Physical inactivity is a risk factor for various chronic conditions including diabetes mellitus, heart disease, stroke and several types of cancers, according to background information in the article. Regular physical activity is often reported to improve mood, reduce stress and increase energy levels, all of which are measurements of quality of life. However, these claims are largely derived from studies composed of participants with serious illnesses and have not been confirmed in healthy populations.

Corby K. Martin, Ph.D., of the Pennington Biomedical Research Center and Louisiana State University System, Baton Rouge and colleagues studied the effect of 50 percent, 100 percent and 150 percent of current public health physical activity recommendations on quality of life in 430 sedentary postmenopausal women (average age 57.4). Participants were randomly assigned to a non-exercise control group (n=92) or one of three exercise groups: exercise energy expenditure of 4 kilocalories per kilogram (2.2 pounds) of body weight per week (4-KKW) (n=147), 8-KKW (n=96) or 12-KKW (n=95). A short health survey was used to measure physical and mental aspects of quality of life at the beginning of the study and six months later.

"Adherence to exercise was 95.4 percent, 88.1 percent and 93.7 percent for the 4-, 8- and 12-KKW groups, respectively, and each group spent 73.9, 138.3 and 183.6 minutes per week exercising," the authors write. The average weight loss in the control, 4-KKW, 8-KKW and 12-KKW groups was 0.94 kilograms (2.07 pounds), 1.34 kilograms (2.95 pounds), 1.86 kilograms (4.10 pounds) and 1.34 kilograms (2.95 pounds), respectively.

"A dose-response effect of exercise on quality of life was noted for all aspects of quality of life except bodily pain," they note. "In addition, the 4-KKW group had significantly improved general health perception, vitality and mental health compared with the control group. All three exercise groups had significantly improved social functioning compared with the control group."

"Our results indicate that improved quality of life can be added to the list of exercise benefits and that these improvements are dose dependent and independent of weight loss, at least among people similar to this study's sample," the authors conclude. "The exercise doses are easily obtainable and were well tolerated by sedentary women, resulting in confidence that the exercise doses used in this study can be achieved by women in the community."

This study was supported by grants from the National Institutes of Health. Life Fitness (Schiller Park, Illinois) provided exercise equipment.

Note: If no author is given, the source is cited instead.

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