To the Editor: It is unclear whether aortic dissection is associated with high-intensity strength training. Methods. From our Yale University aortic database, and from outside cases brought to our attention after lay press reports of our aortic research, we identified and reviewed case materials of 5 patients who experienced acute dissection of the ascending aorta in the setting of high-intensity weight training or other strenuous exercise. Results. The 5 patients ranged in age between 19 and 53 years. None had previously diagnosed aneurysm or personal history of hypertension or collagen vascular disease. Only 1 patient had a family history of aortic disease. None had signs of Marfan syndrome. All patients were involved in strenuous strength training at the instant that their dissection pain occurred. Two patients were weight training, a third was attempting to move a heavy granite structure, and the other 2 were doing push-ups. All patients manifested acute ascending aortic dissection. Diagnosis was made by computed tomography scan in 3 patients, by echocardiography in 1, and by autopsy in the fifth. The diameter of the aorta on the imaging studies performed immediately after dissection ranged from 4.0 to 5.2 cm, indicating underlying enlargement, but not to a level expected to present a high risk of dissection. Three patients underwent successful urgent surgical repair of the acute dissection. These patients survived and are without sequelae at 4, 20, and 48 months. One patient died shortly after diagnosis and before transfer to another facility could be made, and the fifth died before a diagnosis was made. Pathological analysis, available in 4 patients, showed underlying cystic medial necrosis, which was of mild to moderate severity in 2 patients. Comment. The risk of weight lifting as a cause of aortic dissection has generally been underappreciated. We recommend caution in patients with known aneurysms or connective tissue diseases, a family history of aneurysm or dissection, or underlying hypertension, as well those at or beyond middle age, because aneurysm, connective-tissue disease, family history, and hypertension predispose to aortic dissection and because aortic stiffness increases with age. None of the patients in this series, however, had these known risk factors. Furthermore, because limiting maximal effort prevents extreme ( 200 mm Hg) elevations in blood pressure, it also seems reasonable to limit weight lifting in individuals at risk.