Cut Points of Muscle Strength Associated with Metabolic Syndrome in Men

Introduction: The loss of muscle strength with age increases the likelihood of chronic conditions, including metabolic syndrome (MetS). However, the minimal threshold of muscle strength at which the risk for MetS increases has never been established. Objective: This study aimed to identify a threshold of muscle strength associated with MetS in men. Methods: We created receiver operating curves for muscle strength and the risk of MetS from a cross-sectional sample of 5685 men age <50 yr and 1541 men age >= 50 yr enrolled in the Aerobics Center Longitudinal Study. The primary outcome measure, the MetS, was defined according to the National Cholesterol Education Program Adult Treatment Panel III criteria. Upper and lower body muscle strength was treated as a composite measure of one-repetition maximum tests on bench and leg press and scaled to body weight. Low muscle strength was defined as the lowest age-specific 20th percentile, whereas high muscle strength was defined as composite muscle strength above the 20th percentile. Results: In men aged <50 yr, the odds of MetS were 2.20-fold (95% confidence interval = 1.89-2.54) higher in those with low muscle strength, independent of age, smoking, and alcohol intake. The strength of this association was similar for men age >= 50 yr (odds ratio = 2.11, 95% confidence interval = 1.62-2.74). In men age <50 yr, the composite strength threshold associated with MetS was 2.57 kg.kg(-1) body weight, whereas in men age >= 50 yr the threshold was 2.35 kg.kg(-1) body weight. Conclusion: This study is the first to identify a threshold of muscle strength associated with an increased likelihood of MetS in men. Measures of muscle strength may help identify men at risk of chronic disease.