Background Endurance exercise training can increase left ventricular (LV) ejection fraction during dynamic exercise in coronary artery disease. This adaptation may be mediated by altered cardiac loading conditions rather than an improvement in intrinsic LV systolic function. To minimize these confounding effects, we used isometric handgrip exercise to assess the training-induced changes in LV systolic function and ventriculoarterial coupling. Methods Twenty-six patients (52 ± 2 years of age) trained for 12 months. LV function was assessed with radionuclide ventriculograpy. Results LV systolic reserve (the change in LV ejection fraction from rest to handgrip exercise) increased from –7.32 ± 1.2 to –3.4 ± 1.1 (P = .033) without acute changes in end-diastolic volume or the effective arterial load. LV end-systolic elastance increased 37% (P = .039) during handgrip exercise. Resting end-diastolic volume increased and the effective arterial load decreased after training. Conclusions Data suggest that in coronary artery disease adaptations to exercise training include a lower effective arterial load and an increase in EDV at rest, with an improvement in LV systolic function detectable only during afterload stress. (Am Heart J 1999;138:169-74.)