The folks concerned with the fitness of armed-services members are taking some long hard looks at running, at the men and women who run and at the things (mostly good) running does to the body. Not just to muscles (including the heart), but to blood cells, metabolic functions, lipoproteins, clotting mechanisms and a lot of other things.
Air Force cardiologist and physiologist Earl W. Ferguson, who heads a physiology research laboratory (dubbed "Earl's gym" by his graduate students) at the Uniformed Services University of the Health Sciences, has been probing the run-and-jog set for several years. He and his team currently are concluding an 18-month study on three sets of men--sedentary, fit (running 5 to 15 miles a week) and marathon (running more than 50 miles a week).
At the same time, they are beginning studies on women under a contract from the National Aeronautics and Space Administration (NASA) because, says Ferguson, "there is simply not enough data on women." Subjects of both studies are drawn from the general public, not just the military.
Some results of the men's study, which centered in part on the effects of exercise and physical conditioning on the body's blood-clotting system, suggest that the body's so-called fibrolytic activity increased in the groups who were moderate or marathon runners. In other words, exercise seems to stimulate the body's ability to dissolve blood clots more readily--an apparent benefit to cardiovascular health because many strokes and heart attacks are caused by blood clots that block blood flow.
The studies on women are somewhat more complicated, says Ferguson, because "women runners have some additional problems."
For example, some women athletes, especially runners, experience menstrual-cycle irregularities. Some stop menstruating altogether; others skip periods. Researchers do not know what effects oral contraceptives may have on women who exercise vigorously.
As a result, the women's study will be divided into the same three exercise groups as the men--sedentary, fit and marathon. But the marathon runners will be subdivided into women with exercise-induced menstrual-cycle problems--either delay of onset or cessation--and women with normal periods. Each of the women's groups will be divided further in half according to whether or not the subject is using oral contraceptives.
A woman who is accepted in the program comes into "Earl's gym" for one session lasting several hours, sometime between the fifth and 10th day after the onset of her period. She fills out a detailed health history form and is examined by Ferguson or one of his colleagues, mostly for cardiovascular fitness.
She is then ready for a treadmill run that will last until the closely monitored equipment shows that she is beginning to build up lactic acid: usually signaled by fast breathing and "blowing off" greater amounts of carbon dioxide. Before the actual running begins, the subject relaxes for about five minutes. About three tablespoons (50cc) of blood are drawn and skin temperatures are taken at nine different sites. The subjects are then hooked up to elaborate and sensitive equipment (including, but not limited to a 12-lead electrocardiograph). They breathe into a tube that measures oxygen uptake and carbon-dioxide exhalations so minutely that the technicians can tell when a subject is ready to stop even before the runner herself.
Within a minute after they are taken off the treadmill another blood sample is taken. The subject continues at rest, still hooked up to all the measuring devices for about an hour more. "Recovery," says Ferguson, "starts rapidly after exercise and most are completely recovered in 20 minutes." Temperatures, however, may not return to their base line for as long as an hour.
Volunteers receive no pay, but are given a thorough analysis of the physiological findings. Any abnormalities or need for follow-up medical care is discussed. The material is fed into a computerized "health-risk assessment" program at the university (which includes everything from family histories of heart disease to the wearing of auto seat belts) for an "appraised risk of death" age. (If a 40-year-old has an "appraised" age of 30, his or her risk of death is that of a person 10 years younger.)
Candidates for participation should be women between the ages of 18 and 45 who are not obese, are non-smokers, have not had a hysterectomy and, except for exercise-induced irregularities, should have regular menstrual cycles. Subjects should have no significant medical problems and may be on no medications (except oral contraceptives). For 10 days before their lab visit they should abstain even from aspirin.
Runners and non-runners interested in participating in the USUHS program may phone the exercise physiologist Sue Wigutoff, 301-295-3623.