Suzanne DeChillo/The New York Times

Is it better to walk a human or to walk a dog?

New research from the University of Missouri has found that people who walk dogs are more consistent about regular exercise and show more improvement in fitness than people who walk with a human companion. In a 12-week study of 54 older adults at an assisted living home, 35 people were assigned to a walking program for five days a week, while the remaining 19 served as a control group. Among the walkers, 23 selected a friend or spouse to serve as a regular walking partner along a trail laid out near the home. Another 12 participants took a bus daily to a local animal shelter where they were assigned a dog to walk.

To the surprise of the researchers, the dog walkers showed a big improvement in fitness, while the human walkers began making excuses to skip the workout. Walking speed among the dog walkers increased by 28 percent, compared with just a 4 percent increase among the human walkers.

“What happened was nothing short of remarkable,” said Rebecca A. Johnson, a nursing professor and director of the Research Center for Human Animal Interaction at the University of Missouri’s College of Veterinary Medicine. “The improvement in walking speed means their confidence in their walking ability had increased and their balance had increased. To have a 28 percent improvement in walking speed is mind boggling.”

Ms. Johnson said that because some people are afraid of dogs, the participants were given the choice of walking with a human or a dog as the companion. Ms. Johnson said the dog walkers were far more consistent in sticking with the program than those who were walking with humans.

“In the human walking group, they were regularly discouraging each other from walking,” she said. “Missouri is a hot state. We would hear them saying: ‘It’s hot today. I don’t want to walk, do you?’ ”

The response from participants in the dog-walking group — and their dog companions — was very different.

“When the people came to the animal shelter, they bounced off the bus and said, ‘Where’s my dog?”’ Ms. Johnson said. “And the dogs never gave any discouragement from walking.”

Ms. Johnson said she suspects differences will show up in other areas, like depression and anxiety, although that data are still under review and the final study has not yet been published.

But there were also other subtle indicators of improvement among the dog-walking group. Many people in the dog-walking group stopped using canes and walkers. “They would say, ‘Now I’m physically fit enough to take my dog for a walk,”’ Ms. Johnson said.