She has previously been to Nordic Deep , doing a set of spleen on the freedivers there, and has confirmed the fact that the spleen contracts during repeated breath holds. This releases extra red blood cells which the freediver can utilise to store more oxygen and prelong the breath hold. Erika estimates the effect to give up to 30 sek extra in a static attempt! I think I wanna take good care of my spleen now....
I gladly participated in the test, which inclueded two dry breath holds with different warm ups where my spleen was measured continously by ultra sound. The heart rate and oxygen saturation was also measured throughout the test. The main question Erika was asking this time was when do the spleen contract? Their results will be very interesting and might give us freedivers a better idea of how to warm up for a max dive most efficiently.
As you can see on the next picture, my spleen definatly contracted during a static apnea, which means it is a good idea for me to do one or two warm up dives before a max. Then I will have more red blood cells in circulation, and will be able to dive deeper. I must say the human body is a brilliant organism, and the more I learn, the more impressed and curious I become.
That is very cool Elisabeth!
ReplyDeleteAfter seeing that photo with your toe I think you have the best dive reflex in the world - O2% 28 and heart rate of 1!!! Not bad :-)
Yes, definitely interesting and a needed study. I see Erika Schagatay continues in her research of spleen in breath-hold diving. She already published a similar study in 2004. You can find it together with about a dozen other studies about spleen in freediving at this link: http://apnea.cz/?spleen
ReplyDeletePersonally, I am afraid that the breath-hold increase of 30s thanks to the splenic contraction is rather exaggerated. In the older study Erika found that in average the splenic contraction releases 49 ml of blood. Now the hematocrit is packed with the density twice so high as in arterial blood, so let's assume it corresponds to 100 ml. At ~5 l of blood in body, it would make about 2% hematocrit increase. That's consistent with the measurement from Erika's study (2.2% Hct increase).
However, spleen is used as a depository of old hematocrit, where it is then being destroyed. So quite likely this hematocrit released from the spleen has not the same oxygen transport capacity as new one. I wonder if this fact was taken in view in Erika's study.
Even if we speculate with the uncertain 2% increase of Hct, at the max breath-hold of 5 minutes (300s), the 2% would make only 6s. In fact even less, because although the higher Hct will allow saturating the blood with more oxygen during the breath-up, it won't help too much with pulling oxygen from lungs after the start of the apnea. Well, to certain extent the gas exchange with the dropping oxygen level in lungs during the apnea will be more efficient at higher Hct, but likely the difference will be much lower than the Hct increase. Blood pH will be a more important factor, so even with more Hct it won't allow much lower hypoxemia.
Considering the above mentioned facts, I am afraid that the splenic contraction will help with just some very few seconds (2-4s ?). I believe that the 20s or 30s observed in the study of Erika Schagatay can be only attributed to the other remaining factors of the progressing diving response (bradycardia, vasoconstrictions, etc.), and unfortunately not to the splenic contraction.
I'd love though hearing from Erika or other experts on this topic. Of course, having the possibility to increase own breath-hold time by 30s thanks to the splenic contraction would be wonderful, but I am afraid it is just a dream originating probably in the studies of seals, who have indeed huge spleens containing several liters of blood highly packed with Hct.
Erika rocks! Her research is a huge help to all freedivers. I've seen her freediving and she is also a pretty decent athlete.
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