Run (PACER) score, 400 m run time, probability of developing systolic/diastolic hypertension and overweight/obesity in high/very high poverty neighbourhoods (P<0.001). Diastolic blood pressure decreased 3.4 percentile points (95% CI −5.85 to −0.85), 8.1 percentile points (95% CI –11.98 to −4.26), 6.1 percentile points (95% CI −11.49 to −0.66), 7.6 percentile points (95% CI −15.33 to –0.15) and 11.4 percentile points (95% CI −25.32 to 2.61) for 1–5 years, respectively, in high/very high poverty areas. In contrast, significant improvements were found only for PACER score and waist–hip ratio in low/mid poverty areas.

Conclusion This analysis presents compelling evidence demonstrating that park-based afterschool programmes can successfully maintain or improve at-risk youth CVD profiles over multiple years.