http://www.aoa.gov/eldfam/Healthy_Lifestyles/Phy_Act_Nut/Phy_Act_Nut.asp
U.S. Administration on Aging, U.S. Department of Health and Human Services
Inactivity often increases with age. Surveys show that by age 75, one-in-three men and one-in-two women are not physically active. Physical activity can help older adults prolong their independence and improve their quality of life.