How Exercise Keeps Us Young
people physiologically, according to a new
study of the effects of exercise on aging.
The findings suggest that many of our
expectations about the inevitability of
physical decline with advancing years
may be incorrect and that how we age
is, to a large degree, up to us.
Aging remains a surprisingly mysterious
process. A wealth of past scientific
research has shown that many bodily
and cellular processes change in
undesirable ways as we grow older.
But science has not been able to establish
definitively whether such changes result
primarily from the passage of time —
in which case they are inevitable for
anyone with birthdays — or result at
least in part from lifestyle, meaning that they
are mutable.
This conundrum is particularly true in
terms of inactivity. Older people tend
to be quite sedentary nowadays, and
being sedentary affects health, making
it difficult to separate the effects of not
moving from those of getting older.
In the new study, which was published
this week in The Journal of Physiology,
scientists at King’s College London and
the University of Birmingham in England
decided to use a different approach.
They removed inactivity as a factor in
their study of aging by looking at the
health of older people who move quite a bit.
“We wanted to understand what happens
to the functioning of our bodies as we
get older if we take the best-case
scenario,” said Stephen Harridge,
senior author of the study and director
of the Centre of Human and Aerospace
Physiological Sciences at King’s College London.
To accomplish that goal, the scientists
recruited 85 men and 41 women aged
between 55 and 79 who bicycle regularly.
The volunteers were all serious recreational
riders but not competitive athletes.
The men had to be able to ride at least
62 miles in six and a half hours and the
women 37 miles in five and a half hours,
benchmarks typical of a high degree of
fitness in older people.
The scientists then ran each volunteer
through a large array of physical and
cognitive tests. The scientists determined
each cyclist’s endurance capacity, muscular
mass and strength, pedaling power,
metabolic health, balance, memory function,
bone density and reflexes. They also had the volunteers complete the so-called Timed Up
and Go test, during which someone stands
up from a chair without using his or her
arms, briskly walks about 10 feet, turns,
walks back and sits down again.
The researchers compared the results of
cyclists in the study against each other
and also against standard benchmarks
of supposedly normal aging. If a particular
test’s numbers were similar among the
cyclists of all ages, the researchers considered,
then that measure would seem to be more
dependent on activity than on age.
As it turned out, the cyclists did not show
their age. On almost all measures, their
physical functioning remained fairly stable
across the decades and was much closer
to that of young adults than of people their
age. As a group, even the oldest cyclists
had younger people’s levels of balance,
reflexes, metabolic health and memory
ability.
And their Timed Up and Go results were
exemplary. Many older people require
at least 7 seconds to complete the task,
with those requiring 9 or 10 seconds
considered to be on the cusp of frailty,
Dr. Harridge said. But even the oldest
cyclists in this study averaged barely
5 seconds for the walk, which is “well
within the norm reported for healthy
young adults,” the study authors write.
Some aspects of aging did, however,
prove to be ineluctable. The oldest cyclists
had less muscular power and mass than those
in their 50s and early 60s and considerably
lower overall aerobic capacities. Age does
seem to reduce our endurance and
strength to some extent, Dr. Harridge said,
even if we exercise.
But even so, both of those measures were
higher among the oldest cyclists than would
be considered average among people aged
70 or above.
All in all, the numbers suggest that aging is
simply different in the active.
“If you gave this dataset to a clinician and
asked him to predict the age” of one of the
cyclists based on his or her test results, Dr.
Harridge said, “it would be impossible.” On
paper, they all look young.
Of course, this study is based on a single
snapshot of an unusual group of older adults,
Dr. Harridge said. He and his colleagues plan
to retest their volunteers in five and 10 years,
which will provide better information about the ongoing effects of exercise on aging.
But even in advance of those results, said Dr. Harridge, himself almost 50 and an avid cyclist,
this study shows that “being physically active
makes your body function on the inside more
like a young person’s.”
No comments:
Post a Comment
Please feel free to leave any questions or comments!