Occupational and leisure time physical activity and conventional risk factors were determined in the Belgian Physical Fitness Study, a prospective study of 2,363 healthy male factory workers who were aged 40-55 years at entry in 1976-1978 and who were followed for five years. Physical fitness, defined as the interpolated physical working capacity at heart rate 150 beats per minute, was measured in 2,109 subjects. In this subgroup, there were 31 myocardial infarctions and sudden deaths. Smoking, physical fitness, and high density lipoprotein cholesterol (HDL cholesterol) were independent risk indicators for subsequent ischemic heart disease, while both physical activity scores were not. It is concluded that in this healthy, predominantly sedentary population, the fitness level, but not the physical activity pattern, is an independent protective factor against ischemic heart disease.
Twenty-six coal miners, without associated functional chronic obstructive lung disease (COLD), assessed by normal airway resistance, were divided into three groups: (1) Group C, normal X-ray; (2) Group S1, micronodular silicosis; and (3) Group S2, complicated silicosis. All subjects were evaluated while at rest and during exercise. Significant lung volume reduction was observed in the S2 Group only. Blood gases, pulmonary pressure, and cardiac output were found to be within the normal range for all three groups when at rest. The pulmonary pressure and pulmonary vascular resistance were higher, however, for the S1 and S2 Groups when compared to the C Group. During exercise, pulmonary hypertension was observed in 50% of teh patients with complicated silicosis. When all data (N = 26) were included, the high values for pulmonary pressure and pulmonary vascular resistance correlated well with the loss in vital capacity (VC) and the decrease in forced expiratory volume in 1 sec (FEV 1.0). From the initial 26 patients, 19 were selected on the basis of their normal airway resistance and FEV 1.0/VC ratio. This selection did not alter the differences noted for the pulmonary pressure and total pulmonary vascular resistance, which previously existed between the groups, even though the correlations were not statistically significant. We conclude that silicosis without associated COLD leads to mineral hemodynamic impairment at rest and during exercise, and that airway resistance does not detect impairment of flow as effectively as FEV 1.0 reduction. The increased pulmonary vascular resistance observed, especially in complicated silicosis, may be best explained by the loss of lung parenchyma and possible impairment of small airways.
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