Cigarette smoking, exercise and high density lipoprotein cholesterol.

Cigarette smoking is associated with depressed levels of HDL-C, whereas exercise is associated with elevated levels of HDL-C. The purpose was to determine effects of smoking and exercise on blood lipids and lipoproteins in middle-aged males. It was hypothesized that smoking may attenuate the effects of exercise to elevate HDL-C. A total of 269 males (70 smokers) met all criteria for inclusion in the study population. Age, height, weight, body fatness via hydrostatic weighing, daily caloric consumption and alcohol intake, and smoking habits and history were determined. Interviews concerning physical activity patterns were conducted and cardiovascular responses to treadmill exercise were determined. Subjects were grouped as sedentary (low activity), participants in vigorous recreational activities (moderate activity) and joggers/runners (high activity). Analysis of covariance with adjustments for factors which may affect blood lipids and lipoproteins was employed. Smokers demonstrated lower HDL-C and higher total cholesterol levels than nonsmokers. High activity subjects demonstrated significantly higher HDL-C levels than the low and moderate groups which did not differ. High activity smokers did not differ from low activity nonsmokers with respect to HDL-C. This supports the proposed hypothesis. Nonsmokers were higher in weight and body fatness than smokers even though smokers consumed 288 more calories per day on the average. This suggests that smoking may account for a significant number of calories through altered metabolism or some other means.