Endurance exercise training promotes important metabolic adaptations and the adipose tissue is particularly affected. The aim of this study was to investigate how endurance exercise training modulates some aspects of insulin action in isolated adipocytes and in intact adipose tissue. Male Wistar rats were submitted to daily treadmill running (1 hour per day), for 7 weeks. Sedentary age-matched rats were used as controls. Final body weight, body weight gain and epididymal fat pad weight did not show any statistical differences between the groups. Adipocytes from trained rats were smaller than those from sedentary rats (205 ± 16.8 vs. 286 ± 26.4 pl, p<0.05). Trained rats showed decreased plasma glucose (4.9 ± 0.13 vs. 5.3 ± 0.07 mmol/l, p<0.05), and insulin levels (0.24 ± 0.012 vs. 0.41 ± 0.049 mmol/l, p<0.05) and increased insulin-stimulated glucose uptake (23.1 ± 3.1 vs. 12.1 ± 2.9 pmol/cm², p<0.05) when compared to sedentary rats. The number of insulin receptors and the insulin-induced tyrosine phosphorylation (PY) of IR- subunit did not change between the groups. Insulin-induced PY-IRS-1 and -2 increased significantly (1.57- and 2.38-fold, respectively) in trained rats. Insulin-induced IRS-1/PI3-kinase (but not IRS-2/PI3-K) association and serine AKT phosphorylation also increased (2.06- and 3.15-fold, respectively) after training. The protein content of IR- subunit, IRS-1 and -2 did not differ between the groups. Taken together, these data support the hypothesis that the increased adipocyte responsiveness to insulin observed after endurance exercise training is modulated by IRS/PI3-K/AKT pathway.