The reactions that take place in the body that consume oxygen and produce carbon dioxide are reactions that are well defined chemical reactions. They are not subject to being "improved" upon unless you happen to have Divine powers.

You cannot teach your body to be more "efficient". It has very nearly perfect efficiency as it is. There is almost zero food energy (calories) that go utilized and you must, as a matter of fundamental physics, consume enough oxygen to support this utilization.

You cannot "teach" your body to do some quantity of work on less energy than the work requires. What you can do is teach your body to produce the required chemical reactions fast enough to supply your muscles with the energy run at a fast pace. The oxygen consumed will be the same regardless but the rate that it is consumed at is different. That's why you breathe fast when working hard.

Holding your breath will do nothing except impair your ability to supply the oxygen fast enough and thus impair your ability to work hard. What you want to do is run long distances so your body will build the body structures that deliver and use the oxygen and sugars to produce energy to allow you to keep on running long and fast.

There really isn't any shortcut. If you want to be able to run long, you have practise and train at running long.

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gotta run...

http://This message has been edited by reboot (edited Nov-09-2007).

Thanks for the great insight. It was a theory. I was looking for additional edge I could develop while not running. I am increase my mileage weekly, but the times I was walking or watching TV, I thought I could do more to develop my lungs/heart.

But there has to be some advantage... I guess I need to take a biology class or something to get a better understanding of the cardiovascular system.

So the final verdict... is mileage?

Also, running one stretch of 20KM is better than morning/evening split of 2 x 10Kms?

Thanks guys/gals!