Falls are a leading cause of disability in the United States, and cause an estimated 19,000 deaths each year. Kristen J. Mertz, from the University of Pittsburgh (Pennsylvania, USA), and colleagues studied the characteristics of falls among adults to ascertain the link between cardiorespiratory fitness resulting from physical activity and walking-related falls. The team analyzed data collected on participants enrolled in the Aerobics Center Longitudinal Study from 1970 through 1989, who responded to questions on falls on a 1990 follow-up survey. They found that regular exercise reduced the risk of falls, with two hours of aerobic exercise a week exerting the greatest protective effect. While the researchers observed that women were 2.8 times more likely than men to fall while walking, women's fitness levels appeared to make little difference. However, fitness levels in men were important, as men with low fitness levels were 2.2 times more likely to fall than men with high fitness levels. Writing that: "Falls are common throughout adulthood but activities at time of falls differ by age," the team concludes that: "Low fitness levels and physical inactivity may increase risk for walking-related falls."

Kristen J. Mertz, Duck-chul Lee, Xuemei Sui, Kenneth E. Powell, Steven N. Blair. "Falls Among Adults: The Association of Cardiorespiratory Fitness and Physical Activity with Walking-Related Falls." American Journal of Preventive Medicine, Volume 39, Issue 1, July 2010, Pages 15-24