Serum uric acid is positively associated with muscle strength in older men and women: Findings from NHANES 1999-2002.

Summary Background One of the causes of strength loss in older adults is the increased oxidative stress; thus, substances with antioxidants properties may have protective effects on muscle strength. Uric acid (UA) is an important antioxidant and it seems to be positively associated with muscle strength in older adults; however, the current evidence is still limited. Aim To investigate whether serum UA is associated with muscle strength in older men and women. Methods A cross-sectional study was performed evaluating older adults aged from 50 to 85 years, from National Health and Nutrition Examination Survey (NHANES) 1999-2000 and 2001-2002. A total of 2361 individuals (1256 men and 1105 women) were evaluated. The peak isokinetic knee extensor strength was assessed by kinetic communicator isokinetic dynamometer; while UA levels were measured by colorimetric method. Linear regression analyses were performed to estimate the coefficients and 95% confident intervals for muscle strength by quintiles of UA levels, adjusted for potential confounders. Results In the unadjusted analyzes, serum UA was positively associated with peak force in men and in total sample, but not for women. However, after adjustments for confounders, UA levels were positively associated with peak force in total sample (p-trend = 0.007), men (p-trend = 0.044) and women (p-trend = 0.016). Conclusion Serum UA is positively associated with muscle strength in older men and women. These results suggest that UA levels seems to be a protective factor for muscle strength in older adults independent of the sex.