If you want to know how long grandpa is going to live, check his pace of walking.
A report appearing the Journal of the American Medical Association found a strong correlation between walking speed and expected survival rates for persons over 65.
The analysis from nine studies between 1986 and 2000 showed faster walking speed among older adults was associated with increased length of survival.
The average gait speed of the 34,485 participants was 0.92m per second. But analysing results over periods from six to 21 years, the University of Pittsburgh researchers found the faster ones lived longer.
"Walking requires energy, movement control, and support and places demands on multiple organ systems, including the heart, lungs, circulatory, nervous, and musculoskeletal systems," the researchers wrote. "Slowing gait may reflect both damaged systems and a high energy cost of walking."
All studies had participants walk at their usual pace and from a standing start. The walk distance varied from 2.4m to 6m.
Remaining life increased
"Predicted years of remaining life for each sex and age increased as gait speed increased," the researchers said.
"Gait speeds of 1m per second or higher consistently demonstrated survival that was longer than expected by age and sex alone. In this older adult population the relationship of gait speed with remaining years of life was consistent across age groups."
The researchers found that gait speed was associated with differences in the probability of survival at all ages in both sexes, but was especially notable after age 75.
"The data provided herein are intended to aid clinicians, investigators, and health system planners who seek simple indicators of health and survival in older adults," said researchers headed by Pittsburgh's Stephanie Studenski.
"Gait speed has potential to be implemented in practice, using a stop watch and a four-meter course.... Gait speed may be a simple and accessible indicator of the health of the older person."
In an editorial accompanying the report, Matteo Cesari of the Universita Campus Bio-Medico, Rome, said that because no evidence definitively supports the hypothesis that gait speed improvements are associated with better health-related outcomes, gait speed should not be considered as a primary target for interventions at present.
"It represents a global marker of health status, and an optimal secondary and complementary outcome to support research findings, clinical decisions, or both aimed at modifying more pragmatic end points," he wrote.
"Future research will be needed to determine whether gait speed has the potential to change the way in which a patient is defined as geriatric."
(Sapa, January 2011)