Running may reverse
aging in certain ways while walking does not, a noteworthy new study of
active older people finds. The findings raise interesting questions
about whether most of us need to pick up the pace of our workouts in
order to gain the greatest benefit.
Walking is excellent
exercise. No one disputes that idea. Older people who walk typically
have a lower incidence of obesity, arthritis, heart disease and
diabetes, and longer lifespans than people who are sedentary. For many
years, in fact, physicians and scientists have used how far and fast
someone can walk as a marker of health as people age.
But researchers and
older people themselves also have noted that walking ability tends to
decline with age. Older people whose primary exercise is walking often
start walking more slowly and with greater difficulty as the years pass,
fatiguing more easily.
Many of us probably
would assume that this physical slowing is inevitable. And in past
studies of aging walkers, physiologists have found that, almost
invariably, their walking economy declines over time. That is, they
begin using more energy with each step, which makes moving harder and
more tiring.
But researchers at the
University of Colorado in Boulder and Humboldt State University in
Arcata, Calif., began to wonder whether this slow decay of older
people’s physical ease really is inexorable or if it might be slowed or
reversed by other types of exercise and, in particular, by running.
Happily, Boulder has
an unusually large population of highly active older people, so the
scientists did not lack for potential research subjects. Putting the
word out at gyms and among running and walking groups, they soon
recruited 30 men and women in their mid- to late-60s or early 70s.
Fifteen of these
volunteers walked at least three times a week for 30 minutes or more.
The other 15 ran at least three times a week, again for 30 minutes or
more. The runners’ pace varied, but most moved at a gentle jogging
speed.
The scientists
gathered all of the volunteers at the University of Colorado’s
Locomotion Laboratory and had each runner and walker complete three
brief sessions of walking at three different, steadily increasing speeds
on specially equipped treadmills. The treadmills were designed to
measure how the volunteers’ feet hit the ground, in order to assess
their biomechanics.
The volunteers also
wore masks that measured their oxygen intake, data that the researchers
used to determine their basic walking economy.
As it turned out, the
runners were better, more efficient walkers than the walkers. They
required less energy to move at the same pace as the volunteers who only
walked regularly.
In fact, when the
researchers compared their older runners’ walking efficiency to that of
young people, which had been measured in earlier experiments at the same
lab, they found that 70-year-old runners had about the same walking
efficiency as your typical sedentary college student. Old runners, it
appeared, could walk with the pep of young people.
Older walkers, on the
other hand, had about the same walking economy as people of the same age
who were sedentary. In effect, walking did not prevent people from
losing their ability to walk with ease.
More surprising to the
researchers, the biomechanics of the runners and the walkers during
walking were almost identical. Runners did not walk differently than
regular walkers, in terms of how many steps they took or the length of
their strides or other measures of the mechanics of their walking.
But something was different.
The researchers
speculate that this difference resides deep within their volunteers’
muscle cells. Intense or prolonged aerobic exercise, such as running, is
known to increase the number of mitochondria within muscle cells, said
Justus Ortega, now an associate professor of kinesiology at Humboldt
University, who led the study. Mitochondria help to provide energy for
these cells. So more mitochondria allow people to move for longer
periods of time with less effort, he said.
Runners also may have
better coordination between their muscles than walkers do, Dr. Ortega
said, meaning that fewer muscles need to contract during movement,
resulting in less energy being used.
But whatever the
reason, running definitely mitigated the otherwise substantial decline
in walking economy that seems to occur with age, he said, a result that
has implications beyond the physiology lab. If moving feels easier, he
said, people tend to do more of it, improving their health and enhancing
their lives in the process.
The good news for
people who don’t currently run is that you may be able to start at any
age and still benefit, Dr. Ortega said. “Quite a few of our volunteers
hadn’t take up running until they were in their 60s,” he said.
And running itself may
not even be needed. Any physically taxing activity likely would make
you a more efficient physical machine, Dr. Ortega said. So maybe
consider speeding up for a minute or so during your next walk, until
your heart pounds and you pant a bit; ease off; then again pick up the
pace. You will shave time from your walk and potentially decades from
your body’s biological age.
