It has been postulated that platelet function plays an important role in the initiation of atherosclerosis. Currently there are no definitive data on the longer-term effects of regular physical exercise on platelet function in humans. We assessed the influence of regular moderate-intensity physical exercise (brisk walking to slow jogging) on platelet aggregation in a population-based sample of middle-aged, overweight, mildly hypertensive men in eastern Finland. In this controlled study, we evaluated the net effect of exercise on platelet aggregation by studying changes in optical density and ATP release in platelet-rich plasma. A significant inhibition of secondary platelet aggregation from 27% to 36% was observed in the men taking regular exercise. These findings give new insight into the possible protective effects of exercise against the risk of ischemic heart disease. Circulation 74, No. 5, 939-944, 1986. INTERACTIONS among platelets, lipoproteins, and arterial vessel wall have been postulated to be centrally involved in the development of atherosclerosis. Increased low-density lipoprotein (LDL)-cholesterol, causing endothelial injury, together with an increased rate of LDL infiltration promote platelet aggregation. The ensuing smooth muscle cell proliferation and cholesterol accumulation together with the secretion of connective tissue matrix finally initiate the formation of atherosclerotic plaque.1 Furthermore, there is evidence of thrombosis in coronary arteries both in myocardial infarction2 and sudden cardiac ischemic death,3 possibly caused by continuous arterial microemboli.'The initial phase of thrombosis is thrombocyte aggregation, preceded by the activation of platelets.5 An increased activation of platelets has been observed in patients with ischemic heart disease (IHD) during physical exercise,6'7 although not consistently. Vol. 74, No. 5, November 1986 porarily increased platelet aggregation has been observed in healthy young men after both short-term9 and long-terml' strenuous running exercise. At present, no experimental data are available on the longer-term effects of physical training on platelet aggregability in humans. The overall purpose of this study was to investigate the effects of regular low-intensity physical exercise on risk factors for IHD and on platelet function in vitro. Our results demonstrate that exercise training can lower the sensitivity of platelets to the action of agonist, a potentially beneficial effect.

A postmortem coronary angiography technique employing aortic injection of contrast medium and double contrast visualization of the aortic bulb and large epicardial coronary trunks was applied to the study of coronary ostia in a series of I24 deaths from acute myocardial infarction and a series of 89 sudden deaths without recent infarction and 42 violent deaths. A stenosis of50 per cent or more of the lumen was found in the right ostium in 45 per cent and in the left ostium in 8 per cent of infarct cases. The correspondingfigures in sudden deaths were 37 per cent on the right and 4 5 per cent on the left side, and in violent deaths 7 per cent in the right ostium and none in the left. Most ostial stenoses were caused by coronary atherosclerosis. In 9 patients, two with a recent infarct and 7 sudden deaths, an ostial stenosis was the only stenosed site in the coronary arterial tree. Of these 9 patients, 7 were known to have sufferedfrom symptomatic heart disease during life, chest pain on effort and arrhythmias being the most common complaint.There are few documented data concerning the occurrence and significance of coronary ostial changes in patients with ischaemic heart disease. The reason for this has certainly been the difficulty which is associated with the reliable demonstration of the status of coronary ostia. The funnel-shaped coronary orifice in the aortic wall may be visualized in the clinical cine-coronary arteriogram if the semiselective injection technique of the contrast medium is applied and the radiographs are taken in suitable projections (Paulin, I964). Even then, the contrast medium itself may conceal possible pathological changes. The selective catheterization of each coronary ostium is used nowadays in most centres for clinical angiographic study of the coronary arteries (Judkins, I967; Valle, I973). The selective technique does not demonstrate changes in the ostia.At necropsy the estimation of stenosis in coronary orifices may be difficult with the naked eye. In most postmortem coronary angiographic techniques a cannula or a needle is inserted into the main coronary arteries for the injection of contrast medium The drawback of such a technique is that the aortic ostium of the coronary artery is not visualized in the radiograph. Attempts have been made in necropsy studies to assess the possible stenosis of the ostium using graduated probes (Schwartz and Mitchell, I962; Fulton, I965).A postmortem coronary angiography technique employing aortic injection of contrast medium and double contrast visualization of large epicardial coronary trunks (Rissanen, 1970) was applied in the present study for the examination of aortic coronary ostia in a series of deaths from acute myocardial infarction, a series of sudden deaths without recent infarction, and a control series of violent deaths. Material and methodsThe present study formed part of a series of pathoanatomical examinations in a community-wide study of the Ischaemic Heart Disease Register, which was carried out in Helsinki in 1970 (Romo, I973; Ri...

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