Increased Adipose and Muscle Insulin Sensitivity Without Changes in Serum Adiponectin in Young Female Collegiate Athletes

Abstract

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.

Higher circulating adiponectin and lower orosomucoid were associated with postload glucose ≤70 mg/dL, a possible inverse marker for dysglycemia, in young Japanese women

“…We cross-sectionally studied 168 young women (50 collegiate athletes and 118 untrained students of the university), aged 18–24 years, whose details have been reported elsewhere 6 13–15. The athletes were students of the Department of Health and Sports Sciences and had been training regularly for 2 years or longer prior to the study, 5 hours a day, 6 days a week.…”

“…Leptin, adiponectin, high-sensitivity C reactive protein (hsCRP) and plasminogen activator inhibitor-1 (PAI-1) were measured in fasted samples as previously reported 13–15. ORM concentrations were measured in fasted samples by an immunoturbidimetric method using a commercially available kit (N Antiserum to Human α1-acid Glycoprotein, Siemens Healthcare Diagnostics, Tokyo, Japan) and an autoanalyzer (JCA-BM6010, JEOL, Tokyo, Japan).…”

“…Fat and lean mass for arms, legs, trunk and the total body were measured using whole-body dual-energy X-ray absorptiometry (DXA, Hologic QDR-2000, V.7.20D, Waltham, Massachusetts) as previously reported 14 15. The leg region included the entire hip, thigh and leg.…”

“…However, associations between ORM and postload low glycemia were not evaluated in that study 13. Therefore, we aimed to examine whether serum adiponectin and ORM were associated with postload low glycemia, a possible inverse marker for dysglycemia, in 168 young Japanese women recruited from our previous cross-sectional study,6 13 and whether these associations, if any, depend on fat mass and distribution, insulin secretion and insulin resistance (IR) of muscle and adipose tissue, the latter of which was evaluated using fasting free fatty acid (FFA) 14…”

Post-Prandial Plasma Glucose Less Than or Equal to 70 mg/dL Is Not Uncommon in Young Japanese Women

“…Another set of 17 athletes and 18 non-athletes underwent a standardized meal test [4]. PG and serum insulin were measured at 0 (baseline), 30, 60, and 120 min.…”