Quote:
Originally Posted by efattah
diveoceanos,
Having done experiments with apnea diet since 1999, I can make some statements based on personal experiments as well as confirmation from many other freedivers.
Modifying diet does little or nothing to change your blood pH, but it can change the amount of buffers in your blood.
The simplest experiment that anyone can do, is to:
1. Try doing a breath-hold and measure the time of the first contraction
2. Mix 15g of baking soda (NaHCO3) into water and drink
3. Wait 45 minutes
4. Try another breath-hold and measure the time of the first contraction
The contraction will be dramatically delayed. You can then do a control experiment:
1. Try doing a breath-hold and measure the time of the first contraction
2. Drink water
3. Wait 45 minutes
4. Try another breath-hold and measure the time of the first contraction
Compare the results. It will be extremely obvious. This is not a method designed just for freediving -- sprinters and middle distance runners have been doing it for years.
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Eric,
That's all very interesting. I am sure you are aware about Hamish's experiment testing this hypothesis using NaHCO3 and NaCl in the control. Recently it has been published in the journal of Hyperbaric Medicine as well 2007 Mar-Apr;34(2):91-7. One thing I would like to have your opinion in, is the following:
The experiement carried out in non-elite breath-hold divers with Breath-hold times around 2:30 on average. They have compared the Maximium breath hold time (max-BHT) and reached statistically significant differences with NaHCO3 which found to increase the max-BHT by around 15% or 22 seconds (P=0.019), over NaCl. I assume that NaHCO3 increases the buffering capabilities of the plasma and thus we have a scavenger effect of the produced CO2, and the drop in pH is delayed, just like you described above.
In the abstract it is not mentioned that they measured the time to first contraction. But I assume that this was also increased in the NaHCO3 group.
In your opinion if the same experiement was carried out in elite breath-hold divers would the results be different? My question is about differentiating the time to first contraction with the max BHT. I am asking that, because as the body develops higher levels of adaptation the max-BHT is more dependent on oxygen levels rather than CO2. On the other hand contractions are increasing the utilisation of oxygen. Any data on the max-BHT in elite BH-divers?
Sotos Christodoulou
