How to calculate ventilation times for O2 and CO2 tables

[Ms Mer]

Is there a specific formula or recommended guide for working out your ventilation times for static tables? Have no problem with the hold times (CO2 50% PB and O2 80% PB) but wonder how people go about working out the vent times, particularly for O2 tables.

 

[trux]

It is simple: when it is easy, you increase the hold times the next time, when you fail to finish the table, you decrease them.

 

[Ms Mer]

It is simple: when it is easy, you increase the hold times the next time, when you fail to finish the table, you decrease them.

That doesn't answer my question. I'm asking about the ventilation/rest period in between the holds, in particular for O2 tables where the vent time does not change in relation to the hold time.

 

[trux]

You do not change them, you only change the hold times.

 

[Ms Mer]

Yes I know that. My question is how do you go about deciding what the ventilation time will be. Just randomly choose a ventilation time? Or is there some method to it? I don't know how I can explain my question any more clearly.

Looking at the O2 table in the "how to start freediving" thread, the vent time is 2 mins. Why 2 mins? On what basis is it 2 mins? I assume there is some sort of rationale for choosing 2 mins instead of 1 min or 1.30.
1.ventilate 2:00 static 1:00
2.ventilate 2:00 static 1:15
3.ventilate 2:00 static 1:30
4.ventilate 2:00 static 1:45
5.ventilate 2:00 static 2:00
6.ventilate 2:00 static 2:15
7.ventilate 2:00 static 2:30
8.ventilate 2:00 static 2:30
total duration 30:45

 

[growingupninja]

Yes I know that. My question is how do you go about deciding what the ventilation time will be. Just randomly choose a ventilation time? Or is there some method to it? I don't know how I can explain my question any more clearly.

Looking at the O2 table in the "how to start freediving" thread, the vent time is 2 mins. Why 2 mins? On what basis is it 2 mins? I assume there is some sort of rationale for choosing 2 mins instead of 1 min or 1.30.
1.ventilate 2:00 static 1:00
2.ventilate 2:00 static 1:15
3.ventilate 2:00 static 1:30
4.ventilate 2:00 static 1:45
5.ventilate 2:00 static 2:00
6.ventilate 2:00 static 2:15
7.ventilate 2:00 static 2:30
8.ventilate 2:00 static 2:30
total duration 30:45

2 min ventilation after a static hold is enough time for your blood and tissues to be reoxygenated, and for you to vent CO2 accumulated by the hold; brings you more or less back to baseline. It's a guideline. If you reduce the rest time you would reach a point where you do not have sufficient time to vent CO2 before starting the next hold and you would be experiencing a higher CO2 level than the exercise is meant for. You actually don't need much time to reoxygenate--maybe a few breaths but CO2 takes longer to vent.

 

[trux]

Yes I know that. My question is how do you go about deciding what the ventilation time will be. Just randomly choose a ventilation time? Or is there some method to it? I don't know how I can explain my question any more clearly.

Not sure if I understand your question. You write you know you do not adjust the ventialtion time, just the hold times instead, and in the same paragraph you ask how to change it. I can only repeat - you do not change the ventilation times. Neither at an O2 table, nor at a CO2 table. You only adjust the hold times at both table to fit your level. The ventilation times are already designed for the optimal effect. As Growingupninja wrote, the 2 inute are sufficient to replenish oxygen stores and get the CO2 level to normal, and in the same time short enough to keep the DR (incl. the splenic contraction) still active. At CO2 table they are short, so that you keep increasing levels of CO2.

 

[growingupninja]

Not sure if I understand your question. You write you know you do not adjust the ventialtion time, just the hold times instead, and in the same paragraph you ask how to change it. I can only repeat - you do not change the ventilation times. Neither at an O2 table, nor at a CO2 table. You only adjust the hold times at both table to fit your level. The ventilation times are already designed for the optimal effect. As Growingupninja wrote, the 2 inute are sufficient to replenish oxygen stores and get the CO2 level to normal, and in the same time short enough to keep the DR (incl. the splenic contraction) still active. At CO2 table they are short, so that you keep increasing levels of CO2.

Trux are they considered optimized at 2 min--ie verified by experiments or something--even if a diver doesn't need it? Obviously a trained diver would adjust the hold times to be signficantly longer. I read something about too long of a rest (more than 10 mins) between repeat apnea being less useful but I actually never train a full 2 min rest, except perhaps on very difficult dynamics. I don't train much static but am always ready to go much sooner. Iguess now I am asking much the same question Let me rephrase: is there a detrimental effect to training with a shorter rest time provided the diver has reoxygenated and established a baseline CO2 level?

 

[Ms Mer]

2 min ventilation after a static hold is enough time for your blood and tissues to be reoxygenated, and for you to vent CO2 accumulated by the hold; brings you more or less back to baseline. It's a guideline. If you reduce the rest time you would reach a point where you do not have sufficient time to vent CO2 before starting the next hold and you would be experiencing a higher CO2 level than the exercise is meant for. You actually don't need much time to reoxygenate--maybe a few breaths but CO2 takes longer to vent.

Thanks for explaining growingupninja.

 

[trux]

Let me rephrase: is there a detrimental effect to training with a shorter rest time provided the diver has reoxygenated and established a baseline CO2 level?

At O2 tables the purpose is to selectively train hypoxia, while suppressing hypercapnia, hence the rest should be sufficient. By cutting it short, you risk experiencing less hypoxia and/or for shorter times. Also, instead of learning to work with hypoxic symptoms, you'll still train relying on the hypercapnic signs. Of course, exercises with short recovery have its place in the training too, but I would not then speak about a typical hypoxic table. And you for sure need good surveilance when training O2 tables in water.

 

[growingupninja]

At O2 tables the purpose is to selectively train hypoxia, while suppressing hypercapnia, hence the rest should be sufficient. By cutting it short, you risk experiencing less hypoxia and/or for shorter times. Also, instead of learning to work with hypoxic symptoms, you'll still train relying on the hypercapnic signs. Of course, exercises with short recovery have its place in the training too, but I would not then speak about a typical hypoxic table. And you for sure need good surveilance when training O2 tables in water.

Thanks, Trux. Good point. I used to do more low O2/empty lung training but in the last month I have mostly been training for CO2 tolerance and/or aggressive interval dynamic (high CO2, little or no O2 deficit, high lactic acid). I did a few dry full lung statics last night with the O2 meter and the O2 saturation point at which I FEEL the 'okay, I know I could push further but this would not be recreational' had dropped much lower. I am getting to the point where a dive watch for spearing would be wise so I don't end up laying on the bottom too deep too long. I like the idea of a low HR alarm like the Galileo has since for me, I experience degrees of DR from hypercapnia, cold water, and chest compression, but at least on dry land where I have been able to test, when my blood O2 sat drops below a certain point (generally the unfun point), HR consistently takes a dive. And since I have started measuring it, this point has remained consistent (at least with air in the lung).