Air Consumption: Extend Inhale versus Extend Exhale Portion of Breath Cycle

[gregor1234]

In terms of air consumption, I have always been very average and never really worried about it much but I've been reading another thread
http://www.scubaboard.com/showthread.php?t=134626
and in it there was a link posted by LavaSurfer to an interesting article about a Cozumel DM who supposedly has phenomenally low air comsumption
http://www.neptunediveandski.com/breathing.htm
I've never heard of him before but the guy is supposedly not just an instructor giving general suggestions but a really-truly gee whiz expert who consistently returns with 1300-1400 when everyone else is burned dry.

In this article the air consumption guru specifically adocates extending the INHALE portion of the breath cycle as opposed to the exhale portion. He aims at a 10:1 ratio between inhale and exhale times.

I've never done this.. whenever I need ot conserve, I've always tried extending my exhale time simple because it was less work to simply hiss out the air over a longer period of time than to attempt the more strenuous diaphragm control that would be required for extending the inhale time.

I have performed some every simplistic calculations using idealizing assumtions and simple diffusion equations and they show a very slight advantage (5-10%) in terms of CO2 transport to extending the inhale versus the exhale portion of the breathing cycle.

Except for the wisdom of the acknowledged expert in the article, I wonder whether the diffusion advantage gained by inhale extension is not more-than-offset by the extra diaphragm work required using that approach.

Anyone tried both methods and perferred one over the other?

 

[spectrum]

I tend to go slow on the inhale side. By making the exhale a bit quicker I think you can vent CO2 more effectively. The bodies detection of CO2 is the trigger for the need to breathe.

Lots has been written about breath timing but at some point it comes down to what is comfortable for you, your fitness, your gear and the dive, especially the buddy you need to keep up with!

Pausing with an open glotis (not a closed throat breath hold) is also a common oart of the formula.

Of course moment to moment buoyancy mangement trumps any set rythym though you may be able to maintain a rythym in a different lung volume range.

Skin diving where you breathing against 6-8 inches of water column will tone the diaphram. Singing loudly and with verve in the car helps too. Hold long notes and see how long you can sing on one breath. Do not pass out.

Pete

 

[Diver0001]

I don't think it's so much a matter of technique in respiration as a matter of meditation and relaxation. With technique you'll only be able to reduce your SAC to about .35 or maybe a little less. To really reduce your SAC to "gee-whiz" proportions is a meta-physical phenomenon.

Having said that, I do have one comment about your technique. If you spend proportionally a lot of time *exhaling* then the PO2 in your lungs will be constantly declining while the PCO2 in your lungs will be constantly rising. Intuitively, that's bad. if you spend proportionally more time inhaling then the PO2 and PCO2 in your lungs will remain flatter (introducing more O2 and more diluent for the CO2) , which Intuitively seems better.

something to think about.

R..

 

[Mo2vation]

Or, you can carry a 130, breathe normally and not fret about your consumption, because everyone you dive with will burn through their gas long before you even get close to the bottom of your can.



---
Ken

 

[abitton]

Or, you can carry a 130, breathe normally and not fret about your consumption, because everyone you dive with will burn through their gas long before you even get close to the bottom of your can.



---
Ken

Methinks you're onto something....