A new study from researchers at the University of Colorado Boulder and Humboldt State University, published in the journal PLOS ONE, finds that senior citizens who run several times a week expend the same amount of energy as a typical 20-year-old when walking.
"It's been known for a long time that as people age their maximum aerobic capacity, or 'horsepower,' declines, and that is true for runners as well," says study leader Prof. Justus Ortega, from Humboldt State University in Arcata, CA.
"What's new here is we found that old runners maintain their fuel economy," he adds.
The researchers recruited 15 men and 15 women with an average age of 69 who regularly ran or walked for exercise. For this study, "regularly" meant walking or running at least three times a week for a minimum of 30 minutes per workout, for at least 6 months.
After undergoing preliminary health screenings at the University of Colorado Boulder (CU-Boulder) Clinical and Translational Research Center, the subjects were required to walk on a force-measuring treadmill.
The participants' oxygen consumption and carbon dioxide production were measured while they used the treadmill across three speeds - 1.6 mph, 2.8 mph and 3.9 mph. Additional data for the study came from Prof. Ortega's dissertation on energy expended during treadmill tests by sedentary adults of a variety of ages.
Seniors who run for exercise are better at walking than those who walk for exercise
The team found that older adults who regularly participate in highly aerobic activities such as running have "a lower metabolic cost of walking" than older, sedentary adults and seniors who regularly walk for exercise.
The researchers explain that it was surprising to find that older adults who regularly run for exercise are better walkers than older adults who regularly walk for exercise.
The take-home message of the study, the authors say, is that constantly running for exercise "slows down the aging process," allowing older people to move more easily and improving their quality of life.
Co-author Prof. Rodger Kram, of CU-Boulder's Department of Integrative Physiology, explains:
Because we found no external biomechanical differences between the older walkers and runners, we suspect the higher efficiency of senior runners is coming from their muscle cells."
Next, the team will investigate a hypothesis that the "powerhouses" inside individual cells - mitochondria - are implicated in this enhanced walking ability. People who work out regularly tend to have more mitochondria in their cells, in order to provide the energy necessary for powering larger muscles.
Back in July, Medical News Today reported on a study published in the Journal of the American College of Cardiology, which found that running at a slow speed for just 5-10 minutes a day can significantly increase life expectancy.
Leader of that study Duck-Chul Lee, from Iowa State University, said that while running is good for health, "more may not be better. You don't have to think it's a big challenge. We found that even 10 minutes per day is good enough. You don't need to do a lot to get the benefits from running."