Higher levels of both leisure-time physical activity and cardiorespiratory fitness had a strong, graded, inverse association with the risk of acute myocardial infarction, supporting the idea that lower levels of physical activity and cardiorespiratory fitness are independent risk factors for coronary heart disease.
Cardiorespiratory fitness had a strong, graded, inverse association with overall, CVD-related, and non-CVD-related mortality. Maximal oxygen uptake and exercise test duration represent the strongest predictors of mortality.
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.
Both rate and levels of rise in systolic blood pressure during a progressive exercise test were risk predictors for acute myocardial infarction. These measurements provide an incremental predictive value for an acute myocardial infarction to elevated resting systolic blood pressure, emphasizing the importance of regular blood pressure measurements during exercise testing.
The aim of this study was to estimate the physical stress and strain in diary farming, using ambulatory heart rate and oxygen consumption measurements. The rate of perceived exertion was estimated with Borg scale. The maximal oxygen consumption was measured in the laboratory. The study group consisted of eight male and 15 female farmers. The handling of feed and manure was the heaviest work task in dairy farming. The aerobic capacity (VO2 max) of female farmers (26 +/- 3 ml/min/kg) was below average, and their work required over 50% of VO2 max during most of the tasks. The VO2 max of male farmers (32 +/- 10 ml/min/kg) was moderate, and most work tasks required below 50% of VO2 max. The mean heart rate in dairy farming tasks was 99 beats min-1 in men and 116 beats min-1 in women. However, according to the rate of perceived exertion, the mean experienced the same work tasks as subjectively more heavy than did the women. The physical strain of female farmers in dairy farming seems to be too high because of heavy work tasks and relatively low VO2 max of women. Special attention should be paid to these factors in the occupational health services for farmers.
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