Muscular and performance fitness and the incidence of type 2 diabetes: prospective study of Japanese men.

BACKGROUND Limited data are available on the relationship between muscular and performance fitness (MPF) and the incidence of type 2 diabetes. METHODS A cohort of 3792 Japanese men completed a medical examination that included MPF and cardiorespiratory fitness tests. MPF index composite score was calculated using Z-scores from vertical jump, sit-ups, side step, and functional reach tests. RESULTS The mean follow-up period was 187 months (15.6 years). There were 240 patients who developed type 2 diabetes during follow-up. Relative risks and 95% confidence intervals (CI) for incidence of diabetes across baseline quartiles of MPF index composite score were obtained using the Cox proportional hazards model while adjusting for age, BMI, diastolic blood pressure, cigarette smoking, alcohol intake, and family history of diabetes. The relative risks for developing diabetes across quartiles of MPF index composite scores (lowest to highest) were 1.0 (referent), 1.15 (95% CI 0.83-1.60), 1.10 (0.78-1.55), and 0.57 (0.37-0.90) (P for trend = .061). These results were attenuated after adjustment for cardiorespiratory fitness (P for trend = .125). CONCLUSIONS This prospective study suggests that MPF is a predictor of type 2 diabetes, although its predictive ability was attenuated after adjusting for cardiorespiratory fitness.