Temporal relationship between serum uric acid and muscle strength: a cross-sectional and longitudinal study of middle-aged and older adults

The causal temporal association between serum uric acid (SUA) and muscle strength among elderly adults in China remains unclear. This study aimed to investigate both cross-sectional and longitudinal associations between SUA and muscle strength. Cross-sectional and longitudinal analyses were conducted using data from the China Health and Retirement Longitudinal Study (CHARLS). The cross-sectional cohort included 8706 participants from the 2015 wave. Muscle strength was assessed using grip strength and chair rising time. Generalized linear models evaluated associations between SUA and muscle strength. The longitudinal cohort included 3,404 participants from the 2011 wave, followed up in 2015. Cross-lagged panel models were applied to assess causal relationships. Cross-sectionally, SUA was positively associated with grip strength (β = 0.247, 95% CI 0.107-0.387) and negatively with chair rising time (β = - 0.166, 95% CI - 0.228 to - 0.105). No significant associations were found in participants with hyperuricemia. Longitudinally, baseline SUA predicted future grip strength (β = 0.038, 95% CI 0.006-0.072) and chair rising time (β = - 0.063, 95% CI - 0.093 to - 0.032), while baseline muscle strength did not predict future SUA. Higher SUA within the normal range is associated with better muscle strength in elderly adults, but this association is not observed in those with hyperuricemia.