Structured exercise programs can help keep sedentary seniors from losing their independence, new research shows.

"Compared with those who received health education [only], participants in the physical activity group had a lower risk of becoming unable to walk 400 meters," or about a quarter-mile, said lead researcher Dr. Marco Pahor of the University of Florida, Gainesville.

The study, conducted at four centers across the United States, also found it's largely safe for many older adults to start a moderate exercise program.

The study was funded by the U.S. National Institute on Aging (NIA) and included 424 people, ages 70 to 89, who exercised less than 20 minutes a week and had low scores on three physical performance assessments -- walking speed, balance and the ability to get out of chair. They also had to walk 400 meters (about a quarter of a mile) within 15 minutes without sitting or using a cane or any other kind of assistive device.

Half the participants were assigned to a control group that took part in a "successful aging" health-education program that offered information about nutrition, foot care, medications, preventive services, and other health topics. It also included arm-and-shoulder flexibility exercises led by an instructor.

The other participants were enrolled in an exercise program that included individualized counseling and supervised and home-based exercises that focused on areas such as endurance, strengthening, flexibility and balance.

After 6 months and 12 months, seniors in the exercise group had significantly higher physical performance scores than those in the control group and were more likely to maintain their walking speed through the 400-meter walking test.

The findings, published in the November issue of the Journal of Gerontology: Medical Sciences, were to be presented Friday at a meeting of the Gerontological Society of America.

The researchers said their findings from this pilot study confirm the feasibility and safety of testing this kind of exercise program in a larger study.

"As U.S. life expectancy rises, functional decline and disability among older people are growing public health and clinical concerns," Dr. Richard J. Hodes, NIA director, said in a prepared statement.

"This pilot study helps us to understand better the relationship between exercise training and mobility, which is a key to maintaining older adults' independence and quality of life, and provides a basis for designing more definitive large-scale clinical trials," Hodes said.