Exercise training could potentially exert beneficial effects on the signaling events associated with cardiac cell apoptosis. Spontaneously hypertensive rats (SHR) were trained 5 days/week on a treadmill (18 m/min for 120 min/day) between the ages of 4 weeks and 1 week, corresponding to the hypertensive accelerating phase. The effect of exercise training on the expression of anti-apoptotic proteins HSP-72, Bcl-2 and protein kinase B (PKB), and the apoptotic proteins Bax and glycogen synthase kinase-3 (GSK-3) was examined. Exercise had a significant acute lowering effect on blood pressure, but this decrease did not attenuate the progressive increase in blood pressure. In the left ventricles of exercised SHR, PKB phosphorylation of both Ser473 and Thr308 residues was significantly increased by 166% and 120%, respectively, compared to sedentary SHR. PKB phosphorylation significantly correlated with GSK-3beta phosphorylation. HSP-72 and Bcl-2 protein expression were increased in the left ventricle of exercised SHR, and associated with the concomitant increased expression of the protein Bax. Thus, the Bcl-2/Bax ratio was not changed by exercise training, suggesting that the anti-apoptotic mechanism was effective in compensating the increase in the expression of the pro-apoptotic protein Bax in the myocardium of the SHR.