Plasma Uric Acid Is Positively Associated With Muscle Strength In Older Adults - NHANES 2001-2002

PURPOSE: To associate plasma UA with muscle strength in individuals over 50 years. METHODS: A cross-sectional study was performed evaluating 1,433 individuals (731 men and 702 women) from National Health and Nutrition Examination Survey (NHANES) 2001-2002. The analyses included men and women aged 50-85 years who presented complete sociodemographic, anthropometric, body composition, strength, biochemical parameters, food intake, medical conditions and lifestyle data. Plasma UA was measured by colorimetric method; kinetic communicator isokinetic dynamometer was used to evaluate voluntary peak isokinetic knee extensor strength. The outcome measurement was the peak force (Newton) of the quadriceps. Six muscle strength measurements were performed: three initial measurements were considered warm-up/learning measurements and three final measurements were considered valid, the highest peak force value was used. Lean mass was evaluated by dual-energy X-ray absorptiometry. Participants were characterized by UA tercile and sex. To assess the association between UA tercile and strength, multiple linear regression models were performed. The analysis were adjusted for age, race, education level, smoke status, alcohol intake, body mass index, physical activity, protein and energy intake, diabetes, hypertension, glomerular filtration rate and total lean mass. All analyses were performed using Stata 14.0 software. RESULTS: Individuals with higher UA were older, had higher weight, height, lean mass, fat mass, strength, higher proportion of smokers and alcohol users (p<0.05). In addition, they had lower glomerular filtration rate and consumed less protein (p<0.05). Linear regression showed that UA levels were positively associated with muscle strength for men (β of third tercile = 24.8 [1.75;47.9] p-trend=0.028) and women (β of third tercile = 22.2 [1.03;43.3] p-trend = 0.028). CONCLUSIONS: Uric acid was positively associated with muscle strength in older adults.