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STANFORD--Older and middle age couch potatoes can safely achieve significant fitness benefits with either moderate or more strenuous exercise, according to a year-long study of typical healthy, sedentary Americans in Sunnyvale, Calif.

Dr. Abby King, senior research scientist at Stanford University School of Medicine, said the study, published Wednesday (Sept. 18) in the Journal of the American Medical Association, was unusual, because it probed the potential benefits of exercise for persons who hadn't planned to start a program. Volunteers, she said, were recruited randomly via a telephone solicitation in the Northern California community.

"Typically, participants in exercise studies have either been habitual exercisers, medical patients or others who had sought out a health or exercise program. We wanted to see if we could achieve results from a representative sampling of the American population," she said.

The 225 active participants, aged 50 to 65, became equally fit whether they exercised at home or in a class, "which is good news for millions of middle age and older Americans who in the past were often pressured to join a class," said King. The participants also tended to do about as well whether they were placed on a high or lower intensity program, King noted.

The study showed that as a group, the 151 volunteers who exercised at home tended to stick with the 40-minute, three time weekly regimens better than the 74 volunteers who exercised in a group setting. However, King cautioned that "specific individuals who feel more comfortable exercising in a group are most likely to do better there."

Those volunteers assigned to either high intensity (exertion to 73 to 88 percent of maximum heart rate) or low intensity (60 to 73 percent of individual maximum heart rate) programs completed an average of 75 percent of their sessions in the final month of testing, while volunteers in the high intensity group setting completed an average of only 45 percent of their sessions during that same period.

Moreover, the researchers found little difference in fitness improvement between the low and high intensity exercisers, partly because the high intensity exercisers tended to exercise at the lower end of their prescribed heart range, while the low intensity exercisers exercised at the higher end of their range, suggesting a preference for middle-of- the-road, moderate levels of exercise among middle age individuals, the researchers said.

Both the home and class exercise volunteers did significantly better than the 79 persons in a control group, similar Sunnyvale residents who were tested and filled out questionnaires but did not exercise during the year of study.

The study population consisted of 197 men and 160 women (57 people dropped out), and no statistically significant differences were found between the sexes, King said.

No incidents of exercise-related cardiac ailments were reported by any of the participants, suggesting that an exercise program for healthy older adults is relatively safe, she said.

"We conclude that supervised home based exercise training at lower or higher intensity is an effective and attractive option for middle-aged individuals who prefer not to participate in group programs.

"In the current study, both types of programs resulted in a level of improvement in functional capacity that has been linked to important health outcomes in aging adults," the researchers concluded.

However, King cautioned that, "While this level of exercise is going to give people good health benefits, if they want to get additional improvement, they will have to take further steps, such as a formal diet program."

King said the participants were evaluated using standard exercise testing measures, including a treadmill test, which was used to determine how efficiently the body uses oxygen (how much huffing it takes to climb stairs, for example). The exercise program consisted mainly of walking or jogging, although both the home group and the classes occasionally used exercise bicycles or treadmills.

King noted the 19 percent of the men and 24 percent of the women who smoked achieved less benefits than other exercisers, although they too improved their fitness levels during the study. The smokers had more trouble adhering to an exercise routine, the scientists said, although "it is notable that impovements in functional capacity among smokers participating in the lower-intensity regimen were similar to those of non- smokers. This suggests that lower-intensity exercise may be particularly well-suited to smokers," the study said.

None of the smokers permanently quit their habit during the course of the study, King noted.

"This project confirms the results of other studies showing that exercise alone cannot be used as a tool to stop smoking cigarettes. However, we were encouraged to find that smokers do in fact benefit, if they exercise even while they continue to smoke. Ideally, though, individuals, should both increase their activity levels and stop smoking."

The study was sponsored by a grant from the U.S. Public Health Service.

Researchers in addition to King included Drs. William L. Haskell, the principal investigator for the study and professor of medicine; C. Barr Taylor, professor of psychiatry and behavioral sciences; Helena C. Kraemer, professor of psychiatry and behavioral science; and Robert F. DeBusk, professor of medicine (cardiology).


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