Exercise and aging: Can you walk away from Father Time?
and aging: Can you walk away from Father Time?
(This article was first printed in the December
2005 issue of the Harvard Men’s
Health Watch. For more information or to
order, please go to www.health.harvard.edu/mens.)
The clock ticks for all men, and with each tick
comes change. For men who manage to avoid major
medical problems, the changes are slow and gradual,
but they do add up. Here are some things that
aging can do to you — if you give up and
let Father Time take his toll.
Some of the changes of aging start as early
as the third decade of life. After age 25–30,
for example, the average man’s maximum
attainable heart rate declines by about one beat
per minute, per year, and his heart’s peak
capacity to pump blood drifts down by 5%–10%
per decade. That’s why a healthy 25-year-old
heart can pump 2½ quarts of oxygen a minute,
but a 65-year-old heart can’t get above
1½ quarts, and an 80-year-old heart can
pump only about a quart, even if it’s disease-free.
In everyday terms, this diminished aerobic capacity
can produce fatigue and breathlessness with modest
Starting in middle age, a man’s blood
vessels begin to stiffen and his blood pressure
often creeps up as well. His blood itself changes,
becoming more viscous (thicker and stickier)
and harder to pump through the body, even though
the number of oxygen-carrying red blood cells
Most Americans begin to gain weight in midlife,
putting on 3–4 pounds a year. But since
men start to lose muscle in their 40s, that extra
weight is all fat. This extra fat contributes
to a rise in LDL (“bad”) cholesterol
and a fall in HDL (“good") cholesterol.
It also helps explain why blood sugar levels
rise by about 6 points per decade, making type
2 diabetes distressingly common in senior citizens.
The loss of muscle continues, eventually reducing
a man’s musculature by up to 50%, which
contributes to weakness and disability. At the
same time, muscles and ligaments get stiff and
tight. Although men have a lower risk of osteoporosis (“thin
bones”) than women, they do lose bone calcium
as they age, increasing the risk of fractures.
One reason for the drop in muscle mass and bone
density is a drop in the male hormone testosterone,
which declines by about 1% per year after the
age of 40. Though most men continue to have normal
testosterone levels and reproductive capacity
throughout life, many experience a gradual decline
in libido and sexual vigor.
The nervous system also changes over time. Reflexes
are slower, coordination suffers, and memory
lapses often crop up at embarrassing times. The
average person gets less sleep in maturity than
in youth, even if he no longer needs to set his
alarm clock. Not surprisingly, spirits often
sag as the body slows down.
It sounds grim — and these changes happen
to healthy men. Men with medical problems start
to age earlier and slow down even more. All in
all, aging is not for sissies.
No man can stop the clock, but every man can
slow its tick. Research shows that many of the
changes attributed to aging are actually caused
in large part by disuse. It’s new information,
but it confirms the wisdom of Dr. William Buchan,
the 18th-century Scottish physician who wrote, “Of
all the causes which conspire to render the life
of a man short and miserable, none have greater
influence than the want of proper exercise.” And
about the same time, the British poet John Gay
agreed: “Exercise thy lasting youth defends.”
Exercise is not the fountain of youth, but it
is a good long drink of vitality, especially
as part of a comprehensive program. And a unique
study from Texas shows just how important exercise
The Dallas Bed Rest and Training Study
In 1966, five healthy men volunteered for a
research study at the University of Texas Southwestern
Medical School. It must have sounded like the
opportunity of a lifetime; all they had to do
was spend three weeks of their summer vacation
resting in bed. But when they got out of bed
at the end of the trial, it probably didn’t
seem so good. Testing the men before and after
exercise, the researchers found devastating changes
that included faster resting heart rates, higher
systolic blood pressures, a drop in the heart’s
maximum pumping capacity, a rise in body fat,
and a fall in muscle strength.
In just three weeks, these 20-year-olds developed
many physiologic characteristics of men twice
their age. Fortunately, the scientists didn’t
stop there. Instead, they put the men on an 8-week
exercise program. Exercise did more than reverse
the deterioration brought on by bed rest, since
some measurements were better than ever after
The Dallas study was a dramatic demonstration
of the harmful consequences of bed rest. It’s
a lesson that’s been learned yet again
in the era of space travel, and it has helped
change medical practice by encouraging an early
return to physical activity after illness or
surgery. And by revisiting the question 30 years
later, the Texas researchers have also been able
to investigate the interaction between exercise
A second look
The original subjects all agreed to be evaluated
again at the age of 50. All five remained healthy,
and none required long-term medication. Even
so, the 30-year interval had not been kind. Over
the years, the men gained an average of 50 pounds,
or 25% of their weight at age 20. Their average
body fat doubled from 14% to 28% of body weight.
