Nutrition and Aerobic Exercise - ACS Publications - American

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5 Downloaded by UNIV OF MASSACHUSETTS AMHERST on June 1, 2018 | https://pubs.acs.org Publication Date: December 3, 1986 | doi: 10.1021/bk-1986-0294.ch005

The Effect of Exercise on Lipid and Lipoprotein Metabolism P. M . Kris-Etherton Nutrition Program, The Pennsylvania State University, University Park, PA 16802

Associations Between Physical Activity and Coronary Heart Disease Since the late 1960s, the incidence of coronary heart disease (CHD) has decreased in the United States (1). The Surgeon General has attributed this decline to major changes in lifestyle made by Americans (2). Specifically, fewer people smoke, more people monitor their blood pressure and daily stress, many have adopted leaner diets that are lower in cholesterol and saturated fat, and more Americans are participating in daily exercise. According to the results of a Gallup Poll, twice as many Americans reported exercising daily in 1977 as in 1960 (3). Currently, it is estimated that 27-30 million Americans jog a minimum of 1-3 miles weekly, and approximately one-half of American adults report participating in some form of exercise daily. The association between occupational and leisure time physical activity and the incidence of CHD has been recognized since the early 1950s. The incidence of fatal ischemic heart disease (IHD) was two times greater in the professional and business classes than in unskilled workers in Great Britian (4). Bus drivers (who have a low l e v e l of occupational physical a c t i v i t y ) had a higher incidence of mortality from IHD than conductors (who had a higher l e v e l of occupational physical a c t i v i t y ) (5). Ten years l a t e r i t was reported that postal clerks had higher death rates from IHD than mail c a r r i e r s (6,7). Other studies published throughout the 1960s, however, f a i l e d to show a relationship between occupational physical a c t i v i t y and IHD (8-10). Studies published during the 1950s and 1960s that examined the relationship between occupational physical a c t i v i t y and CHD were generally not designed to assess l e i s u r e time physical a c t i v i t y . The f a i l u r e to account for a c t i v i t y during l e i s u r e time probably explains the disparate findings of these epidemiological studies. However, i n three recent studies, where occupational and l e i s u r e time physical a c t i v i t y were both assessed, exercise was associated with a lower incidence of CHD (11-13). In the Framingham study, a prospective investigation was done examining the relationship between l e v e l of physical a c t i v i t y and mortality due to cardiovascular disease (CVD) and IHD. 0097-6156/86/0294-0059$06.25/0 © 1986 American Chemical Society

Layman; Nutrition and Aerobic Exercise ACS Symposium Series; American Chemical Society: Washington, DC, 1986.

Downloaded by UNIV OF MASSACHUSETTS AMHERST on June 1, 2018 | https://pubs.acs.org Publication Date: December 3, 1986 | doi: 10.1021/bk-1986-0294.ch005

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NUTRT IO IN AND AEROBC I EXERCS IE

Approximately 2,000 men and 2,000 women completed a questionnaire designed to assess t h e i r l e v e l of physical a c t i v i t y . They were studied for fourteen years and were observed for the manifestations of CVD. Death due to CVD, IHD, and a l l other causes decreased i n men as t h e i r physical a c t i v i t y increased. After age and associated cardiovascular r i s k factors were taken into account, however, the relationship of physical a c t i v i t y to o v e r a l l mortality persisted but was diminished. Kannel and Sorlie (11) reported a similar relationship between physical a c t i v i t y and mortality due to CVD and IHD i n men when other r i s k factors were considered. In women, however, while there was a s t a t i s t i c a l l y s i g n i f i c a n t relationship between physical a c t i v i t y and mortality due to CVD, t h i s association disappeared when an adjustment was made for age and other r i s k factors. The authors concluded that exercise i s indeed a protective factor against death from coronary disease, but i t s impact i s not as strong as other r i s k factors. Cross-Sectional and Longitudinal Studies on Healthy Subjects, Persons with Hyperlipidemia and Survivors of a Myocardial Infarct Recognition of a b e n e f i c i a l effect of exercise on the incidence of CHD has led to numerous cross-sectional and longitudinal studies designed to examine the influence of physical a c t i v i t y on major coronary r i s k factors, with p a r t i c u l a r emphasis on plasma l i p i d s and lipoproteins. A number of comprehensive reviews have summarized these studies (14-18). In general, i n cross-sectional studies, high density lipoprotein (HDL) cholesterol i s elevated (14) and t o t a l plasma and very low density lipoprotein (VLDL) t r i g l y c e r i d e s are lower i n endurance trained subjects than in sedentary control subjects (14). In a study of 23 top-level male athletes, Lehtonen and V i i k a r i (19) found a s t a t i s t i c a l l y s i g n i f i c a n t relationship between the number of kilometers that the athletes ran or skied weekly and t h e i r plasma HDL cholesterol concentration (P