Association between serum uric acid and cardiovascular fitness among US adults: A cross-sectional study

Background: While serum uric acid (SUA) is known as a cardiovascular disease risk factor and is associated with increased cardiovascular mortality, the relationship between SUA and cardiovascular adaptability under exercise stress remains unclear. Aims: This study aims to elucidate the relationship between SUA levels and cardiovascular fitness, particularly as manifested during cardiopulmonary exercise testing. Methods: Utilizing data from the National Health and Nutrition Examination Survey (NHANES) 1999-2004, this study included 5765 participants aged 12-49 years. Heart rate recovery (HRR) during cardiopulmonary exercise testing was measured as an indicator of cardiovascular fitness. Multivariate linear regression analysis was used to explore the association between SUA levels and heart rate recovery at 1 min (HRR1) and 2 min (HRR2) post-exercise. Results: After adjusting for potential confounders, an inverse relationship was found between SUA levels and both HRR1 and HRR2. Multivariate adjusted smoothing spline plots demonstrated a decrease in HRR1 and HRR2 with increasing SUA levels. This negative correlation was observed across nearly all subgroups. Conclusions: Elevated SUA levels are indicative of poorer cardiovascular adaptability in the adult US population.