In addition, their cardiac function suffered,
with a rise in resting heart rate and blood pressure
and a fall in maximum pumping capacity. In terms
of cardiac function, though, the toll of time
was not as severe as the toll of inactivity;
at 50, the men were far below their 20-year-old
best, but they were not quite as feeble as when
they emerged from three weeks of bed rest in
The researchers did not ask the 50-year-old
volunteers to lie in bed for three weeks; that
could have been hazardous. But they did ask them
to begin an exercise program, and they wisely
constructed a gradual 6-month regimen of walking,
jogging, and cycling instead of the 8-week crash
course that served the 20-year-olds so well.
Slow but steady endurance training carried the
day. At the end of the six months, the men averaged
only a modest 10-pound loss of their excess weight,
but their resting heart rates, blood pressures,
and their heart’s maximum pumping abilities
were back to their baseline level from age 20.
All in all, exercise training reversed 100% of
the 30-year age-related decline in aerobic power.
Even so, exercise did not take the men back to
their peak performance after 8 weeks of intense
training at age 20. The clock does tick, after
all, but exercise did slow the march of time.
The Dallas scientists contributed a great deal
to our understanding of exercise and aging, but
they did not seize the opportunity to evaluate
many of the changes that men experience as they
age. Fortunately, other research has filled in
the gaps. To avoid gaps as you age, construct
a balanced exercise program.
Endurance training. As
the Texas studies showed, endurance exercise
is the best way to improve cardiovascular function.
It helps keep the heart muscle supple and the
arteries flexible, lowers the resting heart rate,
and boosts the heart’s peak ability to
deliver oxygen-rich blood to the body’s
tissues. A related benefit is a fall in blood
Endurance exercise is also the best way to protect
the body’s metabolism from the effects
of age. It reduces body fat, sensitizes the body’s
tissues to insulin, and lowers blood sugar levels.
Exercise boosts the HDL (“good”)
cholesterol and lowers levels of LDL (“bad”)
cholesterol and triglycerides. And the same types
of activity will fight some of the neurological
and psychological changes of aging. Endurance
exercise boosts mood and improves sleep, countering
anxiety and depression. In addition, it improves
reflex time and helps stave off age-related memory
loss. All in all, many of the changes that physiologists
attribute to aging are actually caused by disuse.
Using your body will keep it young (see table
Effect of aging
Effect of exercise
Resting heart rate
Maximum heart rate
Slows the decrease
Maximum pumping capacity
Heart muscle stiffness
Blood vessel stiffness
Number of red blood cells
Blood viscosity (“thickness”)
Maximum oxygen uptake
Speed of emptying
Calcium content and strength
Muscle mass and strength
Sex hormone levels
Nerve conduction and reflexes
Quality of sleep
Risk of depression
The Dallas investigators prescribed walking,
jogging, and biking for endurance training. They
could have achieved the same benefits with swimming,
racquet sports, rowing, cross-country skiing,
aerobic dance, and even golf (as long as players
walk the course). A variety of exercise machines
can also do the job, but only if you use them
properly. The key is regular activity. Start
slowly if you are out of shape, then build up
gradually to 3–4 hours a week. A program
as simple as 30 minutes of brisk walking nearly
every day will produce major benefits.
Resistance exercise using light weights
or exercise machines will enhance muscle mass
and strength and preserve bone calcium. You’ll
need to learn what to do, and instructors can
help. But with simple directions and precautions,
most men can develop a safe and effective home
program for themselves.
Flexibility training will help keep
you supple as you age. Stretching exercises are
an ideal way to warm up before and cool down
after endurance exercise. Like strength training,
20 minutes of dedicated time two or three times
a week is ideal. Yoga classes are very helpful,
but most men can learn to stretch for health
on their own.
