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Why does exercise work? (2/01/12)

February 1, 2012

Making Regeneration More Efficient

People are exhorted every day – exercise,  exercise, exercise.  Many patients I see are annoyed.  Why should I bother? they ask. How much difference can it make?

Next they’re told it will increase their lifespan; lower their blood pressure; decrease the risk of heart attack and stroke; lower the risk of cancer; help treat or prevent depression.

That’s all well and good, they reply.  But why does it really work?

There are many reasons.  Yet some of the new data deliver a potent message that can aid overall health – physical activity makes regeneration more efficient.

From Recycling to Regeneration

What happens to the byproducts of cellular life?  The “garbage” that’s left over gets recycled.

The process is known as autophagy – literally “self-eating.”  Studies of how it works help explain why the human heart is mostly regenerated within 3 days.

Your body uses its “waste” products very efficiently. Animals where autophagy is turned off die.

Recent studies point to exercise making autophagy faster and better.

Moving Mice  in Dallas

Recent work from autophagy researcher Beth Levine at Southwestern Medical School in Dallas has looked at cell recycling in mice.

Mice were put on the treadmill.  The longer they pedaled, the more autophagosomes – cell organelles that recycle cellular waste – appeared.  The autophagosomes seemed to recycle more efficiently.

Through a marvelous trick, the researchers then made mice who did not grow new  autophagosomes with exercise.

Those mice didn’t do as well.

The modified mice did not take up as much glucose when they moved.  Their physical endurance was less.

The normal mice seemed to do a better job at getting rid of old mitochondria – the energy packs of the cell.

And as the Economist reported last week, this ability may be related to delaying aging.   Animals put on very low calorie diets (hasn’t yet been proven for humans)  live longer.

How does calorie restriction work?  Increased autophagy is at least part of that story.

Recycle quickly and effectively and you regenerate well.  Animals live longer.

Is this one way exercise aids health?

There are others.

Brown Fat and White Fat

As was also reported a few weeks ago, mice who exercise change white fat to brown fat.  Brown fat metabolizes far more quickly.

The mice sporting increased brown fat had better glucose control.  Fatty diets did not make them gain weight.

In the experiments that looked at brown fat  – as in the autophagy experiments – exercise increases physiologic effectiveness.  And when it came to fat, similar results seemed to occur with people.

So exercise increases efficient autophagy.  It also increases conversion of fat to a different, faster burning type.


Unappreciated in many of the studies showing positive effects of vitamin D are the “confounding” effects of light.

Light increases vitamin D.  But it is very much drug on its own.

Light tends to make moods better.  Light, particularly sunlight, shifts biological clocks.  Light increases natural killer cell activity.

And people who are physically active get more light.

Multiple studies show light changing the effects of exercise.  For example, morning light plus exercise appears to be a very good way of helping people sleep better.  Light plus exercise also increases the “tightness” of biological clocks.

Light appears to have its useful effects on regeneration, too.

Physical Activity and Health

Exercise has been extolled for health for a long time.  It increases blood flow, which supposedly “cleanses” the body of toxins.  It changes overall fluid balance, and propels muscle, sinew and bone to higher metabolic levels.

Yet what exercise really seems to do is help increase your capacity to regenerate your body.

It improves recycling.  It changes tissue.  It builds muscle.  It decreases fat buildup in arteries.  It appears to decrease inflammation.

            It makes the body’s basic job of replacing and renewing itself more efficient.

Humans evolved to move.  We enjoy doing it.  When we do it we experience more “flow” and peak experiences.

We even look better.  It really pays to use your body the way it’s built.
Rest, sleep, Sarasota Sleep Doctor, well-being, regeneration, longevity, body clocks, insomnia, sleep disorders, the rest doctor, matthew edlund, the power of rest, the body clock, psychology today, huffington post, redbook, longboat key news

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