Background: Effects of endurance training on adipose insulin sensitivity in association with body composition, circulating adipokines, and markers of inflammation have been studied less in young Asian subjects.Methods: Adipose insulin sensitivity/resistance was compared between 170 female Japanese collegiate athletes and 311 nonathletes (18–24 years), who underwent measurements of serum adipokines, markers of insulin sensitivity, inflammation, and dual-energy X-ray absorptiometry. Two separate subsamples of two groups of women underwent either a 75-gram oral glucose tolerance test or a standardized meal test, but not both.Results: As compared with nonathletes, athletes, characterized by higher skeletal muscle mass and lower percentage of body fat (both P < 0.001), had lower adipose insulin resistance (IR) (a product of fasting insulin and nonesterified fatty acid (NEFA) and lower leptin/adiponectin ratio (both P < 0.001). Although athletes had lower postmeal/postglucose insulinemia (P = 0.009 and 0.01, respectively), the two groups did not differ in postmeal percentage NEFA suppression and postmeal/postglucose glycemia, suggesting increased insulin sensitivity in adipose tissue and skeletal muscle, respectively. Serum leptin (P < 0.001) and tumor necrosis factor-α (P = 0.01) were lower in athletes, whereas adiponectin and homeostasis model assessment IR did not differ.Conclusions: Endurance training was associated with increased insulin sensitivity in adipose tissue as well as skeletal muscle without changes in circulating adiponectin even in young, normal-weight Japanese women.

ObjectiveInflammatory markers are elevated in insulin resistance (IR) and diabetes. We tested whether serum orosomucoid (ORM) is associated with postload glucose, β-cell dysfunction and IR inferred from plasma insulin kinetics during a 75 g oral glucose tolerance test (OGTT).Research design and methods75 g OGTTs were performed with multiple postload glucose and insulin measurements over a 30–120 min period in 168 non-obese Japanese women (aged 18–24 years). OGTT responses, serum adiponectin and high-sensitivity C reactive protein (hsCRP) were cross-sectionally analyzed by analysis of variance and then Bonferroni’s multiple comparison procedure. Stepwise multivariate linear regression analyses were used to identify most important determinants of ORM.ResultsOf 168 women, 161 had normal glucose tolerance. Postload glucose levels and the area under the glucose curve (AUCg) increased in a stepwise fashion from the first through the third ORM tertile. In contrast, there was no or modest, if any, association with fat mass index, trunk/leg fat ratio, adiponectin, hsCRP, postload insulinemia, the Matsuda index and homeostasis model assessment IR. In multivariable models, which incorporated the insulinogenic index, the Matsuda index and HOMA-IR, 30 min glucose (standardized β: 0.517) and AUCg (standardized β: 0.495) explained 92.8% of ORM variations.ConclusionsElevated circulating orosomucoid was associated with elevated 30 min glucose and glucose excursion in non-obese young Japanese women independently of adiposity, IR, insulin secretion, adiponectin and other investigated markers of inflammation. Although further research is needed, these results may suggest a clue to identify novel pathways that may have utility in monitoring dysglycemia within normal glucose tolerance.

Physical activity improves various metabolic disturbances. The effect of physical activity on non-alcoholic fatty liver disease (NAFLD) has not been defined, particularly in athletes who are able to consume a diet to increase body mass. The aim of this study was to evaluate the prevalence of NAFLD and associated factors of NAFLD among male university rugby football players [n = 69, 37 forwards (FW) and 32 backs (BK)], relative to age-matched controls (CON; n = 29). For FW players exercise consists of physical contact play, such as ruck, mall, scrum, and tackle. For BK players exercise consists of sprints and endurance running. Liver function tests and bioimpedance analysis to assess body composition were performed. Subjects consuming ≤ 20 g/day of ethanol and exhibiting an aspartate transaminase (AST) level ≥ 33 U/L, and/or alanine transaminase (ALT) level ≥ 43 U/L, were considered to have NAFLD. The PNPLA3 and MTP genotypes were determined using real-time polymerase chain reaction (PCR). The body mass index, body fat mass, and lean body mass were significantly higher in the FW group than in the BK and CON groups (P < 0.05). The total cholesterol, low-density lipoprotein cholesterol, triglyceride, AST, ALT, and alkaline phosphatase levels were significantly higher in the FW group than in the CON group (P < 0.05). The prevalence of NAFLD was significantly higher in the FW group than in the BK group and CON group (18.9, 8.6, and 0.0%, respectively), whereas there were non-significant between-group differences in the frequency of the PNPLA3 and MTP genotypes. These findings indicate that rugby football players, especially those in the FW position, are at higher risk of developing NAFLD, which emphasizes the role of diet and exercise in the development of NAFLD.