title: Fitness Level is Associated with Sex-Specific Regional Fat Differences in Normal Weight Young Adults.
abstract: OBJECTIVE
  To characterize regional body composition and insulin sensitivity differences between young adults who were normal weight with either high or low fitness determined by VO2peak. We hypothesized that higher fitness levels would be associated with reduced visceral fat (VAT) and improved insulin sensitivity.
  
  
  METHODS
  A cross-sectional comparison of normal weight males and females with high or low fitness matched on age and sex.
  
  
  METHODS
  A total of 38 (20M/18F) individuals were recruited for this study. Thirty-two young adults (18M/14F) were matched on age (mean 22.5 ± 3 yrs.) and BMI (22.4 ± 2.4 kg/m2) and sex and classified by high or low fitness based on VO2peak difference (≥ 8ml/kg/min). Total and regional body composition, including VAT, was measured by Dual Energy X-Ray Absorptiometry (DXA). Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp. An analysis of variance compared regional body composition and insulin sensitivity between high and low fitness young adults with a normal BMI.
  
  
  RESULTS
  Higher fitness was associated with significantly lower percent body fat, lower android fat mass and higher insulin sensitivity in males (-7.2%,P<0.001; -0.5kg,P=0.048; 5.6mg/kg (FFM)/min, p=0.002). In females, higher fitness was associated with significantly lower percent body fat, lower leg fat but no difference in insulin sensitivity (-6.7%,P=0.001; -2.7kg,P<0.001; 2.5 mg/kg(FFM)/min,P=0.40). No differences in VAT were observed between high and low fitness groups. Interestingly in females, there was no difference in total lean mass, trunk lean mass or leg lean mass (P=0.59, P=0.17, P=0.99).
  
  
  CONCLUSIONS
  Higher fitness does not influence VAT in normal weight individuals. Sex influenced regional fat and insulin sensitivity differences between high fitness and low fitness groups.
authors.affiliation: Department of Medicine, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
authors.forename: Tyler A
authors.initials: TA
authors.lastname: Bosch
authors.affiliation: School of Kinesiology, University of Minnesota, Minneapolis, MN 55455, USA; Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
authors.forename: Donald R
authors.initials: DR
authors.lastname: Dengel
authors.affiliation: Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN 55455, USA; Division of Epidemiology & Community Health, University of Minnesota School of Public Health, Minneapolis, MN 55455, USA.
authors.forename: Justin R
authors.initials: JR
authors.lastname: Ryder
authors.affiliation: Department of Medicine, University of Minnesota Medical School, Minneapolis, MN 55455, USA; Department of Pediatrics, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
authors.forename: Aaron S
authors.initials: AS
authors.lastname: Kelly
authors.affiliation: Department of Medicine, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
authors.forename: Lisa
authors.initials: L
authors.lastname: Chow
keywords: Adipose Tissue; Body Composition; DXA; Insulin Resistance; Obesity Paradox