Among older adults at risk of disability, participation in a structured moderate-intensity physical activity program, compared with a health education intervention, significantly reduced the risk of major mobility disability (defined in this trial as loss of ability to walk 400 meters, or about a quarter mile), according to a study published by JAMA. The study is being released early online to coincide with its presentation at the American College of Sports Medicine annual meeting.

Mobility - the ability to walk without assistance - is a critical characteristic for functioning independently. Reduced mobility is common in older adults and is an independent risk factor for illness, hospitalization, disability, and death. Limited evidence suggests that physical activity may help prevent mobility disability; however, there are no definitive clinical trials examining whether physical activity prevents or delays mobility disability, according to background information in the article.

Marco Pahor, M.D., of the University of Florida, Gainesville, and colleagues with the Lifestyle Interventions and Independence for Elders (LIFE) study, randomly assigned sedentary men and women (age 70 to 89 years) who were able to walk 400 meters to a structured, moderate-intensity physical activity program (n = 818) conducted in a center and at home that included aerobic, resistance, and flexibility training activities, or to a health education program (n = 817), consisting of workshops on topics relevant to older adults and upper extremity stretching exercises. The adults participated for an average of 2.6 years. Participants were enrolled at 8 centers across the country.

Major mobility disability (loss of ability to walk 400 meters) was experienced by 246 participants (30.1 percent) in the physical activity group and 290 participants (35.5 percent) in the health education group. Persistent mobility disability (two consecutive major mobility disability assessments or major mobility disability followed by death) was ex­perienced by 14.7 percent of participants in the physical activity group and 19.8 percent of participants in the health education group.

A subgroup with lower physical function at study entry, representing 45 percent of the study population, received considerable benefit from the physical activity intervention.

Serious adverse events were reported by 49.4 percent of participants in the physical activity group and 45.7 percent of participants in the health education group.

"These results suggest the potential for structured physical activity as a feasible and effective intervention to reduce the burden of disability among vulnerable older persons, in spite of functional decline in late life. To our knowledge, the LIFE study is the largest and longest duration randomized trial of physical activity in older persons," the authors write.