We assessed the left ventricular (LV) contractile reserve in young adults with repaired coarctation of the aorta and interrupted aortic arch by determination of LV force-frequency relation (FFR). Eighteen (7 men) patients aged 24.2 ± 5.4 years and 20 (9 men) healthy controls were studied. Blood pressures in the right arm were measured by oscillometry. Transmitral early (E) and late (A) diastolic velocities, tissue Doppler-derived mitral annular systolic (sm), early diastolic (em) and late diastolic (am) velocities, and myocardial isovolumic acceleration (IVA) were measured. The LV FFR and average slope were derived from the IVA measured at different heart rates during supine bicycle exercise. Blood pressures at rest were similar between patients and controls (all p >0.05). At baseline, patients compared with controls had significantly greater E velocity, E/A and E/em ratios, and lower sm and em velocities (all p <0.05) but similar IVA (p = 0.18). At submaximal exercise, diastolic (p = 0.001) and mean (p = 0.003) blood pressures became significantly higher in patients than controls, sm (p = 0.001) and em (p <0.001) velocities remained reduced, whereas the IVA became lower (p <0.001). The weighted average FFR was flattened (p <0.001), and average FFR slope was lower (p <0.001) in patients compared with controls. The average FFR slope correlated negatively with the magnitude of exercise-induced increase in systolic (r = -0.32, p = 0.050), mean (r = -0.41, p = 0.011), and diastolic (r = -0.40, p = 0.013) blood pressures. In conclusion, young adults after coarctation of the aorta and interrupted aortic arch repair exhibit reduced LV contractile reserve, which is related to the blood pressure response during exercise stress.