The Return to Exercise

by Russ Roberts on November 15, 2005

in Health

The Washington Post reports (rr) that exercise is good for you.

Sorry, couch potatoes — the verdict is in: People who exercise regularly really do live longer.

In
fact, people who get a good workout almost daily can add nearly four
years to their life spans, according to the first study to quantify the
impact of physical activity this way.

The researchers looked at records of more than 5,000
middle-aged and elderly Americans and found that those who had moderate
to high levels of activity lived 1.3 to 3.7 years longer than those who
got little exercise, largely because they put off developing heart
disease — the nation’s leading killer. Men and women benefited about
equally.

"This shows that physical activity really
does make a difference — not only for how long you live but for how
long you live a healthy life," said Oscar H. Franco of the Erasmus M.C.
University Medical Center in Rotterdam, who led the study, published
yesterday in the Archives of Internal Medicine. "Being more physically
active can give you more time."….

People who engaged in moderate activity — the equivalent of walking
for 30 minutes a day for five days a week — lived about 1.3 to 1.5
years longer than those who were less active. Those who took on more
intense exercise — the equivalent of running half an hour a day five
days every week — extended their lives by about 3.5 to 3.7 years, the
researchers found.

Is it true?  Let’s ignore that for the moment and look at another question—the return on the investment of working out.  Thirty minutes of walking a day, five days a week for 50 years is about one year’s worth of your waking life.  For that you gain a few extra months when you’re old.  So that suggests running is the way to go.  At least you triple your return.  Running a year (spread out over fifty years) gets you an extra two years.  Still not that exciting.  BUt maybe worth it.  I suspect exercise makes your later years more enjoyable.  Probably.  I’d still like to see how the study was done.  Were the data based on retrospective questions?  How many people in the sample ran at least 30 minutes a day, five days a week.

For me, the best case for exercise is that it feels good (sometimes during, sometimes when you stop) and taking care of your body is part of the human enterprise.

I’ve been intrigued lately by the writing of Arthur Devany who particularly disdains jogging and argues for a radically different kind of workout of 1-2 hours per week.  Check out the category in his blog, "Evolutionary Fitness" and then read what he has to say about baseball and steroids.  It’s worth reading just for the powerful cadence of his writing.  And he has something to say as well.

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{ 13 comments }

Mcwop November 15, 2005 at 10:43 pm

Fitness is not about adding extra years. It is about feeling good now. I have sustained nasty injuries working out. These injuries will probably be painful later in life, but I had so much fun doing the activities, that caused the injuries.

ziemer November 16, 2005 at 12:44 am

i saw the same article in the paper today.

in an unrelated, but equally useless, article, it was reported that researchers discovered that the more often children eat in restaurants, the more likely they are to be fat.

i wonder how much tax money was spent, and which agency approved it — the Department of the Self-Evident?

Russell Nelson November 16, 2005 at 2:41 am

External exercise is important, but so is internal work. Herbs and supplements are helpful, but the real elixer of life is already within you.
-russ

Joe November 16, 2005 at 9:10 am

In other news….
Columbus discovers America.

Randy November 16, 2005 at 10:15 am

Mcwop,

Agreed. The idea of living 3.7 years longer doesn't intrigue me much. I hike. And I do it because I like it. I don't think Americans have ever "exercised". They used to work harder – and walked more before they could drive everywhere. But they've never "exercised". Exercise is just another job.

Gravity November 16, 2005 at 12:18 pm

I'm sure you're all aware of this, but I'll state it anyway:

Because it's not a randomized study, it's not clear which way the causality runs. Does exercising make you more healthy or does being healthy make you exercise more?

Joel B. November 16, 2005 at 4:49 pm

Yeah, I think all this study has shown is that the Net Present Value of exercise is negative. No real surprise there, not to me anyway.

I do some sports and exercise, but I don't feel obligated to spend my time on a treadmill doing something I dread, when I could be doing something I enjoy.

The interesting thing of course about exercise and sports, it is seems to me, that the most "athletic" also have the most complications beat up knees and ankles especially. There have been numerous times when you're running playing football or something and I feel my ankle roll a little bit, when that happens I can't help but wonder that maybe if I damaged my ankle when I was younger doing all this great exercise, I would only be hurting myself more.

Wild Pegasus November 16, 2005 at 6:24 pm

Resistance training improves physical appearance (treadmill/jogging doesn't do much). Improving your physical appearance makes you more attractive to potential mates. Having more mates among which to choose allows you to pick one that is attractive. Attractiveness is generally a marker of health. Health allows stronger and better childre to be produced, strengthening your genetic line. For single people, exercise can generate tremendous long-term economic benefit from a selfish gene perspective.

Interestingly enough, that benefit may be smaller for men (who are generally more exercise-focussed) than for women. Men can often attract women through power and wealth, whereas women generally have to rely on straight attractiveness.

- Josh

dearieme November 16, 2005 at 11:04 pm

I cycle to work and I jump to conclusions. Good or bad?

jomama November 17, 2005 at 10:17 am

Have a friend that jogged regularly almost every day from a very early age.

At age 60+, his knees bother him so bad he can barely walk.

I prefer regular sex, fine exercise and all I need. It also burns a lot of calories leaving me fat free.

Highly recommend. Leaves one feeling good.

master of the obvious,

jomama

Jim November 17, 2005 at 11:28 pm

It is likely that people who excercise regularly eat a more healthy diet (on average) than people who do not. It is also likely that people who excercise regularly care more about their health than people who do not. So, unless studies have been done on people of equal eating habits and disposition towards the importance of being healthy, the data is inconclusive.

Death is inevitable, so trying to prolong life is a futile endeavor. It seems to me more worthwhile to spend time, energy, resources, etc. on giving what life we do have (whether long or short) significance.

If the end of excercise is to prolong life, then the return on investment idea is one way of looking at this. (Do we have to compute the net present value of the time we get later for the time we give today?) Since I don't think prolonging life is very important, I am inclined to recommend excercise only to those who derive some enjoyment (either direct or indirect) from it.

Neal Phenes November 18, 2005 at 9:18 am

If you combine running 3 miles for between 3-5 days a week and combine it with watching as much sports on TV as you can, you will add another 4.7 years to your life. However, reduce that by 3.4 years if you root for the Yankees.

John Lott November 28, 2005 at 2:06 am

Russell, what about the interest rate? How could you forget to include that in the discussion?

From the article: "People who engaged in moderate activity — the equivalent of walking for 30 minutes a day for five days a week — lived about 1.3 to 1.5 years longer than those who were less active. Those who took on more intense exercise — the equivalent of running half an hour a day five days every week — extended their lives by about 3.5 to 3.7 years, the researchers found."

Suppose one exercises at the moderate level:
per year that is 130 hours = 52 (weeks)*5 (days)*.5 hours
over 50 years that is: 6,500 hours

There are 5,840 waking hours in a year. 8,175 over 1.4 years. At any reasonable interest rate, in terms of purely longevity, there is a strong negative return to exercise.

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