[chris (OP)]

I received this intriguing question from Goran this evening. What do we think about this one:

It is known that athletes who train on high altitudes, where the air is thinner, have more red-blood cells in their blood, so that they can absorb oxygen more efficiently.

I am interested if the same effect can be achieved by training on sea-level altitude and deliberately breathing more slowly or in a way that the body gets less air, for example by breathing through the nose instead of the mouth, or by holding the breath.

Thank you for your answer.
Regards, Goran

Thoughts, everyone...

[chris (OP)]

Almost certainly not. Red cell mass is increased by hypoxia (low oxygen tension in the blood) stimulating the releasing of erythropoietin (epo) from the kidney. This is a growth factor which instructs the bone marrow stem cells to make more red blood cells. At altitude, where oxygen partial pressure is lower, one is subject to chronic hypoxia, which activates the epo signal.

However, the extent of hypoxia needs to be reasonably high and prolonged to achieve a measurable effect.

You wouldn't be able to achieve this through breath-holding for a start and, more importantly, you would accumulate carbon dioxide (CO2), which would be such a powerful stimulus to breathing that you would not be able to continuing holding your breath. And what about at night? Unless you are insomniac, as soon as you fell asleep your voluntary control over respiratory rate would be lost.

There is a good reason why athletes go to the inconvenience and expense of training at altitude, because there are very few workable and effective alternatives.

[alancalverd]

A more convenient alternative is to dilute your ambient oxygen with nitrogen. Nitrogen hypoxia is a very pleasant method of euthanasia but at some intermediate level you should be able to reduce the oxygen concentration to a point that stimulates epo release. DON'T TRY THIS AT HOME: it could be an interesting experiment to run in a controlled environment, but given the choice between wearing a mask in a sweaty Bradford gym or subsidised crosssountry skiing in the Rockies, I guess most elite athletes would go for the latter.

[chris (OP)]

That's a good point, Alan. When I was at medical school they made me a physiology experiment subject and gave me a large bag of "Everest air" to breathe, which had half as much oxygen as normal; it was delivered over half an hour via a mask, so I had to breathe it. My haemoglobin saturation didn't change very much actually, so I clearly compensated quite well by increasing respiratory rate. But from a practical perspective, there's definitely no way I could have gone around wearing a mask like that all day...!