Exercises for balance will also help
retard some common effects of aging. They will
help you move gracefully, avoid injuries, and
prevent the falls that cripple so many older
Helen Hayes was right when she proclaimed, “Resting
is rusting.” But although exercise can
do much to remove the rust of aging, it can’t
do it all. Even a balanced exercise program won’t
keep reading glasses off a man’s nose or
prevent cataracts from forming in due time. Exercise
can’t keep a man’s prostate small
or his testosterone levels high, but it can reduce
his risk of erectile dysfunction.
To keep your body as young as possible for as
long as possible, keep it moving. As usual, Hippocrates
got it right about 2,400 years ago, explaining, “That
which is used develops; that which is not wastes
Exercise, illness, and longevity
A proper exercise program will help men delay
many of the changes of aging, particularly when
they combine it with other preventive measures
(see “Not by exercise alone,” below).
And the same program can help ward off many of
the chronic illnesses that too often tarnish
a man’s golden years.
Not by exercise alone
Exercise is one way to slow the aging
process, but it works best in combination
with other measures. Here are some other
tips to help you age well:
- Avoid tobacco in all its forms.
- Eat properly. Reduce your consumption
of saturated fat, trans fatty acids,
and cholesterol. The omega-3s and monounsaturated
fats in fish, nuts, olive oil, and possibly
canola oil are desirable in moderation.
Eat lots of fruits, vegetables, whole
grains, and nonfat dairy products. Favor
complex carbohydrates and high-fiber
foods, but reduce your consumption of
simple sugars. Get about 15% of your
calories from protein. Cut back on salt
and processed foods. Keep your caloric
consumption down and stay as lean as
- Consider simple supplements such as
a daily multivitamin and low-dose aspirin
(81 mg a day).
- If you choose to drink, be responsible,
and limit yourself to two drinks a day.
- Keep your mind active and stimulated.
Mental exercise is an important complement
to physical exercise.
- Build strong social networks. People
are good medicine at any age.
- Get regular medical care. Good medicine
is good medicine.
- A balanced program is best. That’s
why Cicero proclaimed, “Exercise
and temperance will preserve something
of our youthful vigor, even into old
Heart disease is the leading killer of American
men. Because exercise helps improve so many cardiac
risk factors (cholesterol, blood pressure, diabetes,
obesity, and stress), it should have a powerful
protective influence on heart attacks — and
it does. Back in 1978, the Harvard Alumni Study
found that men who exercise regularly are 39%
less likely to suffer heart attacks than their
sedentary peers. It was a groundbreaking observation,
and it’s been confirmed many times over.
Stroke is the third leading cause of death in
America. Like heart disease, many strokes are
caused by atherosclerosis, which is why heart
attacks and stroke share so many risk factors.
It’s no surprise, then, that exercise can
reduce the risk of stroke. Twenty-four years
after its report on exercise and heart disease,
the Harvard Alumni Study linked mild exercise
to a 24% risk reduction; moderate to intensive
exercise was even better, reducing risk by 46%.
Cancer is different — but exercise can
also help fight the nation’s second leading
killer. Colon cancer is the clearest example;
Harvard’s Health Professionals Follow-Up
Study found that highly active men are 47% less
likely to develop the disease than their sedentary
peers, and many other studies agree. Although
the evidence is far less conclusive, regular
exercise may even help prevent prostate cancer.
Exercise is wonderful for health — but
to get gain without pain, you must do it
wisely, using restraint and judgment every
step of the way. Here are a few tips:
- Get a medical check-up before you begin
a moderate to vigorous exercise program,
particularly if you are older than 40,
if you have medical problems, or if you
have not exercised previously. Although
treadmill stress tests were once considered
an important precaution, they are not
necessary for most people who are healthy,
even if they are senior citizens. But
even if stress tests before exercise
are not useful for healthy men, they
are mandatory for anyone with heart disease
or symptoms that suggest problems.
- Eat and drink appropriately. Don’t
eat for two hours before you exercise,
but drink plenty of water before, during,
and after exercise, particularly in warm
- Warm up before you exercise and cool
down afterward. Stroll before you walk,
and walk before you jog. Stretches and
light calisthenics are ideal warm-up
and cool-down activities.
- Dress simply, aiming for comfort, convenience,
and safety rather than style.
- Use good equipment, especially good
- Exercise regularly. Unless you are
ill or injured, try to exercise nearly
every day, but alternate harder workouts
with easier ones. Give yourself enough
time to recover from injuries and illness — and
remember that recovery may take longer
as you age.
