Relationship Between Aerobic Fitness and Adipose Tissue Insulin Resistance

Objective: Aerobic fitness is associated with greater skeletal muscle insulin sensitivity with regards to glucose uptake. Whether fitness is associated with an improvement in the insulin36 regulation of adipose tissue lipolysis is unknown. Methods: We collated adipose insulin sensitivity, body composition and fitness data from six of our previously published and two of our unpublished studies. ADIPO- IR palmitate data was available for 340 volunteers and the insulin concentration resulting in a 50% suppression of palmitate rate of appearance (FFApalmitate IC 50 ) measured using the insulin clamp technique was available for 108 volunteers. Pearson correlation and multiple linear regression analysis were performed to assess the relationship between the independent variables of aerobic fitness (VO2 peak, mL•kg FFM -1 •min -1 ), age, sex, BMI, visceral adipose tissue (VAT), body fat, percent body fat and the dependent variables ADIPO-IR palmitate and FFApalmitate IC 50 . Results: Factors that were univariately correlated (p<0.001) with ADIPO- IR palmitate and FFApalmitate IC 50 were BMI, percent body fat, body fat and VAT. Fitness correlated negatively with ADIPO- IR palmitate and FFApalmitate IC 50 . Stepwise regression analysis showed that fitness independently predicted ADIPO- IR palmitate and FFApalmitate IC 50 after adjusting for the other significant factors. Conclusions: These findings suggest that aerobic fitness may promote metabolic health through positive effects on adipose tissue.