Adults over age 65 who run at least 30 minutes three times per week are less likely to experience age-related physical decline in walking efficiency than those who walk, according to a small new study by researchers at Humboldt State University and the University of Colorado in the US.

For those who jog, walking comes at a lower "metabolic cost,"-- the scientific expression for saying it's easier -- which not only makes life easier but also preserves one's ability to walk.

This is important, they say, because decline in walking ability through gait changes due to poor posture or high metabolic cost of the effort is a key predictor of morbidity in older adults.

"What we found is that older adults who regularly participate in high aerobic activities -- running in particular -- have what we call a lower metabolic cost of walking than older, sedentary adults," says Justus Ortega, a Kinesiology Professor at Humboldt State and director of HSU's Biomechanics Lab. "In fact, their metabolic cost of walking is similar to young adults in their 20s."

In the study, Dr. Ortega and his team worked with 15 joggers over the age of 65 who claimed to run at least 30 minutes per day, three times per week. They also worked with 15 seniors who claimed to walk three times per week for 30 minutes.

Researchers asked participants to walk on a treadmill at three speeds (1.6, 2.8 and 3.9 miles per hour) and measured their oxygen consumption and carbon dioxide production.

The joggers were seven to 10 percent more efficient at walking than the exercise walkers, and their metabolic cost was similar to that of 20-somethings -- due, the team speculates, to healthier mitochondria in the muscles.

"The bottom line is that running keeps you younger, at least in terms of efficiency," says Rodger Kram, a Professor of Integrative Physiology at the University of Colorado, Boulder, and a co-author of the paper.

The team plans to study the effect of other highly aerobic activities such as swimming and cycling on the aging body.

The study was published in PloS ONE.