Running Better Than Walking For Maintaining Energy Efficiency In Seniors

Chuck Bednar for redOrbit.com – Your Universe Online

Seniors who regularly run several times each week in order to keep fit typically walk as efficiently as someone in their 20s, researchers from the University of Colorado Boulder and Humboldt State University report in a new study.

However, older adults who walk for exercise instead of jog typically expended the same amount of energy walking as older, sedentary adults, and both of those groups expend as much as 22 percent more energy walking than 20-somethings, Humboldt State professor Justus Ortega and his colleagues wrote in Thursday’s online edition of the journal PLOS ONE.

As part of their study, the researchers recruited 30 healthy adult volunteers (15 men and 15 women) with an average age of 69. Each participant regularly ran or walked at least three times a week for a minimum of 30 minutes per workout for at least six months, and all of them were given preliminary health screenings at the CU-Boulder Clinical and Translational Research Center (CTRC).

The subjects were then asked to walk at three different speeds (1.6 mph, 2.8 mph, and 3.9 mph) on a force-measuring treadmill at a locomotion laboratory operated by Rodger Kram, an associate professor at the CU-Boulder Department of Integrative Physiology. Their oxygen consumption and carbon dioxide production was measured during the training session, and older runners were found to have a greater energy economy than older walkers.

“Older adults who regularly participate in highly aerobic activities – running in particular – have a lower metabolic cost of walking than older, sedentary adults and… seniors who regularly walk for exercise,” Ortega said in a statement. “It’s been known for a long time that as people age their maximum aerobic capacity… declines, and that is true for runners as well. What’s new here is we found that old runners maintain their fuel economy.”

“The bottom line is that running keeps you younger, at least in terms of energy efficiency,” added Kram, a co-author on the study. “Walking for exercise has many positive health effects, like fending off heart disease, diabetes, weight gain and depression – it’s just that walking efficiency does not seem to be one of them. 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.”

Specifically, he believed that mitochondria could be involved. Mitochondria, which are small bodies found inside individual cells, generate a type of chemical energy (adenosine triphosphate or ATP) that powers a person’s muscle fibers and allows them to move, lift heavy objects and, of course, run.

Those who exercise regularly generally have greater amounts of mitochondria in their cells, which given them more energy to power larger muscles, Kram said. However, he noted that additional research was required to determine exactly what impact mitochondria have on the increased energy efficiency demonstrated by seniors who run.

“It was surprising to find that older adults who regularly run for exercise are better walkers than older adults who regularly walk for exercise,” noted Owen Beck, a co-author of the study and a graduate student at CU-Boulder. “The take-home message of the study is that consistently running for exercise seems to slow down the aging process and allows older individuals to move more easily, improving their independence and quality of life.”

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