Effect of aerobic exercise intervention on markers of insulin resistance in breast cancer women

Insulin may affect breast cancer ( BC ) risk and prognosis. Exercise reduces insulin in obese BC survivors. We designed a randomised controlled trial to test the effect of an aerobic exercise intervention ( AEI ) on insulin parameters and body composition in non‐obese BC women without insulin resistance. Thirty‐eight BC women were randomised into an intervention group ( IG  = 18) or control group ( CG  = 20). IG participated in a structured AEI for 3 months, while CG received only the Word Cancer Research Fund/American Institute Cancer Research ( WCRF / AICR ) recommendation to be physically active . Fasting insulin, homeostasis model assessment of insulin resistance ( HOMA ‐ IR ) index, metabolic parameters and body composition were collected at baseline and after the AEI . IG reduced insulin and HOMA ‐ IR index by 15% and 14%, while CG increased these parameters (+12% and +16%). Insulin changed differently over time in the two randomised groups ( p interaction  = .04). The between‐group differences in the change of insulin ( IG  = −1.2 μU/ml versus CG  = +0.8 μU/ml) and HOMA ‐ IR index ( IG  = −0.26 versus CG  = +0.25) were respectively significant ( p  = .04) and non‐significant ( p  = .06). IG significantly improved lower limb muscle mass in comparison with CG ( p  = .03). A structured AEI may improve insulin, HOMA ‐ IR index and body composition in non‐obese BC survivors without insulin resistance.