[Purpose] To investigate the relation between isotonic leg extension strength (ILES) and the prevalence of metabolic syndrome (MS) in Japanese male adults.[Methods] This cross-sectional study included 395 Japanese men. Metabolic syndrome was determined according to the criteria of International Diabetes Federation (IDF), Japan Society for the Study of Obesity (JASSO), or National Cholesterol Education Program's Adults Treatment Panel III (NCEP-ATPIII). Muscular strength was measured on a horizontal dynamometer. Subjects were divided into tertile levels according to ILES (watts/kg). Multiple logistic regression analysis was used to examine the relation between ILES levels and the prevalence of MS.[Results] The prevalence of MS were 14.4% (IDF), 17.0%(JASSO), and 20.0% (NCEP-ATPIII). After adjustment for confounding factors, the odd's ratios (95% confidence interval) of MS (IDF) compared with the lowest ILES level were 0.90 (0.48-1.68) and 0.31 (0.13-0.64) in the middle and high levels of ILES (p for trend=0.03). The association between the level of ILES and the prevalence of MS by JASSO and NCEP-ATPIIIcriteria were similar.[Conclusion] The prevalence of MS was associated with the level of ILES.

Coffee administration has been shown to increase maximum voluntary contraction and muscular endurance. However, no study has addressed the association between daily consumption of coffee with muscular function. This cross sectional study aimed to investigate the association between frequency of coffee consumption (CC) in daily life and muscle strength among a population of working adult men. This cross sectional study included men (n = 516, mean age: 47.1) who participated in an annual health examination conducted in Sendai. The monthly frequency of coffee consumed was reported by a brief-type self-administered dietary history questionnaire. Leg extension power (LEP) was measured as an index of muscle strength. Subjects were divided into tertile levels according to CC. Analysis of covariance was used to examine the relation between the tertile levels of CC and LEP. After adjustment for potential confounders (including all lifestyle factors), the adjusted means (95% confidence interval) of LEP across the tertiles of CC were 17.4 (16.6 - 18.1) for the lowest tertile, 17.9 (17.4 - 18.5) for the mid tertile, and 18.9 (18.3 - 19.5) for the highest tertile (p for trend = 0.007). Higher frequency of monthly coffee consumption was associated with higher muscle strength.