Influence of leisure time physical activity and television watching on atherosclerosis risk factors in the NHLBI Family Heart Study

Physical activity favorably influences atherosclerosis risk factors but onl y a few studies in adults considered the time watching television (TV) as a measure of physical inactivity. We therefore determined in a population-ba sed sample of 1778 subjects from the NHLBI Family Heart Study (FHS) whether leisure time physical activity and TV watching have independent or interac tive associations with cardiovascular disease risk factors and carotid arte ry intima-media wall thickness (IMT). Subjects were free from diabetes mell itus and clinically-ascertained coronary artery disease and did not take li pid-lowering or antihypertensive drugs. Only 0.7 and 1.3% of the variance i n leisure time physical activity in women and men, respectively, was explai ned by the amount of TV watching. Leisure time physical activity had a clea rly favorable, and TV watching an unfavorable association with anthropometr ic measurements (BMI (body mass index), waist girth, waist-hip ratio, subsc apular and triceps skinfold thickness). The odds ratio (95% CI) of being ov erweight was 0.41 (0.28-0.62) in women and 0.69 (0.46-1.03) in men in the h ighest quartile of leisure time physical activity compared to the lowest qu artile. The odds ratio increased for increasing quartiles of TV watching to 2.12 (1.45-3.10) in women and 1.61 (1.07-2.43) in men. Watching TV only 1 h per day in women with a BMI of 30 kg/m(2) and doing about 75 min of moder ate exercise per week was associated with a BMI 1.8 kg/m(2) lower than in w omen watching TV 3 h per day and doing the same amount of exercise. Those w ith twice the amount of moderate exercise and watching TV 1 h per day had a BMI 0.45 kg/m(2) lower. Furthermore, leisure time physical activity was ne gatively associated with concentrations of triglycerides and positively wit h HDL cholesterol in both genders. TV watching was significantly positively associated with triglycerides and slightly negatively with HDL cholesterol in men. The observed associations of leisure time physical activity and TV watching with atherosclerosis risk factors were independent from each othe r. Finally, we analyzed the relation between leisure time physical activity , TV watching and the degree of IMT of the carotid arteries. Neither of the se two measures was significantly associated with IMT. In summary, TV watch ing, in addition to leisure time physical activity, shows an independent as sociation with obesity-related anthropometric measurements, HDL and triglyc erides. Decreasing the amount of TV watching might be effective as a first step in reducing atherosclerosis risk factors, especially overweight. (C) 2 000 Elsevier Science Ireland Ltd. All rights reserved.