BACKGROUND:
Hypertension and atherosclerotic cardiovascular disease have been ascribed to a variety of host-environmental characteristics -- cigarette smoking, modern-day dietary practices, abnormal blood lipid and blood glucose patterns, obesity, psychosocial factors, genetics, etc. -- together with the decline in vigorous job activity because of mechanization and related developments in industry and transportation. To the extent that job assignments limit exercise opportunities, leisure-time physical activity may be of increasing importance in the control and reduction of coronary heart disease. There is need to determine what levels, frequencies, and intensities of exercise exist in modern American lifestyles--particularly the trends of exercise enthusiasm, and how these have changed during the periods of increasing and decreasing cardiovascular incidence from 1912-1967 and 1968 to date, respectively. There is need to know what physical demands on the human body are essential to maintain cardiac and vascular well-being in successive age groups, including old age, and what conversion from a sedentary to an active lifestyle can mean to the betterment or detriment of man's health. The present study began as an intramural project of the National Heart Institute in 1961 and has continued to date, becoming an extramural project in 1968. Approval was received from the NIH and the universities concerned to use the baseline data collected from college physical examinations, social and athletic records of male students examined at Harvard University between 1916-1950 and at the University of Pennsylvania between 1931-1940.
DESIGN NARRATIVE:
This longitudinal study began in 1984 and built on college data from entrance physical examinations, social and athletic records for 1916-1950, self-assessed mail questionnaire responses on six occasions from 1962-1980 and death certificates from 1916 to date. A seventh lifestyle and health questionnaire was sent to living alumni in 1988. Exercise findings gathered from this and former questionnaires were converted into a physical activity index on the basis of estimated energy output ratings expressed in kilocalorie per unit of time and kilocalorie per kilogram per unit of time. The 1988 questionnaire preserved comparability with earlier observations but allowed assessment of endurance, body weight, standard caloric values of specific physical activities, and intensity and frequency of effort. It was felt that such distinctions would aid an attempt to devise exercise prescriptions for men of differing ages and conditions of health. To obtain current and historical medical data on alumni, permission was requested of the study subjects to contact personal physicians. Results of physical examinations completed by staff in 1962-1965 were provided to personal physicians of study subjects. Similar results were provided to personal physicians of alumni undergoing treadmill and clinical testing in 1988.
The study was renewed in 1996 in order to : refine and extend observations on continuity and change in physical activity for relation to cardiovascular disease (CVD) morbidity and mortality, to functional capacity and quality of life, and to longevity; and to direct special emphasis to the type, intensity, duration, and timing of exercise that distinguish the effects of light, moderate, and vigorous activities on health. In accomplishing these aims, confounding, interaction, and trends of relations with personal characteristics and other health habits are taken into account. Resources for study include: 1) college student data of 1916-1950 collected from health, social, and athletic records; 2) contemporary alumni(ae) data collected on eight occasions, 1962-1993, by mail questionnaires pertaining to physician-diagnosed disease, physical exercise, cigarette smoking, body size and shape, diet, alcohol consumption, other life way elements, and family disease patterns; and 3) annual cause-specific mortality certification, 1916-1998. Anticipated deaths (1989-1998) from CHD will approximate 5,500; from stroke, 1,000; and from all causes, 14,500. Non-fatal CHD and stroke events will increase these already large numbers substantially. Using both prior and redefined definitions of physical activity, the investigators will direct attention to continued and altered exercise patterns, both increases and decreases in energy expenditure, between the 1960s and 70s, between the 70s and 80s, and between the 80s and 90s for relation through 1998 to incidence of non-fatal and fatal CVD, and to quality-adjusted years of life remaining. Statistical power to detect relations between exercise and CVD will be considerable for alumni, although weak for alumnae. Special efforts are made to collect data from women in the Pennsylvania cohort. The study ends in June, 2000.