- Explore a variety of activities to
find what suits you best. Variety will
keep your muscles fresh and will keep
you from getting stale or bored. Build
a well-rounded program. Add strength
training, stretches, and exercises for
balance to your basic endurance exercise.
Consider getting instruction or joining
a health club.
- Exercise safely. It makes little sense
to reduce your risk of heart attack or
stroke by increasing your risk of accidental
injury or death. Adjust your routine
in weather that is hot, cold, or wet.
- Listen to your body. Learn warning
signals of heart disease, including chest
pain or pressure, disproportionate shortness
of breath, fatigue, or sweating, erratic
pulse, lightheadedness, or even indigestion.
Do not ignore aches and pains that may
signify injury; early treatment can often
prevent more serious problems. Do not
exercise if you are feverish or ill.
Work yourself back into shape gradually
after a layoff, particularly after illness
Helping to prevent heart disease, cancer, stroke — exercise
is worth the effort. And there’s more.
Physical activity can help reduce your risk for
many of the chronic illnesses that produce so
much distress and disability as men age. The
list includes hypertension, diabetes, osteoporosis,
and even Alzheimer’s disease. It also includes “minor” ailments
such as painful gallbladder attacks and bothersome
symptoms of benign prostatic hyperplasia. And
if that’s not enough motivation, consider
that the Health Professionals Study linked regular
exercise to a 30% reduction in a man’s
risk of impotence.
Regular exercise helps people age more slowly
and live healthier, more vigorous lives. And
it also helps people live longer. Calculations
based on the Harvard Alumni Study suggest that
men who exercise regularly can gain about two
hours of life expectancy for each hour of exercise.
Over the course of a lifetime, that adds up to
about two extra years. Maximum benefit does require
regular exercise over the years, but it doesn’t
mean a trip to the gym every day. In fact, just
30 minutes of brisk walking every day will go
a long way toward enhancing your health.
Calculations are one thing, observations another.
Scientists have evaluated men in Hawaii, Seventh-day
Adventists in California, male and female residents
of Framingham, Massachusetts, elderly American
women, British joggers, middle-aged Englishmen,
retired Dutchmen, and residents of Copenhagen,
among others. Although the details vary, the
essential message is remarkably uniform: Regular
exercise prolongs life and reduces the burden
of disease and disability in old age. In reviewing
the data, Dr. J. Michael McGinnis of the Office
of Disease Prevention and Health Promotion (U.S.
Department of Health and Human Services) concludes
that regular physical activity appears to reduce
the overall mortality rate by more than a quarter
and to increase the life expectancy by more than
two years compared with the sedentary population’s
It’s never too late
One of the most impressive things about the
Dallas Bed Rest and Training Study was that the
men responded nearly as well to exercise training
at 50 as they did at 20. In fact, men can benefit
from exercise at any age, though senior citizens
do need to take extra care, especially if they
are just getting started. Perhaps the most dramatic
example comes from a Harvard study that demonstrated
important improvements in 87- to 90-year-old
nursing home patients who were put on a weight-lifting
program. This study evaluated muscular function,
but the Harvard Alumni Study examined mortality.
The latter study found that previously sedentary
men who began exercising after the age of 45
enjoyed a 24% lower death rate than their classmates
who remained inactive. The maximum benefits were
linked to an amount of exercise equivalent to
walking for about 45 minutes a day at about 17
minutes per mile. On average, sedentary people
gained about 1.6 years of life expectancy from
becoming active later in life.
Studies from Harvard, Norway, and England all
confirm the benefits of exercise later in life.
It’s important research, but it confirms
the wisdom of the Roman poet Cicero, who said, “No
one is so old that he does not think he could
live another year.”
Beat the clock
Aging is inevitable, but it has an undeservedly
fearsome reputation. No man can stop the clock,
but most can slow its tick and enjoy life as
they age with grace and vigor. Jonathan Swift
was right when he said, “Every man desires
to live long, but no man would be old.” Regular
exercise, along with a good diet, good medical
care, good genes, and a bit of luck, can make
Exercise and longevity — it’s Darwin
redux: The survival of the fittest.
(This article was first printed in the December
2005 issue of the Harvard Men’s
Health Watch. For more information or to
order, please go to www.health.harvard.edu/mens.)
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